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* Re: git only one file
From: gsky @ 2009-10-02 17:24 UTC (permalink / raw)
  To: git
In-Reply-To: <25140456.post@talk.nabble.com>




synhedionn wrote:
> 
> with git add .  , a directory is expected, but I don't need all my files
> to be recorded, only one of my thousands, so how can I record just 1 file?
> 

git add /path/to/file
-- 
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^ permalink raw reply

* HTTP NTLM Authentication
From: gsky @ 2009-10-02 17:28 UTC (permalink / raw)
  To: git


Is is possible for me to pass arguments to the curl calls that git uses to
access a repository hosted over HTTP?

I am having a problem accessing the repository as it is authenticated using
NTLM, I can curl the repository using

curl --ntlm http://username:pass@machine.domain/git

How can I do the same for the git clone of the repository?  Is it possible
easily, or do I have to modify the source and recompile?

gsky
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^ permalink raw reply

* Re: git as a versioned filesystem
From: Avery Pennarun @ 2009-10-02 18:11 UTC (permalink / raw)
  To: Scott Wiersdorf, git
In-Reply-To: <20091002164929.GA12725@perlcode.org>

On Fri, Oct 2, 2009 at 12:49 PM, Scott Wiersdorf <scott@perlcode.org> wrote:
> Git seems like the perfect tool for this, but I'm still not sure how
> to adapt it to our situation. I'm building a tool that uses git to let
> the developers commit their binary changes to this master image into
> the git repository, which hopefully will allow me to offer the QA team
> some ability to cherry-pick updates or revert regressions and make a
> clean dist image from week to week.

Beware that git performs rather badly on binary files, especially huge
ones, which it tries to load entirely into RAM.  It also keeps every
revision of every file that was ever committed (and every user who
checks it out needs to download the whole thing), so your giant binary
repository is going to get very big, very fast.

I've looked into using git for this kind of situation myself.  It's
close, but not quite there (for my purposes anyway).  It basically
just needs some optimizations and some improved support for "shallow
clones."

But on to your actual question:

> But now it's a few weeks later and we're ready to do another
> dist. What I *want* to do is create a *copy* of branch B1 to give the
> release manager a reference point for him to bring things up to
> date. What is the best way to do that?
>
> If I branch off of B1, now I have the burden of doing a whole lot of
> cherry-picks and having a challenging time getting things back in sync:
>
> -----a----b--T1-------c--------d-e---f------g [master]
>               \   (a)  \         \   \
>                ----|----c'---     \   \      [B1]
>                               \    \   \
>                                -----e'--f'---[B2]
>
> Ugh. Now B2 is kind of a mess. If I rebase it on master, I'll get (d)
> and maybe (a) again, which I don't want. [side question: unless
> there's a way to rebase on master but still exclude
> commits... possible?]. B3 and B4 are going to look even worse and the
> risk of drifting so far away from the master is unappealing.

If you rebase your "release" changes onto current master, you'll get
the revert-a patch applied, so (a) will still be gone.  Rebase will
also probably be smart enough to throw away c', since it's identical
to (c).  You will indeed end up with the unwanted (d), but you can
just revert that in B2.

> Ideally I'd want each week's release to come directly from the master,
> kind of the flying-fish approach:
>
>                               ----e'--f'---  [B2]
>                             /    /   /
> -----a----b--T1-------c--------d-e---f------g [master]
>               \   (a)  \
>                ----|----c'---                [B1]
>
> The problem with this is that now B2 contains (a), so I'll have to
> revert that again--which I can do happily--but I just wonder if
> there's a better way. If it's possible to simply *copy* branch B1 to
> B2 without making B2 a branch off of B1.

"revert-a" is a patch on its own.  Git doesn't think of reverting (a)
as anything special; it's just a change that happens to reverse what
(a) does.  So if you rebase B1 onto master, it will get copied.  It
sounds rebase will produce exactly the results you're looking for
here.

Now, that said, this release process seems extremely suspicious to me.

To summarize what I'm hearing: you have a 'master' branch that people
put stuff into, but which doesn't actually work correctly.  At the
last minute before a release, you make a new branch, drop out the
stuff that doesn't work, and put it into production.

This sounds problematic.  If (a) and (d) don't work, why are they in
master at all?  Git makes branching really easy: get people to put
their not-quite-working features into a different branch, and let the
release manager merge those branches into master when they're actually
ready.

If you do that, you'll always be releasing straight out of master, and
your life will be a lot simpler.  And if you "merge --squash" from the
feature branches into master, you can throw away the interim versions
of the feature branches, which should help keep your repository from
growing so quickly with tons of binary file revisions that never even
got released.

>  ## is there way besides rebase to clean out a revert as if it never
>  ## happened? I suppose I could branch again and repeat this as
>  ## needed.

You probably want "git revert -i".

Have fun,

Avery

^ permalink raw reply

* Re: Figuring out which patches have been applied
From: Julian Phillips @ 2009-10-02 18:45 UTC (permalink / raw)
  To: Jon Smirl; +Cc: Git Mailing List
In-Reply-To: <9e4733910910020736n539f4331nfd61175b275c7d28@mail.gmail.com>

On Fri, 2 Oct 2009, Jon Smirl wrote:

> I have a stack of 100 patches against 2.6.30. A lot of these got
> merged between 2.6.30-32.  How can I tell which ones have been
> applied?
>
> It doesn't work to check if patch A has been applied to 2.6.32. Other
> patches may have been applied on top of patch A obscuring it.
>
> Once solution would be to rebase the patch stack forward one commit at
> a time. That solves the problem of later patches obscuring patch A. Is
> there a better way to do this?

Have you tried using git-cherry?  I belive that it was intended for this 
purpose?

-- 
Julian

  ---
Progress might have been all right once, but it's gone on too long.
 		-- Ogden Nash

^ permalink raw reply

* Re: Git push over git protocol for corporate environment
From: Ismael Luceno @ 2009-10-02 18:54 UTC (permalink / raw)
  To: Eugene Sajine; +Cc: git
In-Reply-To: <76c5b8580910020741p2024f6c0w70be53338924e7e8@mail.gmail.com>

[-- Attachment #1: Type: text/plain, Size: 1077 bytes --]

Eugene Sajine escribió:
> I think that this is what is missing right now in order for git to get
> rocket start and spread inside companies: secure and easy to maintain
> mainline hosting.
> 

It looks like your problem is using cygwin. It's more complicated on a
MS-Windows environment, and personally I think it's a _very bad idea_.

Git is really easy to use in fact, you just set up the repo with:

  mkdir repo.git
  cd repo.git
  git init --bare --shared=all

--shared=all makes the repo readable to anyone, and ensures push rights
to users under the same group as the user setting up the repo. You can
change the group with chmod of course.

SSH access will be needed to push, unless the users can remotely mount
the repo via NFS or any other protocol.

Pulling is possible over http too, you just need to make
hooks/post-update executable. To export via git protocol you must create
an empty file named "git-daemon-export-ok".

Besides setting a web repo browser and git-server there's nothing else
specific to git.

-- 
Ismael Luceno


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^ permalink raw reply

* [PATCH] Use the best HTTP authentication method supported by the server
From: Nicholas Miell @ 2009-10-02 19:04 UTC (permalink / raw)
  To: gsky51; +Cc: git, Nicholas Miell
In-Reply-To: <25718488.post@talk.nabble.com>

Currently, libcurl is limited to using HTTP Basic authentication if a
username and password are specified. HTTP Basic passes the username
and password to the server as plaintext, which is obviously
suboptimal. Furthermore, some servers are configured to require a more
secure authentication method (e.g. Digest or NTLM), which means that
git can't talk to them at all.

This is easily solved by telling libcurl to use any HTTP
authentication method it pleases. I leave the decision as to whether
HTTP Basic (i.e. completely insecure) should be allowed at all to
somebody else.  This can be easily changed in the future by using
CURLAUTH_ANYSAFE instead of CURLAUTH_ANY.

Signed-off-by: Nicholas Miell <nmiell@gmail.com>
---
 http.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

This passes make test; but I haven't actually tested it on a real
HTTP server.

diff --git a/http.c b/http.c
index 23b2a19..1937b45 100644
--- a/http.c
+++ b/http.c
@@ -185,6 +185,7 @@ static void init_curl_http_auth(CURL *result)
 		if (!user_pass)
 			user_pass = xstrdup(getpass("Password: "));
 		strbuf_addf(&up, "%s:%s", user_name, user_pass);
+		curl_easy_setopt(result, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
 		curl_easy_setopt(result, CURLOPT_USERPWD,
 				 strbuf_detach(&up, NULL));
 	}
-- 
1.6.2.5

^ permalink raw reply related

* Re: Figuring out which patches have been applied
From: skillzero @ 2009-10-02 19:16 UTC (permalink / raw)
  To: Jon Smirl; +Cc: Git Mailing List
In-Reply-To: <9e4733910910020736n539f4331nfd61175b275c7d28@mail.gmail.com>

On Fri, Oct 2, 2009 at 7:36 AM, Jon Smirl <jonsmirl@gmail.com> wrote:
> I have a stack of 100 patches against 2.6.30. A lot of these got
> merged between 2.6.30-32.  How can I tell which ones have been
> applied?
>
> It doesn't work to check if patch A has been applied to 2.6.32. Other
> patches may have been applied on top of patch A obscuring it.
>
> Once solution would be to rebase the patch stack forward one commit at
> a time. That solves the problem of later patches obscuring patch A. Is
> there a better way to do this?

There may be a better way, but I needed to do a similar thing with
commits that were cherry-pick'd so I wrote a simple
git-contains-equivalent script to search for equivalent patch ID's
given a commit ID. You could do something like that, but using
git-patch-id as the source instead getting it from an existing commit
like the following script does.

#!/bin/bash

set -o pipefail
searchCommitID=`git rev-parse $1`
searchPatchID=`git show $searchCommitID | git patch-id`
if [ $? -ne 0 ]; then
	exit 1
fi
searchPatchID=${searchPatchID% *}

echo "Searching for equivalents to commit $searchCommitID (patch
$searchPatchID)..."
git log --all -p | git patch-id | grep $searchPatchID |
while read patchID commitID; do
	if [ "$commitID" = "$searchCommitID" ]; then
		echo "Exact commit $commitID is on the following branches:"
	else
		echo "Equivalent commit $commitID is on the following branches:"
	fi
	git branch -a --contains $commitID
done

^ permalink raw reply

* Re: How to delete large files
From: Nils Homer @ 2009-10-02 19:20 UTC (permalink / raw)
  To: git
In-Reply-To: <4AC6031A.2070409@viscovery.net>

Thank-you for all of your insightful help. Combining all the advice, the
commands that worked are:

git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch
$files" --tag-name-filter cat -- --all

git -rf .git/refs/original

git reflog expire --expire=now

git gc --prune=now

I then cloned the repository to a different location and replaced my
centralized version with the cloned copy.

Thanks,

Nils


On 10/2/09 6:41 AM, "Johannes Sixt" <j.sixt@viscovery.net> wrote:

> Mikael Magnusson schrieb:
>> Well, you just gave "HEAD" to git filter-branch to rewrite, i think
>> you want --all to rewrite all refs you have.
> 
> ... and '--tag-filter cat' to rewrite tags as well.
> 
> -- Hannes

^ permalink raw reply

* "Not currently on any branch"
From: Tim @ 2009-10-02 20:08 UTC (permalink / raw)
  To: git

I have some code in a git repo that is "Not currently on any branch". Now,
there's the master branch and another branch 'ui-integration' that I'm using in
this project. I don't know how the project got into this headless state, but I
need to be using the 'ui-integration' branch. 

I tried looking around the blogosphere for a solution, and tried what I found
here. But it seems like only my last commit (not the previous 10 I made) shows
up in the master branch (not ui-integration ).  
http://blog.kortina.net/post/71935540/fix-git-not-currently-on-any-branch-problem

What's the most straightforward & cleanest way to merge my changes in the
headless branch to my 'ui-integration' branch? 

Thanks in advance
Tim

^ permalink raw reply

* Re: "Not currently on any branch"
From: Steven Noonan @ 2009-10-02 20:58 UTC (permalink / raw)
  To: Tim; +Cc: git
In-Reply-To: <loom.20091002T215942-663@post.gmane.org>

On Fri, Oct 2, 2009 at 1:08 PM, Tim <timothyjwashington@yahoo.ca> wrote:
> I have some code in a git repo that is "Not currently on any branch". Now,
> there's the master branch and another branch 'ui-integration' that I'm using in
> this project. I don't know how the project got into this headless state, but I
> need to be using the 'ui-integration' branch.
>
> I tried looking around the blogosphere for a solution, and tried what I found
> here. But it seems like only my last commit (not the previous 10 I made) shows
> up in the master branch (not ui-integration ).
> http://blog.kortina.net/post/71935540/fix-git-not-currently-on-any-branch-problem
>
> What's the most straightforward & cleanest way to merge my changes in the
> headless branch to my 'ui-integration' branch?
>

Try 'git checkout -b temp', which creates a branch called 'temp' with
its HEAD at where you currently are, and then merge your changes to
ui-integration via 'git checkout ui-integration; git merge temp', and
finally drop the junk branch with 'git branch -d temp'

- Steven

^ permalink raw reply

* [PATCH] MSVC: fix build warnings
From: Michael Wookey @ 2009-10-02 21:40 UTC (permalink / raw)
  To: git

When building with MSVC, the following warnings are issued:

  warning C4700: uninitialized local variable 'xxx' used

Where 'xxx' is the name of the uninitialised variable that is being used
to initialise another variable. In all instances, the variable 'xxx' is
being used to initialise itself. Remove the use of initialising a
variable with itself to suppress these warnings with MSVC.

Some of these variables require an initial value. This is to prevent gcc
from issuing a warning about a variable being used before it has been
initialised. Suppress these gcc warnings by explicitly initialising the
required variables.

Signed-off-by: Michael Wookey <michaelwookey@gmail.com>
---
This patch is but a small step in removing the build warnings that are
generated when compiling with MSVC.

 builtin-branch.c      |    2 +-
 builtin-cat-file.c    |    2 +-
 builtin-fast-export.c |    2 +-
 builtin-fetch--tool.c |    4 ++--
 builtin-rev-list.c    |    2 +-
 fast-import.c         |    4 ++--
 match-trees.c         |   12 ++++++------
 merge-recursive.c     |    2 +-
 run-command.c         |    2 +-
 transport.c           |    2 +-
 wt-status.c           |    2 +-
 11 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/builtin-branch.c b/builtin-branch.c
index 9f57992..cf6a9ca 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -93,7 +93,7 @@ static const char *branch_get_color(enum color_branch ix)

 static int delete_branches(int argc, const char **argv, int force, int kinds)
 {
-	struct commit *rev, *head_rev = head_rev;
+	struct commit *rev, *head_rev;
 	unsigned char sha1[20];
 	char *name = NULL;
 	const char *fmt, *remote;
diff --git a/builtin-cat-file.c b/builtin-cat-file.c
index 5906842..669608a 100644
--- a/builtin-cat-file.c
+++ b/builtin-cat-file.c
@@ -152,7 +152,7 @@ static int batch_one_object(const char *obj_name,
int print_contents)
 	unsigned char sha1[20];
 	enum object_type type = 0;
 	unsigned long size;
-	void *contents = contents;
+	void *contents;

 	if (!obj_name)
 	   return 1;
diff --git a/builtin-fast-export.c b/builtin-fast-export.c
index b0a4029..07e41ea 100644
--- a/builtin-fast-export.c
+++ b/builtin-fast-export.c
@@ -422,7 +422,7 @@ static void get_tags_and_duplicates(struct
object_array *pending,
 	for (i = 0; i < pending->nr; i++) {
 		struct object_array_entry *e = pending->objects + i;
 		unsigned char sha1[20];
-		struct commit *commit = commit;
+		struct commit *commit;
 		char *full_name;

 		if (dwim_ref(e->name, strlen(e->name), sha1, &full_name) != 1)
diff --git a/builtin-fetch--tool.c b/builtin-fetch--tool.c
index 3dbdf7a..8463f66 100644
--- a/builtin-fetch--tool.c
+++ b/builtin-fetch--tool.c
@@ -416,14 +416,14 @@ static int expand_refs_wildcard(const char
*ls_remote_result, int numrefs,
 static int pick_rref(int sha1_only, const char *rref, const char
*ls_remote_result)
 {
 	int err = 0;
-	int lrr_count = lrr_count, i, pass;
+	int lrr_count, i, pass;
 	const char *cp;
 	struct lrr {
 		const char *line;
 		const char *name;
 		int namelen;
 		int shown;
-	} *lrr_list = lrr_list;
+	} *lrr_list;

 	for (pass = 0; pass < 2; pass++) {
 		/* pass 0 counts and allocates, pass 1 fills... */
diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index 4ba1c12..b7b9fe3 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c
@@ -386,7 +386,7 @@ int cmd_rev_list(int argc, const char **argv,
const char *prefix)
 		mark_edges_uninteresting(revs.commits, &revs, show_edge);

 	if (bisect_list) {
-		int reaches = reaches, all = all;
+		int reaches, all;

 		revs.commits = find_bisection(revs.commits, &reaches, &all,
 					      bisect_find_all);
diff --git a/fast-import.c b/fast-import.c
index 7ef9865..6ed1602 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1858,7 +1858,7 @@ static void file_change_m(struct branch *b)
 	const char *p = command_buf.buf + 2;
 	static struct strbuf uq = STRBUF_INIT;
 	const char *endp;
-	struct object_entry *oe = oe;
+	struct object_entry *oe;
 	unsigned char sha1[20];
 	uint16_t mode, inline_data = 0;

@@ -2084,7 +2084,7 @@ static int parse_from(struct branch *b)

 static struct hash_list *parse_merge(unsigned int *count)
 {
-	struct hash_list *list = NULL, *n, *e = e;
+	struct hash_list *list = NULL, *n, *e;
 	const char *from;
 	struct branch *s;

diff --git a/match-trees.c b/match-trees.c
index 0fd6df7..99d559e 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -72,12 +72,12 @@ static int score_trees(const unsigned char *hash1,
const unsigned char *hash2)
 		die("%s is not a tree", sha1_to_hex(hash2));
 	init_tree_desc(&two, two_buf, size);
 	while (one.size | two.size) {
-		const unsigned char *elem1 = elem1;
-		const unsigned char *elem2 = elem2;
-		const char *path1 = path1;
-		const char *path2 = path2;
-		unsigned mode1 = mode1;
-		unsigned mode2 = mode2;
+		const unsigned char *elem1 = NULL;
+		const unsigned char *elem2 = NULL;
+		const char *path1 = NULL;
+		const char *path2 = NULL;
+		unsigned mode1 = 0;
+		unsigned mode2 = 0;
 		int cmp;

 		if (one.size)
diff --git a/merge-recursive.c b/merge-recursive.c
index f55b7eb..8d7de22 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1267,7 +1267,7 @@ int merge_recursive(struct merge_options *o,
 {
 	struct commit_list *iter;
 	struct commit *merged_common_ancestors;
-	struct tree *mrtree = mrtree;
+	struct tree *mrtree;
 	int clean;

 	if (show(o, 4)) {
diff --git a/run-command.c b/run-command.c
index cf2d8f7..014f723 100644
--- a/run-command.c
+++ b/run-command.c
@@ -19,7 +19,7 @@ int start_command(struct child_process *cmd)
 {
 	int need_in, need_out, need_err;
 	int fdin[2], fdout[2], fderr[2];
-	int failed_errno = failed_errno;
+	int failed_errno;

 	/*
 	 * In case of errors we must keep the promise to close FDs
diff --git a/transport.c b/transport.c
index 644a30a..c6bb992 100644
--- a/transport.c
+++ b/transport.c
@@ -102,7 +102,7 @@ static void insert_packed_refs(const char
*packed_refs, struct ref **list)
 		return;

 	for (;;) {
-		int cmp = cmp, len;
+		int cmp, len;

 		if (!fgets(buffer, sizeof(buffer), f)) {
 			fclose(f);
diff --git a/wt-status.c b/wt-status.c
index 38eb245..060ad17 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -133,7 +133,7 @@ static void wt_status_print_change_data(struct wt_status *s,
 {
 	struct wt_status_change_data *d = it->util;
 	const char *c = color(change_type, s);
-	int status = status;
+	int status = 0;
 	char *one_name;
 	char *two_name;
 	const char *one, *two;
-- 
1.6.5.rc2

^ permalink raw reply related

* Re: "Not currently on any branch"
From: Alex Riesen @ 2009-10-02 21:46 UTC (permalink / raw)
  To: Tim; +Cc: git
In-Reply-To: <loom.20091002T215942-663@post.gmane.org>

On Fri, Oct 2, 2009 at 22:08, Tim <timothyjwashington@yahoo.ca> wrote:
> What's the most straightforward & cleanest way to merge my changes in the
> headless branch to my 'ui-integration' branch?

Assuming you use a Bourne shell:

$ prev=$(git rev-parse HEAD)
$ git checkout ui-integration && git merge $prev

^ permalink raw reply

* Re: [PATCH] MSVC: fix build warnings
From: Junio C Hamano @ 2009-10-02 22:05 UTC (permalink / raw)
  To: Michael Wookey; +Cc: git
In-Reply-To: <d2e97e800910021440q46bd46c4y8a5af987620ffc5c@mail.gmail.com>

Michael Wookey <michaelwookey@gmail.com> writes:

> diff --git a/builtin-branch.c b/builtin-branch.c
> index 9f57992..cf6a9ca 100644
> --- a/builtin-branch.c
> +++ b/builtin-branch.c
> @@ -93,7 +93,7 @@ static const char *branch_get_color(enum color_branch ix)
>
>  static int delete_branches(int argc, const char **argv, int force, int kinds)
>  {
> -	struct commit *rev, *head_rev = head_rev;

I haven't tried, but the patch may break build with "gcc -Werror".

This is a common and unfortunate idiom to tell the readers of the code
that this initialization is unnecessary, gcc is not clever enough to
notice and gives warnings, and we are squelching it, knowing what we are
doing.

^ permalink raw reply

* Re: [PATCH 2/6 (v4)] basic revision cache system, no integration or features
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkovjtdk399@sirnot.private>

Second in the revision cache series, this particular patch provides:
  - minimal API: caching only commit topo data
  - minimal porcelain: add and walk cache slices
  - appropriate tests

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
removed useless test.

  Makefile                  |    2 +
  builtin-rev-cache.c       |  207 ++++++++
  builtin.h                 |    1 +
  commit.c                  |    2 +
  git.c                     |    1 +
  rev-cache.c               | 1171 +++++++++++++++++++++++++++++++++++++++++++++
  rev-cache.h               |  107 ++++
  revision.c                |    2 +-
  revision.h                |   26 +-
  t/t6017-rev-cache-list.sh |  106 ++++
  10 files changed, 1623 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 12defd4..3098cc7 100644
--- a/Makefile
+++ b/Makefile
@@ -534,6 +534,7 @@ LIB_OBJS += refs.o
  LIB_OBJS += remote.o
  LIB_OBJS += replace_object.o
  LIB_OBJS += rerere.o
+LIB_OBJS += rev-cache.o
  LIB_OBJS += revision.o
  LIB_OBJS += run-command.o
  LIB_OBJS += server-info.o
@@ -626,6 +627,7 @@ BUILTIN_OBJS += builtin-remote.o
  BUILTIN_OBJS += builtin-replace.o
  BUILTIN_OBJS += builtin-rerere.o
  BUILTIN_OBJS += builtin-reset.o
+BUILTIN_OBJS += builtin-rev-cache.o
  BUILTIN_OBJS += builtin-rev-list.o
  BUILTIN_OBJS += builtin-rev-parse.o
  BUILTIN_OBJS += builtin-revert.o
diff --git a/builtin-rev-cache.c b/builtin-rev-cache.c
new file mode 100644
index 0000000..6eb7065
--- /dev/null
+++ b/builtin-rev-cache.c
@@ -0,0 +1,207 @@
+#include "cache.h"
+#include "object.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
+#include "rev-cache.h"
+
+/* porcelain for rev-cache.c */
+static int handle_add(int argc, const char *argv[]) /* args beyond this command */
+{
+	struct rev_info revs;
+	struct rev_cache_info rci;
+	char dostdin = 0;
+	unsigned int flags = 0;
+	int i, retval;
+	unsigned char cache_sha1[20];
+	struct commit_list *starts = 0, *ends = 0;
+	struct commit *commit;
+
+	init_revisions(&revs, 0);
+	init_rev_cache_info(&rci);
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--stdin"))
+			dostdin = 1;
+		else if (!strcmp(argv[i], "--fresh") || !strcmp(argv[i], "--incremental"))
+			starts_from_slices(&revs, UNINTERESTING);
+		else if (!strcmp(argv[i], "--not"))
+			flags ^= UNINTERESTING;
+		else if (!strcmp(argv[i], "--legs"))
+			rci.legs = 1;
+		else if (!strcmp(argv[i], "--no-objects"))
+			rci.objects = 0;
+		else if (!strcmp(argv[i], "--all")) {
+			const char *args[2];
+			int argn = 0;
+
+			args[argn++] = "rev-list";
+			args[argn++] = "--all";
+			setup_revisions(argn, args, &revs, 0);
+		} else
+			handle_revision_arg(argv[i], &revs, flags, 1);
+	}
+
+	if (dostdin) {
+		char line[1000];
+
+		flags = 0;
+		while (fgets(line, sizeof(line), stdin)) {
+			int len = strlen(line);
+			while (len && (line[len - 1] == '\n' || line[len - 1] == '\r'))
+				line[--len] = 0;
+
+			if (!len)
+				break;
+
+			if (!strcmp(line, "--not"))
+				flags ^= UNINTERESTING;
+			else
+				handle_revision_arg(line, &revs, flags, 1);
+		}
+	}
+
+	retval = make_cache_slice(&rci, &revs, &starts, &ends, cache_sha1);
+	if (retval < 0)
+		return retval;
+
+	printf("%s\n", sha1_to_hex(cache_sha1));
+
+	fprintf(stderr, "endpoints:\n");
+	while ((commit = pop_commit(&starts)))
+		fprintf(stderr, "S %s\n", sha1_to_hex(commit->object.sha1));
+	while ((commit = pop_commit(&ends)))
+		fprintf(stderr, "E %s\n", sha1_to_hex(commit->object.sha1));
+
+	return 0;
+}
+
+static int handle_walk(int argc, const char *argv[])
+{
+	struct commit *commit;
+	struct rev_info revs;
+	struct commit_list *queue, *work, **qp;
+	unsigned char *sha1p, *sha1pt;
+	unsigned long date = 0;
+	unsigned int flags = 0;
+	int retval, slop = 5, i;
+
+	init_revisions(&revs, 0);
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--not"))
+			flags ^= UNINTERESTING;
+		else if (!strcmp(argv[i], "--objects"))
+			revs.tree_objects = revs.blob_objects = 1;
+		else
+			handle_revision_arg(argv[i], &revs, flags, 1);
+	}
+
+	work = 0;
+	sha1p = 0;
+	for (i = 0; i < revs.pending.nr; i++) {
+		commit = lookup_commit(revs.pending.objects[i].item->sha1);
+
+		sha1pt = get_cache_slice(commit);
+		if (!sha1pt)
+			die("%s: not in a cache slice", sha1_to_hex(commit->object.sha1));
+
+		if (!i)
+			sha1p = sha1pt;
+		else if (sha1p != sha1pt)
+			die("walking porcelain is /per/ cache slice; commits cannot be spread out amoung several");
+
+		insert_by_date(commit, &work);
+	}
+
+	if (!sha1p)
+		die("nothing to traverse!");
+
+	queue = 0;
+	qp = &queue;
+	commit = pop_commit(&work);
+	retval = traverse_cache_slice(&revs, sha1p, commit, &date, &slop, &qp, &work);
+	if (retval < 0)
+		return retval;
+
+	fprintf(stderr, "queue:\n");
+	while ((commit = pop_commit(&queue)) != 0) {
+		printf("%s\n", sha1_to_hex(commit->object.sha1));
+	}
+
+	fprintf(stderr, "work:\n");
+	while ((commit = pop_commit(&work)) != 0) {
+		printf("%s\n", sha1_to_hex(commit->object.sha1));
+	}
+
+	fprintf(stderr, "pending:\n");
+	for (i = 0; i < revs.pending.nr; i++) {
+		struct object *obj = revs.pending.objects[i].item;
+
+		/* unfortunately, despite our careful generation, object duplication *is* a possibility...
+		 * (eg. same object introduced into two different branches) */
+		if (obj->flags & SEEN)
+			continue;
+
+		printf("%s\n", sha1_to_hex(revs.pending.objects[i].item->sha1));
+		obj->flags |= SEEN;
+	}
+
+	return 0;
+}
+
+static int handle_help(void)
+{
+	char *usage = "\
+usage:\n\
+git-rev-cache COMMAND [options] [<commit-id>...]\n\
+commands:\n\
+  add    - add revisions to the cache.  reads commit ids from stdin, \n\
+           formatted as: START START ... --not END END ...\n\
+           options:\n\
+            --all                  use all branch heads as starts\n\
+            --fresh/--incremental  exclude everything already in a cache slice\n\
+            --stdin                also read commit ids from stdin (same form\n\
+                                   as cmd)\n\
+            --legs                 ensure branch is entirely self-contained\n\
+            --no-objects           don't add non-commit objects to slice\n\
+  walk   - walk a cache slice based on set of commits; formatted as add\n\
+           options:\n\
+           --objects               include non-commit objects in traversals\n\
+  fuse   - coalesce cache slices into a single cache.\n\
+           options:\n\
+            --all                  include all objects in repository\n\
+            --no-objects           don't add non-commit objects to slice\n\
+            --ignore-size[=N]      ignore slices of size >= N; defaults to ~5MB\n\
+  index  - regnerate the cache index.";
+
+	puts(usage);
+
+	return 0;
+}
+
+int cmd_rev_cache(int argc, const char *argv[], const char *prefix)
+{
+	const char *arg;
+	int r;
+
+	git_config(git_default_config, NULL);
+
+	if (argc > 1)
+		arg = argv[1];
+	else
+		arg = "";
+
+	argc -= 2;
+	argv += 2;
+	if (!strcmp(arg, "add"))
+		r = handle_add(argc, argv);
+	else if (!strcmp(arg, "walk"))
+		r = handle_walk(argc, argv);
+	else
+		return handle_help();
+
+	fprintf(stderr, "final return value: %d\n", r);
+
+	return 0;
+}
diff --git a/builtin.h b/builtin.h
index a2174dc..2f89feb 100644
--- a/builtin.h
+++ b/builtin.h
@@ -86,6 +86,7 @@ extern int cmd_remote(int argc, const char **argv, const char *prefix);
  extern int cmd_config(int argc, const char **argv, const char *prefix);
  extern int cmd_rerere(int argc, const char **argv, const char *prefix);
  extern int cmd_reset(int argc, const char **argv, const char *prefix);
+extern int cmd_rev_cache(int argc, const char **argv, const char *prefix);
  extern int cmd_rev_list(int argc, const char **argv, const char *prefix);
  extern int cmd_rev_parse(int argc, const char **argv, const char *prefix);
  extern int cmd_revert(int argc, const char **argv, const char *prefix);
diff --git a/commit.c b/commit.c
index fedbd5e..61d83c6 100644
--- a/commit.c
+++ b/commit.c
@@ -252,6 +252,8 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
  	item->tree = lookup_tree(parent);
  	bufptr += 46; /* "tree " + "hex sha1" + "\n" */
  	pptr = &item->parents;
+	while (pop_commit(pptr))
+		; /* clear anything from cache */

