[PATCH v4 1/2] worktrees: add find_shared_symref

[PATCH v4 1/2] worktrees: add find_shared_symref

[David Turner]

Add a new function, find_shared_symref, which contains the heart of
die_if_checked_out, but works for all symrefs.  Refactor
die_if_checked_out to use the same infrastructure as
find_shared_symref.

Soon, we will use find_shared_symref to protect notes merges in
worktrees.

Signed-off-by: David Turner <dturner@twopensource.com>
---

This version includes Junio's suggested comment fix, and Eric's
suggestions for error message improvements.

---
 branch.c | 39 ++++++++++++++++++++++++++++-----------
 branch.h |  8 ++++++++
 2 files changed, 36 insertions(+), 11 deletions(-)

diff --git a/branch.c b/branch.c
index c85be07..9b5e3b3 100644
--- a/branch.c
+++ b/branch.c
@@ -311,21 +311,22 @@ void remove_branch_state(void)
 	unlink(git_path("SQUASH_MSG"));
 }
 
-static void check_linked_checkout(const char *branch, const char *id)
+static char *find_linked_symref(const char *symref, const char *branch,
+				const char *id)
 {
 	struct strbuf sb = STRBUF_INIT;
 	struct strbuf path = STRBUF_INIT;
 	struct strbuf gitdir = STRBUF_INIT;
 
 	/*
-	 * $GIT_COMMON_DIR/HEAD is practically outside
-	 * $GIT_DIR so resolve_ref_unsafe() won't work (it
-	 * uses git_path). Parse the ref ourselves.
+	 * $GIT_COMMON_DIR/$symref (e.g. HEAD) is practically outside
+	 * $GIT_DIR so resolve_ref_unsafe() won't work (it uses
+	 * git_path). Parse the ref ourselves.
 	 */
 	if (id)
-		strbuf_addf(&path, "%s/worktrees/%s/HEAD", get_git_common_dir(), id);
+		strbuf_addf(&path, "%s/worktrees/%s/%s", get_git_common_dir(), id, symref);
 	else
-		strbuf_addf(&path, "%s/HEAD", get_git_common_dir());
+		strbuf_addf(&path, "%s/%s", get_git_common_dir(), symref);
 
 	if (!strbuf_readlink(&sb, path.buf, 0)) {
 		if (!starts_with(sb.buf, "refs/") ||
@@ -349,31 +350,47 @@ static void check_linked_checkout(const char *branch, const char *id)
 		strbuf_addstr(&gitdir, get_git_common_dir());
 	skip_prefix(branch, "refs/heads/", &branch);
 	strbuf_strip_suffix(&gitdir, ".git");
-	die(_("'%s' is already checked out at '%s'"), branch, gitdir.buf);
+	return strbuf_detach(&gitdir, NULL);
 done:
 	strbuf_release(&path);
 	strbuf_release(&sb);
 	strbuf_release(&gitdir);
+
+	return NULL;
 }
 
-void die_if_checked_out(const char *branch)
+char *find_shared_symref(const char *symref, const char *target)
 {
 	struct strbuf path = STRBUF_INIT;
 	DIR *dir;
 	struct dirent *d;
+	char *existing;
 
-	check_linked_checkout(branch, NULL);
+	if ((existing = find_linked_symref(symref, target, NULL)))
+		return existing;
 
 	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
 	dir = opendir(path.buf);
 	strbuf_release(&path);
 	if (!dir)
-		return;
+		return NULL;
 
 	while ((d = readdir(dir)) != NULL) {
 		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
 			continue;
-		check_linked_checkout(branch, d->d_name);
+		if ((existing = find_linked_symref(symref, target, d->d_name)))
+			return existing;
 	}
 	closedir(dir);
+
+	return NULL;
+}
+
+void die_if_checked_out(const char *branch)
+{
+	char *existing;
+
+	existing = find_shared_symref("HEAD", branch);
+	if (existing)
+		die(_("'%s' is already checked out at '%s'"), branch, existing);
 }
diff --git a/branch.h b/branch.h
index 58aa45f..0f466c7 100644
--- a/branch.h
+++ b/branch.h
@@ -59,4 +59,12 @@ extern int read_branch_desc(struct strbuf *, const char *branch_name);
  */
 extern void die_if_checked_out(const char *branch);
 