  	graft = lookup_commit_graft(item->object.sha1);
  	while (bufptr + 48 < tail && !memcmp(bufptr, "parent ", 7)) {
diff --git a/git.c b/git.c
index 9883009..dfaa07f 100644
--- a/git.c
+++ b/git.c
@@ -343,6 +343,7 @@ static void handle_internal_command(int argc, const char **argv)
  		{ "repo-config", cmd_config },
  		{ "rerere", cmd_rerere, RUN_SETUP },
  		{ "reset", cmd_reset, RUN_SETUP },
+		{ "rev-cache", cmd_rev_cache, RUN_SETUP },
  		{ "rev-list", cmd_rev_list, RUN_SETUP },
  		{ "rev-parse", cmd_rev_parse },
  		{ "revert", cmd_revert, RUN_SETUP | NEED_WORK_TREE },
diff --git a/rev-cache.c b/rev-cache.c
new file mode 100644
index 0000000..8951cdf
--- /dev/null
+++ b/rev-cache.c
@@ -0,0 +1,1171 @@
+#include "cache.h"
+#include "object.h"
+#include "commit.h"
+#include "tree.h"
+#include "tree-walk.h"
+#include "blob.h"
+#include "tag.h"
+#include "diff.h"
+#include "revision.h"
+#include "rev-cache.h"
+#include "run-command.h"
+
+/* list resembles pack index format */
+static uint32_t fanout[0xff + 2];
+
+static unsigned char *idx_map;
+static int idx_size;
+static struct rc_index_header idx_head;
+static unsigned char *idx_caches;
+static char no_idx;
+
+static struct strbuf *acc_buffer;
+
+#define SLOP			5
+
+/* initialization */
+
+struct rc_index_entry *from_disked_rc_index_entry(struct rc_index_entry_ondisk *src, struct rc_index_entry *dst)
+{
+	static struct rc_index_entry entry[4];
+	static int cur;
+
+	if (!dst)
+		dst = &entry[cur++ & 0x3];
+
+	dst->sha1 = src->sha1;
+	dst->is_start = !!(src->flags & 0x80);
+	dst->cache_index = src->flags & 0x7f;
+	dst->pos = ntohl(src->pos);
+
+	return dst;
+}
+
+struct rc_index_entry_ondisk *to_disked_rc_index_entry(struct rc_index_entry *src, struct rc_index_entry_ondisk *dst)
+{
+	static struct rc_index_entry_ondisk entry[4];
+	static int cur;
+
+	if (!dst)
+		dst = &entry[cur++ & 0x3];
+
+	if (dst->sha1 != src->sha1)
+		hashcpy(dst->sha1, src->sha1);
+	dst->flags = (unsigned char)src->is_start << 7 | (unsigned char)src->cache_index;
+	dst->pos = htonl(src->pos);
+
+	return dst;
+}
+
+struct rc_object_entry *from_disked_rc_object_entry(struct rc_object_entry_ondisk *src, struct rc_object_entry *dst)
+{
+	static struct rc_object_entry entry[4];
+	static int cur;
+
+	if (!dst)
+		dst = &entry[cur++ & 0x3];
+
+	dst->type = src->flags >> 5;
+	dst->is_end = !!(src->flags & 0x10);
+	dst->is_start = !!(src->flags & 0x08);
+	dst->uninteresting = !!(src->flags & 0x04);
+	dst->include = !!(src->flags & 0x02);
+	dst->flag = !!(src->flags & 0x01);
+
+	dst->sha1 = src->sha1;
+	dst->merge_nr = src->merge_nr;
+	dst->split_nr = src->split_nr;
+
+	dst->size_size = src->sizes >> 5;
+	dst->padding = src->sizes & 0x1f;
+
+	dst->date = ntohl(src->date);
+	dst->path = ntohs(src->path);
+
+	return dst;
+}
+
+struct rc_object_entry_ondisk *to_disked_rc_object_entry(struct rc_object_entry *src, struct rc_object_entry_ondisk *dst)
+{
+	static struct rc_object_entry_ondisk entry[4];
+	static int cur;
+
+	if (!dst)
+		dst = &entry[cur++ & 0x3];
+
+	dst->flags  = (unsigned char)src->type << 5;
+	dst->flags |= (unsigned char)src->is_end << 4;
+	dst->flags |= (unsigned char)src->is_start << 3;
+	dst->flags |= (unsigned char)src->uninteresting << 2;
+	dst->flags |= (unsigned char)src->include << 1;
+	dst->flags |= (unsigned char)src->flag;
+
+	if (dst->sha1 != src->sha1)
+		hashcpy(dst->sha1, src->sha1);
+	dst->merge_nr = src->merge_nr;
+	dst->split_nr = src->split_nr;
+
+	dst->sizes  = (unsigned char)src->size_size << 5;
+	dst->sizes |= (unsigned char)src->padding;
+
+	dst->date = htonl(src->date);
+	dst->path = htons(src->path);
+
+	return dst;
+}
+
+static int get_index_head(unsigned char *map, int len, struct rc_index_header *head, uint32_t *fanout, unsigned char **caches)
+{
+	struct rc_index_header whead;
+	int i, index = sizeof(struct rc_index_header);
+
+	memcpy(&whead, map, sizeof(struct rc_index_header));
+	if (memcmp(whead.signature, "REVINDEX", 8) || whead.version != SUPPORTED_REVINDEX_VERSION)
+		return -1;
+
+	memcpy(head->signature, "REVINDEX", 8);
+	head->version = whead.version;
+	head->ofs_objects = ntohl(whead.ofs_objects);
+	head->object_nr = ntohl(whead.object_nr);
+	head->cache_nr = whead.cache_nr;
+	head->max_date = ntohl(whead.max_date);
+
+	if (len < index + head->cache_nr * 20 + 0x100 * sizeof(uint32_t))
+		return -2;
+
+	*caches = xmalloc(head->cache_nr * 20);
+	memcpy(*caches, map + index, head->cache_nr * 20);
+	index += head->cache_nr * 20;
+
+	memcpy(fanout, map + index, 0x100 * sizeof(uint32_t));
+	for (i = 0; i <= 0xff; i++)
+		fanout[i] = ntohl(fanout[i]);
+	fanout[0x100] = len;
+
+	return 0;
+}
+
+/* added in init_index */
+static void cleanup_cache_slices(void)
+{
+	if (idx_map) {
+		free(idx_caches);
+		munmap(idx_map, idx_size);
+		idx_map = 0;
+	}
+
+}
+
+static int init_index(void)
+{
+	int fd;
+	struct stat fi;
+
+	fd = open(git_path("rev-cache/index"), O_RDONLY);
+	if (fd == -1 || fstat(fd, &fi))
+		goto end;
+	if (fi.st_size < sizeof(struct rc_index_header))
+		goto end;
+
+	idx_size = fi.st_size;
+	idx_map = xmmap(0, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if (idx_map == MAP_FAILED)
+		goto end;
+	if (get_index_head(idx_map, fi.st_size, &idx_head, fanout, &idx_caches))
+		goto end;
+
+	atexit(cleanup_cache_slices);
+
+	return 0;
+
+end:
+	idx_map = 0;
+	no_idx = 1;
+	return -1;
+}
+
+/* this assumes index is already loaded */
+static struct rc_index_entry_ondisk *search_index_1(unsigned char *sha1)
+{
+	int start, end, starti, endi, i, len, r;
+	struct rc_index_entry_ondisk *ie;
+
+	if (!idx_map)
+		return 0;
+
+	/* binary search */
+	start = fanout[(int)sha1[0]];
+	end = fanout[(int)sha1[0] + 1];
+	len = (end - start) / sizeof(struct rc_index_entry_ondisk);
+	if (!len || len * sizeof(struct rc_index_entry_ondisk) != end - start)
+		return 0;
+
+	starti = 0;
+	endi = len - 1;
+	for (;;) {
+		i = (endi + starti) / 2;
+		ie = (struct rc_index_entry_ondisk *)(idx_map + start + i * sizeof(struct rc_index_entry_ondisk));
+		r = hashcmp(sha1, ie->sha1);
+
+		if (r) {
+			if (starti + 1 == endi) {
+				starti++;
+				continue;
+			} else if (starti == endi)
+				break;
+
+			if (r > 0)
+				starti = i;
+			else /* r < 0 */
+				endi = i;
+		} else
+			return ie;
+	}
+
+	return 0;
+}
+
+static struct rc_index_entry *search_index(unsigned char *sha1)
+{
+	struct rc_index_entry_ondisk *ied = search_index_1(sha1);
+
+	if (ied)
+		return from_disked_rc_index_entry(ied, 0);
+
+	return 0;
+}
+
+unsigned char *get_cache_slice(struct commit *commit)
+{
+	struct rc_index_entry *ie;
+
+	if (!idx_map) {
+		if (no_idx)
+			return 0;
+		init_index();
+	}
+
+	if (commit->date > idx_head.max_date)
+		return 0;
+
+	ie = search_index(commit->object.sha1);
+	if (ie && ie->cache_index < idx_head.cache_nr)
+		return idx_caches + ie->cache_index * 20;
+
+	return 0;
+}
+
+
+/* traversal */
+
+static int setup_traversal(struct rc_slice_header *head, unsigned char *map, struct commit *commit, struct commit_list **work)
+{
+	struct rc_index_entry *iep;
+	struct rc_object_entry *oep;
+	struct commit_list *prev, *wp, **wpp;
+	int retval;
+
+	iep = search_index(commit->object.sha1), 0;
+	oep = RC_OBTAIN_OBJECT_ENTRY(map + iep->pos);
+
+	/* the .uniniteresting bit isn't strictly necessary, as we check the object during traversal as well,
+	 * but we might as well initialize it while we're at it */
+	oep->include = 1;
+	oep->uninteresting = !!(commit->object.flags & UNINTERESTING);
+	to_disked_rc_object_entry(oep, (struct rc_object_entry_ondisk *)(map + iep->pos));
+	retval = iep->pos;
+
+	/* include any others in the work array */
+	prev = 0;
+	wpp = work;
+	wp = *work;
+	while (wp) {
+		struct object *obj = &wp->item->object;
+		struct commit *co;
+
+		/* is this in our cache slice? */
+		iep = search_index(obj->sha1);
+		if (!iep || hashcmp(idx_caches + iep->cache_index * 20, head->sha1)) {
+			prev = wp;
+			wp = wp->next;
+			wpp = &wp;
+			continue;
+		}
+
+		if (iep->pos < retval)
+			retval = iep->pos;
+
+		oep = RC_OBTAIN_OBJECT_ENTRY(map + iep->pos);
+
+		/* mark this for later */
+		oep->include = 1;
+		oep->uninteresting = !!(obj->flags & UNINTERESTING);
+		to_disked_rc_object_entry(oep, (struct rc_object_entry_ondisk *)(map + iep->pos));
+
+		/* remove from work list */
+		co = pop_commit(wpp);
+		wp = *wpp;
+		if (prev)
+			prev->next = wp;
+	}
+
+	return retval;
+}
+
+#define IPATH				0x40
+#define UPATH				0x80
+
+#define GET_COUNT(x)		((x) & 0x3f)
+#define SET_COUNT(x, s)		((x) = ((x) & ~0x3f) | ((s) & 0x3f))
+
+static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *map,
+	struct rev_info *revs, struct commit *commit,
+	unsigned long *date_so_far, int *slop_so_far,
+	struct commit_list ***queue, struct commit_list **work)
+{
+	struct commit_list *insert_cache = 0;
+	struct commit **last_objects, *co;
+	int i, total_path_nr = head->path_nr, retval = -1;
+	char consume_children = 0;
+	unsigned char *paths;
+
+	i = setup_traversal(head, map, commit, work);
+	if (i < 0)
+		return -1;
+
+	paths = xcalloc(total_path_nr, sizeof(uint16_t));
+	last_objects = xcalloc(total_path_nr, sizeof(struct commit *));
+
+	/* i already set */
+	while (i < head->size) {
+		struct rc_object_entry *entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
+		int path = entry->path;
+		struct object *obj;
+		int index = i;
+
+		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);
+
+		/* add extra objects if necessary */
+		if (entry->type != OBJ_COMMIT)
+			continue;
+		else
+			consume_children = 0;
+
+		if (path >= total_path_nr)
+			goto end;
+
+		/* in one of our branches?
+		 * uninteresting trumps interesting */
+		if (entry->include)
+			paths[path] |= entry->uninteresting ? UPATH : IPATH;
+		else if (!paths[path])
+			continue;
+
+		/* date stuff */
+		if (revs->max_age != -1 && entry->date < revs->max_age)
+			paths[path] |= UPATH;
+
+		/* lookup object */
+		co = lookup_commit(entry->sha1);
+		obj = &co->object;
+
+		if (obj->flags & UNINTERESTING)
+			paths[path] |= UPATH;
+
+		if ((paths[path] & IPATH) && (paths[path] & UPATH)) {
+			paths[path] = UPATH;
+
+			/* mark edge */
+			if (last_objects[path]) {
+				parse_commit(last_objects[path]);
+
+				last_objects[path]->object.flags &= ~FACE_VALUE;
+				last_objects[path] = 0;
+			}
+		}
+
+		/* now we gotta re-assess the whole interesting thing... */
+		entry->uninteresting = !!(paths[path] & UPATH);
+
+		/* first close paths */
+		if (entry->split_nr) {
+			int j, off = index + sizeof(struct rc_object_entry_ondisk) + RC_PATH_SIZE(entry->merge_nr);
+
+			for (j = 0; j < entry->split_nr; j++) {
+				unsigned short p = ntohs(*(uint16_t *)(map + off + RC_PATH_SIZE(j)));
+
+				if (p >= total_path_nr)
+					goto end;
+
+				/* boundary commit? */
+				if ((paths[p] & IPATH) && entry->uninteresting) {
+					if (last_objects[p]) {
+						parse_commit(last_objects[p]);
+
+						last_objects[p]->object.flags &= ~FACE_VALUE;
+						last_objects[p] = 0;
+					}
+				} else if (last_objects[p] && !last_objects[p]->object.parsed)
+					commit_list_insert(co, &last_objects[p]->parents);
+
+				/* can't close a merge path until all are parents have been encountered */
+				if (GET_COUNT(paths[p])) {
+					SET_COUNT(paths[p], GET_COUNT(paths[p]) - 1);
+
+					if (GET_COUNT(paths[p]))
+						continue;
+				}
+
+				paths[p] = 0;
+				last_objects[p] = 0;
+			}
+		}
+
+		/* make topo relations */
+		if (last_objects[path] && !last_objects[path]->object.parsed)
+			commit_list_insert(co, &last_objects[path]->parents);
+
+		/* initialize commit */
+		if (!entry->is_end) {
+			co->date = entry->date;
+			obj->flags |= ADDED | FACE_VALUE;
+		} else
+			parse_commit(co);
+
+		obj->flags |= SEEN;
+
+		if (entry->uninteresting)
+			obj->flags |= UNINTERESTING;
+
+		/* we need to know what the edges are */
+		last_objects[path] = co;
+
+		/* add to list */
+		if (!(obj->flags & UNINTERESTING) || revs->show_all) {
+			if (entry->is_end)
+				insert_by_date_cached(co, work, insert_cache, &insert_cache);
+			else
+				*queue = &commit_list_insert(co, *queue)->next;
+
+			/* add children to list as well */
+			if (obj->flags & UNINTERESTING)
+				consume_children = 0;
+			else
+				consume_children = 1;
+		}
+
+		/* open parents */
+		if (entry->merge_nr) {
+			int j, off = index + sizeof(struct rc_object_entry_ondisk);
+			char flag = entry->uninteresting ? UPATH : IPATH;
+
+			for (j = 0; j < entry->merge_nr; j++) {
+				unsigned short p = ntohs(*(uint16_t *)(map + off + RC_PATH_SIZE(j)));
+
+				if (p >= total_path_nr)
+					goto end;
+
+				if (paths[p] & flag)
+					continue;
+
+				paths[p] |= flag;
+			}
+
+			/* make sure we don't use this path before all our parents have had their say */
+			SET_COUNT(paths[path], entry->merge_nr);
+		}
+
+	}
+
+	retval = 0;
+
+end:
+	free(paths);
+	free(last_objects);
+
+	return retval;
+}
+
+static int get_cache_slice_header(unsigned char *cache_sha1, unsigned char *map, int len, struct rc_slice_header *head)
+{
+	int t;
+
+	memcpy(head, map, sizeof(struct rc_slice_header));
+	head->ofs_objects = ntohl(head->ofs_objects);
+	head->object_nr = ntohl(head->object_nr);
+	head->size = ntohl(head->size);
+	head->path_nr = ntohs(head->path_nr);
+
+	if (memcmp(head->signature, "REVCACHE", 8))
+		return -1;
+	if (head->version != SUPPORTED_REVCACHE_VERSION)
+		return -2;
+	if (hashcmp(head->sha1, cache_sha1))
+		return -3;
+	t = sizeof(struct rc_slice_header);
+	if (t != head->ofs_objects || t >= len)
+		return -4;
+
+	head->size = len;
+
+	return 0;
+}
+
+int traverse_cache_slice(struct rev_info *revs,
+	unsigned char *cache_sha1, struct commit *commit,
+	unsigned long *date_so_far, int *slop_so_far,
+	struct commit_list ***queue, struct commit_list **work)
+{
+	int fd = -1, retval = -3;
+	struct stat fi;
+	struct rc_slice_header head;
+	struct rev_cache_info *rci;
+	unsigned char *map = MAP_FAILED;
+
+	/* the index should've been loaded already to find cache_sha1, but it's good
+	 * to be absolutely sure... */
+	if (!idx_map)
+		init_index();
+	if (!idx_map)
+		return -1;
+
+	/* load options */
+	rci = &revs->rev_cache_info;
+
+	memset(&head, 0, sizeof(struct rc_slice_header));
+
+	fd = open(git_path("rev-cache/%s", sha1_to_hex(cache_sha1)), O_RDONLY);
+	if (fd == -1)
+		goto end;
+	if (fstat(fd, &fi) || fi.st_size < sizeof(struct rc_slice_header))
+		goto end;
+
+	map = xmmap(0, fi.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (map == MAP_FAILED)
+		goto end;
+	if (get_cache_slice_header(cache_sha1, map, fi.st_size, &head))
+		goto end;
+
+	retval = traverse_cache_slice_1(&head, map, revs, commit, date_so_far, slop_so_far, queue, work);
+
+end:
+	if (map != MAP_FAILED)
+		munmap(map, fi.st_size);
+	if (fd != -1)
+		close(fd);
+
+	return retval;
+}
+
+
+
+/* generation */
+
+struct path_track {
+	struct commit *commit;
+	int path; /* for keeping track of children */
+
+	struct path_track *next, *prev;
+};
+
+static unsigned char *paths;
+static int path_nr = 1, path_sz;
+
+static struct path_track *path_track;
+static struct path_track *path_track_alloc;
+
+#define PATH_IN_USE			0x80 /* biggest bit we can get as a char */
+
+static int get_new_path(void)
+{
+	int i;
+
+	for (i = 1; i < path_nr; i++)
+		if (!paths[i])
+			break;
+
+	if (i == path_nr) {
+		if (path_nr >= path_sz) {
+			path_sz += 50;
+			paths = xrealloc(paths, path_sz);
+			memset(paths + path_sz - 50, 0, 50);
+		}
+		path_nr++;
+	}
+
+	paths[i] = PATH_IN_USE;
+	return i;
+}
+
+static void remove_path_track(struct path_track **ppt, char total_free)
+{
+	struct path_track *t = *ppt;
+
+	if (t->next)
+		t->next->prev = t->prev;
+	if (t->prev)
+		t->prev->next = t->next;
+
+	t = t->next;
+
+	if (total_free)
+		free(*ppt);
+	else {
+		(*ppt)->next = path_track_alloc;
+		path_track_alloc = *ppt;
+	}
+
+	*ppt = t;
+}
+
+static struct path_track *make_path_track(struct path_track **head, struct commit *commit)
+{
+	struct path_track *pt;
+
+	if (path_track_alloc) {
+		pt = path_track_alloc;
+		path_track_alloc = pt->next;
+	} else
+		pt = xmalloc(sizeof(struct path_track));
+
+	memset(pt, 0, sizeof(struct path_track));
+	pt->commit = commit;
+
+	pt->next = *head;
+	if (*head)
+		(*head)->prev = pt;
+	*head = pt;
+
+	return pt;
+}
+
+static void add_path_to_track(struct commit *commit, int path)
+{
+	make_path_track(&path_track, commit);
+	path_track->path = path;
+}
+
+static void handle_paths(struct commit *commit, struct rc_object_entry *object, struct strbuf *merge_str, struct strbuf *split_str)
+{
+	int child_nr, parent_nr, open_parent_nr, this_path;
+	struct commit_list *list;
+	struct commit *first_parent;
+	struct path_track **ppt, *pt;
+
+	/* we can only re-use a closed path once all it's children have been encountered,
+	 * as we need to keep track of commit boundaries */
+	ppt = &path_track;
+	pt = *ppt;
+	child_nr = 0;
+	while (pt) {
+		if (pt->commit == commit) {
+			uint16_t write_path;
+
+			if (paths[pt->path] != PATH_IN_USE)
+				paths[pt->path]--;
+
+			/* make sure we can handle this */
+			child_nr++;
+			if (child_nr > 0x7f)
+				die("%s: too many branches!  rev-cache can only handle %d parents/children per commit",
+					sha1_to_hex(object->sha1), 0x7f);
+
+			/* add to split list */
+			object->split_nr++;
+			write_path = htons((uint16_t)pt->path);
+			strbuf_add(split_str, &write_path, sizeof(uint16_t));
+
+			remove_path_track(ppt, 0);
+			pt = *ppt;
+		} else {
+			pt = pt->next;
+			ppt = &pt;
+		}
+	}
+
+	/* initialize our self! */
+	if (!commit->indegree) {
+		commit->indegree = get_new_path();
+		object->is_start = 1;
+	}
+
+	this_path = commit->indegree;
+	paths[this_path] = PATH_IN_USE;
+	object->path = this_path;
+
+	/* count interesting parents */
+	parent_nr = open_parent_nr = 0;
+	first_parent = 0;
+	for (list = commit->parents; list; list = list->next) {
+		if (list->item->object.flags & UNINTERESTING) {
+			object->is_end = 1;
+			continue;
+		}
+
+		parent_nr++;
+		if (!list->item->indegree)
+			open_parent_nr++;
+		if (!first_parent)
+			first_parent = list->item;
+	}
+
+	if (!parent_nr)
+		return;
+
+	if (parent_nr == 1 && open_parent_nr == 1) {
+		first_parent->indegree = this_path;
+		return;
+	}
+
+	/* bail out on obscene parent/child #s */
+	if (parent_nr > 0x7f)
+		die("%s: too many parents in merge!  rev-cache can only handle %d parents/children per commit",
+			sha1_to_hex(object->sha1), 0x7f);
+
+	/* make merge list */
+	object->merge_nr = parent_nr;
+	paths[this_path] = parent_nr;
+
+	for (list = commit->parents; list; list = list->next) {
+		struct commit *p = list->item;
+		uint16_t write_path;
+
+		if (p->object.flags & UNINTERESTING)
+			continue;
+
+		/* unfortunately due to boundary tracking we can't re-use merge paths
+		 * (unable to guarantee last parent path = this -> last won't always be able to
+		 * set this as a boundary object */
+		if (!p->indegree)
+			p->indegree = get_new_path();
+
+		write_path = htons((uint16_t)p->indegree);
+		strbuf_add(merge_str, &write_path, sizeof(uint16_t));
+
+		/* make sure path is properly ended */
+		add_path_to_track(p, this_path);
+	}
+
+}
+
+
+static void add_object_entry(const unsigned char *sha1, int type, struct rc_object_entry *nothisone,
+	struct strbuf *merge_str, struct strbuf *split_str)
+{
+	struct rc_object_entry object;
+
+	if (!nothisone) {
+		memset(&object, 0, sizeof(object));
+		object.sha1 = (unsigned char *)sha1;
+		object.type = type;
+
+		if (merge_str)
+			object.merge_nr = merge_str->len / sizeof(uint16_t);
+		if (split_str)
+			object.split_nr = split_str->len / sizeof(uint16_t);
+
+		nothisone = &object;
+	}
+
+	strbuf_add(acc_buffer, to_disked_rc_object_entry(nothisone, 0), sizeof(struct rc_object_entry_ondisk));
+
+	if (merge_str && merge_str->len)
+		strbuf_add(acc_buffer, merge_str->buf, merge_str->len);
+	if (split_str && split_str->len)
+		strbuf_add(acc_buffer, split_str->buf, split_str->len);
+
+}
+
+static void init_revcache_directory(void)
+{
+	struct stat fi;
+
+	if (stat(git_path("rev-cache"), &fi) || !S_ISDIR(fi.st_mode))
+		if (mkdir(git_path("rev-cache"), 0777))
+			die("can't make rev-cache directory");
+
+}
+
+void init_rev_cache_info(struct rev_cache_info *rci)
+{
+	rci->objects = 1;
+	rci->legs = 0;
+	rci->make_index = 1;
+
+	rci->add_to_pending = 1;
+
+	rci->ignore_size = 0;
+}
+
+void maybe_fill_with_defaults(struct rev_cache_info *rci)
+{
+	static struct rev_cache_info def_rci;
+
+	if (rci)
+		return;
+
+	init_rev_cache_info(&def_rci);
+	rci = &def_rci;
+}
+
+int make_cache_slice(struct rev_cache_info *rci,
+	struct rev_info *revs, struct commit_list **starts, struct commit_list **ends,
+	unsigned char *cache_sha1)
+{
+	struct rev_info therevs;
+	struct strbuf buffer, startlist, endlist;
+	struct rc_slice_header head;
+	struct commit *commit;
+	unsigned char sha1[20];
+	struct strbuf merge_paths, split_paths;
+	int object_nr, total_sz, fd;
+	char file[PATH_MAX], *newfile;
+	struct rev_cache_info *trci;
+	git_SHA_CTX ctx;
+
+	maybe_fill_with_defaults(rci);
+
+	init_revcache_directory();
+	strcpy(file, git_path("rev-cache/XXXXXX"));
+	fd = xmkstemp(file);
+
+	strbuf_init(&buffer, 0);
+	strbuf_init(&startlist, 0);
+	strbuf_init(&endlist, 0);
+	strbuf_init(&merge_paths, 0);
+	strbuf_init(&split_paths, 0);
+	acc_buffer = &buffer;
+
+	if (!revs) {
+		revs = &therevs;
+		init_revisions(revs, 0);
+
+		/* we're gonna assume no one else has already traversed this... */
+		while ((commit = pop_commit(starts)))
+			add_pending_object(revs, &commit->object, 0);
+
+		while ((commit = pop_commit(ends))) {
+			commit->object.flags |= UNINTERESTING;
+			add_pending_object(revs, &commit->object, 0);
+		}
+	}
+
+	/* write head placeholder */
+	memset(&head, 0, sizeof(head));
+	head.ofs_objects = htonl(sizeof(head));
+	xwrite(fd, &head, sizeof(head));
+
+	/* init revisions! */
+	revs->tree_objects = 1;
+	revs->blob_objects = 1;
+	revs->topo_order = 1;
+	revs->lifo = 1;
+
+	/* re-use info from other caches if possible */
+	trci = &revs->rev_cache_info;
+	init_rev_cache_info(trci);
+	trci->add_to_pending = 0;
+
+	setup_revisions(0, 0, revs, 0);
+	if (prepare_revision_walk(revs))
+		die("died preparing revision walk");
+
+	object_nr = total_sz = 0;
+	while ((commit = get_revision(revs)) != 0) {
+		struct rc_object_entry object;
+
+		strbuf_setlen(&merge_paths, 0);
+		strbuf_setlen(&split_paths, 0);
+
+		memset(&object, 0, sizeof(object));
+		object.type = OBJ_COMMIT;
+		object.date = commit->date;
+		object.sha1 = commit->object.sha1;
+
+		handle_paths(commit, &object, &merge_paths, &split_paths);
+
+		if (object.is_end) {
+			strbuf_add(&endlist, object.sha1, 20);
+			if (ends)
+				commit_list_insert(commit, ends);
+		}
+		/* the two *aren't* mutually exclusive */
+		if (object.is_start) {
+			strbuf_add(&startlist, object.sha1, 20);
+			if (starts)
+				commit_list_insert(commit, starts);
+		}
+
+		commit->indegree = 0;
+
+		add_object_entry(0, 0, &object, &merge_paths, &split_paths);
+		object_nr++;
+
+		/* print every ~1MB or so */
+		if (buffer.len > 1000000) {
+			write_in_full(fd, buffer.buf, buffer.len);
+			total_sz += buffer.len;
+
+			strbuf_setlen(&buffer, 0);
+		}
+	}
+
+	if (buffer.len) {
+		write_in_full(fd, buffer.buf, buffer.len);
+		total_sz += buffer.len;
+	}
+
+	/* go ahead a free some stuff... */
+	strbuf_release(&buffer);
+	strbuf_release(&merge_paths);
+	strbuf_release(&split_paths);
+	if (path_sz)
+		free(paths);
+	while (path_track_alloc)
+		remove_path_track(&path_track_alloc, 1);
+
+	/* the meaning of the hash name is more or less irrelevant, it's the uniqueness that matters */
+	strbuf_add(&endlist, startlist.buf, startlist.len);
+	git_SHA1_Init(&ctx);
+	git_SHA1_Update(&ctx, endlist.buf, endlist.len);
+	git_SHA1_Final(sha1, &ctx);
+
+	/* now actually initialize header */
+	strcpy(head.signature, "REVCACHE");
+	head.version = SUPPORTED_REVCACHE_VERSION;
+
+	head.object_nr = htonl(object_nr);
+	head.size = htonl(ntohl(head.ofs_objects) + total_sz);
+	head.path_nr = htons(path_nr);
+	hashcpy(head.sha1, sha1);
+
+	/* some info! */
+	fprintf(stderr, "objects: %d\n", object_nr);
+	fprintf(stderr, "paths: %d\n", path_nr);
+
+	lseek(fd, 0, SEEK_SET);
+	xwrite(fd, &head, sizeof(head));
+
+	if (rci->make_index && make_cache_index(rci, sha1, fd, ntohl(head.size)) < 0)
+		die("can't update index");
+
+	close(fd);
+
+	newfile = git_path("rev-cache/%s", sha1_to_hex(sha1));
+	if (rename(file, newfile))
+		die("can't move temp file");
+
+	/* let our caller know what we've just made */
+	if (cache_sha1)
+		hashcpy(cache_sha1, sha1);
+
+	strbuf_release(&endlist);
+	strbuf_release(&startlist);
+
+	return 0;
+}
+
+
+static int index_sort_hash(const void *a, const void *b)
+{
+	return hashcmp(((struct rc_index_entry_ondisk *)a)->sha1, ((struct rc_index_entry_ondisk *)b)->sha1);
+}
+
+static int write_cache_index(struct strbuf *body)
+{
+	struct rc_index_header whead;
+	struct lock_file *lk;
+	int fd, i;
+
+	/* clear index map if loaded */
+	if (idx_map) {
+		munmap(idx_map, idx_size);
+		idx_map = 0;
+	}
+
+	lk = xcalloc(sizeof(struct lock_file), 1);
+	fd = hold_lock_file_for_update(lk, git_path("rev-cache/index"), 0);
+	if (fd < 0) {
+		free(lk);
+		return -1;
+	}
+
+	/* endianness yay! */
+	memset(&whead, 0, sizeof(whead));
+	memcpy(whead.signature, "REVINDEX", 8);
+	whead.version = idx_head.version;
+	whead.ofs_objects = htonl(idx_head.ofs_objects);
+	whead.object_nr = htonl(idx_head.object_nr);
+	whead.cache_nr = idx_head.cache_nr;
+	whead.max_date = htonl(idx_head.max_date);
+
+	write(fd, &whead, sizeof(struct rc_index_header));
+	write_in_full(fd, idx_caches, idx_head.cache_nr * 20);
+
+	for (i = 0; i <= 0xff; i++)
+		fanout[i] = htonl(fanout[i]);
+	write_in_full(fd, fanout, 0x100 * sizeof(uint32_t));
+
+	write_in_full(fd, body->buf, body->len);
+
+	if (commit_lock_file(lk) < 0)
+		return -2;
+
+	/* lk freed by lockfile.c */
+
+	return 0;
+}
+
+int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
+	int fd, unsigned int size)
+{
+	struct strbuf buffer;
+	int i, cache_index, cur;
+	unsigned char *map;
+	unsigned long max_date;
+
+	if (!idx_map)
+		init_index();
+
+	lseek(fd, 0, SEEK_SET);
+	map = xmmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (map == MAP_FAILED)
+		return -1;
+
+	strbuf_init(&buffer, 0);
+	if (idx_map) {
+		strbuf_add(&buffer, idx_map + fanout[0], fanout[0x100] - fanout[0]);
+	} else {
+		/* not an update */
+		memset(&idx_head, 0, sizeof(struct rc_index_header));
+		idx_caches = 0;
+
+		strcpy(idx_head.signature, "REVINDEX");
+		idx_head.version = SUPPORTED_REVINDEX_VERSION;
+		idx_head.ofs_objects = sizeof(struct rc_index_header) + 0x100 * sizeof(uint32_t);
+	}
+
+	/* are we remaking a slice? */
+	for (i = 0; i < idx_head.cache_nr; i++)
+		if (!hashcmp(idx_caches + i * 20, cache_sha1))
+			break;
+
+	if (i == idx_head.cache_nr) {
+		cache_index = idx_head.cache_nr++;
+		idx_head.ofs_objects += 20;
+
+		idx_caches = xrealloc(idx_caches, idx_head.cache_nr * 20);
+		hashcpy(idx_caches + cache_index * 20, cache_sha1);
+	} else
+		cache_index = i;
+
+	i = sizeof(struct rc_slice_header); /* offset */
+	max_date = idx_head.max_date;
+	while (i < size) {
+		struct rc_index_entry index_entry, *entry;
+		struct rc_index_entry_ondisk *disked_entry;
+		struct rc_object_entry *object_entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
+		unsigned long date;
+		int off, pos = i;
+
+		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(object_entry);
+
+		if (object_entry->type != OBJ_COMMIT)
+			continue;
+
+		/* don't include ends; otherwise we'll find ourselves in loops */
+		if (object_entry->is_end)
+			continue;
+
+		/* handle index duplication
+		 * -> keep old copy unless new one is a start -- based on expected usage, older ones will be more
+		 * likely to lead to greater slice traversals than new ones */
+		date = object_entry->date;
+		if (date > idx_head.max_date) {
+			disked_entry = 0;
+			if (date > max_date)
+				max_date = date;
+		} else
+			disked_entry = search_index_1(object_entry->sha1);
+
+		if (disked_entry && !object_entry->is_start)
+			continue;
+		else if (disked_entry) {
+			/* mmm, pointer arithmetic... tasty */  /* (entry - idx_map = offset, so cast is valid) */
+			off = (unsigned int)((unsigned char *)disked_entry - idx_map) - fanout[0];
+			disked_entry = (struct rc_index_entry_ondisk *)(buffer.buf + off);
+			entry = from_disked_rc_index_entry(disked_entry, 0);
+		} else
+			entry = &index_entry;
+
+		memset(entry, 0, sizeof(index_entry));
+		entry->sha1 = object_entry->sha1;
+		entry->is_start = object_entry->is_start;
+		entry->cache_index = cache_index;
+		entry->pos = pos;
+
+		if (entry == &index_entry) {
+			strbuf_add(&buffer, to_disked_rc_index_entry(entry, 0), sizeof(struct rc_index_entry_ondisk));
+			idx_head.object_nr++;
+		} else
+			to_disked_rc_index_entry(entry, disked_entry);
+
+	}
+
+	idx_head.max_date = max_date;
+	qsort(buffer.buf, buffer.len / sizeof(struct rc_index_entry_ondisk), sizeof(struct rc_index_entry_ondisk), index_sort_hash);
+
+	/* generate fanout */
+	cur = 0x00;
+	for (i = 0; i < buffer.len; i += sizeof(struct rc_index_entry_ondisk)) {
+		struct rc_index_entry_ondisk *entry = (struct rc_index_entry_ondisk *)(buffer.buf + i);
+
+		while (cur <= entry->sha1[0])
+			fanout[cur++] = i + idx_head.ofs_objects;
+	}
+
+	while (cur <= 0xff)
+		fanout[cur++] = idx_head.ofs_objects + buffer.len;
+
+	/* BOOM! */
+	if (write_cache_index(&buffer))
+		return -1;
+
+	munmap(map, size);
+	strbuf_release(&buffer);
+
+	/* idx_map is unloaded without cleanup_cache_slices(), so regardless of previous index existence
+	 * we can still free this up */
+	free(idx_caches);
+
+	return 0;
+}
+
+
+/* add start-commits from each cache slice (uninterestingness will be propogated) */
+void starts_from_slices(struct rev_info *revs, unsigned int flags)
+{
+	struct commit *commit;
+	int i;
+
+	if (!idx_map)
+		init_index();
+	if (!idx_map)
+		return;
+
+	for (i = idx_head.ofs_objects; i < idx_size; i += sizeof(struct rc_index_entry_ondisk)) {
+		struct rc_index_entry *entry = RC_OBTAIN_INDEX_ENTRY(idx_map + i);
+
+		if (!entry->is_start)
+			continue;
+
+		commit = lookup_commit(entry->sha1);
+		if (!commit)
+			continue;
+
+		commit->object.flags |= flags;
+		add_pending_object(revs, &commit->object, 0);
+	}
+
+}
diff --git a/rev-cache.h b/rev-cache.h
new file mode 100644
index 0000000..a76dc53
--- /dev/null
+++ b/rev-cache.h
@@ -0,0 +1,107 @@
+#ifndef REV_CACHE_H
+#define REV_CACHE_H
+
+#define SUPPORTED_REVCACHE_VERSION 		1
+#define SUPPORTED_REVINDEX_VERSION		1
+
+#define RC_PATH_SIZE(x)	(sizeof(uint16_t) * (x))
+
+#define RC_OBTAIN_OBJECT_ENTRY(p)			from_disked_rc_object_entry((struct rc_object_entry_ondisk *)(p), 0)
+#define RC_OBTAIN_INDEX_ENTRY(p)			from_disked_rc_index_entry((struct rc_index_entry_ondisk *)(p), 0)
+
+#define RC_ACTUAL_OBJECT_ENTRY_SIZE(e)		(sizeof(struct rc_object_entry_ondisk) + RC_PATH_SIZE((e)->merge_nr + (e)->split_nr) + (e)->size_size)
+
+/* single index maps objects to cache files */
+struct rc_index_header {
+	char signature[8]; /* REVINDEX */
+	unsigned char version;
+	uint32_t ofs_objects;
+
+	uint32_t object_nr;
+	unsigned char cache_nr;
+
+	uint32_t max_date;
+};
+
+struct rc_index_entry_ondisk {
+	unsigned char sha1[20];
+	unsigned char flags;
+	uint32_t pos;
+};
+
+struct rc_index_entry {
+	unsigned char *sha1;
+	unsigned is_start:1;
+	unsigned cache_index:7;
+	uint32_t pos;
+};
+
+
+/* structure for actual cache file */
+struct rc_slice_header {
+	char signature[8]; /* REVCACHE */
+	unsigned char version;
+	uint32_t ofs_objects;
+
+	uint32_t object_nr;
+	uint16_t path_nr;
+	uint32_t size;
+
+	unsigned char sha1[20];
+};
+
+struct rc_object_entry_ondisk {
+	unsigned char flags;
+	unsigned char sha1[20];
+
+	unsigned char merge_nr;
+	unsigned char split_nr;
+	unsigned char sizes;
+
+	uint32_t date;
+	uint16_t path;
+};
+
+struct rc_object_entry {
+	unsigned type:3;
+	unsigned is_end:1;
+	unsigned is_start:1;
+	unsigned uninteresting:1;
+	unsigned include:1;
+	unsigned flag:1; /* unused */
+	unsigned char *sha1; /* 20 byte */
+
+	unsigned char merge_nr; /* : 7 */
+	unsigned char split_nr; /* : 7 */
+	unsigned size_size:3;
+	unsigned padding:5;
+
+	uint32_t date;
+	uint16_t path;
+
+	/* merge paths */
+	/* split paths */
+	/* size */
+};
+
+struct rc_index_entry *from_disked_rc_index_entry(struct rc_index_entry_ondisk *src, struct rc_index_entry *dst);
+struct rc_index_entry_ondisk *to_disked_rc_index_entry(struct rc_index_entry *src, struct rc_index_entry_ondisk *dst);
+struct rc_object_entry *from_disked_rc_object_entry(struct rc_object_entry_ondisk *src, struct rc_object_entry *dst);
+struct rc_object_entry_ondisk *to_disked_rc_object_entry(struct rc_object_entry *src, struct rc_object_entry_ondisk *dst);
+
+extern unsigned char *get_cache_slice(struct commit *commit);
+extern int traverse_cache_slice(struct rev_info *revs,
+	unsigned char *cache_sha1, struct commit *commit,
+	unsigned long *date_so_far, int *slop_so_far,
+	struct commit_list ***queue, struct commit_list **work);
+
+extern void init_rev_cache_info(struct rev_cache_info *rci);
+extern int make_cache_slice(struct rev_cache_info *rci,
+	struct rev_info *revs, struct commit_list **starts, struct commit_list **ends,
+	unsigned char *cache_sha1);
+extern int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
+	int fd, unsigned int size);
+
+extern void starts_from_slices(struct rev_info *revs, unsigned int flags);
+
+#endif
diff --git a/revision.c b/revision.c
index 35eca4a..c7fd35f 100644
--- a/revision.c
+++ b/revision.c
@@ -432,7 +432,7 @@ static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
  	commit->object.flags |= TREESAME;
  }

-static void insert_by_date_cached(struct commit *p, struct commit_list **head,
+void insert_by_date_cached(struct commit *p, struct commit_list **head,
  		    struct commit_list *cached_base, struct commit_list **cache)
  {
  	struct commit_list *new_entry;
diff --git a/revision.h b/revision.h
index 9d0dddb..7db4b9e 100644
--- a/revision.h
+++ b/revision.h
@@ -13,7 +13,8 @@
  #define CHILD_SHOWN	(1u<<6)
  #define ADDED		(1u<<7)	/* Parents already parsed and added? */
  #define SYMMETRIC_LEFT	(1u<<8)
-#define ALL_REV_FLAGS	((1u<<9)-1)
+#define FACE_VALUE	(1u<<9)
+#define ALL_REV_FLAGS	((1u<<10)-1)

  #define DECORATE_SHORT_REFS	1
  #define DECORATE_FULL_REFS	2
@@ -21,6 +22,19 @@
  struct rev_info;
  struct log_info;

+struct rev_cache_info {
+	/* generation flags */
+	unsigned objects : 1,
+		legs : 1,
+		make_index : 1;
+
+	/* traversal flags */
+	unsigned add_to_pending : 1;
+
+	/* fuse options */
+	unsigned int ignore_size;
+};
+
  struct rev_info {
  	/* Starting list */
  	struct commit_list *commits;
@@ -76,6 +90,10 @@ struct rev_info {
  			dense_combined_merges:1,
  			always_show_header:1;

+	/* rev-cache flags */
+	unsigned int for_pack:1,
+		dont_cache_me:1;
+
  	/* Format info */
  	unsigned int	shown_one:1,
  			show_merge:1,
@@ -119,6 +137,9 @@ struct rev_info {
  	struct reflog_walk_info *reflog_info;
  	struct decoration children;
  	struct decoration merge_simplification;
+
+	/* caching info, used ONLY by traverse_cache_slice */
+	struct rev_cache_info rev_cache_info;
  };

  #define REV_TREE_SAME		0
@@ -171,4 +192,7 @@ enum commit_action {
  extern enum commit_action get_commit_action(struct rev_info *revs, struct commit *commit);
  extern enum commit_action simplify_commit(struct rev_info *revs, struct commit *commit);

+extern void insert_by_date_cached(struct commit *p, struct commit_list **head,
+		    struct commit_list *cached_base, struct commit_list **cache);
+
  #endif
diff --git a/t/t6017-rev-cache-list.sh b/t/t6017-rev-cache-list.sh
new file mode 100755
index 0000000..f59f568
--- /dev/null
+++ b/t/t6017-rev-cache-list.sh
@@ -0,0 +1,106 @@
+#!/bin/sh
+
+test_description='git rev-cache tests'
+. ./test-lib.sh
+
+test_cmp_sorted() {
+	grep -io "[a-f0-9]*" $1 | sort >.tmpfile1 &&
+	grep -io "[a-f0-9]*" $2 | sort >.tmpfile2 &&
+	test_cmp .tmpfile1 .tmpfile2
+}
+
+# we want a totally wacked out branch structure...
+# we need branching and merging of sizes up through 3, tree
+# addition/deletion, and enough branching to exercise path
+# reuse
+test_expect_success 'init repo' '
+	echo bla >file &&
+	git add . &&
+	git commit -m "bla" &&
+
+	git branch b1 &&
+	git checkout b1 &&
+	echo blu >file2 &&
+	mkdir d1 &&
+	echo bang >d1/filed1 &&
+	git add . &&
+	git commit -m "blu" &&
+
+	git checkout master &&
+	git branch b2 &&
+	git checkout b2 &&
+	echo kaplaa >>file &&
+	git commit -a -m "kaplaa" &&
+
+	git checkout master &&
+	mkdir smoke &&
+	echo omg >smoke/bong &&
+	git add . &&
+	git commit -m "omg" &&
+
+	git branch b4 &&
+	git checkout b4 &&
+	echo shazam >file8 &&
+	git add . &&
+	git commit -m "shazam" &&
+	git merge -m "merge b2" b2 &&
+
+	echo bam >smoke/pipe &&
+	git add .
+	git commit -m "bam" &&
+
+	git checkout master &&
+	echo pow >file7 &&
+	git add . &&
+	git commit -m "pow" &&
+	git merge -m "merge b4" b4 &&
+
+	git checkout b1 &&
+	echo stuff >d1/filed1 &&
+	git commit -a -m "stuff" &&
+
+	git branch b11 &&
+	git checkout b11 &&
+	echo wazzup >file3 &&
+	git add file3 &&
+	git commit -m "wazzup" &&
+
+	git checkout b1 &&
+	mkdir d1/d2 &&
+	echo lol >d1/d2/filed2 &&
+	git add . &&
+	git commit -m "lol" &&
+
+	git checkout master &&
+	git merge -m "triple merge" b1 b11 &&
+	git rm -r d1 &&
+	git commit -a -m "oh noes"
+'
+
+git-rev-list HEAD --not HEAD~3 >proper_commit_list_limited
+git-rev-list HEAD >proper_commit_list
+git-rev-list HEAD --objects >proper_object_list
+
+test_expect_success 'make cache slice' '
+	git-rev-cache add HEAD 2>output.err &&
+	grep "final return value: 0" output.err
+'
+
+test_expect_success 'remake cache slice' '
+	git-rev-cache add HEAD 2>output.err &&
+	grep "final return value: 0" output.err
+'
+
+#check core mechanics and rev-list hook for commits
+test_expect_success 'test rev-caches walker directly (limited)' '
+	git-rev-cache walk HEAD --not HEAD~3 >list &&
+	test_cmp_sorted list proper_commit_list_limited
+'
+
+test_expect_success 'test rev-caches walker directly (unlimited)' '
+	git-rev-cache walk HEAD >list &&
+	test_cmp_sorted list proper_commit_list
+'
+
+test_done
+
-- 
tg: (a6dbf88..) t/revcache/basic (depends on: master)

^ permalink raw reply related

* Re: [PATCH 3/6 (v4)] support for non-commit object caching in rev-cache
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkrfntdk399@sirnot.private>

Summarized, this third patch contains:
  - support for non-commit object caching
  - expansion of porcelain to accomodate non-commit objects
  - appropriate tests

Objects are stored relative to the commit in which they were introduced --
commits are 'diffed' against their parents.  This will eliminate the need for
tree recursion in cached commits (significantly reducing I/O), and potentially
be useful to external applications.

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
  rev-cache.c               |  202 ++++++++++++++++++++++++++++++++++++++++++++-
  t/t6017-rev-cache-list.sh |    6 ++
  2 files changed, 206 insertions(+), 2 deletions(-)

diff --git a/rev-cache.c b/rev-cache.c
index 8951cdf..ef6b58a 100644
--- a/rev-cache.c
+++ b/rev-cache.c
@@ -259,6 +259,32 @@ unsigned char *get_cache_slice(struct commit *commit)

  /* traversal */

+static void handle_noncommit(struct rev_info *revs, unsigned char *ptr, struct rc_object_entry *entry)
+{
+	struct object *obj = 0;
+
+	switch (entry->type) {
+	case OBJ_TREE:
+		if (revs->tree_objects)
+			obj = (struct object *)lookup_tree(entry->sha1);
+		break;
+	case OBJ_BLOB:
+		if (revs->blob_objects)
+			obj = (struct object *)lookup_blob(entry->sha1);
+		break;
+	case OBJ_TAG:
+		if (revs->tag_objects)
+			obj = (struct object *)lookup_tag(entry->sha1);
+		break;
+	}
+
+	if (!obj)
+		return;
+
+	obj->flags |= FACE_VALUE;
+	add_pending_object(revs, obj, "");
+}
+
  static int setup_traversal(struct rc_slice_header *head, unsigned char *map, struct commit *commit, struct commit_list **work)
  {
  	struct rc_index_entry *iep;
@@ -347,9 +373,12 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);

  		/* add extra objects if necessary */
-		if (entry->type != OBJ_COMMIT)
+		if (entry->type != OBJ_COMMIT) {
+			if (consume_children)
+				handle_noncommit(revs, map + index, entry);
+
  			continue;
-		else
+		} else
  			consume_children = 0;

  		if (path >= total_path_nr)
@@ -777,6 +806,171 @@ static void add_object_entry(const unsigned char *sha1, int type, struct rc_obje

  }

+/* returns non-zero to continue parsing, 0 to skip */
+typedef int (*dump_tree_fn)(const unsigned char *, const char *, unsigned int); /* sha1, path, mode */
+
+/* we need to walk the trees by hash, so unfortunately we can't use traverse_trees in tree-walk.c */
+static int dump_tree(struct tree *tree, dump_tree_fn fn)
+{
+	struct tree_desc desc;
+	struct name_entry entry;
+	struct tree *subtree;
+	int r;
+
+	if (parse_tree(tree))
+		return -1;
+
+	init_tree_desc(&desc, tree->buffer, tree->size);
+	while (tree_entry(&desc, &entry)) {
+		switch (fn(entry.sha1, entry.path, entry.mode)) {
+		case 0:
+			goto continue_loop;
+		default:
+			break;
+		}
+
+		if (S_ISDIR(entry.mode)) {
+			subtree = lookup_tree(entry.sha1);
+			if (!subtree)
+				return -2;
+
+			if ((r = dump_tree(subtree, fn)) < 0)
+				return r;
+		}
+
+continue_loop:
+		continue;
+	}
+
+	return 0;
+}
+
+static int dump_tree_callback(const unsigned char *sha1, const char *path, unsigned int mode)
+{
+	unsigned char data[21];
+
+	hashcpy(data, sha1);
+	data[20] = !!S_ISDIR(mode);
+
+	strbuf_add(acc_buffer, data, 21);
+
+	return 1;
+}
+
+static void tree_addremove(struct diff_options *options,
+	int whatnow, unsigned mode,
+	const unsigned char *sha1,
+	const char *concatpath)
+{
+	unsigned char data[21];
+
+	if (whatnow != '+')
+		return;
+
+	hashcpy(data, sha1);
+	data[20] = !!S_ISDIR(mode);
+
+	strbuf_add(acc_buffer, data, 21);
+}
+
+static void tree_change(struct diff_options *options,
+	unsigned old_mode, unsigned new_mode,
+	const unsigned char *old_sha1,
+	const unsigned char *new_sha1,
+	const char *concatpath)
+{
+	unsigned char data[21];
+
+	if (!hashcmp(old_sha1, new_sha1))
+		return;
+
+	hashcpy(data, new_sha1);
+	data[20] = !!S_ISDIR(new_mode);
+
+	strbuf_add(acc_buffer, data, 21);
+}
+
+static int sort_type_hash(const void *a, const void *b)
+{
+	const unsigned char *sa = (const unsigned char *)a,
+		*sb = (const unsigned char *)b;
+
+	if (sa[20] == sb[20])
+		return hashcmp(sa, sb);
+
+	return sa[20] > sb[20] ? -1 : 1;
+}
+
+static int add_unique_objects(struct commit *commit)
+{
+	struct commit_list *list;
+	struct strbuf os, ost, *orig_buf;
+	struct diff_options opts;
+	int i, j, next;
+	char is_first = 1;
+
+	strbuf_init(&os, 0);
+	strbuf_init(&ost, 0);
+	orig_buf = acc_buffer;
+
+	diff_setup(&opts);
+	DIFF_OPT_SET(&opts, RECURSIVE);
+	DIFF_OPT_SET(&opts, TREE_IN_RECURSIVE);
+	opts.change = tree_change;
+	opts.add_remove = tree_addremove;
+
+	/* this is only called for non-ends (ie. all parents interesting) */
+	for (list = commit->parents; list; list = list->next) {
+		if (is_first)
+			acc_buffer = &os;
+		else
+			acc_buffer = &ost;
+
+		strbuf_setlen(acc_buffer, 0);
+		diff_tree_sha1(list->item->tree->object.sha1, commit->tree->object.sha1, "", &opts);
+		qsort(acc_buffer->buf, acc_buffer->len / 21, 21, (int (*)(const void *, const void *))hashcmp);
+
+		/* take intersection */
+		if (!is_first) {
+			for (next = i = j = 0; i < os.len; i += 21) {
+				while (j < ost.len && hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)) < 0)
+					j += 21;
+
+				if (j >= ost.len || hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)))
+					continue;
+
+				if (next != i)
+					memcpy(os.buf + next, os.buf + i, 21);
+				next += 21;
+			}
+
+			if (next != i)
+				strbuf_setlen(&os, next);
+		} else
+			is_first = 0;
+	}
+
+	if (is_first) {
+		acc_buffer = &os;
+		dump_tree(commit->tree, dump_tree_callback);
+	}
+
+	if (os.len)
+		qsort(os.buf, os.len / 21, 21, sort_type_hash);
+
+	acc_buffer = orig_buf;
+	for (i = 0; i < os.len; i += 21)
+		add_object_entry((unsigned char *)(os.buf + i), os.buf[i + 20] ? OBJ_TREE : OBJ_BLOB, 0, 0, 0);
+
+	/* last but not least, the main tree */
+	add_object_entry(commit->tree->object.sha1, OBJ_TREE, 0, 0, 0);
+
+	strbuf_release(&ost);
+	strbuf_release(&os);
+
+	return i / 21 + 1;
+}
+
  static void init_revcache_directory(void)
  {
  	struct stat fi;
@@ -902,6 +1096,10 @@ int make_cache_slice(struct rev_cache_info *rci,
  		add_object_entry(0, 0, &object, &merge_paths, &split_paths);
  		object_nr++;

+		/* add all unique children for this commit */
+		if (rci->objects && !object.is_end)
+			object_nr += add_unique_objects(commit);
+
  		/* print every ~1MB or so */
  		if (buffer.len > 1000000) {
  			write_in_full(fd, buffer.buf, buffer.len);
diff --git a/t/t6017-rev-cache-list.sh b/t/t6017-rev-cache-list.sh
index f59f568..dc0fc07 100755
--- a/t/t6017-rev-cache-list.sh
+++ b/t/t6017-rev-cache-list.sh
@@ -102,5 +102,11 @@ test_expect_success 'test rev-caches walker directly (unlimited)' '
  	test_cmp_sorted list proper_commit_list
  '

+#do the same for objects
+test_expect_success 'test rev-caches walker with objects' '
+	git-rev-cache walk --objects HEAD >list &&
+	test_cmp_sorted list proper_object_list
+'
+
  test_done

-- 
tg: (ec20331..) t/revcache/objects (depends on: t/revcache/basic)

^ permalink raw reply related

* Re: [PATCH 5/6 (v4)] full integration of rev-cache into git, completed test suite
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkuoxtdk399@sirnot.private>

This patch provides a working integration of rev-cache into the revision
walker, along with some touch-ups:
  - integration into revision walker and list-objects
  - refactor object generation for more coherent code structure
  - more fluid handling of damaged cache slices (remembering bad slices)
  - numerous tests for both features from the previous patch, and the
integration's integrity

'Integration' is rather broad -- a more detailed description follows for each
aspect:
  - rev-cache
the traversal mechanism is updated to handle many of the non-prune options
rev-list does (date limiting, slop-handling, etc.), and is adjusted to allow
for non-fatal cache-traversal failures.