+/*
+ * Check if a per-worktree symref points to a ref in the main worktree
+ * or any linked worktree, and return the path to the exising worktree
+ * if it is.  Returns NULL if there is no existing ref.  The caller is
+ * responsible for freeing the returned path.
+ */
+extern char *find_shared_symref(const char *symref, const char *branch);
+
 #endif
-- 
2.0.4.315.gad8727a-twtrsrc

[PATCH v4 2/2] notes: handle multiple worktrees

[David Turner]

Before creating NOTES_MERGE_REF, check NOTES_MERGE_REF using
find_shared_symref and die if we find one.  This prevents simultaneous
merges to the same notes branch from different worktrees.

Signed-off-by: David Turner <dturner@twopensource.com>
---
 builtin/notes.c                  |  5 +++
 t/t3320-notes-merge-worktrees.sh | 72 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)
 create mode 100755 t/t3320-notes-merge-worktrees.sh

diff --git a/builtin/notes.c b/builtin/notes.c
index 63f95fc..e4dda79 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -19,6 +19,7 @@
 #include "string-list.h"
 #include "notes-merge.h"
 #include "notes-utils.h"
+#include "branch.h"
 
 static const char * const git_notes_usage[] = {
 	N_("git notes [--ref <notes-ref>] [list [<object>]]"),
@@ -825,10 +826,14 @@ static int merge(int argc, const char **argv, const char *prefix)
 		update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 	else { /* Merge has unresolved conflicts */
+		char *existing;
 		/* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
 		update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
 			   0, UPDATE_REFS_DIE_ON_ERR);
 		/* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
+		existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
+		if (existing)
+			die(_("A notes merge on %s is already in-progress for %s"), default_notes_ref(), existing);
 		if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
 			die("Failed to store link to current notes ref (%s)",
 			    default_notes_ref());
diff --git a/t/t3320-notes-merge-worktrees.sh b/t/t3320-notes-merge-worktrees.sh
new file mode 100755
index 0000000..997621f
--- /dev/null
+++ b/t/t3320-notes-merge-worktrees.sh
@@ -0,0 +1,72 @@
+#!/bin/sh
+#
+# Copyright (c) 2015 Twitter, Inc
+#
+
+test_description='Test merging of notes trees in multiple worktrees'
+
+. ./test-lib.sh
+
+test_expect_success 'setup commit' '
+	test_commit tantrum
+'
+
+commit_tantrum=$(git rev-parse tantrum^{commit})
+
+test_expect_success 'setup notes ref (x)' '
+	git config core.notesRef refs/notes/x &&
+	git notes add -m "x notes on tantrum" tantrum
+'
+
+test_expect_success 'setup local branch (y)' '
+	git update-ref refs/notes/y refs/notes/x &&
+	git config core.notesRef refs/notes/y &&
+	git notes remove tantrum
+'
+
+test_expect_success 'setup remote branch (z)' '
+	git update-ref refs/notes/z refs/notes/x &&
+	git config core.notesRef refs/notes/z &&
+	git notes add -f -m "conflicting notes on tantrum" tantrum
+'
+
+test_expect_success 'modify notes ref ourselves (x)' '
+	git config core.notesRef refs/notes/x &&
+	git notes add -f -m "more conflicting notes on tantrum" tantrum
+'
+
+test_expect_success 'create some new worktrees' '
+	git worktree add -b newbranch worktree master &&
+	git worktree add -b newbranch2 worktree2 master
+'
+
+test_expect_success 'merge z into y fails and sets NOTES_MERGE_REF' '
+	git config core.notesRef refs/notes/y &&
+	test_must_fail git notes merge z &&
+	echo "ref: refs/notes/y" > expect &&
+	test_cmp .git/NOTES_MERGE_REF expect
+'
+
+test_expect_success 'merge z into y while mid-merge in another workdir fails' '
+	(
+		cd worktree &&
+		git config core.notesRef refs/notes/y &&
+		test_must_fail git notes merge z 2>err &&
+		grep "A notes merge on refs/notes/y is already in-progress for" err
+	) &&
+	test_path_is_missing .git/worktrees/worktree/NOTES_MERGE_REF
+'
+
+test_expect_success 'merge z into x while mid-merge on y succeeds' '
+	(
+		cd worktree2 &&
+		git config core.notesRef refs/notes/x &&
+		test_must_fail git notes merge z 2>&1 >out &&
+		grep "Automatic notes merge failed" out
+		grep -v "A notes merge on refs/notes/x is already in-progress for" out
+	) &&
+	echo "ref: refs/notes/x" > expect &&
+	test_cmp .git/worktrees/worktree2/NOTES_MERGE_REF expect
+'
+
+test_done
-- 
2.0.4.315.gad8727a-twtrsrc

Re: [PATCH v4 1/2] worktrees: add find_shared_symref

[Eric Sunshine]

On Fri, Jul 31, 2015 at 6:11 PM, David Turner <dturner@twopensource.com> wrote:
> Add a new function, find_shared_symref, which contains the heart of
> die_if_checked_out, but works for all symrefs.  Refactor

Slightly more explanatory:

    ..., but works for any symref, not just HEAD. Refactor

More below.

> die_if_checked_out to use the same infrastructure as
> find_shared_symref.
>
> Soon, we will use find_shared_symref to protect notes merges in
> worktrees.
>
> Signed-off-by: David Turner <dturner@twopensource.com>
> ---
> diff --git a/branch.c b/branch.c
> index c85be07..9b5e3b3 100644
> --- a/branch.c
> +++ b/branch.c
> @@ -349,31 +350,47 @@ static void check_linked_checkout(const char *branch, const char *id)
>                 strbuf_addstr(&gitdir, get_git_common_dir());
>         skip_prefix(branch, "refs/heads/", &branch);
>         strbuf_strip_suffix(&gitdir, ".git");
> -       die(_("'%s' is already checked out at '%s'"), branch, gitdir.buf);
> +       return strbuf_detach(&gitdir, NULL);

By returning here, you're now leaking 'path' and 'sb' (see the 'done'
label below).

>  done:
>         strbuf_release(&path);
>         strbuf_release(&sb);
>         strbuf_release(&gitdir);
> +
> +       return NULL;
>  }
>
> -void die_if_checked_out(const char *branch)
> +char *find_shared_symref(const char *symref, const char *target)
>  {
>         struct strbuf path = STRBUF_INIT;
>         DIR *dir;
>         struct dirent *d;
> +       char *existing;
>
> -       check_linked_checkout(branch, NULL);
> +       if ((existing = find_linked_symref(symref, target, NULL)))
> +               return existing;
>
>         strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
>         dir = opendir(path.buf);
>         strbuf_release(&path);
>         if (!dir)
> -               return;
> +               return NULL;
>
>         while ((d = readdir(dir)) != NULL) {
>                 if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
>                         continue;
> -               check_linked_checkout(branch, d->d_name);
> +               if ((existing = find_linked_symref(symref, target, d->d_name)))
> +                       return existing;

By returning here, you're leaking the open 'dir'.

>         }
>         closedir(dir);
> +
> +       return NULL;
> +}
> +
> +void die_if_checked_out(const char *branch)
> +{
> +       char *existing;
> +
> +       existing = find_shared_symref("HEAD", branch);
> +       if (existing)
> +               die(_("'%s' is already checked out at '%s'"), branch, existing);
>  }
> diff --git a/branch.h b/branch.h
> index 58aa45f..0f466c7 100644
> --- a/branch.h
> +++ b/branch.h
> @@ -59,4 +59,12 @@ extern int read_branch_desc(struct strbuf *, const char *branch_name);
>   */
>  extern void die_if_checked_out(const char *branch);
>
> +/*
> + * Check if a per-worktree symref points to a ref in the main worktree
> + * or any linked worktree, and return the path to the exising worktree
> + * if it is.  Returns NULL if there is no existing ref.  The caller is
> + * responsible for freeing the returned path.
> + */
> +extern char *find_shared_symref(const char *symref, const char *branch);

I think you meant s/branch/target/.