  - revision walker
both limited and unlimited traversal attempt to use the cache when possible,
smoothly falling back if it's not.

  - list-objects
object listing does not recurse into cached trees, and has been adjusted to
guarantee commit-tag-tree-blob ordering.

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
tweak test for compatability.

  builtin-rev-cache.c       |   40 ++++++++
  list-objects.c            |   46 ++++++++-
  rev-cache.c               |  231 +++++++++++++++++++++++++++++++++++++++------
  revision.c                |   88 ++++++++++++++---
  t/t6017-rev-cache-list.sh |  151 ++++++++++++++++++++++++++++-
  5 files changed, 501 insertions(+), 55 deletions(-)

diff --git a/builtin-rev-cache.c b/builtin-rev-cache.c
index b894c54..8f41123 100644
--- a/builtin-rev-cache.c
+++ b/builtin-rev-cache.c
@@ -4,6 +4,7 @@
  #include "diff.h"
  #include "revision.h"
  #include "rev-cache.h"
+#include "list-objects.h"

  unsigned long default_ignore_size = 50 * 1024 * 1024; /* 50mb */

@@ -78,6 +79,43 @@ static int handle_add(int argc, const char *argv[]) /* args beyond this command
  	return 0;
  }

+static void show_commit(struct commit *commit, void *data)
+{
+	printf("%s\n", sha1_to_hex(commit->object.sha1));
+}
+
+static void show_object(struct object *obj, const struct name_path *path, const char *last)
+{
+	printf("%s\n", sha1_to_hex(obj->sha1));
+}
+
+static int test_rev_list(int argc, const char *argv[])
+{
+	struct rev_info revs;
+	unsigned int flags = 0;
+	int i;
+
+	init_revisions(&revs, 0);
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--not"))
+			flags ^= UNINTERESTING;
+		else if (!strcmp(argv[i], "--objects"))
+			revs.tree_objects = revs.blob_objects = 1;
+		else
+			handle_revision_arg(argv[i], &revs, flags, 1);
+	}
+
+	setup_revisions(0, 0, &revs, 0);
+	revs.topo_order = 1;
+	revs.lifo = 1;
+	prepare_revision_walk(&revs);
+
+	traverse_commit_list(&revs, show_commit, show_object, 0);
+
+	return 0;
+}
+
  static int handle_walk(int argc, const char *argv[])
  {
  	struct commit *commit;
@@ -271,6 +309,8 @@ int cmd_rev_cache(int argc, const char *argv[], const char *prefix)
  		r = handle_walk(argc, argv);
  	else if (!strcmp(arg, "index"))
  		r = handle_index(argc, argv);
+	else if (!strcmp(arg, "test"))
+		r = test_rev_list(argc, argv);
  	else if (!strcmp(arg, "alt"))
  		r = handle_alt(argc, argv);
  	else
diff --git a/list-objects.c b/list-objects.c
index 8953548..b8c3370 100644
--- a/list-objects.c
+++ b/list-objects.c
@@ -74,22 +74,34 @@ static void process_tree(struct rev_info *revs,
  		die("bad tree object");
  	if (obj->flags & (UNINTERESTING | SEEN))
  		return;
+	if (obj->flags & FACE_VALUE) {
+		obj->flags |= SEEN;
+		show(obj, path, name);
+		/* not parsing the tree saves a lot of time! */
+		return;
+	}
+
  	if (parse_tree(tree) < 0)
  		die("bad tree object %s", sha1_to_hex(obj->sha1));
  	obj->flags |= SEEN;
  	show(obj, path, name);
+
  	me.up = path;
  	me.elem = name;
  	me.elem_len = strlen(name);
-
  	init_tree_desc(&desc, tree->buffer, tree->size);

  	while (tree_entry(&desc, &entry)) {
-		if (S_ISDIR(entry.mode))
+		if (S_ISDIR(entry.mode)) {
+			struct tree *subtree = lookup_tree(entry.sha1);
+			if (!subtree)
+				continue;
+
+			subtree->object.flags &= ~FACE_VALUE;
  			process_tree(revs,
-				     lookup_tree(entry.sha1),
+				     subtree,
  				     show, &me, entry.path);
-		else if (S_ISGITLINK(entry.mode))
+		} else if (S_ISGITLINK(entry.mode))
  			process_gitlink(revs, entry.sha1,
  					show, &me, entry.path);
  		else
@@ -136,6 +148,7 @@ void mark_edges_uninteresting(struct commit_list *list,

  static void add_pending_tree(struct rev_info *revs, struct tree *tree)
  {
+	tree->object.flags &= ~FACE_VALUE;
  	add_pending_object(revs, &tree->object, "");
  }

@@ -146,17 +159,27 @@ void traverse_commit_list(struct rev_info *revs,
  {
  	int i;
  	struct commit *commit;
+	enum object_type what = OBJ_TAG;
+	char face_value = 0;

  	while ((commit = get_revision(revs)) != NULL) {
-		add_pending_tree(revs, commit->tree);
+		if (!(commit->object.flags & FACE_VALUE))
+			add_pending_tree(revs, commit->tree);
+		else
+			face_value = 1;
  		show_commit(commit, data);
  	}
+
+loop_objects:
  	for (i = 0; i < revs->pending.nr; i++) {
  		struct object_array_entry *pending = revs->pending.objects + i;
  		struct object *obj = pending->item;
  		const char *name = pending->name;
  		if (obj->flags & (UNINTERESTING | SEEN))
  			continue;
+		if (obj->type != what && face_value)
+			continue;
+
  		if (obj->type == OBJ_TAG) {
  			obj->flags |= SEEN;
  			show_object(obj, NULL, name);
@@ -175,6 +198,19 @@ void traverse_commit_list(struct rev_info *revs,
  		die("unknown pending object %s (%s)",
  		    sha1_to_hex(obj->sha1), name);
  	}
+	if (face_value) {
+		switch (what) {
+		case OBJ_TAG:
+			what = OBJ_TREE;
+			goto loop_objects;
+		case OBJ_TREE:
+			what = OBJ_BLOB;
+			goto loop_objects;
+		default:
+			break;
+		}
+	}
+
  	if (revs->pending.nr) {
  		free(revs->pending.objects);
  		revs->pending.nr = 0;
diff --git a/rev-cache.c b/rev-cache.c
index e401978..4ef5287 100644
--- a/rev-cache.c
+++ b/rev-cache.c
@@ -11,6 +11,12 @@
  #include "run-command.h"
  #include "string-list.h"

+
+struct bad_slice {
+	unsigned char sha1[20];
+	struct bad_slice *next;
+};
+
  struct cache_slice_pointer {
  	char signature[8]; /* REVCOPTR */
  	char version;
@@ -23,8 +29,9 @@ static uint32_t fanout[0xff + 2];
  static unsigned char *idx_map;
  static int idx_size;
  static struct rc_index_header idx_head;
+static char no_idx, add_to_pending;
+static struct bad_slice *bad_slices;
  static unsigned char *idx_caches;
-static char no_idx;

  static struct strbuf *acc_buffer;

@@ -121,6 +128,30 @@ struct rc_object_entry_ondisk *to_disked_rc_object_entry(struct rc_object_entry
  	return dst;
  }

+static void mark_bad_slice(unsigned char *sha1)
+{
+	struct bad_slice *bad;
+
+	bad = xcalloc(sizeof(struct bad_slice), 1);
+	hashcpy(bad->sha1, sha1);
+
+	bad->next = bad_slices;
+	bad_slices = bad;
+}
+
+static int is_bad_slice(unsigned char *sha1)
+{
+	struct bad_slice *bad = bad_slices;
+
+	while (bad) {
+		if (!hashcmp(bad->sha1, sha1))
+			return 1;
+		bad = bad->next;
+	}
+
+	return 0;
+}
+
  static int get_index_head(unsigned char *map, int len, struct rc_index_header *head, uint32_t *fanout, unsigned char **caches)
  {
  	struct rc_index_header whead;
@@ -246,6 +277,7 @@ static struct rc_index_entry *search_index(unsigned char *sha1)
  unsigned char *get_cache_slice(struct commit *commit)
  {
  	struct rc_index_entry *ie;
+	unsigned char *sha1;

  	if (!idx_map) {
  		if (no_idx)
@@ -257,8 +289,13 @@ unsigned char *get_cache_slice(struct commit *commit)
  		return 0;

  	ie = search_index(commit->object.sha1);
-	if (ie && ie->cache_index < idx_head.cache_nr)
-		return idx_caches + ie->cache_index * 20;
+	if (ie && ie->cache_index < idx_head.cache_nr) {
+		sha1 = idx_caches + ie->cache_index * 20;
+
+		if (is_bad_slice(sha1))
+			return 0;
+		return sha1;
+	}

  	return 0;
  }
@@ -268,6 +305,20 @@ unsigned char *get_cache_slice(struct commit *commit)

  static unsigned long decode_size(unsigned char *str, int len);

+/* on failure */
+static void restore_commit(struct commit *commit)
+{
+	commit->object.flags &= ~(ADDED | SEEN | FACE_VALUE);
+
+	if (!commit->object.parsed) {
+		while (pop_commit(&commit->parents))
+			;
+
+		parse_commit(commit);
+	}
+
+}
+
  static void handle_noncommit(struct rev_info *revs, struct commit *commit, unsigned char *ptr, struct rc_object_entry *entry)
  {
  	struct blob *blob;
@@ -307,23 +358,27 @@ static void handle_noncommit(struct rev_info *revs, struct commit *commit, unsig
  	}

  	obj->flags |= FACE_VALUE;
-	add_pending_object(revs, obj, "");
+	if (add_to_pending)
+		add_pending_object(revs, obj, "");
  }

-static int setup_traversal(struct rc_slice_header *head, unsigned char *map, struct commit *commit, struct commit_list **work)
+static int setup_traversal(struct rc_slice_header *head, unsigned char *map, struct commit *commit, struct commit_list **work,
+	struct commit_list **unwork, int *ipath_nr, int *upath_nr, char *ioutside)
  {
  	struct rc_index_entry *iep;
  	struct rc_object_entry *oep;
  	struct commit_list *prev, *wp, **wpp;
  	int retval;

-	iep = search_index(commit->object.sha1), 0;
+	iep = search_index(commit->object.sha1);
  	oep = RC_OBTAIN_OBJECT_ENTRY(map + iep->pos);
+	if (commit->object.flags & UNINTERESTING) {
+		++*upath_nr;
+		oep->uninteresting = 1;
+	} else
+		++*ipath_nr;

-	/* the .uniniteresting bit isn't strictly necessary, as we check the object during traversal as well,
-	 * but we might as well initialize it while we're at it */
  	oep->include = 1;
-	oep->uninteresting = !!(commit->object.flags & UNINTERESTING);
  	to_disked_rc_object_entry(oep, (struct rc_object_entry_ondisk *)(map + iep->pos));
  	retval = iep->pos;

@@ -338,6 +393,10 @@ static int setup_traversal(struct rc_slice_header *head, unsigned char *map, str
  		/* is this in our cache slice? */
  		iep = search_index(obj->sha1);
  		if (!iep || hashcmp(idx_caches + iep->cache_index * 20, head->sha1)) {
+			/* there are interesing objects outside the slice */
+			if (!(obj->flags & UNINTERESTING))
+				*ioutside = 1;
+
  			prev = wp;
  			wp = wp->next;
  			wpp = &wp;
@@ -354,11 +413,20 @@ static int setup_traversal(struct rc_slice_header *head, unsigned char *map, str
  		oep->uninteresting = !!(obj->flags & UNINTERESTING);
  		to_disked_rc_object_entry(oep, (struct rc_object_entry_ondisk *)(map + iep->pos));

+		/* count even if not in slice so we can stop enumerating if possible */
+		if (obj->flags & UNINTERESTING)
+			++*upath_nr;
+		else
+			++*ipath_nr;
+
  		/* remove from work list */
  		co = pop_commit(wpp);
  		wp = *wpp;
  		if (prev)
  			prev->next = wp;
+
+		/* ...and store in temp list so we can restore work on failure */
+		commit_list_insert(co, unwork);
  	}

  	return retval;
@@ -375,13 +443,18 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  	unsigned long *date_so_far, int *slop_so_far,
  	struct commit_list ***queue, struct commit_list **work)
  {
-	struct commit_list *insert_cache = 0;
+	struct commit_list *insert_cache = 0, *myq = 0, **myqp = &myq, *mywork = 0, **myworkp = &mywork, *unwork = 0;
  	struct commit **last_objects, *co;
-	int i, total_path_nr = head->path_nr, retval = -1;
-	char consume_children = 0;
+	unsigned long date = date_so_far ? *date_so_far : ~0ul;
+	int i, ipath_nr = 0, upath_nr = 0, orig_obj_nr = 0,
+		total_path_nr = head->path_nr, retval = -1, slop = slop_so_far ? *slop_so_far : SLOP;
+	char consume_children = 0, ioutside = 0;
  	unsigned char *paths;

-	i = setup_traversal(head, map, commit, work);
+	/* take note in case we need to regress */
+	orig_obj_nr = revs->pending.nr;
+
+	i = setup_traversal(head, map, commit, work, &unwork, &ipath_nr, &upath_nr, &ioutside);
  	if (i < 0)
  		return -1;

@@ -429,6 +502,7 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m

  		if ((paths[path] & IPATH) && (paths[path] & UPATH)) {
  			paths[path] = UPATH;
+			ipath_nr--;

  			/* mark edge */
  			if (last_objects[path]) {
@@ -439,6 +513,7 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  				last_objects[path]->object.flags &= ~FACE_VALUE;
  				last_objects[path] = 0;
  			}
+			obj->flags |= BOUNDARY;
  		}

  		/* now we gotta re-assess the whole interesting thing... */
@@ -462,8 +537,10 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  						last_objects[p]->object.flags &= ~FACE_VALUE;
  						last_objects[p] = 0;
  					}
-				} else if (last_objects[p] && !last_objects[p]->object.parsed)
+					obj->flags |= BOUNDARY;
+				} else if (last_objects[p] && !last_objects[p]->object.parsed) {
  					commit_list_insert(co, &last_objects[p]->parents);
+				}

  				/* can't close a merge path until all are parents have been encountered */
  				if (GET_COUNT(paths[p])) {
@@ -473,14 +550,33 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  						continue;
  				}

+				if (paths[p] & IPATH)
+					ipath_nr--;
+				else
+					upath_nr--;
+
  				paths[p] = 0;
  				last_objects[p] = 0;
  			}
  		}

  		/* make topo relations */
-		if (last_objects[path] && !last_objects[path]->object.parsed)
+		if (last_objects[path] && !last_objects[path]->object.parsed) {
  			commit_list_insert(co, &last_objects[path]->parents);
+		}
+
+		/* we've been here already */
+		if (obj->flags & ADDED) {
+			if (entry->uninteresting && !(obj->flags & UNINTERESTING)) {
+				obj->flags |= UNINTERESTING;
+				mark_parents_uninteresting(co);
+				upath_nr--;
+			} else if (!entry->uninteresting)
+				ipath_nr--;
+
+			paths[path] = 0;
+			continue;
+		}

  		/* initialize commit */
  		if (!entry->is_end) {
@@ -493,24 +589,51 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m

  		if (entry->uninteresting)
  			obj->flags |= UNINTERESTING;
+		else if (co->date < date)
+			date = co->date;

  		/* we need to know what the edges are */
  		last_objects[path] = co;

  		/* add to list */
-		if (!(obj->flags & UNINTERESTING) || revs->show_all) {
-			if (entry->is_end)
-				insert_by_date_cached(co, work, insert_cache, &insert_cache);
-			else
-				*queue = &commit_list_insert(co, *queue)->next;
+		if (slop && !(revs->min_age != -1 && co->date > revs->min_age)) {
+
+			if (!(obj->flags & UNINTERESTING) || revs->show_all) {
+				if (entry->is_end)
+					myworkp = &commit_list_insert(co, myworkp)->next;
+				else
+					myqp = &commit_list_insert(co, myqp)->next;
+
+				/* add children to list as well */
+				if (obj->flags & UNINTERESTING)
+					consume_children = 0;
+				else
+					consume_children = 1;
+			}

-			/* add children to list as well */
-			if (obj->flags & UNINTERESTING)
-				consume_children = 0;
-			else
-				consume_children = 1;
  		}

+		/* should we continue? */
+		if (!slop) {
+			if (!upath_nr) {
+				break;
+			} else if (ioutside || revs->show_all) {
+				/* pass it back to rev-list
+				 * we purposely ignore everything outside this cache, so we don't needlessly traverse the whole
+				 * thing on uninteresting, but that does mean that we may need to bounce back
+				 * and forth a few times with rev-list */
+				myworkp = &commit_list_insert(co, myworkp)->next;
+
+				paths[path] = 0;
+				upath_nr--;
+			} else {
+				break;
+			}
+		} else if (!ipath_nr && co->date <= date)
+			slop--;
+		else
+			slop = SLOP;
+
  		/* open parents */
  		if (entry->merge_nr) {
  			int j, off = index + sizeof(struct rc_object_entry_ondisk);
@@ -525,6 +648,11 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  				if (paths[p] & flag)
  					continue;

+				if (flag == IPATH)
+					ipath_nr++;
+				else
+					upath_nr++;
+
  				paths[p] |= flag;
  			}

@@ -534,12 +662,54 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m

  	}

+	if (date_so_far)
+		*date_so_far = date;
+	if (slop_so_far)
+		*slop_so_far = slop;
  	retval = 0;

+	/* success: attach to given lists */
+	if (myqp != &myq) {
+		**queue = myq;
+		*queue = myqp;
+	}
+
+	while ((co = pop_commit(&mywork)) != 0)
+		insert_by_date_cached(co, work, insert_cache, &insert_cache);
+
+	/* free backup */
+	while (pop_commit(&unwork))
+		;
+
  end:
  	free(paths);
  	free(last_objects);

+	/* failure: restore work to previous condition
+	 * (cache corruption should *not* be fatal) */
+	if (retval) {
+		while ((co = pop_commit(&unwork)) != 0) {
+			restore_commit(co);
+			co->object.flags |= SEEN;
+			insert_by_date(co, work);
+		}
+
+		/* free lists */
+		while ((co = pop_commit(&myq)) != 0)
+			restore_commit(co);
+
+		while ((co = pop_commit(&mywork)) != 0)
+			restore_commit(co);
+
+		/* truncate object array */
+		for (i = orig_obj_nr; i < revs->pending.nr; i++) {
+			struct object *obj = revs->pending.objects[i].item;
+
+			obj->flags &= ~FACE_VALUE;
+		}
+		revs->pending.nr = orig_obj_nr;
+	}
+
  	return retval;
  }

@@ -630,6 +800,7 @@ int traverse_cache_slice(struct rev_info *revs,

  	/* load options */
  	rci = &revs->rev_cache_info;
+	add_to_pending = rci->add_to_pending;

  	memset(&head, 0, sizeof(struct rc_slice_header));

@@ -653,6 +824,10 @@ end:
  	if (fd != -1)
  		close(fd);

+	/* remember this! */
+	if (retval)
+		mark_bad_slice(cache_sha1);
+
  	return retval;
  }

@@ -811,7 +986,7 @@ static void handle_paths(struct commit *commit, struct rc_object_entry *object,
  	int child_nr, parent_nr, open_parent_nr, this_path;
  	struct commit_list *list;
  	struct commit *first_parent;
-	struct pa\th_track **ppt, *pt;
+	struct path_track **ppt, *pt;

  	/* we can only re-use a closed path once all it's children have been encountered,
  	 * as we need to keep track of commit boundaries */
@@ -1128,7 +1303,7 @@ static int add_objects_verbatim_1(struct rev_cache_slice_map *mapping, int *inde
  	while (i < mapping->size) {
  		int pos = i;

-		entry = RC_OBTAIN_OBJECT_ENTRY(map + i;
+		entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
  		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);

  		if (entry->type == OBJ_COMMIT) {
diff --git a/revision.c b/revision.c
index c7fd35f..ed21885 100644
--- a/revision.c
+++ b/revision.c
@@ -12,6 +12,7 @@
  #include "patch-ids.h"
  #include "decorate.h"
  #include "log-tree.h"
+#include "rev-cache.h"

  volatile show_early_output_fn_t show_early_output;

@@ -638,6 +639,8 @@ static int limit_list(struct rev_info *revs)
  	struct commit_list *list = revs->commits;
  	struct commit_list *newlist = NULL;
  	struct commit_list **p = &newlist;
+	unsigned char *cache_sha1;
+	char used_cache;

  	while (list) {
  		struct commit_list *entry = list;
@@ -650,24 +653,39 @@ static int limit_list(struct rev_info *revs)

  		if (revs->max_age != -1 && (commit->date < revs->max_age))
  			obj->flags |= UNINTERESTING;
-		if (add_parents_to_list(revs, commit, &list, NULL) < 0)
-			return -1;
-		if (obj->flags & UNINTERESTING) {
-			mark_parents_uninteresting(commit);
-			if (revs->show_all)
-				p = &commit_list_insert(commit, p)->next;
-			slop = still_interesting(list, date, slop);
-			if (slop)
+
+		/* rev-cache to the rescue!!! */
+		used_cache = 0;
+		if (!revs->dont_cache_me && !(obj->flags & ADDED)) {
+			cache_sha1 = get_cache_slice(commit);
+			if (cache_sha1) {
+				if (traverse_cache_slice(revs, cache_sha1, commit, &date, &slop, &p, &list) < 0)
+					used_cache = 0;
+				else
+					used_cache = 1;
+			}
+		}
+
+		if (!used_cache) {
+			if (add_parents_to_list(revs, commit, &list, NULL) < 0)
+				return -1;
+			if (obj->flags & UNINTERESTING) {
+				mark_parents_uninteresting(commit); /* ME: why? */
+				if (revs->show_all)
+					p = &commit_list_insert(commit, p)->next;
+				slop = still_interesting(list, date, slop);
+				if (slop > 0)
+					continue;
+				/* If showing all, add the whole pending list to the end */
+				if (revs->show_all)
+					*p = list;
+				break;
+			}
+			if (revs->min_age != -1 && (commit->date > revs->min_age))
  				continue;
-			/* If showing all, add the whole pending list to the end */
-			if (revs->show_all)
-				*p = list;
-			break;
+			date = commit->date;
+			p = &commit_list_insert(commit, p)->next;
  		}
-		if (revs->min_age != -1 && (commit->date > revs->min_age))
-			continue;
-		date = commit->date;
-		p = &commit_list_insert(commit, p)->next;

  		show = show_early_output;
  		if (!show)
@@ -813,6 +831,8 @@ void init_revisions(struct rev_info *revs, const char *prefix)
  		revs->diffopt.prefix = prefix;
  		revs->diffopt.prefix_length = strlen(prefix);
  	}
+
+	init_rev_cache_info(&revs->rev_cache_info);
  }

  static void add_pending_commit_list(struct rev_info *revs,
@@ -1372,6 +1392,11 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
  	if (revs->reflog_info && revs->graph)
  		die("cannot combine --walk-reflogs with --graph");

+	/* limits on caching
+	 * todo: implement this functionality */
+	if (revs->prune || revs->diff)
+		revs->dont_cache_me = 1;
+
  	return left;
  }

@@ -1654,6 +1679,8 @@ static int commit_match(struct commit *commit, struct rev_info *opt)
  {
  	if (!opt->grep_filter.pattern_list)
  		return 1;
+	if (!commit->object.parsed)
+		parse_commit(commit);
  	return grep_buffer(&opt->grep_filter,
  			   NULL, /* we say nothing, not even filename */
  			   commit->buffer, strlen(commit->buffer));
@@ -1717,6 +1744,7 @@ static struct commit *get_revision_1(struct rev_info *revs)
  	do {
  		struct commit_list *entry = revs->commits;
  		struct commit *commit = entry->item;
+		struct object *obj = &commit->object;

  		revs->commits = entry->next;
  		free(entry);
@@ -1733,11 +1761,39 @@ static struct commit *get_revision_1(struct rev_info *revs)
  			if (revs->max_age != -1 &&
  			    (commit->date < revs->max_age))
  				continue;
+
+			if (!revs->dont_cache_me) {
+				struct commit_list *queue = 0, **queuep = &queue;
+				unsigned char *cache_sha1;
+
+				if (obj->flags & ADDED)
+					goto skip_parenting;
+
+				cache_sha1 = get_cache_slice(commit);
+				if (cache_sha1) {
+					if (!traverse_cache_slice(revs, cache_sha1, commit, 0, 0, &queuep, &revs->commits)) {
+						struct commit_list *work = revs->commits;
+
+						/* attach queue to end of ->commits */
+						while (work && work->next)
+							work = work->next;
+
+						if (work)
+							work->next = queue;
+						else
+							revs->commits = queue;
+
+						goto skip_parenting;
+					}
+				}
+			}
+
  			if (add_parents_to_list(revs, commit, &revs->commits, NULL) < 0)
  				die("Failed to traverse parents of commit %s",
  				    sha1_to_hex(commit->object.sha1));
  		}

+skip_parenting:
  		switch (simplify_commit(revs, commit)) {
  		case commit_ignore:
  			continue;
diff --git a/t/t6017-rev-cache-list.sh b/t/t6017-rev-cache-list.sh
index dc0fc07..982fb15 100755
--- a/t/t6017-rev-cache-list.sh
+++ b/t/t6017-rev-cache-list.sh
@@ -38,6 +38,7 @@ test_expect_success 'init repo' '
  	git add . &&
  	git commit -m "omg" &&

+	sleep 2 &&
  	git branch b4 &&
  	git checkout b4 &&
  	echo shazam >file8 &&
@@ -46,7 +47,7 @@ test_expect_success 'init repo' '
  	git merge -m "merge b2" b2 &&

  	echo bam >smoke/pipe &&
-	git add .
+	git add . &&
  	git commit -m "bam" &&

  	git checkout master &&
@@ -71,18 +72,26 @@ test_expect_success 'init repo' '
  	git add . &&
  	git commit -m "lol" &&

+	sleep 2 &&
  	git checkout master &&
  	git merge -m "triple merge" b1 b11 &&
  	git rm -r d1 &&
+	sleep 2 &&
  	git commit -a -m "oh noes"
  '

-git-rev-list HEAD --not HEAD~3 >proper_commit_list_limited
-git-rev-list HEAD >proper_commit_list
-git-rev-list HEAD --objects >proper_object_list
+max_date=`git-rev-list --timestamp HEAD~1 --max-count=1 | grep -e "^[0-9]*" -o`
+min_date=`git-rev-list --timestamp b4 --max-count=1 | grep -e "^[0-9]*" -o`
+
+git-rev-list --topo-order HEAD --not HEAD~3 >proper_commit_list_limited
+git-rev-list --topo-order HEAD --not HEAD~2 >proper_commit_list_limited2
+git-rev-list --topo-order HEAD >proper_commit_list
+git-rev-list --objects HEAD >proper_object_list
+git-rev-list HEAD --max-age=$min_date --min-age=$max_date >proper_list_date_limited
+
+cache_sha1=`git-rev-cache add HEAD 2>output.err`

  test_expect_success 'make cache slice' '
-	git-rev-cache add HEAD 2>output.err &&
  	grep "final return value: 0" output.err
  '