>  #endif
> --
> 2.0.4.315.gad8727a-twtrsrc

Re: [PATCH v4 2/2] notes: handle multiple worktrees

[Johan Herland]

On Sat, Aug 1, 2015 at 12:11 AM, David Turner <dturner@twopensource.com> wrote:
> Before creating NOTES_MERGE_REF, check NOTES_MERGE_REF using
> find_shared_symref and die if we find one.  This prevents simultaneous
> merges to the same notes branch from different worktrees.
>
> Signed-off-by: David Turner <dturner@twopensource.com>
> ---
>  builtin/notes.c                  |  5 +++
>  t/t3320-notes-merge-worktrees.sh | 72 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 77 insertions(+)
>  create mode 100755 t/t3320-notes-merge-worktrees.sh
>
> diff --git a/builtin/notes.c b/builtin/notes.c
> index 63f95fc..e4dda79 100644
> --- a/builtin/notes.c
> +++ b/builtin/notes.c
> @@ -19,6 +19,7 @@
>  #include "string-list.h"
>  #include "notes-merge.h"
>  #include "notes-utils.h"
> +#include "branch.h"
>
>  static const char * const git_notes_usage[] = {
>         N_("git notes [--ref <notes-ref>] [list [<object>]]"),
> @@ -825,10 +826,14 @@ static int merge(int argc, const char **argv, const char *prefix)
>                 update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
>                            0, UPDATE_REFS_DIE_ON_ERR);
>         else { /* Merge has unresolved conflicts */
> +               char *existing;
>                 /* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
>                 update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
>                            0, UPDATE_REFS_DIE_ON_ERR);
>                 /* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
> +               existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());

Please confirm my assumption here: existing originally comes from a
strbuf_detach(), so it's the caller's (i.e. our) responsibility to
free() it, but we don't care, as we just die()d anyway. Correct?

> +               if (existing)
> +                       die(_("A notes merge on %s is already in-progress for %s"), default_notes_ref(), existing);

Not sure about your prepositions here. Would this maybe read better?:

  A notes merge into %s is already in-progress at %s

>                 if (create_symref("NOTES_MERGE_REF", default_notes_ref(), NULL))
>                         die("Failed to store link to current notes ref (%s)",
>                             default_notes_ref());
> diff --git a/t/t3320-notes-merge-worktrees.sh b/t/t3320-notes-merge-worktrees.sh
> new file mode 100755
> index 0000000..997621f
> --- /dev/null
> +++ b/t/t3320-notes-merge-worktrees.sh
> @@ -0,0 +1,72 @@
> +#!/bin/sh
> +#
> +# Copyright (c) 2015 Twitter, Inc
> +#
> +
> +test_description='Test merging of notes trees in multiple worktrees'
> +
> +. ./test-lib.sh
> +
> +test_expect_success 'setup commit' '
> +       test_commit tantrum
> +'
> +
> +commit_tantrum=$(git rev-parse tantrum^{commit})
> +
> +test_expect_success 'setup notes ref (x)' '
> +       git config core.notesRef refs/notes/x &&
> +       git notes add -m "x notes on tantrum" tantrum
> +'
> +
> +test_expect_success 'setup local branch (y)' '
> +       git update-ref refs/notes/y refs/notes/x &&
> +       git config core.notesRef refs/notes/y &&
> +       git notes remove tantrum
> +'
> +
> +test_expect_success 'setup remote branch (z)' '
> +       git update-ref refs/notes/z refs/notes/x &&
> +       git config core.notesRef refs/notes/z &&
> +       git notes add -f -m "conflicting notes on tantrum" tantrum
> +'
> +
> +test_expect_success 'modify notes ref ourselves (x)' '
> +       git config core.notesRef refs/notes/x &&
> +       git notes add -f -m "more conflicting notes on tantrum" tantrum
> +'
> +
> +test_expect_success 'create some new worktrees' '
> +       git worktree add -b newbranch worktree master &&
> +       git worktree add -b newbranch2 worktree2 master
> +'
> +
> +test_expect_success 'merge z into y fails and sets NOTES_MERGE_REF' '
> +       git config core.notesRef refs/notes/y &&
> +       test_must_fail git notes merge z &&
> +       echo "ref: refs/notes/y" > expect &&
> +       test_cmp .git/NOTES_MERGE_REF expect
> +'
> +
> +test_expect_success 'merge z into y while mid-merge in another workdir fails' '
> +       (
> +               cd worktree &&
> +               git config core.notesRef refs/notes/y &&
> +               test_must_fail git notes merge z 2>err &&
> +               grep "A notes merge on refs/notes/y is already in-progress for" err
> +       ) &&
> +       test_path_is_missing .git/worktrees/worktree/NOTES_MERGE_REF
> +'
> +
> +test_expect_success 'merge z into x while mid-merge on y succeeds' '
> +       (
> +               cd worktree2 &&
> +               git config core.notesRef refs/notes/x &&
> +               test_must_fail git notes merge z 2>&1 >out &&
> +               grep "Automatic notes merge failed" out

Missing &&?

> +               grep -v "A notes merge on refs/notes/x is already in-progress for" out
> +       ) &&
> +       echo "ref: refs/notes/x" > expect &&
> +       test_cmp .git/worktrees/worktree2/NOTES_MERGE_REF expect
> +'
> +
> +test_done

Otherwise, this looks good to me.


...Johan

> --
> 2.0.4.315.gad8727a-twtrsrc
>
> --
> To unsubscribe from this list: send the line "unsubscribe git" in
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-- 
Johan Herland, <johan@herland.net>
www.herland.net

Re: [PATCH v4 2/2] notes: handle multiple worktrees

[David Turner]

On Sat, 2015-08-01 at 15:51 +0200, Johan Herland wrote:
> On Sat, Aug 1, 2015 at 12:11 AM, David Turner <dturner@twopensource.com> wrote:
> > Before creating NOTES_MERGE_REF, check NOTES_MERGE_REF using
> > find_shared_symref and die if we find one.  This prevents simultaneous
> > merges to the same notes branch from different worktrees.
> >
> > Signed-off-by: David Turner <dturner@twopensource.com>
> > ---
> >  builtin/notes.c                  |  5 +++
> >  t/t3320-notes-merge-worktrees.sh | 72 ++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 77 insertions(+)
> >  create mode 100755 t/t3320-notes-merge-worktrees.sh
> >
> > diff --git a/builtin/notes.c b/builtin/notes.c
> > index 63f95fc..e4dda79 100644
> > --- a/builtin/notes.c
> > +++ b/builtin/notes.c
> > @@ -19,6 +19,7 @@
> >  #include "string-list.h"
> >  #include "notes-merge.h"
> >  #include "notes-utils.h"
> > +#include "branch.h"
> >
> >  static const char * const git_notes_usage[] = {
> >         N_("git notes [--ref <notes-ref>] [list [<object>]]"),
> > @@ -825,10 +826,14 @@ static int merge(int argc, const char **argv, const char *prefix)
> >                 update_ref(msg.buf, default_notes_ref(), result_sha1, NULL,
> >                            0, UPDATE_REFS_DIE_ON_ERR);
> >         else { /* Merge has unresolved conflicts */
> > +               char *existing;
> >                 /* Update .git/NOTES_MERGE_PARTIAL with partial merge result */
> >                 update_ref(msg.buf, "NOTES_MERGE_PARTIAL", result_sha1, NULL,
> >                            0, UPDATE_REFS_DIE_ON_ERR);
> >                 /* Store ref-to-be-updated into .git/NOTES_MERGE_REF */
> > +               existing = find_shared_symref("NOTES_MERGE_REF", default_notes_ref());
> 
> Please confirm my assumption here: existing originally comes from a
> strbuf_detach(), so it's the caller's (i.e. our) responsibility to
> free() it, but we don't care, as we just die()d anyway. Correct?

Confirmed.

 I will fix the other issues you reported.