@@ -102,11 +111,141 @@ test_expect_success 'test rev-caches walker directly (unlimited)' '
  	test_cmp_sorted list proper_commit_list
  '

+test_expect_success 'test rev-list traversal (limited)' '
+	git-rev-list HEAD --not HEAD~3 >list &&
+	test_cmp list proper_commit_list_limited
+'
+
+test_expect_success 'test rev-list traversal (unlimited)' '
+	git-rev-list HEAD >list &&
+	test_cmp list proper_commit_list
+'
+
  #do the same for objects
  test_expect_success 'test rev-caches walker with objects' '
  	git-rev-cache walk --objects HEAD >list &&
  	test_cmp_sorted list proper_object_list
  '

-test_done
+test_expect_success 'test rev-list with objects (topo order)' '
+	git-rev-list --topo-order --objects HEAD >list &&
+	test_cmp_sorted list proper_object_list
+'
+
+test_expect_success 'test rev-list with objects (no order)' '
+	git-rev-list --objects HEAD >list &&
+	test_cmp_sorted list proper_object_list
+'
+
+#verify age limiting
+test_expect_success 'test rev-list date limiting (topo order)' '
+	git-rev-list --topo-order --max-age=$min_date --min-age=$max_date HEAD >list &&
+	test_cmp_sorted list proper_list_date_limited
+'
+
+test_expect_success 'test rev-list date limiting (no order)' '
+	git-rev-list --max-age=$min_date --min-age=$max_date HEAD >list &&
+	test_cmp_sorted list proper_list_date_limited
+'
+
+#check partial cache slice
+test_expect_success 'saving old cache and generating partial slice' '
+	cp ".git/rev-cache/$cache_sha1" .git/rev-cache/.old &&
+	rm ".git/rev-cache/$cache_sha1" .git/rev-cache/index &&
+
+	git-rev-cache add HEAD~2 2>output.err &&
+	grep "final return value: 0" output.err
+'
+
+test_expect_success 'rev-list with wholly interesting partial slice' '
+	git-rev-list --topo-order HEAD >list &&
+	test_cmp list proper_commit_list
+'
+
+test_expect_success 'rev-list with partly uninteresting partial slice' '
+	git-rev-list --topo-order HEAD --not HEAD~3 >list &&
+	test_cmp list proper_commit_list_limited
+'
+
+test_expect_success 'rev-list with wholly uninteresting partial slice' '
+	git-rev-list --topo-order HEAD --not HEAD~2 >list &&
+	test_cmp list proper_commit_list_limited2
+'
+
+#try out index generation and fuse (note that --all == HEAD in this case)
+#probably should make a test for that too...
+test_expect_success 'test (non-)fusion of one slice' '
+	git-rev-cache fuse >output.err &&
+	grep "nothing to fuse" output.err
+'

+test_expect_success 'make fresh slice' '
+	git-rev-cache add --all --fresh 2>output.err &&
+	grep "final return value: 0" output.err
+'
+
+test_expect_success 'check dual slices' '
+	git-rev-list --topo-order HEAD~2 HEAD >list &&
+	test_cmp list proper_commit_list
+'
+
+test_expect_success 'regenerate index' '
+	rm .git/rev-cache/index &&
+	git-rev-cache index 2>output.err &&
+	grep "final return value: 0" output.err
+'
+
+test_expect_success 'fuse slices' '
+	test -e .git/rev-cache/.old &&
+	git-rev-cache fuse 2>output.err &&
+	grep "final return value: 0" output.err &&
+	test_cmp .git/rev-cache/$cache_sha1 .git/rev-cache/.old
+'
+
+#make sure we can smoothly handle corrupted caches
+test_expect_success 'corrupt slice' '
+	echo bla >.git/rev-cache/$cache_sha1
+'
+
+test_expect_success 'test rev-list traversal (limited) (corrupt slice)' '
+	git-rev-list --topo-order HEAD --not HEAD~3 >list &&
+	test_cmp list proper_commit_list_limited
+'
+
+test_expect_success 'test rev-list traversal (unlimited) (corrupt slice)' '
+	git-rev-list HEAD >list &&
+	test_cmp_sorted list proper_commit_list
+'
+
+test_expect_success 'corrupt index' '
+	echo blu >.git/rev-cache/index
+'
+
+test_expect_success 'test rev-list traversal (limited) (corrupt index)' '
+	git-rev-list --topo-order HEAD --not HEAD~3 >list &&
+	test_cmp list proper_commit_list_limited
+'
+
+test_expect_success 'test rev-list traversal (unlimited) (corrupt index)' '
+	git-rev-list HEAD >list &&
+	test_cmp_sorted list proper_commit_list
+'
+
+#test --ignore-size in fuse
+rm .git/rev-cache/*
+cache_sha1=`git-rev-cache add HEAD~2 2>output.err`
+
+test_expect_success 'make fragmented slices' '
+	git-rev-cache add HEAD~1 --not HEAD~2 2>>output.err &&
+	git-rev-cache add HEAD --fresh 2>>output.err &&
+	test `grep "final return value: 0" output.err | wc -l` -eq 3
+'
+
+cache_size=$(wc -c < .git/rev-cache/$cache_sha1)
+test_expect_success 'test --ignore-size function in fuse' '
+	git-rev-cache fuse --ignore-size=$cache_size 2>output.err &&
+	grep "final return value: 0" output.err &&
+	test -e .git/rev-cache/$cache_sha1
+'
+
+test_done
-- 
tg: (13365da..) t/revcache/integration (depends on: t/revcache/misc)

^ permalink raw reply related

* Re: [PATCH 6/6 (v4)] support for path name caching in rev-cache
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkwjotdk399@sirnot.private>

An update to caching mechanism, allowing path names to be cached for blob and
tree objects.  A list of names appearing in each cache slice is appended to the
end of the slice, which is referenced by variable-sized indexes per entry.
This allows pack-objects to more intelligently schedule unpacked/poorly packed
object, and enables proper duplication of rev-list's behaivor.

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
  builtin-rev-cache.c       |    3 +-
  rev-cache.c               |  332 +++++++++++++++++++++++++++++++++++++--------
  rev-cache.h               |   16 ++-
  revision.h                |    6 +-
  t/t6017-rev-cache-list.sh |    8 +-
  5 files changed, 300 insertions(+), 65 deletions(-)

diff --git a/builtin-rev-cache.c b/builtin-rev-cache.c
index 8f41123..4c1766d 100644
--- a/builtin-rev-cache.c
+++ b/builtin-rev-cache.c
@@ -177,13 +177,14 @@ static int handle_walk(int argc, const char *argv[])
  	fprintf(stderr, "pending:\n");
  	for (i = 0; i < revs.pending.nr; i++) {
  		struct object *obj = revs.pending.objects[i].item;
+		const char *name = revs.pending.objects[i].name;

  		/* unfortunately, despite our careful generation, object duplication *is* a possibility...
  		 * (eg. same object introduced into two different branches) */
  		if (obj->flags & SEEN)
  			continue;

-		printf("%s\n", sha1_to_hex(revs.pending.objects[i].item->sha1));
+		printf("%s %s\n", sha1_to_hex(revs.pending.objects[i].item->sha1), name);
  		obj->flags |= SEEN;
  	}

diff --git a/rev-cache.c b/rev-cache.c
index 4ef5287..6c96297 100644
--- a/rev-cache.c
+++ b/rev-cache.c
@@ -17,6 +17,14 @@ struct bad_slice {
  	struct bad_slice *next;
  };

+struct name_list {
+	unsigned char sha1[20];
+	unsigned int len;
+	struct name_list *next;
+
+	char buf[FLEX_ARRAY];
+};
+
  struct cache_slice_pointer {
  	char signature[8]; /* REVCOPTR */
  	char version;
@@ -29,10 +37,13 @@ static uint32_t fanout[0xff + 2];
  static unsigned char *idx_map;
  static int idx_size;
  static struct rc_index_header idx_head;
-static char no_idx, add_to_pending;
-static struct bad_slice *bad_slices;
+static char no_idx, add_to_pending, add_names;
  static unsigned char *idx_caches;

+static struct bad_slice *bad_slices;
+static struct name_list *name_lists, *cur_name_list;
+
+static struct strbuf *acc_name_buffer;
  static struct strbuf *acc_buffer;

  #define SLOP			5
@@ -79,7 +90,7 @@ struct rc_object_entry *from_disked_rc_object_entry(struct rc_object_entry_ondis
  	if (!dst)
  		dst = &entry[cur++ & 0x3];

-	dst->type = src->flags >> 5;
+	dst->type = src->flags >> 5 & 0x03;
  	dst->is_end = !!(src->flags & 0x10);
  	dst->is_start = !!(src->flags & 0x08);
  	dst->uninteresting = !!(src->flags & 0x04);
@@ -90,8 +101,9 @@ struct rc_object_entry *from_disked_rc_object_entry(struct rc_object_entry_ondis
  	dst->merge_nr = src->merge_nr;
  	dst->split_nr = src->split_nr;

-	dst->size_size = src->sizes >> 5;
-	dst->padding = src->sizes & 0x1f;
+	dst->size_size = src->sizes >> 5 & 0x03;
+	dst->name_size = src->sizes >> 2 & 0x03;
+	dst->padding = src->sizes & 0x02;

  	dst->date = ntohl(src->date);
  	dst->path = ntohs(src->path);
@@ -120,6 +132,7 @@ struct rc_object_entry_ondisk *to_disked_rc_object_entry(struct rc_object_entry
  	dst->split_nr = src->split_nr;

  	dst->sizes  = (unsigned char)src->size_size << 5;
+	dst->sizes |= (unsigned char)src->name_size << 2;
  	dst->sizes |= (unsigned char)src->padding;

  	dst->date = htonl(src->date);
@@ -192,6 +205,12 @@ static void cleanup_cache_slices(void)
  		idx_map = 0;
  	}

+	while (name_lists) {
+		struct name_list *nl = name_lists->next;
+		free(name_lists);
+		name_lists = nl;
+	}
+
  }

  static int init_index(void)
@@ -324,7 +343,7 @@ static void handle_noncommit(struct rev_info *revs, struct commit *commit, unsig
  	struct blob *blob;
  	struct tree *tree;
  	struct object *obj;
-	unsigned long size;
+	unsigned long size, name_index;

  	size = decode_size(ptr + RC_ENTRY_SIZE_OFFSET(entry), entry->size_size);
  	switch (entry->type) {
@@ -357,9 +376,23 @@ static void handle_noncommit(struct rev_info *revs, struct commit *commit, unsig
  		return;
  	}

+	if (add_names && cur_name_list) {
+		name_index = decode_size(ptr + RC_ENTRY_NAME_OFFSET(entry), entry->name_size);
+
+		if (name_index >= cur_name_list->len)
+			name_index = 0;
+	} else
+		name_index = 0;
+
  	obj->flags |= FACE_VALUE;
-	if (add_to_pending)
-		add_pending_object(revs, obj, "");
+	if (add_to_pending) {
+		char *name = "";
+
+		if (name_index)
+			name = cur_name_list->buf + name_index;
+
+		add_pending_object(revs, obj, name);
+	}
  }

  static int setup_traversal(struct rc_slice_header *head, unsigned char *map, struct commit *commit, struct commit_list **work,
@@ -713,15 +746,44 @@ end:
  	return retval;
  }

-static int get_cache_slice_header(unsigned char *cache_sha1, unsigned char *map, int len, struct rc_slice_header *head)
+static struct name_list *get_cache_slice_name_list(struct rc_slice_header *head, int fd)
+{
+	struct name_list *nl = name_lists;
+
+	while (nl) {
+		if (!hashcmp(nl->sha1, head->sha1))
+			break;
+		nl = nl->next;
+	}
+
+	if (nl)
+		return nl;
+
+	nl = xcalloc(1, sizeof(struct name_list) + head->name_size);
+	nl->len = head->name_size;
+	hashcpy(nl->sha1, head->sha1);
+
+	lseek(fd, head->size, SEEK_SET);
+	read_in_full(fd, nl->buf, head->name_size);
+
+	nl->next = name_lists;
+	name_lists = nl;
+
+	return nl;
+}
+
+static int get_cache_slice_header(int fd, unsigned char *cache_sha1, int len, struct rc_slice_header *head)
  {
  	int t;

-	memcpy(head, map, sizeof(struct rc_slice_header));
+	if (xread(fd, head, sizeof(struct rc_slice_header)) != sizeof(struct rc_slice_header))
+		return -1;
+
  	head->ofs_objects = ntohl(head->ofs_objects);
  	head->object_nr = ntohl(head->object_nr);
  	head->size = ntohl(head->size);
  	head->path_nr = ntohs(head->path_nr);
+	head->name_size = ntohl(head->name_size);

  	if (memcmp(head->signature, "REVCACHE", 8))
  		return -1;
@@ -730,10 +792,10 @@ static int get_cache_slice_header(unsigned char *cache_sha1, unsigned char *map,
  	if (hashcmp(head->sha1, cache_sha1))
  		return -3;
  	t = sizeof(struct rc_slice_header);
-	if (t != head->ofs_objects || t >= len)
+	if (t != head->ofs_objects)
  		return -4;
-
-	head->size = len;
+	if (head->size + head->name_size != len)
+		return -5;

  	return 0;
  }
@@ -785,7 +847,7 @@ int traverse_cache_slice(struct rev_info *revs,
  	unsigned long *date_so_far, int *slop_so_far,
  	struct commit_list ***queue, struct commit_list **work)
  {
-	int fd = -1, retval = -3;
+	int fd = -1, t, retval;
  	struct stat fi;
  	struct rc_slice_header head;
  	struct rev_cache_info *rci;
@@ -801,26 +863,31 @@ int traverse_cache_slice(struct rev_info *revs,
  	/* load options */
  	rci = &revs->rev_cache_info;
  	add_to_pending = rci->add_to_pending;
+	add_names = rci->add_names;

  	memset(&head, 0, sizeof(struct rc_slice_header));
+#	define ERROR(x)		do { retval = (x); goto end; } while (0);

  	fd = open_cache_slice(cache_sha1, O_RDONLY);
  	if (fd == -1)
-		goto end;
+		ERROR(-1);
  	if (fstat(fd, &fi) || fi.st_size < sizeof(struct rc_slice_header))
-		goto end;
+		ERROR(-2);
+
+	if ((t = get_cache_slice_header(fd, cache_sha1, fi.st_size, &head)) < 0)
+		ERROR(-t);
+	if (add_names)
+		cur_name_list = get_cache_slice_name_list(&head, fd);

-	map = xmmap(0, fi.st_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	map = xmmap(0, head.size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
  	if (map == MAP_FAILED)
-		goto end;
-	if (get_cache_slice_header(cache_sha1, map, fi.st_size, &head))
-		goto end;
+		ERROR(-3);

  	retval = traverse_cache_slice_1(&head, map, revs, commit, date_so_far, slop_so_far, queue, work);

  end:
  	if (map != MAP_FAILED)
-		munmap(map, fi.st_size);
+		munmap(map, head.size);
  	if (fd != -1)
  		close(fd);

@@ -828,6 +895,7 @@ end:
  	if (retval)
  		mark_bad_slice(cache_sha1);

+#	undef ERROR
  	return retval;
  }

@@ -1112,23 +1180,110 @@ static unsigned long decode_size(unsigned char *str, int len)
  	return size;
  }

+
+#define NL_HASH_TABLE_SIZE		(0xffff + 1)
+#define NL_HASH_NUMBER			(NL_HASH_TABLE_SIZE >> 3)
+
+struct name_list_hash {
+	int ind;
+	struct name_list_hash *next;
+};
+
+static struct name_list_hash **nl_hash_table;
+static unsigned char *nl_hashes;
+
+/* FNV-1a hash */
+static unsigned int hash_name(const char *name)
+{
+	unsigned int hash = 2166136261ul;
+	const char *p = name;
+
+	while (*p) {
+		hash ^= *p++;
+		hash *= 16777619ul;
+	}
+
+	return hash & 0xffff;
+}
+
+static int name_in_list(const char *name)
+{
+	unsigned int h = hash_name(name);
+	struct name_list_hash *entry = nl_hash_table[h];
+
+	while (entry && strcmp(acc_name_buffer->buf + entry->ind, name))
+		entry = entry->next;
+
+	if (entry)
+		return entry->ind;
+
+	/* add name to buffer and create hash reference */
+	entry = xcalloc(1, sizeof(struct name_list_hash));
+	entry->ind = acc_name_buffer->len;
+	strbuf_add(acc_name_buffer, name, strlen(name) + 1);
+
+	entry->next = nl_hash_table[h];
+	nl_hash_table[h] = entry;
+
+	nl_hashes[h / 8] |= h % 8;
+
+	return entry->ind;
+}
+
+static void init_name_list_hash(void)
+{
+	nl_hash_table = xcalloc(NL_HASH_TABLE_SIZE, sizeof(struct name_list_hash));
+	nl_hashes = xcalloc(NL_HASH_NUMBER, 1);
+}
+
+static void cleanup_name_list_hash(void)
+{
+	int i;
+
+	for (i = 0; i < NL_HASH_NUMBER; i++) {
+		int j, ind = nl_hashes[i];
+
+		if (!ind)
+			continue;
+
+		for (j = 0; j < 8; j++) {
+			struct name_list_hash **entryp;
+
+			if (!(ind & 1 << j))
+				continue;
+
+			entryp = &nl_hash_table[i * 8 + j];
+			while (*entryp) {
+				struct name_list_hash *t = (*entryp)->next;
+
+				free(*entryp);
+				*entryp = t;
+			}
+		}
+	} /* code overhang! */
+
+	free(nl_hashes);
+	free(nl_hash_table);
+}
+
  static void add_object_entry(const unsigned char *sha1, struct rc_object_entry *entryp,
-	struct strbuf *merge_str, struct strbuf *split_str)
+	struct strbuf *merge_str, struct strbuf *split_str, char *name, unsigned long size)
  {
  	struct rc_object_entry entry;
-	unsigned char size_str[7];
-	unsigned long size;
+	unsigned char size_str[7], name_str[7];
  	enum object_type type;
  	void *data;

  	if (entryp)
  		sha1 = entryp->sha1;

-	/* retrieve size data */
-	data = read_sha1_file(sha1, &type, &size);
+	if (!size) {
+		/* retrieve size data */
+		data = read_sha1_file(sha1, &type, &size);

-	if (data)
-		free(data);
+		if (data)
+			free(data);
+	}

  	/* initialize! */
  	if (!entryp) {
@@ -1146,6 +1301,9 @@ static void add_object_entry(const unsigned char *sha1, struct rc_object_entry *

  	entryp->size_size = encode_size(size, size_str);

+	if (name)
+		entryp->name_size = encode_size(name_in_list(name), name_str);
+
  	/* write the muvabitch */
  	strbuf_add(acc_buffer, to_disked_rc_object_entry(entryp, 0), sizeof(struct rc_object_entry_ondisk));

@@ -1155,25 +1313,36 @@ static void add_object_entry(const unsigned char *sha1, struct rc_object_entry *
  		strbuf_add(acc_buffer, split_str->buf, split_str->len);

  	strbuf_add(acc_buffer, size_str, entryp->size_size);
+
+	if (name)
+		strbuf_add(acc_buffer, name_str, entryp->name_size);
  }

  /* returns non-zero to continue parsing, 0 to skip */
  typedef int (*dump_tree_fn)(const unsigned char *, const char *, unsigned int); /* sha1, path, mode */

  /* we need to walk the trees by hash, so unfortunately we can't use traverse_trees in tree-walk.c */
-static int dump_tree(struct tree *tree, dump_tree_fn fn)
+static int dump_tree(struct tree *tree, dump_tree_fn fn, char *base)
  {
  	struct tree_desc desc;
  	struct name_entry entry;
  	struct tree *subtree;
-	int r;
+	char concatpath[PATH_MAX];
+	int r, baselen;

  	if (parse_tree(tree))
  		return -1;

+	baselen = strlen(base);
+	strcpy(concatpath, base);
+
  	init_tree_desc(&desc, tree->buffer, tree->size);
  	while (tree_entry(&desc, &entry)) {
-		switch (fn(entry.sha1, entry.path, entry.mode)) {
+		if (baselen + strlen(entry.path) + 1 >= PATH_MAX)
+			die("we have a problem: %s%s is too big for me to handle", base, entry.path);
+		strcpy(concatpath + baselen, entry.path);
+
+		switch (fn(entry.sha1, concatpath, entry.mode)) {
  		case 0:
  			goto continue_loop;
  		default:
@@ -1185,7 +1354,8 @@ static int dump_tree(struct tree *tree, dump_tree_fn fn)
  			if (!subtree)
  				return -2;

-			if ((r = dump_tree(subtree, fn)) < 0)
+			strcat(concatpath, "/");
+			if ((r = dump_tree(subtree, fn, concatpath)) < 0)
  				return r;
  		}

@@ -1199,6 +1369,9 @@ continue_loop:
  static int dump_tree_callback(const unsigned char *sha1, const char *path, unsigned int mode)
  {
  	strbuf_add(acc_buffer, sha1, 20);
+	strbuf_add(acc_buffer, (char *)&acc_name_buffer->len, sizeof(size_t));
+
+	strbuf_add(acc_name_buffer, path, strlen(path) + 1);

  	return 1;
  }
@@ -1212,6 +1385,9 @@ static void tree_addremove(struct diff_options *options,
  		return;

  	strbuf_add(acc_buffer, sha1, 20);
+	strbuf_add(acc_buffer, (char *)&acc_name_buffer->len, sizeof(size_t));
+
+	strbuf_add(acc_name_buffer, concatpath, strlen(concatpath) + 1);
  }

  static void tree_change(struct diff_options *options,
@@ -1224,12 +1400,15 @@ static void tree_change(struct diff_options *options,
  		return;

  	strbuf_add(acc_buffer, new_sha1, 20);
+	strbuf_add(acc_buffer, (char *)&acc_name_buffer->len, sizeof(size_t));
+
+	strbuf_add(acc_name_buffer, concatpath, strlen(concatpath) + 1);
  }

  static int add_unique_objects(struct commit *commit)
  {
  	struct commit_list *list;
-	struct strbuf os, ost, *orig_buf;
+	struct strbuf os, ost, names, *orig_name_buf, *orig_buf;
  	struct diff_options opts;
  	int i, j, next;
  	char is_first = 1;
@@ -1237,13 +1416,17 @@ static int add_unique_objects(struct commit *commit)
  	/* ...no, calculate unique objects */
  	strbuf_init(&os, 0);
  	strbuf_init(&ost, 0);
+	strbuf_init(&names, 0);
  	orig_buf = acc_buffer;
+	orig_name_buf = acc_name_buffer;
+	acc_name_buffer = &names;

  	diff_setup(&opts);
  	DIFF_OPT_SET(&opts, RECURSIVE);
  	DIFF_OPT_SET(&opts, TREE_IN_RECURSIVE);
  	opts.change = tree_change;
  	opts.add_remove = tree_addremove;
+#	define ENTRY_SIZE (20 + sizeof(size_t))

  	/* this is only called for non-ends (ie. all parents interesting) */
  	for (list = commit->parents; list; list = list->next) {
@@ -1254,20 +1437,20 @@ static int add_unique_objects(struct commit *commit)

  		strbuf_setlen(acc_buffer, 0);
  		diff_tree_sha1(list->item->tree->object.sha1, commit->tree->object.sha1, "", &opts);
-		qsort(acc_buffer->buf, acc_buffer->len / 20, 20, (int (*)(const void *, const void *))hashcmp);
+		qsort(acc_buffer->buf, acc_buffer->len / ENTRY_SIZE, ENTRY_SIZE, (int (*)(const void *, const void *))hashcmp);

  		/* take intersection */
  		if (!is_first) {
-			for (next = i = j = 0; i < os.len; i += 20) {
+			for (next = i = j = 0; i < os.len; i += ENTRY_SIZE) {
  				while (j < ost.len && hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)) < 0)
-					j += 20;
+					j += ENTRY_SIZE;

  				if (j >= ost.len || hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)))
  					continue;

  				if (next != i)
-					memcpy(os.buf + next, os.buf + i, 20);
-				next += 20;
+					memcpy(os.buf + next, os.buf + i, ENTRY_SIZE);
+				next += ENTRY_SIZE;
  			}

  			if (next != i)
@@ -1279,29 +1462,37 @@ static int add_unique_objects(struct commit *commit)
  	/* no parents (!) */
  	if (is_first) {
  		acc_buffer = &os;
-		dump_tree(commit->tree, dump_tree_callback);
+		dump_tree(commit->tree, dump_tree_callback, "");
  	}

  	/* the ordering of non-commit objects dosn't really matter, so we're not gonna bother */
  	acc_buffer = orig_buf;
-	for (i = 0; i < os.len; i += 20)
-		add_object_entry((unsigned char *)(os.buf + i), 0, 0, 0);
+	acc_name_buffer = orig_name_buf;
+	for (i = 0; i < os.len; i += ENTRY_SIZE)
+		add_object_entry((unsigned char *)(os.buf + i), 0, 0, 0, names.buf + *(size_t *)(os.buf + i + 20), 0);

  	/* last but not least, the main tree */
-	add_object_entry(commit->tree->object.sha1, 0, 0, 0);
+	add_object_entry(commit->tree->object.sha1, 0, 0, 0, 0, 0);

-	return i / 20 + 1;
+	strbuf_release(&ost);
+	strbuf_release(&os);
+	strbuf_release(&names);
+
+	return i / ENTRY_SIZE + 1;
+#	undef ENTRY_SIZE
  }

  static int add_objects_verbatim_1(struct rev_cache_slice_map *mapping, int *index)
  {
-	unsigned char *map = mapping->map;
  	int i = *index, object_nr = 0;
+	unsigned char *map = mapping->map;
  	struct rc_object_entry *entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
+	unsigned long size;

  	i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);
  	while (i < mapping->size) {
-		int pos = i;
+		char *name;
+		int name_index, pos = i;

  		entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
  		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);
@@ -1311,7 +1502,15 @@ static int add_objects_verbatim_1(struct rev_cache_slice_map *mapping, int *inde
  			return object_nr;
  		}

-		strbuf_add(acc_buffer, map + pos, i - pos);
+		name_index = decode_size(map + pos + RC_ENTRY_NAME_OFFSET(entry), entry->name_size);
+		if (name_index && name_index < mapping->name_size)
+			name = mapping->names + name_index;
+		else
+			name = 0;
+
+		size = decode_size(map + pos + RC_ENTRY_SIZE_OFFSET(entry), entry->size_size);
+
+		add_object_entry(0, entry, 0, 0, name, size);
  		object_nr++;
  	}

@@ -1396,6 +1595,7 @@ void init_rev_cache_info(struct rev_cache_info *rci)
  	rci->overwrite_all = 0;

  	rci->add_to_pending = 1;
+	rci->add_names = 1;

  	rci->ignore_size = 0;
  }
@@ -1420,9 +1620,9 @@ int make_cache_slice(struct rev_cache_info *rci,
  	struct rc_slice_header head;
  	struct commit *commit;
  	unsigned char sha1[20];
-	struct strbuf merge_paths, split_paths;
+	struct strbuf merge_paths, split_paths, namelist;
  	int object_nr, total_sz, fd;
-	char file[PATH_MAX], *newfile;
+	char file[PATH_MAX], null, *newfile;
  	struct rev_cache_info *trci;
  	git_SHA_CTX ctx;

@@ -1437,7 +1637,13 @@ int make_cache_slice(struct rev_cache_info *rci,
  	strbuf_init(&endlist, 0);
  	strbuf_init(&merge_paths, 0);
  	strbuf_init(&split_paths, 0);
+	strbuf_init(&namelist, 0);
  	acc_buffer = &buffer;
+	acc_name_buffer = &namelist;
+
+	null = 0;
+	strbuf_add(&namelist, &null, 1);
+	init_name_list_hash();

  	if (!revs) {
  		revs = &therevs;
@@ -1468,6 +1674,7 @@ int make_cache_slice(struct rev_cache_info *rci,
  	trci = &revs->rev_cache_info;
  	init_rev_cache_info(trci);
  	trci->add_to_pending = 0;
+	trci->add_names = 0;

  	setup_revisions(0, 0, revs, 0);
  	if (prepare_revision_walk(revs))
@@ -1505,7 +1712,7 @@ int make_cache_slice(struct rev_cache_info *rci,

  		commit->indegree = 0;

-		add_object_entry(0, &object, &merge_paths, &split_paths);
+		add_object_entry(0, &object, &merge_paths, &split_paths, 0, 0);
  		object_nr++;

  		if (rci->objects && !object.is_end) {
@@ -1531,10 +1738,16 @@ int make_cache_slice(struct rev_cache_info *rci,
  		total_sz += buffer.len;
  	}

+	/* write path name lookup list */
+	head.name_size = htonl(namelist.len);
+	write_in_full(fd, namelist.buf, namelist.len);
+
  	/* go ahead a free some stuff... */
  	strbuf_release(&buffer);
  	strbuf_release(&merge_paths);
  	strbuf_release(&split_paths);
+	strbuf_release(&namelist);
+	cleanup_name_list_hash();
  	if (path_sz)
  		free(paths);
  	while (path_track_alloc)
@@ -1992,6 +2205,7 @@ int fuse_cache_slices(struct rev_cache_info *rci, struct rev_info *revs)
  	for (i = idx_head.cache_nr - 1; i >= 0; i--) {
  		struct rev_cache_slice_map *map = rci->maps + i;
  		struct stat fi;
+		struct rc_slice_header head;
  		int fd;

  		if (!map->size)
@@ -2004,13 +2218,20 @@ int fuse_cache_slices(struct rev_cache_info *rci, struct rev_info *revs)
  			continue;
  		if (fi.st_size < sizeof(struct rc_slice_header))
  			continue;
+		if (get_cache_slice_header(fd, idx_caches + i * 20, fi.st_size, &head))
+			continue;

-		map->map = xmmap(0, fi.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+		map->map = xmmap(0, head.size, PROT_READ, MAP_PRIVATE, fd, 0);
  		if (map->map == MAP_FAILED)
  			continue;

+		lseek(fd, head.size, SEEK_SET);
+		map->names = xcalloc(head.name_size, 1);
+		read_in_full(fd, map->names, head.name_size);
+
  		close(fd);
-		map->size = fi.st_size;
+		map->size = head.size;
+		map->name_size = head.name_size;
  	}

  	rci->make_index = 0;
@@ -2027,6 +2248,7 @@ int fuse_cache_slices(struct rev_cache_info *rci, struct rev_info *revs)
  		if (!map->size)
  			continue;

+		free(map->names);
  		munmap(map->map, map->size);
  	}
  	free(rci->maps);
@@ -2048,7 +2270,6 @@ static int verify_cache_slice(const char *slice_path, unsigned char *sha1)
  {
  	struct rc_slice_header head;
  	int fd, len, retval = -1;
-	unsigned char *map = MAP_FAILED;
  	struct stat fi;

  	len = strlen(slice_path);
@@ -2063,17 +2284,12 @@ static int verify_cache_slice(const char *slice_path, unsigned char *sha1)
  	if (fstat(fd, &fi) || fi.st_size < sizeof(head))
  		goto end;

-	map = xmmap(0, sizeof(head), PROT_READ, MAP_PRIVATE, fd, 0);
-	if (map == MAP_FAILED)
-		goto end;
-	if (get_cache_slice_header(sha1, map, fi.st_size, &head))
+	if (get_cache_slice_header(fd, sha1, fi.st_size, &head))
  		goto end;

  	retval = 0;

  end:
-	if (map != MAP_FAILED)
-		munmap(map, sizeof(head));
  	if (fd > 0)
  		close(fd);

diff --git a/rev-cache.h b/rev-cache.h
index a1af337..0fa9b44 100644
--- a/rev-cache.h
+++ b/rev-cache.h
@@ -10,8 +10,14 @@
  #define RC_OBTAIN_OBJECT_ENTRY(p)			from_disked_rc_object_entry((struct rc_object_entry_ondisk *)(p), 0)
  #define RC_OBTAIN_INDEX_ENTRY(p)			from_disked_rc_index_entry((struct rc_index_entry_ondisk *)(p), 0)

-#define RC_ACTUAL_OBJECT_ENTRY_SIZE(e)		(sizeof(struct rc_object_entry_ondisk) + RC_PATH_SIZE((e)->merge_nr + (e)->split_nr) + (e)->size_size)
-#define RC_ENTRY_SIZE_OFFSET(e)				(RC_ACTUAL_OBJECT_ENTRY_SIZE(e) - (e)->size_size)
+#define RC_ACTUAL_OBJECT_ENTRY_SIZE(e)	(\
+	sizeof(struct rc_object_entry_ondisk) + \
+	RC_PATH_SIZE((e)->merge_nr + (e)->split_nr) + \
+	(e)->size_size + \
+	(e)->name_size\
+)
+#define RC_ENTRY_SIZE_OFFSET(e)			(RC_ACTUAL_OBJECT_ENTRY_SIZE(e) - (e)->name_size - (e)->size_size)
+#define RC_ENTRY_NAME_OFFSET(e)			(RC_ACTUAL_OBJECT_ENTRY_SIZE(e) - (e)->name_size)

  /* single index maps objects to cache files */
  struct rc_index_header {
@@ -50,6 +56,8 @@ struct rc_slice_header {
  	uint32_t size;

  	unsigned char sha1[20];
+
+	uint32_t name_size;
  };

  struct rc_object_entry_ondisk {
@@ -76,7 +84,8 @@ struct rc_object_entry {
  	unsigned char merge_nr; /* : 7 */
  	unsigned char split_nr; /* : 7 */
  	unsigned size_size:3;
-	unsigned padding:5;
+	unsigned name_size:3;
+	unsigned padding:2;

  	uint32_t date;
  	uint16_t path;
@@ -84,6 +93,7 @@ struct rc_object_entry {
  	/* merge paths */
  	/* split paths */
  	/* size */
+	/* name id */
  };

  struct rc_index_entry *from_disked_rc_index_entry(struct rc_index_entry_ondisk *src, struct rc_index_entry *dst);
diff --git a/revision.h b/revision.h
index cc5c259..c62e85b 100644
--- a/revision.h
+++ b/revision.h
@@ -26,6 +26,9 @@ struct rev_cache_slice_map {
  	unsigned char *map;
  	int size;
  	int last_index;
+
+	char *names;
+	int name_size;
  };

  struct rev_cache_info {
@@ -39,7 +42,8 @@ struct rev_cache_info {
  	unsigned overwrite_all : 1;

  	/* traversal flags */
-	unsigned add_to_pending : 1;
+	unsigned add_to_pending : 1,
+		add_names : 1;

  	/* fuse options */
  	unsigned int ignore_size;
diff --git a/t/t6017-rev-cache-list.sh b/t/t6017-rev-cache-list.sh
index 982fb15..f0f3bcf 100755
--- a/t/t6017-rev-cache-list.sh
+++ b/t/t6017-rev-cache-list.sh
@@ -4,8 +4,10 @@ test_description='git rev-cache tests'
  . ./test-lib.sh

  test_cmp_sorted() {
-	grep -io "[a-f0-9]*" $1 | sort >.tmpfile1 &&
-	grep -io "[a-f0-9]*" $2 | sort >.tmpfile2 &&
+# note that we're tip-toeing around the corner case of two objects/names
+# for the same SHA-1 => discrepencies between cached and non-cached walks
+	sort $1 >.tmpfile1 &&
+	sort $2 >.tmpfile2 &&
  	test_cmp .tmpfile1 .tmpfile2
  }

@@ -15,6 +17,8 @@ test_cmp_sorted() {
  # reuse
  test_expect_success 'init repo' '
  	echo bla >file &&
+	mkdir amaindir &&
+	echo watskeburt >amaindir/file &&
  	git add . &&
  	git commit -m "bla" &&

-- 
tg: (2b7d538..) t/revcache/names (depends on: t/revcache/docs)

^ permalink raw reply related

* Re: [PATCH 4/6 (v4)] administrative functions for rev-cache, start of integration into git
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkstatdk399@sirnot.private>

This patch, fourth, contains miscellaneous (maintenance) features:
  - support for cache slice fusion, index regeneration and object size caching
  - non-commit object generation refactored
  - porcelain updated to support feature additions

The beginnings of integration into git are present in this patch, mainly
centered on caching object size; the object generation is refactored to more
elegantly exploit this.  Fusion allows smaller (incremental) slices to be
coagulated into a larger slice, reducing overhead, while index regeneration
enables repair or cleaning of the cache index.

Note that tests for these features are included in the following patch, as they
take advantage of the rev-cache's integration into the revision walker.

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
  builtin-gc.c        |    9 +
  builtin-rev-cache.c |   77 ++++++-
  rev-cache.c         |  719 +++++++++++++++++++++++++++++++++++++++++++++------
  rev-cache.h         |    9 +-
  revision.h          |   16 +-
  5 files changed, 750 insertions(+), 80 deletions(-)

diff --git a/builtin-gc.c b/builtin-gc.c
index 7d3e9cc..c92511a 100644
--- a/builtin-gc.c
+++ b/builtin-gc.c
@@ -22,6 +22,7 @@ static const char * const builtin_gc_usage[] = {
  	NULL
  };

+static char do_rev_cache = 0;
  static int pack_refs = 1;
  static int aggressive_window = 250;
  static int gc_auto_threshold = 6700;
@@ -34,9 +35,14 @@ static const char *argv_reflog[] = {"reflog", "expire", "--all", NULL};
  static const char *argv_repack[MAX_ADD] = {"repack", "-d", "-l", NULL};
  static const char *argv_prune[] = {"prune", "--expire", NULL, NULL};
  static const char *argv_rerere[] = {"rerere", "gc", NULL};
+static const char *argv_rev_cache[] = {"rev-cache", "fuse", "--all", "--ignore-size", NULL};

  static int gc_config(const char *var, const char *value, void *cb)
  {
+	if (!strcmp(var, "gc.revcache")) {
+		do_rev_cache = 1;
+		return 0;
+	}
  	if (!strcmp(var, "gc.packrefs")) {
  		if (value && !strcmp(value, "notbare"))
  			pack_refs = -1;
@@ -244,6 +250,9 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
  	if (run_command_v_opt(argv_rerere, RUN_GIT_CMD))
  		return error(FAILED_RUN, argv_rerere[0]);

+	if (do_rev_cache && run_command_v_opt(argv_rev_cache, RUN_GIT_CMD))
+		return error(FAILED_RUN, argv_rev_cache[0]);
+
  	if (auto_gc && too_many_loose_objects())
  		warning("There are too many unreachable loose objects; "
  			"run 'git prune' to remove them.");
diff --git a/builtin-rev-cache.c b/builtin-rev-cache.c
index 6eb7065..b894c54 100644
--- a/builtin-rev-cache.c
+++ b/builtin-rev-cache.c
@@ -5,6 +5,8 @@
  #include "revision.h"
  #include "rev-cache.h"

+unsigned long default_ignore_size = 50 * 1024 * 1024; /* 50mb */
+
  /* porcelain for rev-cache.c */
  static int handle_add(int argc, const char *argv[]) /* args beyond this command */
  {
@@ -24,7 +26,7 @@ static int handle_add(int argc, const char *argv[]) /* args beyond this command
  		if (!strcmp(argv[i], "--stdin"))
  			dostdin = 1;
  		else if (!strcmp(argv[i], "--fresh") || !strcmp(argv[i], "--incremental"))
-			starts_from_slices(&revs, UNINTERESTING);
+			starts_from_slices(&revs, UNINTERESTING, 0, 0);
  		else if (!strcmp(argv[i], "--not"))
  			flags ^= UNINTERESTING;
  		else if (!strcmp(argv[i], "--legs"))
@@ -150,6 +152,57 @@ static int handle_walk(int argc, const char *argv[])
  	return 0;
  }

+static int handle_fuse(int argc, const char *argv[])
+{
+	struct rev_info revs;
+	struct rev_cache_info rci;
+	const char *args[5];
+	int i, argn = 0;
+	char add_all = 0;
+
+	init_revisions(&revs, 0);
+	init_rev_cache_info(&rci);
+	args[argn++] = "rev-list";
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--all")) {
+			args[argn++] = "--all";
+			setup_revisions(argn, args, &revs, 0);
+			add_all = 1;
+		} else if (!strcmp(argv[i], "--no-objects"))
+			rci.objects = 0;
+		else if (!strncmp(argv[i], "--ignore-size", 13)) {
+			unsigned long sz;
+
+			if (argv[i][13] == '=')
+				git_parse_ulong(argv[i] + 14, &sz);
+			else
+				sz = default_ignore_size;
+
+			rci.ignore_size = sz;
+		} else
+			continue;
+	}
+
+	if (!add_all)
+		starts_from_slices(&revs, 0, 0, 0);
+
+	return fuse_cache_slices(&rci, &revs);
+}
+
+static int handle_index(int argc, const char *argv[])
+{
+	return regenerate_cache_index(0);
+}
+
+static int handle_alt(int argc, const char *argv[])
+{
+	if (argc < 1)
+		return -1;
+
+	return make_cache_slice_pointer(0, argv[0]);
+}
+
  static int handle_help(void)
  {
  	char *usage = "\
@@ -180,12 +233,28 @@ commands:\n\
  	return 0;
  }

+static int rev_cache_config(const char *k, const char *v, void *cb)
+{
+	/* this could potentially be related to pack.windowmemory, but we want a max around 50mb,
+	 * and .windowmemory is often >700mb, with *large* variations */
+	if (!strcmp(k, "revcache.ignoresize")) {
+		int t;
+
+		t = git_config_ulong(k, v);
+		if (t)
+			default_ignore_size = t;
+	}
+
+	return 0;
+}
+
  int cmd_rev_cache(int argc, const char *argv[], const char *prefix)
  {
  	const char *arg;
  	int r;

  	git_config(git_default_config, NULL);
+	git_config(rev_cache_config, NULL);

  	if (argc > 1)
  		arg = argv[1];
@@ -196,8 +265,14 @@ int cmd_rev_cache(int argc, const char *argv[], const char *prefix)
  	argv += 2;
  	if (!strcmp(arg, "add"))
  		r = handle_add(argc, argv);
+	else if (!strcmp(arg, "fuse"))
+		r = handle_fuse(argc, argv);
  	else if (!strcmp(arg, "walk"))
  		r = handle_walk(argc, argv);
+	else if (!strcmp(arg, "index"))
+		r = handle_index(argc, argv);
+	else if (!strcmp(arg, "alt"))
+		r = handle_alt(argc, argv);
  	else
  		return handle_help();

diff --git a/rev-cache.c b/rev-cache.c
index ef6b58a..e401978 100644
--- a/rev-cache.c
+++ b/rev-cache.c
@@ -9,6 +9,13 @@
  #include "revision.h"
  #include "rev-cache.h"
  #include "run-command.h"
+#include "string-list.h"
+
+struct cache_slice_pointer {
+	char signature[8]; /* REVCOPTR */
+	char version;
+	char path[PATH_MAX + 1];
+};

  /* list resembles pack index format */
  static uint32_t fanout[0xff + 2];
@@ -259,27 +266,45 @@ unsigned char *get_cache_slice(struct commit *commit)

  /* traversal */

-static void handle_noncommit(struct rev_info *revs, unsigned char *ptr, struct rc_object_entry *entry)
+static unsigned long decode_size(unsigned char *str, int len);
+
+static void handle_noncommit(struct rev_info *revs, struct commit *commit, unsigned char *ptr, struct rc_object_entry *entry)
  {
-	struct object *obj = 0;
+	struct blob *blob;
+	struct tree *tree;
+	struct object *obj;
+	unsigned long size;

+	size = decode_size(ptr + RC_ENTRY_SIZE_OFFSET(entry), entry->size_size);
  	switch (entry->type) {
  	case OBJ_TREE:
-		if (revs->tree_objects)
-			obj = (struct object *)lookup_tree(entry->sha1);
+		if (!revs->tree_objects)
+			return;
+
+		tree = lookup_tree(entry->sha1);
+		if (!tree)
+			return;
+
+		tree->size = size;
+		commit->tree = tree;
+		obj = (struct object *)tree;
  		break;
+
  	case OBJ_BLOB:
-		if (revs->blob_objects)
-			obj = (struct object *)lookup_blob(entry->sha1);
-		break;
-	case OBJ_TAG:
-		if (revs->tag_objects)
-			obj = (struct object *)lookup_tag(entry->sha1);
+		if (!revs->blob_objects)
+			return;
+
+		blob = lookup_blob(entry->sha1);
+		if (!blob)
+			return;
+
+		obj = (struct object *)blob;
  		break;
-	}

-	if (!obj)
+	default:
+		/* tag objects aren't really supposed to be here */
  		return;
+	}

  	obj->flags |= FACE_VALUE;
  	add_pending_object(revs, obj, "");
@@ -375,7 +400,7 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  		/* add extra objects if necessary */
  		if (entry->type != OBJ_COMMIT) {
  			if (consume_children)
-				handle_noncommit(revs, map + index, entry);
+				handle_noncommit(revs, co, map + index, entry);

  			continue;
  		} else
@@ -409,6 +434,8 @@ static int traverse_cache_slice_1(struct rc_slice_header *head, unsigned char *m
  			if (last_objects[path]) {
  				parse_commit(last_objects[path]);

+				/* we needn't worry about the unique field; that will be valid as
+				 * long as we're not a end entry */
  				last_objects[path]->object.flags &= ~FACE_VALUE;
  				last_objects[path] = 0;
  			}
@@ -541,6 +568,48 @@ static int get_cache_slice_header(unsigned char *cache_sha1, unsigned char *map,
  	return 0;
  }

+int open_cache_slice(unsigned char *sha1, int flags)
+{
+	int fd;
+	char signature[8];
+
+	fd = open(git_path("rev-cache/%s", sha1_to_hex(sha1)), flags);
+	if (fd <= 0)
+		goto end;
+
+	if (read(fd, signature, 8) != 8)
+		goto end;
+
+	/* a normal revision slice */
+	if (!memcmp(signature, "REVCACHE", 8)) {
+		lseek(fd, 0, SEEK_SET);
+		return fd;
+	}
+
+	/* slice pointer */
+	if (!memcmp(signature, "REVCOPTR", 8)) {
+		struct cache_slice_pointer ptr;
+
+		lseek(fd, 0, SEEK_SET);
+		if (read_in_full(fd, &ptr, sizeof(ptr)) != sizeof(ptr))
+			goto end;
+
+		if (ptr.version != SUPPORTED_REVCOPTR_VERSION)
+			goto end;
+
+		close(fd);
+		fd = open(ptr.path, flags);
+
+		return fd;
+	}
+
+end:
+	if (fd > 0)
+		close(fd);
+
+	return -1;
+}
+
  int traverse_cache_slice(struct rev_info *revs,
  	unsigned char *cache_sha1, struct commit *commit,
  	unsigned long *date_so_far, int *slop_so_far,
@@ -564,7 +633,7 @@ int traverse_cache_slice(struct rev_info *revs,

  	memset(&head, 0, sizeof(struct rc_slice_header));

-	fd = open(git_path("rev-cache/%s", sha1_to_hex(cache_sha1)), O_RDONLY);
+	fd = open_cache_slice(cache_sha1, O_RDONLY);
  	if (fd == -1)
  		goto end;
  	if (fstat(fd, &fi) || fi.st_size < sizeof(struct rc_slice_header))
@@ -591,6 +660,68 @@ end:

  /* generation */

+static int is_endpoint(struct commit *commit)
+{
+	struct commit_list *list = commit->parents;
+
+	while (list) {
+		if (!(list->item->object.flags & UNINTERESTING))
+			return 0;
+
+		list = list->next;
+	}
+
+	return 1;
+}
+
+/* ensures branch is self-contained: parents are either all interesting or all uninteresting */
+static void make_legs(struct rev_info *revs)
+{
+	struct commit_list *list, **plist;
+	int total = 0;
+
+	/* attach plist to end of commits list */
+	list = revs->commits;
+	while (list && list->next)
+		list = list->next;
+
+	if (list)
+		plist = &list->next;
+	else
+		return;
+
+	/* duplicates don't matter, as get_revision() ignores them */
+	for (list = revs->commits; list; list = list->next) {
+		struct commit *item = list->item;
+		struct commit_list *parents = item->parents;
+
+		if (item->object.flags & UNINTERESTING)
+			continue;
+		if (is_endpoint(item))
+			continue;
+
+		while (parents) {
+			struct commit *p = parents->item;
+			parents = parents->next;
+
+			if (!(p->object.flags & UNINTERESTING))
+				continue;
+
+			p->object.flags &= ~UNINTERESTING;
+			parse_commit(p);
+			plist = &commit_list_insert(p, plist)->next;
+
+			if (!(p->object.flags & SEEN))
+				total++;
+		}
+	}
+
+	if (total)
+		sort_in_topological_order(&revs->commits, 1);
+
+}
+
+
  struct path_track {
  	struct commit *commit;
  	int path; /* for keeping track of children */
@@ -680,7 +811,7 @@ static void handle_paths(struct commit *commit, struct rc_object_entry *object,
  	int child_nr, parent_nr, open_parent_nr, this_path;
  	struct commit_list *list;
  	struct commit *first_parent;
-	struct path_track **ppt, *pt;
+	struct pa\th_track **ppt, *pt;

  	/* we can only re-use a closed path once all it's children have been encountered,
  	 * as we need to keep track of commit boundaries */
@@ -779,31 +910,76 @@ static void handle_paths(struct commit *commit, struct rc_object_entry *object,
  }


-static void add_object_entry(const unsigned char *sha1, int type, struct rc_object_entry *nothisone,
+static int encode_size(unsigned long size, unsigned char *out)
+{
+	int len = 0;
+
+	while (size) {
+		*out++ = (unsigned char)(size & 0xff);
+		size >>= 8;
+		len++;
+	}
+
+	return len;
+}
+
+static unsigned long decode_size(unsigned char *str, int len)
+{
+	unsigned long size = 0;
+	int shift = 0;
+
+	while (len--) {
+		size |= (unsigned long)*str << shift;
+		shift += 8;
+		str++;
+	}
+
+	return size;
+}
+
+static void add_object_entry(const unsigned char *sha1, struct rc_object_entry *entryp,
  	struct strbuf *merge_str, struct strbuf *split_str)
  {
-	struct rc_object_entry object;
+	struct rc_object_entry entry;
+	unsigned char size_str[7];
+	unsigned long size;
+	enum object_type type;
+	void *data;

-	if (!nothisone) {
-		memset(&object, 0, sizeof(object));
-		object.sha1 = (unsigned char *)sha1;
-		object.type = type;
+	if (entryp)
+		sha1 = entryp->sha1;
+
+	/* retrieve size data */
+	data = read_sha1_file(sha1, &type, &size);
+
+	if (data)
+		free(data);
+
+	/* initialize! */
+	if (!entryp) {
+		memset(&entry, 0, sizeof(entry));
+		entry.sha1 = (unsigned char *)sha1;
+		entry.type = type;

  		if (merge_str)
-			object.merge_nr = merge_str->len / sizeof(uint16_t);
+			entry.merge_nr = merge_str->len / sizeof(uint16_t);
  		if (split_str)
-			object.split_nr = split_str->len / sizeof(uint16_t);
+			entry.split_nr = split_str->len / sizeof(uint16_t);

-		nothisone = &object;
+		entryp = &entry;
  	}

-	strbuf_add(acc_buffer, to_disked_rc_object_entry(nothisone, 0), sizeof(struct rc_object_entry_ondisk));
+	entryp->size_size = encode_size(size, size_str);

-	if (merge_str && merge_str->len)
+	/* write the muvabitch */
+	strbuf_add(acc_buffer, to_disked_rc_object_entry(entryp, 0), sizeof(struct rc_object_entry_ondisk));
+
+	if (merge_str)
  		strbuf_add(acc_buffer, merge_str->buf, merge_str->len);
-	if (split_str && split_str->len)
+	if (split_str)
  		strbuf_add(acc_buffer, split_str->buf, split_str->len);

+	strbuf_add(acc_buffer, size_str, entryp->size_size);
  }

  /* returns non-zero to continue parsing, 0 to skip */
@@ -847,12 +1023,7 @@ continue_loop:

  static int dump_tree_callback(const unsigned char *sha1, const char *path, unsigned int mode)
  {
-	unsigned char data[21];
-
-	hashcpy(data, sha1);
-	data[20] = !!S_ISDIR(mode);
-
-	strbuf_add(acc_buffer, data, 21);
+	strbuf_add(acc_buffer, sha1, 20);

  	return 1;
  }
@@ -862,15 +1033,10 @@ static void tree_addremove(struct diff_options *options,
  	const unsigned char *sha1,
  	const char *concatpath)
  {
-	unsigned char data[21];
-
  	if (whatnow != '+')
  		return;

-	hashcpy(data, sha1);
-	data[20] = !!S_ISDIR(mode);
-
-	strbuf_add(acc_buffer, data, 21);
+	strbuf_add(acc_buffer, sha1, 20);
  }

  static void tree_change(struct diff_options *options,
@@ -879,26 +1045,10 @@ static void tree_change(struct diff_options *options,
  	const unsigned char *new_sha1,
  	const char *concatpath)
  {
-	unsigned char data[21];
-
  	if (!hashcmp(old_sha1, new_sha1))
  		return;

-	hashcpy(data, new_sha1);
-	data[20] = !!S_ISDIR(new_mode);
-
-	strbuf_add(acc_buffer, data, 21);
-}
-
-static int sort_type_hash(const void *a, const void *b)
-{
-	const unsigned char *sa = (const unsigned char *)a,
-		*sb = (const unsigned char *)b;
-
-	if (sa[20] == sb[20])
-		return hashcmp(sa, sb);
-
-	return sa[20] > sb[20] ? -1 : 1;
+	strbuf_add(acc_buffer, new_sha1, 20);
  }

  static int add_unique_objects(struct commit *commit)
@@ -909,6 +1059,7 @@ static int add_unique_objects(struct commit *commit)
  	int i, j, next;
  	char is_first = 1;

+	/* ...no, calculate unique objects */
  	strbuf_init(&os, 0);
  	strbuf_init(&ost, 0);
  	orig_buf = acc_buffer;
@@ -928,20 +1079,20 @@ static int add_unique_objects(struct commit *commit)

  		strbuf_setlen(acc_buffer, 0);
  		diff_tree_sha1(list->item->tree->object.sha1, commit->tree->object.sha1, "", &opts);
-		qsort(acc_buffer->buf, acc_buffer->len / 21, 21, (int (*)(const void *, const void *))hashcmp);
+		qsort(acc_buffer->buf, acc_buffer->len / 20, 20, (int (*)(const void *, const void *))hashcmp);

  		/* take intersection */
  		if (!is_first) {
-			for (next = i = j = 0; i < os.len; i += 21) {
+			for (next = i = j = 0; i < os.len; i += 20) {
  				while (j < ost.len && hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)) < 0)
-					j += 21;
+					j += 20;

  				if (j >= ost.len || hashcmp((unsigned char *)(ost.buf + j), (unsigned char *)(os.buf + i)))
  					continue;

  				if (next != i)
-					memcpy(os.buf + next, os.buf + i, 21);
-				next += 21;
+					memcpy(os.buf + next, os.buf + i, 20);
+				next += 20;
  			}

  			if (next != i)
@@ -950,25 +1101,102 @@ static int add_unique_objects(struct commit *commit)
  			is_first = 0;
  	}

+	/* no parents (!) */
  	if (is_first) {
  		acc_buffer = &os;
  		dump_tree(commit->tree, dump_tree_callback);
  	}

-	if (os.len)
-		qsort(os.buf, os.len / 21, 21, sort_type_hash);
-
+	/* the ordering of non-commit objects dosn't really matter, so we're not gonna bother */
  	acc_buffer = orig_buf;
-	for (i = 0; i < os.len; i += 21)
-		add_object_entry((unsigned char *)(os.buf + i), os.buf[i + 20] ? OBJ_TREE : OBJ_BLOB, 0, 0, 0);
+	for (i = 0; i < os.len; i += 20)
+		add_object_entry((unsigned char *)(os.buf + i), 0, 0, 0);

  	/* last but not least, the main tree */
-	add_object_entry(commit->tree->object.sha1, OBJ_TREE, 0, 0, 0);
+	add_object_entry(commit->tree->object.sha1, 0, 0, 0);
+
+	return i / 20 + 1;
+}
+
+static int add_objects_verbatim_1(struct rev_cache_slice_map *mapping, int *index)
+{
+	unsigned char *map = mapping->map;
+	int i = *index, object_nr = 0;
+	struct rc_object_entry *entry = RC_OBTAIN_OBJECT_ENTRY(map + i);
+
+	i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);
+	while (i < mapping->size) {
+		int pos = i;

-	strbuf_release(&ost);
-	strbuf_release(&os);
+		entry = RC_OBTAIN_OBJECT_ENTRY(map + i;
+		i += RC_ACTUAL_OBJECT_ENTRY_SIZE(entry);
+
+		if (entry->type == OBJ_COMMIT) {
+			*index = pos;
+			return object_nr;
+		}

-	return i / 21 + 1;
+		strbuf_add(acc_buffer, map + pos, i - pos);
+		object_nr++;
+	}
+
+	*index = 0;
+	return object_nr;
+}
+
+static int add_objects_verbatim(struct rev_cache_info *rci, struct commit *commit)
+{
+	struct rev_cache_slice_map *map;
+	char found = 0;
+	struct rc_index_entry *ie;
+	struct rc_object_entry *entry;
+	int object_nr, i;
+
+	if (!rci->maps)
+		return -1;
+
+	/* check if we can continue where we left off */
+	map = rci->last_map;
+	if (!map)
+		goto search_me;
+
+	i = map->last_index;
+	entry = RC_OBTAIN_OBJECT_ENTRY(map->map + i);
+	if (hashcmp(entry->sha1, commit->object.sha1))
+		goto search_me;
+
+	found = 1;
+
+search_me:
+	if (!found) {
+		ie = search_index(commit->object.sha1);
+		if (!ie || ie->cache_index >= idx_head.cache_nr)
+			return -2;
+
+		map = rci->maps + ie->cache_index;
+		if (!map->size)
+			return -3;
+
+		i = ie->pos;
+		entry = RC_OBTAIN_OBJECT_ENTRY(map->map + i);
+		if (entry->type != OBJ_COMMIT || hashcmp(entry->sha1, commit->object.sha1))
+			return -4;
+	}
+
+	/* can't handle end commits */
+	if (entry->is_end)
+		return -5;
+
+	object_nr = add_objects_verbatim_1(map, &i);
+
+	/* remember this */
+	if (i) {
+		rci->last_map = map;
+		map->last_index = i;
+	} else
+		rci->last_map = 0;
+
+	return object_nr;
  }

  static void init_revcache_directory(void)
@@ -983,9 +1211,14 @@ static void init_revcache_directory(void)

  void init_rev_cache_info(struct rev_cache_info *rci)
  {
+	memset(rci, 0, sizeof(struct rev_cache_info));
+
  	rci->objects = 1;
  	rci->legs = 0;
  	rci->make_index = 1;
+	rci->fuse_me = 0;
+
+	rci->overwrite_all = 0;

  	rci->add_to_pending = 1;

@@ -1065,9 +1298,13 @@ int make_cache_slice(struct rev_cache_info *rci,
  	if (prepare_revision_walk(revs))
  		die("died preparing revision walk");

+	if (rci->legs)
+		make_legs(revs);
+
  	object_nr = total_sz = 0;
  	while ((commit = get_revision(revs)) != 0) {
  		struct rc_object_entry object;
+		int t;

  		strbuf_setlen(&merge_paths, 0);
  		strbuf_setlen(&split_paths, 0);
@@ -1093,12 +1330,17 @@ int make_cache_slice(struct rev_cache_info *rci,

  		commit->indegree = 0;

-		add_object_entry(0, 0, &object, &merge_paths, &split_paths);
+		add_object_entry(0, &object, &merge_paths, &split_paths);
  		object_nr++;

-		/* add all unique children for this commit */
-		if (rci->objects && !object.is_end)
-			object_nr += add_unique_objects(commit);
+		if (rci->objects && !object.is_end) {
+			if (rci->fuse_me && (t = add_objects_verbatim(rci, commit)) >= 0)
+				/* yay!  we did it! */
+				object_nr += t;
+			else
+				/* add all unique children for this commit */
+				object_nr += add_unique_objects(commit);
+		}

  		/* print every ~1MB or so */
  		if (buffer.len > 1000000) {
@@ -1223,6 +1465,8 @@ int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
  	unsigned char *map;
  	unsigned long max_date;

+	maybe_fill_with_defaults(rci);
+
  	if (!idx_map)
  		init_index();

@@ -1287,7 +1531,7 @@ int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
  		} else
  			disked_entry = search_index_1(object_entry->sha1);

-		if (disked_entry && !object_entry->is_start)
+		if (disked_entry && !object_entry->is_start && !rci->overwrite_all)
  			continue;
  		else if (disked_entry) {
  			/* mmm, pointer arithmetic... tasty */  /* (entry - idx_map = offset, so cast is valid) */
@@ -1341,8 +1585,7 @@ int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
  }


-/* add start-commits from each cache slice (uninterestingness will be propogated) */
-void starts_from_slices(struct rev_info *revs, unsigned int flags)
+void starts_from_slices(struct rev_info *revs, unsigned int flags, unsigned char *which, int n)
  {
  	struct commit *commit;
  	int i;
@@ -1358,6 +1601,18 @@ void starts_from_slices(struct rev_info *revs, unsigned int flags)
  		if (!entry->is_start)
  			continue;

+		/* only include entries in 'which' slices */
+		if (n) {
+			int j;
+
+			for (j = 0; j < n; j++)
+				if (!hashcmp(idx_caches + entry->cache_index * 20, which + j * 20))
+					break;
+
+			if (j == n)
+				continue;
+		}
+
  		commit = lookup_commit(entry->sha1);
  		if (!commit)
  			continue;
@@ -1367,3 +1622,313 @@ void starts_from_slices(struct rev_info *revs, unsigned int flags)
  	}

  }
+
+
+struct slice_fd_time {
+	unsigned char sha1[20];
+	int fd;
+	struct stat fi;
+};
+
+int slice_time_sort(const void *a, const void *b)
+{
+	unsigned long at, bt;
+
+	at = ((struct slice_fd_time *)a)->fi.st_ctime;
+	bt = ((struct slice_fd_time *)b)->fi.st_ctime;
+
+	if (at == bt)
+		return 0;
+
+	return at > bt ? 1 : -1;
+}
+
+int regenerate_cache_index(struct rev_cache_info *rci)
+{
+	DIR *dirh;
+	int i;
+	struct slice_fd_time info;
+	struct strbuf slices;
+
+	/* first remove old index if it exists */
+	unlink_or_warn(git_path("rev-cache/index"));
+
+	strbuf_init(&slices, 0);
+
+	dirh = opendir(git_path("rev-cache"));
+	if (dirh) {
+		struct dirent *de;
+		struct stat fi;
+		int fd;
+		unsigned char sha1[20];
+
+		while ((de = readdir(dirh))) {
+			if (de->d_name[0] == '.')
+				continue;
+
+			if (get_sha1_hex(de->d_name, sha1))
+				continue;
+
+			/* open with RDWR because of mmap call in make_cache_index() */
+			fd = open_cache_slice(sha1, O_RDONLY);
+			if (fd < 0 || fstat(fd, &fi)) {
+				warning("bad cache found [%s]; fuse recommended", de->d_name);
+				if (fd > 0)
+					close(fd);
+				continue;
+			}
+
+			hashcpy(info.sha1, sha1);
+			info.fd = fd;
+			memcpy(&info.fi, &fi, sizeof(struct stat));
+
+			strbuf_add(&slices, &info, sizeof(info));
+		}
+
+		closedir(dirh);
+	}
+
+	/* we want oldest first -> upon overlap, older slices are more likely to have a larger section,
+	 * as of the overlapped commit */
+	qsort(slices.buf, slices.len / sizeof(info), sizeof(info), slice_time_sort);
+
+	for (i = 0; i < slices.len; i += sizeof(info)) {
+		struct slice_fd_time *infop = (struct slice_fd_time *)(slices.buf + i);
+		struct stat *fip = &infop->fi;
+		int fd = infop->fd;
+
+		if (make_cache_index(rci, infop->sha1, fd, fip->st_size) < 0)
+			die("error writing cache");
+
+		close(fd);
+	}
+
+	strbuf_release(&slices);
+
+	return 0;
+}
+
+static int add_slices_for_fuse(struct rev_cache_info *rci, struct string_list *files, struct strbuf *ignore)
+{
+	unsigned char sha1[20];
+	char base[PATH_MAX];
+	int baselen, i, slice_nr = 0;
+	struct stat fi;
+	DIR *dirh;
+	struct dirent *de;
+
+	strncpy(base, git_path("rev-cache"), sizeof(base));
+	baselen = strlen(base);
+
+	dirh = opendir(base);
+	if (!dirh)
+		return 0;
+
+	while ((de = readdir(dirh))) {
+		if (de->d_name[0] == '.')
+			continue;
+
+		base[baselen] = '/';
+		strncpy(base + baselen + 1, de->d_name, sizeof(base) - baselen - 1);
+
+		if (get_sha1_hex(de->d_name, sha1)) {
+			/* whatever it is, we don't need it... */
+			string_list_insert(base, files);
+			continue;
+		}
+
+		/* _theoretically_ it is possible a slice < ignore_size to map objects not covered by, yet reachable from,
+		 * a slice >= ignore_size, meaning that we could potentially delete an 'unfused' slice; but if that
+		 * ever *did* happen their cache structure'd be so fucked up they might as well refuse the entire thing.
+		 * and at any rate the worst it'd do is make rev-list revert to standard walking in that (small) bit.
+		 */
+		if (rci->ignore_size) {
+			if (stat(base, &fi))
+				warning("can't query file %s\n", base);
+			else if (fi.st_size >= rci->ignore_size) {
+				strbuf_add(ignore, sha1, 20);
+				continue;
+			}
+		} else {
+			/* check if a pointer */
+			struct cache_slice_pointer ptr;
+			int fd = open(base, O_RDONLY);
+
+			if (fd < 0)
+				goto dont_save;
+			if (sizeof(ptr) != read_in_full(fd, &ptr, sizeof(ptr)))
+				goto dont_save;
+
+			close(fd);
+			if (!strcmp(ptr.signature, "REVCOPTR")) {
+				strbuf_add(ignore, sha1, 20);
+				continue;
+			}
+		}
+
+dont_save:
+		for (i = idx_head.cache_nr - 1; i >= 0; i--) {
+			if (!hashcmp(idx_caches + i * 20, sha1))
+				break;
+		}
+
+		if (i >= 0)
+			rci->maps[i].size = 1;
+
+		string_list_insert(base, files);
+		slice_nr++;
+	}
+
+	closedir(dirh);
+
+	return slice_nr;
+}
+
+/* the most work-intensive attributes in the cache are the unique objects and size, both
+ * of which can be re-used.  although path structures will be isomorphic, path generation is
+ * not particularly expensive, and at any rate we need to re-sort the commits */
+int fuse_cache_slices(struct rev_cache_info *rci, struct rev_info *revs)
+{
+	unsigned char cache_sha1[20];
+	struct string_list files = {0, 0, 0, 1}; /* dup */
+	struct strbuf ignore;
+	int i;
+
+	maybe_fill_with_defaults(rci);
+
+	if (!idx_map)
+		init_index();
+	if (!idx_map)
+		return -1;
+
+	strbuf_init(&ignore, 0);
+	rci->maps = xcalloc(idx_head.cache_nr, sizeof(struct rev_cache_slice_map));
+	if (add_slices_for_fuse(rci, &files, &ignore) <= 1) {
+		printf("nothing to fuse\n");
+		return 1;
+	}
+
+	if (ignore.len) {
+		starts_from_slices(revs, UNINTERESTING, (unsigned char *)ignore.buf, ignore.len / 20);
+		strbuf_release(&ignore);
+	}
+
+	/* initialize mappings */
+	for (i = idx_head.cache_nr - 1; i >= 0; i--) {
+		struct rev_cache_slice_map *map = rci->maps + i;
+		struct stat fi;
+		int fd;
+
+		if (!map->size)
+			continue;
+		map->size = 0;
+
+		/* pointers are never fused, so we can use open directly */
+		fd = open(git_path("rev-cache/%s", sha1_to_hex(idx_caches + i * 20)), O_RDONLY);
+		if (fd <= 0 || fstat(fd, &fi))
+			continue;
+		if (fi.st_size < sizeof(struct rc_slice_header))
+			continue;
+
+		map->map = xmmap(0, fi.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+		if (map->map == MAP_FAILED)
+			continue;
+
+		close(fd);
+		map->size = fi.st_size;
+	}
+
+	rci->make_index = 0;
+	rci->fuse_me = 1;
+	if (make_cache_slice(rci, revs, 0, 0, cache_sha1) < 0)
+		die("can't make cache slice");
+
+	printf("%s\n", sha1_to_hex(cache_sha1));
+
+	/* clean up time! */
+	for (i = idx_head.cache_nr - 1; i >= 0; i--) {
+		struct rev_cache_slice_map *map = rci->maps + i;
+
+		if (!map->size)
+			continue;
+
+		munmap(map->map, map->size);
+	}
+	free(rci->maps);
+	cleanup_cache_slices();
+
+	for (i = 0; i < files.nr; i++) {
+		char *name = files.items[i].string;
+
+		fprintf(stderr, "removing %s\n", name);
+		unlink_or_warn(name);
+	}
+
+	string_list_clear(&files, 0);
+
+	return regenerate_cache_index(rci);
+}
+
+static int verify_cache_slice(const char *slice_path, unsigned char *sha1)
+{
+	struct rc_slice_header head;
+	int fd, len, retval = -1;
+	unsigned char *map = MAP_FAILED;
+	struct stat fi;
+
+	len = strlen(slice_path);
+	if (len < 40)
+		return -2;
+	if (get_sha1_hex(slice_path + len - 40, sha1))
+		return -3;
+
+	fd = open(slice_path, O_RDONLY);
+	if (fd == -1)
+		goto end;
+	if (fstat(fd, &fi) || fi.st_size < sizeof(head))
+		goto end;
+
+	map = xmmap(0, sizeof(head), PROT_READ, MAP_PRIVATE, fd, 0);
+	if (map == MAP_FAILED)
+		goto end;
+	if (get_cache_slice_header(sha1, map, fi.st_size, &head))
+		goto end;
+
+	retval = 0;
+
+end:
+	if (map != MAP_FAILED)
+		munmap(map, sizeof(head));
+	if (fd > 0)
+		close(fd);
+
+	return retval;
+}
+
+int make_cache_slice_pointer(struct rev_cache_info *rci, const char *slice_path)
+{
+	struct cache_slice_pointer ptr;
+	int fd;
+	unsigned char sha1[20];
+
+	maybe_fill_with_defaults(rci);
+	rci->overwrite_all = 1;
+
+	if (verify_cache_slice(slice_path, sha1) < 0)
+		return -1;
+
+	strcpy(ptr.signature, "REVCOPTR");
+	ptr.version = SUPPORTED_REVCOPTR_VERSION;
+	strcpy(ptr.path, make_nonrelative_path(slice_path));
+
+	fd = open(git_path("rev-cache/%s", sha1_to_hex(sha1)), O_RDWR | O_CREAT | O_TRUNC, 0666);
+	if (fd < 0)
+		return -2;
+
+	write_in_full(fd, &ptr, sizeof(ptr));
+	make_cache_index(rci, sha1, fd, sizeof(ptr));
+
+	close(fd);
+
+	return 0;
+}
diff --git a/rev-cache.h b/rev-cache.h
index a76dc53..a1af337 100644
--- a/rev-cache.h
+++ b/rev-cache.h
@@ -3,6 +3,7 @@

  #define SUPPORTED_REVCACHE_VERSION 		1
  #define SUPPORTED_REVINDEX_VERSION		1
+#define SUPPORTED_REVCOPTR_VERSION		1

  #define RC_PATH_SIZE(x)	(sizeof(uint16_t) * (x))

@@ -10,6 +11,7 @@
  #define RC_OBTAIN_INDEX_ENTRY(p)			from_disked_rc_index_entry((struct rc_index_entry_ondisk *)(p), 0)

  #define RC_ACTUAL_OBJECT_ENTRY_SIZE(e)		(sizeof(struct rc_object_entry_ondisk) + RC_PATH_SIZE((e)->merge_nr + (e)->split_nr) + (e)->size_size)
+#define RC_ENTRY_SIZE_OFFSET(e)				(RC_ACTUAL_OBJECT_ENTRY_SIZE(e) - (e)->size_size)

  /* single index maps objects to cache files */
  struct rc_index_header {
@@ -90,6 +92,7 @@ struct rc_object_entry *from_disked_rc_object_entry(struct rc_object_entry_ondis
  struct rc_object_entry_ondisk *to_disked_rc_object_entry(struct rc_object_entry *src, struct rc_object_entry_ondisk *dst);

  extern unsigned char *get_cache_slice(struct commit *commit);
+extern int open_cache_slice(unsigned char *sha1, int flags);
  extern int traverse_cache_slice(struct rev_info *revs,
  	unsigned char *cache_sha1, struct commit *commit,
  	unsigned long *date_so_far, int *slop_so_far,
@@ -102,6 +105,10 @@ extern int make_cache_slice(struct rev_cache_info *rci,
  extern int make_cache_index(struct rev_cache_info *rci, unsigned char *cache_sha1,
  	int fd, unsigned int size);

-extern void starts_from_slices(struct rev_info *revs, unsigned int flags);
+extern void starts_from_slices(struct rev_info *revs, unsigned int flags, unsigned char *which, int n);
+extern int fuse_cache_slices(struct rev_cache_info *rci, struct rev_info *revs);
+extern int regenerate_cache_index(struct rev_cache_info *rci);
+extern int make_cache_slice_pointer(struct rev_cache_info *rci, const char *slice_path);

  #endif
+
diff --git a/revision.h b/revision.h
index 7db4b9e..cc5c259 100644
--- a/revision.h
+++ b/revision.h
@@ -22,17 +22,31 @@
  struct rev_info;
  struct log_info;

+struct rev_cache_slice_map {
+	unsigned char *map;
+	int size;
+	int last_index;
+};
+
  struct rev_cache_info {
  	/* generation flags */
  	unsigned objects : 1,
  		legs : 1,
-		make_index : 1;
+		make_index : 1,
+		fuse_me : 1;
+
+	/* index inclusion */
+	unsigned overwrite_all : 1;

  	/* traversal flags */
  	unsigned add_to_pending : 1;

  	/* fuse options */
  	unsigned int ignore_size;
+
+	/* reserved */
+	struct rev_cache_slice_map *maps,
+		*last_map;
  };

  struct rev_info {
-- 
tg: (5021136..) t/revcache/misc (depends on: t/revcache/objects)

^ permalink raw reply related

* Re: [PATCH 1/6 (v4)] man page and technical discussion for rev-cache
From: Nick Edelen @ 2009-10-02 22:12 UTC (permalink / raw)
  To: Nick Edelen, Junio C Hamano, Nicolas Pitre, Johannes Schindelin,
	Sam Vilain
In-Reply-To: <op.uyuwkmv0tdk399@sirnot.private>

Before any code is introduced the full documentation is put forth.  This
provides a man page for the porcelain, and a technical doc in technical/.  The
latter describes the API, and discusses rev-cache's design, file format and
mechanics.

Signed-off-by: Nick Edelen <sirnot@gmail.com>

---
clean resend of patches.  this set fixes a small bug in graft handling, and
tweaks test for compatability.

  Documentation/git-rev-cache.txt       |  190 ++++++++++
  Documentation/technical/rev-cache.txt |  634 +++++++++++++++++++++++++++++++++
  2 files changed, 824 insertions(+), 0 deletions(-)

diff --git a/Documentation/git-rev-cache.txt b/Documentation/git-rev-cache.txt
new file mode 100644
index 0000000..5a713ad
--- /dev/null
+++ b/Documentation/git-rev-cache.txt
@@ -0,0 +1,190 @@
+git-rev-cache(1)
+================
+
+NAME
+----
+git-rev-cache - Add, walk and maintain revision cache slices
+
+SYNOPSIS
+--------
+'git-rev-cache' COMMAND [options] [<commit>...]
+
+DESCRIPTION
+-----------
+The revision cache ('rev-cache') provides a mechanism for significantly
+speeding up revision traversals.  It does this by creating an efficient
+database (cache) of commits, their related objects and topological relations.
+Independant of packs and the object store, this database is composed of
+rev-cache "slices" -- each a different file storing a given segment of commit
+history.  To map commits to their respective slices, a single index file is
+kept for the rev-cache.
+
+'git-rev-cache' provides a front-end for the rev-cache mechanism, intended for
+updating and maintaining rev-cache slices in the current repository.  New cache
+slice files can be 'add'ed, to keep the cache up-to-date; individual slices can
+be traversed; smaller slices can be 'fuse'd into a larger slice; and the
+rev-cache index can be regenerated.
+
+COMMANDS
+--------
+
+add
+~~~
+Add revisions to the cache by creating a new cache slice.  Reads a revision
+list from the command line, formatted as: `START START ... \--not END END ...`
+
+Options
+^^^^^^^
+
+\--all::
+	Include all refs in the new cache slice, like the \--all option in
+	'rev-list'.
+
+\--fresh/\--incremental::
+	Exclude everything already in the revision cache, analogous to
+	\--incremental in 'pack-objects'.
+
+\--stdin::
+	Read newline-seperated revisions from the standard input.  Use \--not
+	to exclude commits, as on the command line.
+
+\--legs::
+	Ensure newly-generated cache slice has no partial ends.  This means that
+	no commit has partially cached parents, in that all its parents are
+	cached or none of them are.  99.9% of users can ignore this command.
++
+\--legs will cause 'rev-cache' to expand potential slice end-points (creating
+"legs") until this condition is met, simplifying the cache slice structure.
+'rev-cache' itself does not care if a slice has legs or not, but the condition
+may reduce the required complexity of other applications that might use the
+revision cache.
+
+\--no-objects::
+	Non-commit objects are normally included along with the commit with
+	which they were introduced.  This is obviously very benificial, but can
+	take longer in cache slice generation.  Using this option will disable
+	non-commit object caching.
++
+\--no-objects is mainly intended for debugging or development purposes, but may
+find use in special situations (e.g. common traversal of only commits).
+
+Output
+^^^^^^
+
+On `stderr` 'add' outputs general information about the generated slice,
+including the number of objects and paths, and the start/end commits (prefix S
+indicates start, E an end).  Through `stdout` it emits only the SHA-1 of the
+slice.
+
+walk
+~~~~
+Analogous to a slice-oriented 'rev-list', 'walk' will traverse a region in a
+particular cache slice.  Interesting and uninteresting (delimited, as with
+'rev-list', with \--not) are specified on the command line, and output is the
+same as vanilla 'rev-list'.
+
+Options
+^^^^^^^
+
+\--objects::
+	Like 'rev-list', 'walk' will normally only list commits.  Use this
+	option to list non-commit objects as well, if they are present in the
+	cache slice.
+
+Output
+^^^^^^
+
+'walk' will simply dump the contents of the output commit list, work list, and
+pending object array.  The headers are outputed on `stderr`, the object hashes
+and names on `stdout`.
+
+fuse
+~~~~
+Merge several cache slices into a single large slice, like 'repack' for
+'rev-cache'.  On each invocation of 'add' a new file ("slice") is added to the
+revision cache directory, and after several additions the directory may become
+populated with many, relatively small slices.  Numerous smaller slices will
+yield poorer performance than a one or two large ones, because of the overhead
+of loading new slices into memory.
+
+Running 'fuse' every once in a while will solve this problem by coalescing all
+the cache slices into one larger slice.  For very large projects, using
+\--ignore-size is advisable to prevent overly large cache slices.  This can be
+set to run on garbage collection; see 'Automation' for more info.
+
+Note that 'fuse' uses the internal revision walker, so the options used in
+fusion override those of the cache slices upon which it operates.  For example,
+if some slices were generated with \--no-objects, yet 'fuse' was performed with
+non-commit objects, the resulting slice would still contain objects but would
+take longer to generate.
+
+Options
+^^^^^^^
+
+\--all::
+	Normally fuse will only include everything that's already in the
+	revision cache.  \--all tells it to start walking from the branch
+	heads, effectively a `add --all --fresh; fuse`
+	(pseudo-revcache-command).
+
+\--no-objects::
+	As in 'add', this option disables inclusion of non-commit objects.  If
+	some cache slices do contain such objects, the information will be lost.
+
+\--ignore-size[=N]::
+	Do not merge cache slices of size >=N (be aware that slices must be
+	mapped to memory).  N can have a suffix of "k" or "m", denoting N as
+	kilobytes and megabytes, respectively.  If N is not provided 'fuse'
+	will default to a size specified in `revcache.ignoresize`, or ~25MB if
+	the config var is not set.
+
+Output
+^^^^^^
+
+This command prints the SHA-1 of the new slice on `stdout`, and information
+about its work on `stderr` -- specifically which files it's removing.
+
+Automation
+^^^^^^^^^^
+
+Set the git configuration variable `gc.revcache` to run 'fuse' on garbage
+collection.  The arguments passed are `fuse \--all \--ignore-size`; i.e. 'gc'
+will keep everything cached into size-regulated slices.
+
+index
+~~~~~
+Regenerate the revision cache index.  If the rev-cache index file associating
+objects with cache slices gets corrupted, lost, or otherwise becomes unusable,
+'index' will quickly regenerate the file.  It's most likely that this won't be
+needed in every day use, as it is targeted towards debugging and development.
+
+alt
+~~~
+Create a cache slice pointer to another slice, identified by its full path:
+`fuse path/to/other/slice`
+
+This command is useful if you have several repositories sharing a common
+history.  Although space requirements for rev-cache are slim anyway, you can in
+this situation reduce it further by using slice pointers, pointing to relavant
+slices in other repositories.  Note that only one level of redirection is
+allowed, and the slice pointer will break if the original slice is removed.
+'fuse' will not touch slice pointers.
+
+NOTES
+-----
+In certain circumstances there may be some inconsistencies with object names
+between cached and non-cached walks.  Specifically, if two objects in a commit
+tree have the same content (= same SHA-1); or if objects of the same SHA-1 are
+introduced independantly in parallel branches.
+
+In the first case rev-cache will use the name of the youngest file, while
+vanilla rev-list will return the name of the entry first encountered in walking
+the tree.  The latter case is a result of rev-cache's internal topological
+ordering: the difference is the same between sorted and unsorted revision walks.
+
+See 'Discussion' for the underlying reasons for the discrepencies.
+
+DISCUSSION
+----------
+For an explanation of the API and its inner workings, see
+link:technical/rev-cache.txt[technical info on rev-cache].
diff --git a/Documentation/technical/rev-cache.txt b/Documentation/technical/rev-cache.txt
new file mode 100644
index 0000000..91fce8b
--- /dev/null
+++ b/Documentation/technical/rev-cache.txt
@@ -0,0 +1,634 @@
+rev-cache
+=========
+
+The revision cache API ('rev-cache') provides a method for efficiently storing
+and accessing commit branch sections.  Such branch slices are defined by a
+series of start/top (interesting) and end/bottom (uninteresting) commits.  Each
+slice contains information on commits in topological order.  Recorded with each
+commit is:
+
+* All intra-slice topological relations, encoded into path "channels" (see
+  'Mechanics' for full explanation).
+* Object meta-data: type, SHA-1, size, date (for commits).
+* Objects introduced by that commit, not present in the its cached parents.
+
+In addition to the API, basic structures are exported for the possibility of
+direct access.
+
+The API
+-------
+You can find the function prototypes in `revision.h`.
+
+Data Structures
+~~~~~~~~~~~~~~~
+The `rev_cache_info` struct holds all the options and flags for the API.
+
+----
+struct rev_cache_info {
+	/* generation flags */
+	unsigned objects : 1,
+		legs : 1,
+		make_index : 1,
+		fuse_me : 1;
+
+	/* index inclusion */
+	unsigned overwrite_all : 1;
+
+	/* traversal flags */
+	unsigned add_to_pending : 1;
+
+	/* fuse options */
+	unsigned int ignore_size;
+
+	/* reserved */
+	struct rev_cache_slice_map *maps,
+		*last_map;
+};
+----
+
+The fields:
+
+`objects`::
+	Add non-commit objects to slice.
+
+`legs`::
+	Ensure end/bottom commits have no children.
+
+`make_index`::
+	Integrate newly-made slice into index.
+
+`fuse_me`::
+	This is specified if a fuse is occuring, and slices are to be reused.
+	This option requires `maps` and `last_maps` to be initialized.
+
+`overwrite_all`::
+	When a cache slice is added to the index, sometimes overlap occures
+	between it and other slices.  Normally, original index entries are kept
+	unless the new entry represents a start commit (older entries are more
+	likely to lead to greater in-slice traversals).  This options overrides
+	that, and updates all entries of the new slice.
+
+`add_to_pending`::
+	Append unique non-commit objects to the `pending` object list in the
+	passed `rev_info` instance.
+
+`add_names`::
+	Include non-commit object names in the pending object entries if
+	`add_to_pending` is set.
+
+`ignore_size`::
+	If non-zero, ignore slices with size greater or equal to this during
+fusion.
+
+`maps`/`last_map`::
+	An array of slice mappings, indexed by their id in the slice index
+	header, to be re-used with `fuse_me`.  `last_map` points to the last
+	mapping used, and should be initialized to 0.
+
+Functions
+~~~~~~~~~
+
+init_rev_cache
+^^^^^^^^^^^^^^
+----
+void init_rev_cache_info(
+	struct rev_cache_info *rci OUT
+)
+----
+
+Initialize `rci` to default options.
+
+make_cache_slice
+^^^^^^^^^^^^^^^^
+----
+int make_cache_slice(
+	struct rev_cache_info *rci IN,
+	struct rev_info *revs IN,
+	struct commit_list **starts IN/OUT,
+	struct commit_list **ends IN/OUT,
+	unsigned char *cache_sha1 OUT
+)
+----
+
+Create a cache slice based on either `revs` (if non-NULL) *or* the `starts` and
+`ends` lists.  The actual list of start and end commits of the slice may be
+different from the parameters, based on what defines the branch segment, and
+this actual list is passed back through `starts` and `ends`.
+
+The cache slice is identified via a SHA-1 generated from the actual start/end
+commit lists.  `cache_sha1`, if non-NULL, can recieve the cache slice name.
+`rci` is used to specify generation options, but can be NULL if you want
+`make_cache_slice` to fall back on defaults.  Returns 0 on success, non-zero on
+failure.
+
+make_cache_index
+^^^^^^^^^^^^^^^^
+----
+int make_cache_index(
+	struct rev_cache_info *rci IN,
+	unsigned char *cache_sha1 IN,
+	int fd IN,
+	unsigned int size IN
+)
+----
+
+Add a slice to the rev-cache index.  `cache_sha1` is the identity hash of the
+cache slice; `fd` is a file descriptor of the cache slice opened with
+read/write privileges (the slice is not actually modified); `size` is the size
+of the cache slice.  Although there are currently no options for index
+updating, `rci` is a placeholder in case of future options.  Note that this
+function is normally called by `make_cache_slice`.  Returns 0 on success,
+non-zero on failure.
+
+open_cache_slice
+^^^^^^^^^^^^^^^^
+----
+int open_cache_slice(
+	unsigned char *sha1 IN,
+	int flags IN
+)
+----
+
+Returns a file descriptor to a cache slice described by `sha1` hash, using
+`flags` as the access mode.  This will follow cache slice pointers to one level
+of indirection.
+
+get_cache_slice
+^^^^^^^^^^^^^^^
+----
+unsigned char *get_cache_slice(
+	struct commit *commit IN
+)
+----
+
+Given a commit object `get_cache_slice` will search the revision cache index
+and return, if found, the cache slice SHA-1.
+
+traverse_cache_slice
+^^^^^^^^^^^^^^^^^^^^
+----
+int traverse_cache_slice(
+	struct rev_info *revs IN/OUT,
+	unsigned char *cache_sha1 IN,
+	struct commit *commit IN,
+	unsigned long *date_so_far IN/OUT,
+	int *slop_so_far IN/OUT,
+	struct commit_list ***queue OUT,
+	struct commit_list **work IN/OUT
+)
+----
+
+Traverse a specified cache slice.  An explanation of the each field:
+
+`revs`::
+	The revision walk instance.  `traverse_cache_slice` uses this for
+	general options (e.g. which objects are included) and slice traversal
+	options (in the `rev_cache_info` field).  If the `add_to_pending`
+	option is specified, non-commit objects are appended to the `pending`
+	object list field.
+
+`cache_sha1`::
+	SHA-1 identifying the cache slice to use.  This can be taken directly
+	from `get_cache_slice`.
+
+`commit`::
+	The current commit object in the revision walk, i.e. the commit which
+	inspired this slice traversal.  Although theoretically redundant in
+	view of the `work` list, this simplifies interaction with normal
+	revision walks, which pop commits from `work` before analyzing them.
+
+`date_so_far`::
+	The date of the oldest encountered interesting commit.  Passing NULL
+	will let `traverse_cache_slice` use defaults.
+
+`slop_so_far`::
+	The `slop` value, a la revision.c.  This is a counter used to determine
+	when to stop traversing, based on how many extra uninteresting commits
+	should be encountered.  NULL will enable defaults, as above.
+
+`queue`::
+	Refers to a pointer to the head of a FIFO commit list, recieving the
+	commits we've seen and added.
+
+`work`::
+	A date-ordered list of commits that have yet to be processed (i.e. seen
+	but not added).  Commits from here present in the slice are removed
+	(and, obviously, used as starting places for traversal), and any end
+	commits encountered are inserted.
+
+starts_from_slices
+^^^^^^^^^^^^^^^^^^
+----
+void starts_from_slices(
+	struct rev_info *revs OUT,
+	unsigned int flags IN,
+	unsigned char *which IN,
+	int n IN
+)
+----
+
+Will mark start-commits in certain rev-cache slices with `flag`, and added them
+to the pending list of `revs`.  If `n` is zero, `starts_from_slices` will use
+all slices.  Otherwise `which` will specify an *unseperated* list of cache
+SHA-1s to use (20 bytes each), and `n` will contain the number of slices (i.e.
+20 * `n` = size of `which`).
+
+fuse_cache_slices
+^^^^^^^^^^^^^^^^^
+----
+int fuse_cache_slices(
+	struct rev_cache_info *rci IN,
+	struct rev_info *revs IN
+)
+----
+
+Generate a slice based on `revs`, replacing all encountered slices with one
+(larger) slice.  The `ignore_size` field in `rci`, if non-zero, will dictate
+which cache slice sizes to ignore in both traversal and replacement.
+
+regenerate_cache_index
+^^^^^^^^^^^^^^^^^^^^^^
+----
+int regenerate_cache_index(
+	struct rev_cache_info *rci IN
+)
+----
+
+Remake the revision cache index, including all the slices.  Currently no
+options in `rci` exist for index (re)generation, but some may develop in the
+future.
+
+to/from_disked_rc_object/index_entry
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+----
+struct rc_object/index_entry *from_disked_rc_object/index_entry(
+	struct rc_object/index_entry_ondisk *src IN,
+	struct rc_object/index_entry *dst OUT
+)
+
+struct rc_object/index_entry_ondisk *to_disked_rc_object/index_entry(
+	struct rc_object/index_entry *src IN,
+	struct rc_object/index_entry_ondisk *dst OUT
+)
+----
+
+Functions to convert between the internal and storage (`_ondisk`) versions of
+object and index entry structures.  These are necessary for direct access to
+the cache slices.  If NULL is provided for `dst` a statically allocated
+structure is used, and a pointer to the struct is returned.  Otherwise the
+functions return `dst`.
+
+Example Usage
+-------------
+
+A few examples to demonstrate usage:
+
+.Creating a slice
+----
+/* pretend you're a porcelain for rev-cache reading from the command line */
+struct rev_info revs;
+struct rev_cache_info rci;
+
+init_revisions(&revs, 0);
+init_rci(&rci);
+
+flags = 0;
+for (i = 1; i < argc; i++) {
+        if (!strcmp(argv[i], "--not"))
+                flags ^= UNINTERESTING;
+        else if(!strcmp(argv[i], "--fresh"))
+                starts_from_slices(&revs, UNINTERESTING, 0, 0);
+        else
+                handle_revision_arg(argv[i], &revs, flags, 1);
+}
+
+/* we want to explicitly set certain options */
+rci.objects = 0;
+
+if (!make_cache_slice(&rci, &revs, 0, 0, cache_sha1))
+        printf("made slice!  it's called %s\n", sha1_to_hex(cache_sha1));
+----
+
+.Traversing a slice
+----
+/* let's say you're walking the tree with a 'work' list of current heads and a
+ * FILO output list 'out' */
+out = 0;
+outp = &out;
+
+while (work) {
+        struct commit *commit = pop_commit(&work);
+        struct object *object = &commit->object;
+        unsigned char *cache_sha1;
+
+        if (cache_sha1 = get_cache_slice(object->sha1)) {
+                /* note that this will instatiate any topo-relations
+                 * as it goes */
+                if (traverse_cache_slice(&revs, cache_sha1,
+                        commit, 0, 0, /* use defaults */
+                        &outp, &work) < 0)
+                        die("I'm overreacting to a non-fatal cache error");
+        } else {
+                struct commit_list *parents = commit->parents;
+
+                while (parents) {
+                        struct commit *p = parents->item;
+                        struct object *po = &p->object;
+
+                        parents = parents->next;
+                        if (po->flags & UNINTERESTING)
+                                continue;
+
+                        if (object->flags & UNINTERESTING)
+                                po->flags |= UNINTERESTING;
+                        else if (po->flags & SEEN)
+                                continue;
+
+                        if (!po->parsed)
+                                parse_commit(p);
+                        insert_by_date(p, &work);
+                }
+
+                if (object->flags & (SEEN | UNINTERESTING) == 0)
+                        outp = &commit_list_insert(commit, outp)->next;
+                object->flags |= SEEN;
+        }
+}
+----
+
+Some Internals
+--------------
+For more advanced usage, the slice and index file(s) may be accessed directly.
+Relavant structures are availabe in `rev-cache.h`.
+
+File Formats
+~~~~~~~~~~~~
+
+Cache Slices
+^^^^^^^^^^^^
+A slice has a basic fixed-size header, followed by a certain number of object
+entries, then a NULL-seperated list of object names.  Commits are sorted in
+topo-order, and each commit entry is followed by the objects added in that
+commit.
+
+----
+         -- +--------------------------------+
+header      | object number, etc...          |
+         -- +--------------------------------+
+commit      | commit info                    |
+entry       | path data                      |
+            +--------------------------------+
+            | tree/blob info                 |
+            +--------------------------------+
+            | tree/blob info                 |
+            +--------------------------------+
+            | ...                            |
+         -- +--------------------------------+
+commit      | commit info                    |
+entry       | path data                      |
+            +--------------------------------+
+            | tree/blob info                 |
+            +--------------------------------+
+            | ...                            |
+         -- +--------------------------------+
+...         ...
+         -- +--------------------------------+
+name list   | \0some_file_name\0             |
+(note       +--------------------------------+
+preceeding  | another_file\0                 |
+null)       ...                              |
+            +--------------------------------+
+----
+
+Here is the header:
+
+----
+struct rc_cache_slice_header {
+	char signature[8]; /* REVCACHE */
+	unsigned char version;
+	uint32_t ofs_objects;
+
+	uint32_t object_nr;
+	uint16_t path_nr;
+	uint32_t size;
+
+	unsigned char sha1[20];
+
+	uint32_t names_size;
+};
+----
+
+Explanations:
+
+`signature`::
+	The identifying signature of cache slice file.  Always "REVCACHE".
+`version`::
+	The version number, currently 1.
+`ofs_objects`::
+	The byte offset at which the commit/object listing starts.  Always
+	present at the 10th byte, regardless of file version.
+`object_nr`::
+	The total number of objects (commit + non-commit objects) present in
+	the slice.
+`path_nr`::
+	The total number of paths/channels used in encoding the topological
+	data.  Note that paths are reused (see 'Mechanics'), so there will
+	never be more than a few hundred paths (if that) used.
+`size`::
+	The size of the slice *excluding* the name list.  In other words, the
+	size of the portion mapped to memory.
+`sha1`::
+	The cache slice SHA-1.
+`names_size`::
+	The size of the name list.  `size` + `names_size` = size of slice
+
+Revision Cache Index
+^^^^^^^^^^^^^^^^^^^^
+The index is a single file that associates SHA-1s with cache slices and file
+positions.  It is somewhat similar to pack-file indexes, containing a fanout
+table and a list of index entries sorted by hash.
+
+----
+         -- +--------------------------------+
+header      | object #, cache #, etc.        |
+         -- +--------------------------------+
+sha1s of    | SHA-1                          |
+slices      | ...                            |
+         -- +--------------------------------+
+fanout      | fanout[0x00]                   |
+table       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+            | fanout[0xff]                   |
+         -- +--------------------------------+
+index       | SHA-1 of object                |
+entries     | index of cache slice SHA-1     |
+            | position in cache slice        |
+            +--------------------------------+
+            |                                |
+            ...
+            +--------------------------------+
+----
+
+The header:
+
+----
+struct rc_index_header {
+	char signature[8]; /* REVINDEX */
+	unsigned char version;
+	uint32_t ofs_objects;
+
+	uint32_t object_nr;
+	unsigned char cache_nr;
+
+	uint32_t max_date;
+};
+----
+
+Explanations:
+
+`signature`::
+	Always "REVINDEX".
+`version`::
+	Version number, currently 1.
+`ofs_objects`::
+	Offset at which the entry objects begin.  This is more obviously useful
+	in the index because the list of slice SHA-1s is variably-sized.
+`object_nr`::
+	Number of index entry objects present.
+`cache_nr`::
+	Number of cache slices to which the index maps, and hence the number of
+slice SHA-1s listed.
+`max_date`::
+	The oldest commit represented in the index.  This is used to help speed
+up lookup times by knowing what range of commits we definitely don't have
+cached.  Normal usage of 'rev-cache' would leave no "holes" in its coverage of
+commit history -- once a commit is cached, everything reachable from it should
+be cached as well.  Most of the time refs are added to rev-cache simultaneous
+as well.  This means that in most situations almost everything <= `max_date`
+will be cached.
+
+Mechanics
+~~~~~~~~~
+
+The most important part of rev-cache is its method of encoding topological
+relations.  To ensure fluid traversal and reconstruction, commits are related
+through high-level "streams"/"channels" rather than individual
+interconnections.  Intuitively, rev-cache stores history the way gitk shows it:
+commits strung up on lines, which interconnect at merges and branches.
+
+Each commit is associated to a given channel/path via a 'path id', and
+variable-length fields govern which paths (if any) are closed or opened at that
+object.  This means that topo-data can be preserved in only a few bytes extra
+per object entry.  Other information stored per entry is the sha-1 hash, type,
+date, size, name, and status in cache slice.  Here is format of an object
+entry, both on-disk and in-memory:
+
+----
+struct object_entry {
+        unsigned type : 3;
+        unsigned is_end : 1;
+        unsigned is_start : 1;
+        unsigned uninteresting : 1;
+        unsigned include : 1;
+        unsigned flags : 1;
+        unsigned char sha1[20];
+
+        unsigned char merge_nr;
+        unsigned char split_nr;
+        unsigned size_size : 3;
+        unsigned name_size : 3;
+
+        uint32_t date;
+        uint16_t path;
+
+        /* merge paths */
+        /* split paths */
+        /* size */
+        /* name index */
+};
+----
+
+An explanation of each field:
+
+`type`::
+	Object type
+`is_end`::
+	The commit has some parents outside the cache slice (all if slice has
+	legs)
+`is_start`::
+	The commit has no children in cache slice
+`uninteresting`::
+	Run-time flag, used in traversal
+`include`::
+	Run-time flag, used in traversal (initialization)
+`flags`::
+	Currently unused, extra bit
+`sha1`::
+	Object SHA-1 hash
+
+`merge_nr`::
+	The number of paths the current channel diverges into; the current path
+	ends upon any merge.
+`split_nr`::
+	The number of paths this commit ends; used on both merging and
+	branching.
+`size_size`::
+	Number of bytes the object size takes up.
+`name_size`::
+	Number of bytes the name index takes up.
+
+`date`::
+	The date of the commit.
+`path`::
+	The path ID of the channel with which this commit is associated.
+
+merge paths::
+	The path IDs (16-bit) that are to be created.  Overflow is not a
+	problem as path IDs are reused, leaving even complicated projects to
+	consume no more than a few hundred IDs.
+split paths::
+	The path IDs (16-bit) that are to be ended.
+size::
+	The size split into the minimum number of bytes.  That is, 1-8 bytes
+	representing the size, least-significant byte first.
+name index::
+	An offset for the null-seperated, object name list at the end of the
+	cache slice.  Also split into the minimum number of bytes.
+
+Each path ID refers to an index in a 'path array', which stores the current
+status (eg. active, interestingness) of each channel.
+
+Due to topo-relations and boundary tracking, all of a commit's parents must be
+encountered before the path is reallocated.  This is achieved by using a
+counter system per merge: starting at the parent number, the counter is
+decremented as each parent is encountered (dictated by 'split paths'); at 0 the
+path is cleared.
+
+Boundary tracking is necessary because non-commits are stored relative to the
+commit in which they were introduced.  If a series of commits is not included
+in the output, the last interesting commit must be parsed manually to ensure
+all objects are accounted for.
+
+To prevent list-objects from recursing into trees that we've already taken care
+of, the flag `FACE_VALUE` is introduced.  An object with this flag is not
+explored (= "taken at face value"), significantly reducing I/O and processing
+time.
+
+Notes
+~~~~~
+
+Due to rev-cache's internal storage format, walking may lead to some
+discrepencies between cached and uncached repositories.  Although noticeable to
+users directly calling rev-list, these are unused or corner cases and
+internally a non-issue.
+
+First note that rev-cache records commits in topological order.  Large portions
+of commit history will already be sorted topologically in the revision walk,
+yielding a different output for unsorted calls to rev-list.  A more obscure
+consquence occurs when two objects of the same SHA-1, but different name, are
+introduced seperately in parallel branches: different names might be shown for
+that object depending on which object entry was encountered first.
+
+A similar disparity arises when two objects of same SHA-1/different name are
+present in the same tree structure.  rev-cache, walking objects as they were
+introduced, lists the youngest file's name; rev-list, walking the full trees
+each commit, shows the first file encountered.
-- 
tg: (5bbb081..) t/revcache/docs (depends on: t/revcache/integration)

^ permalink raw reply related

* Re: "Not currently on any branch"
From: Sean Estabrooks @ 2009-10-02 23:15 UTC (permalink / raw)
  To: Alex Riesen; +Cc: Tim, git
In-Reply-To: <81b0412b0910021446nb07e7e9l465f588168297fe9@mail.gmail.com>

On Fri, 2 Oct 2009 23:46:53 +0200
Alex Riesen <raa.lkml@gmail.com> wrote:

> On Fri, Oct 2, 2009 at 22:08, Tim <timothyjwashington@yahoo.ca> wrote:
> > What's the most straightforward & cleanest way to merge my changes in the
> > headless branch to my 'ui-integration' branch?
> 
> Assuming you use a Bourne shell:
> 
> $ prev=$(git rev-parse HEAD)
> $ git checkout ui-integration && git merge $prev
> 
> 

You could also rely on the reflog to avoid the need to store off the
previous HEAD value, so just:

$ git checkout ui-integration && git merge HEAD@{1}


Sean

^ permalink raw reply

* Re: [PATCH] MSVC: fix build warnings
From: Michael Wookey @ 2009-10-02 23:28 UTC (permalink / raw)
  To: Junio C Hamano, git
In-Reply-To: <7v7hvd4flb.fsf@alter.siamese.dyndns.org>

2009/10/3 Junio C Hamano <gitster@pobox.com>:
> Michael Wookey <michaelwookey@gmail.com> writes:
>
>> diff --git a/builtin-branch.c b/builtin-branch.c
>> index 9f57992..cf6a9ca 100644
>> --- a/builtin-branch.c
>> +++ b/builtin-branch.c
>> @@ -93,7 +93,7 @@ static const char *branch_get_color(enum color_branch ix)
>>
>>  static int delete_branches(int argc, const char **argv, int force, int kinds)
>>  {
>> -     struct commit *rev, *head_rev = head_rev;
>
> I haven't tried, but the patch may break build with "gcc -Werror".
>
> This is a common and unfortunate idiom to tell the readers of the code
> that this initialization is unnecessary, gcc is not clever enough to
> notice and gives warnings, and we are squelching it, knowing what we are
> doing.

I can't build with -Werror on Ubuntu 9.04 (gcc 4.3.3) because of the following:

  http://article.gmane.org/gmane.comp.version-control.git/127477

With the current git.rc2, I also get the following warnings:

  builtin-mailinfo.c: In function 'handle_commit_msg':
  builtin-mailinfo.c:789: warning: ignoring return value of
'ftruncate', declared with attribute warn_unused_result

It would be nice to get those warnings removed.

I just tried my patch with gcc 4.2.1 (Mac OSX 10.6) and there are a
few warnings that are generated because some of the variables have had
their initial values removed. I can send a V2 if you like, however
these variable were initialised that way for a reason and it might not
be sensible to clean them up in the way I was proposing.

What would be a good method of fixing these warnings now that we have
the ability to compile with MSVC? Explicitly initialising the
variables (to something sane) or should we start to introduce compiler
specific pragmas (ugly...) that aim to clean the various build
warnings? I just want to reduce (and eventually remove) all the build
noise when building using MSVC.

From what I have seen so far, building with MSVC spews out a lot of
warnings. I am building with MSVC in both the IDE and from a build
console via:

    devenv git.sln /useenv /build "Debug|Win32"

If you compile using gcc with "-Wextra" you will see a similar amount
of build noise that gets generated. See the following for some
previous discussion:

  http://article.gmane.org/gmane.comp.version-control.git/128967

^ permalink raw reply

* [PATCH/RFC 1/7] imap-send: use separate read and write fds
From: Erik Faye-Lund @ 2009-10-03  0:39 UTC (permalink / raw)
  To: msysgit; +Cc: git

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
---
 imap-send.c |   37 +++++++++++++++++++++++--------------
 1 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index 3847fd1..ba50961 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -154,7 +154,7 @@ struct imap_list {
 };
 
 struct imap_socket {
-	int fd;
+	int fd[2];
 	SSL *ssl;
 };
 
@@ -304,8 +304,12 @@ static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int ve
 		ssl_socket_perror("SSL_new");
 		return -1;
 	}
-	if (!SSL_set_fd(sock->ssl, sock->fd)) {
-		ssl_socket_perror("SSL_set_fd");
+	if (!SSL_set_rfd(sock->ssl, sock->fd[0])) {
+		ssl_socket_perror("SSL_set_rfd");
+		return -1;
+	}
+	if (!SSL_set_wfd(sock->ssl, sock->fd[1])) {
+		ssl_socket_perror("SSL_set_wfd");
 		return -1;
 	}
 
@@ -327,11 +331,12 @@ static int socket_read(struct imap_socket *sock, char *buf, int len)
 		n = SSL_read(sock->ssl, buf, len);
 	else
 #endif
-		n = xread(sock->fd, buf, len);
+		n = xread(sock->fd[0], buf, len);
 	if (n <= 0) {
 		socket_perror("read", sock, n);
-		close(sock->fd);
-		sock->fd = -1;
+		close(sock->fd[0]);
+		close(sock->fd[1]);
+		sock->fd[0] = sock->fd[1] = -1;
 	}
 	return n;
 }
@@ -344,11 +349,12 @@ static int socket_write(struct imap_socket *sock, const char *buf, int len)
 		n = SSL_write(sock->ssl, buf, len);
 	else
 #endif
-		n = write_in_full(sock->fd, buf, len);
+		n = write_in_full(sock->fd[1], buf, len);
 	if (n != len) {
 		socket_perror("write", sock, n);
-		close(sock->fd);
-		sock->fd = -1;
+		close(sock->fd[0]);
+		close(sock->fd[1]);
+		sock->fd[0] = sock->fd[1] = -1;
 	}
 	return n;
 }
@@ -361,7 +367,8 @@ static void socket_shutdown(struct imap_socket *sock)
 		SSL_free(sock->ssl);
 	}
 #endif
-	close(sock->fd);
+	close(sock->fd[0]);
+	close(sock->fd[1]);
 }
 
 /* simple line buffering */
@@ -960,7 +967,7 @@ static void imap_close_server(struct imap_store *ictx)
 {
 	struct imap *imap = ictx->imap;
 
-	if (imap->buf.sock.fd != -1) {
+	if (imap->buf.sock.fd[0] != -1) {
 		imap_exec(ictx, NULL, "LOGOUT");
 		socket_shutdown(&imap->buf.sock);
 	}
@@ -988,7 +995,7 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 	ctx = xcalloc(sizeof(*ctx), 1);
 
 	ctx->imap = imap = xcalloc(sizeof(*imap), 1);
-	imap->buf.sock.fd = -1;
+	imap->buf.sock.fd[0] = imap->buf.sock.fd[1] = -1;
 	imap->in_progress_append = &imap->in_progress;
 
 	/* open connection to IMAP server */
@@ -1015,7 +1022,8 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 
 		close(a[0]);
 
-		imap->buf.sock.fd = a[1];
+		imap->buf.sock.fd[0] = a[1];
+		imap->buf.sock.fd[1] = dup(a[1]);
 
 		imap_info("ok\n");
 	} else {
@@ -1092,7 +1100,8 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 			goto bail;
 		}
 
-		imap->buf.sock.fd = s;
+		imap->buf.sock.fd[0] = s;
+		imap->buf.sock.fd[1] = dup(s);
 
 		if (srvc->use_ssl &&
 		    ssl_socket_connect(&imap->buf.sock, 0, srvc->ssl_verify)) {
-- 
1.6.5.rc2.7.g4f8d3

^ permalink raw reply related

* [PATCH/RFC 2/7] imap-send: use run-command API for tunneling
From: Erik Faye-Lund @ 2009-10-03  0:39 UTC (permalink / raw)
  To: msysgit; +Cc: git
In-Reply-To: <1254530385-2824-1-git-send-email-kusmabite@gmail.com>

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
---
 imap-send.c |   37 ++++++++++++++++---------------------
 1 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index ba50961..55a663a 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -24,6 +24,7 @@
 
 #include "cache.h"
 #include "exec_cmd.h"
+#include "run-command.h"
 #ifdef NO_OPENSSL
 typedef void *SSL;
 #endif
@@ -989,8 +990,7 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 	struct imap_store *ctx;
 	struct imap *imap;
 	char *arg, *rsp;
-	int s = -1, a[2], preauth;
-	pid_t pid;
+	int s = -1, preauth;
 
 	ctx = xcalloc(sizeof(*ctx), 1);
 
@@ -1001,29 +1001,24 @@ static struct store *imap_open_store(struct imap_server_conf *srvc)
 	/* open connection to IMAP server */
 
 	if (srvc->tunnel) {
-		imap_info("Starting tunnel '%s'... ", srvc->tunnel);
+		const char *argv[4];
+		struct child_process tunnel = {0};
 
-		if (socketpair(PF_UNIX, SOCK_STREAM, 0, a)) {
-			perror("socketpair");
-			exit(1);
-		}
+		imap_info("Starting tunnel '%s'... ", srvc->tunnel);
 
-		pid = fork();
-		if (pid < 0)
-			_exit(127);
-		if (!pid) {
-			if (dup2(a[0], 0) == -1 || dup2(a[0], 1) == -1)
-				_exit(127);
-			close(a[0]);
-			close(a[1]);
-			execl("/bin/sh", "sh", "-c", srvc->tunnel, NULL);
-			_exit(127);
-		}
+		argv[0] = "/bin/sh";
+		argv[1] = "-c";
+		argv[2] = srvc->tunnel;
+		argv[3] = NULL;
 
-		close(a[0]);
+		tunnel.argv = argv;
+		tunnel.in = -1;
+		tunnel.out = -1;
+		if (start_command(&tunnel))
+			die("cannot start proxy %s", argv[0]);
 
-		imap->buf.sock.fd[0] = a[1];
-		imap->buf.sock.fd[1] = dup(a[1]);
+		imap->buf.sock.fd[0] = tunnel.out;
+		imap->buf.sock.fd[1] = tunnel.in;
 
 		imap_info("ok\n");
 	} else {
-- 
1.6.5.rc2.7.g4f8d3

^ permalink raw reply related

* [PATCH/RFC 3/7] imap-send: fix compilation-error on Windows
From: Erik Faye-Lund @ 2009-10-03  0:39 UTC (permalink / raw)
  To: msysgit; +Cc: git
In-Reply-To: <1254530385-2824-2-git-send-email-kusmabite@gmail.com>

mmsystem.h (included from windows.h) defines DRV_OK to 1. To avoid
an error due to DRV_OK redefenition, this patch undefines the old
definition (i.e the one from mmsystem.h) before defining DRV_OK.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
---
 imap-send.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/imap-send.c b/imap-send.c
index 55a663a..8338717 100644
--- a/imap-send.c
+++ b/imap-send.c
@@ -94,6 +94,10 @@ struct msg_data {
 	unsigned int crlf:1;
 };
 
+#ifdef DRV_OK
+#undef DRV_OK
+#endif
+
 #define DRV_OK          0
 #define DRV_MSG_BAD     -1
 #define DRV_BOX_BAD     -2
-- 
1.6.5.rc2.7.g4f8d3

^ permalink raw reply related

* [PATCH/RFC 4/7] imap-send: build imap-send on Windows
From: Erik Faye-Lund @ 2009-10-03  0:39 UTC (permalink / raw)
  To: msysgit; +Cc: git
In-Reply-To: <1254530385-2824-3-git-send-email-kusmabite@gmail.com>

Since the POSIX-specific tunneling code has been replaced
by the run-command API (and a compile-error has been
cleaned away), we can now enable imap-send on Windows
builds.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
---
 Makefile |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/Makefile b/Makefile
index 12defd4..8ba789a 100644
--- a/Makefile
+++ b/Makefile
@@ -361,6 +361,7 @@ PROGRAMS += git-show-index$X
 PROGRAMS += git-unpack-file$X
 PROGRAMS += git-upload-pack$X
 PROGRAMS += git-var$X
+PROGRAMS += git-imap-send$X
 
 # List built-in command $C whose implementation cmd_$C() is not in
 # builtin-$C.o but is linked in as part of some other command.
@@ -1056,7 +1057,6 @@ EXTLIBS += -lz
 
 ifndef NO_POSIX_ONLY_PROGRAMS
 	PROGRAMS += git-daemon$X
-	PROGRAMS += git-imap-send$X
 endif
 ifndef NO_OPENSSL
 	OPENSSL_LIBSSL = -lssl
-- 
1.6.5.rc2.7.g4f8d3

^ permalink raw reply related


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