[PATCH 0/2] Two small 'git repack' fixes

[PATCH 0/2] Two small 'git repack' fixes

[Derrick Stolee via GitGitGadget]

I was experimenting with some ideas in 'git repack' and discovered these two
bugs.

The first is a "real" bug in that it repacks much more data than is
necessary when repacking with '--write-midx -b' and there exists a .keep
pack. The fix is simple, which is to change a condition that was added for
the '-b' case before '--write-midx' existed.

The second is a UX bug in that '--quiet' did not disable all progress, at
least when stderr was interactive.

Thanks, -Stolee

Derrick Stolee (2):
  repack: respect kept objects with '--write-midx -b'
  repack: make '--quiet' disable progress

 builtin/repack.c  |  8 +++++---
 t/t7700-repack.sh | 15 +++++++++++++++
 2 files changed, 20 insertions(+), 3 deletions(-)


base-commit: 69a9c10c95e28df457e33b3c7400b16caf2e2962
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1098%2Fderrickstolee%2Frepack-fixes-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1098/derrickstolee/repack-fixes-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1098
-- 
gitgitgadget

[PATCH 1/2] repack: respect kept objects with '--write-midx -b'

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <dstolee@microsoft.com>

Historically, we needed a single packfile in order to have reachability
bitmaps. This introduced logic that when 'git repack' had a '-b' option
that we should stop sending the '--honor-pack-keep' option to the 'git
pack-objects' child process, ensuring that we create a packfile
containing all reachable objects.

In the world of multi-pack-index bitmaps, we no longer need to repack
all objects into a single pack to have valid bitmaps. Thus, we should
continue sending the '--honor-pack-keep' flag to 'git pack-objects'.

The fix is very simple: only disable the flag when writing bitmaps but
also _not_ writing the multi-pack-index.

This opens the door to new repacking strategies that might want to keep
some historical set of objects in a stable pack-file while only
repacking more recent objects.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/repack.c  |  2 +-
 t/t7700-repack.sh | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 9b0be6a6ab3..1f128b7c90b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -693,7 +693,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		write_bitmaps = 0;
 	}
 	if (pack_kept_objects < 0)
-		pack_kept_objects = write_bitmaps > 0;
+		pack_kept_objects = write_bitmaps > 0 && !write_midx;
 
 	if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
 		die(_(incremental_bitmap_conflict_error));
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 0260ad6f0e0..8c4ba6500be 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -372,4 +372,19 @@ test_expect_success '--write-midx with preferred bitmap tips' '
 	)
 '
 
+test_expect_success '--write-midx -b packs non-kept objects' '
+	git init midx-kept &&
+	test_when_finished "rm -fr midx-kept" &&
+	(
+		cd midx-kept &&
+		test_commit_bulk 100 &&
+		GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
+			git repack --write-midx -a -b &&
+		cat trace.txt | \
+			grep \"event\":\"start\" | \
+			grep pack-objects | \
+			grep \"--honor-pack-keep\"
+	)
+'
+
 test_done
-- 
gitgitgadget

Re: [PATCH 1/2] repack: respect kept objects with '--write-midx -b'

[Jeff King]

On Fri, Dec 17, 2021 at 04:28:45PM +0000, Derrick Stolee via GitGitGadget wrote:

> From: Derrick Stolee <dstolee@microsoft.com>
> 
> Historically, we needed a single packfile in order to have reachability
> bitmaps. This introduced logic that when 'git repack' had a '-b' option
> that we should stop sending the '--honor-pack-keep' option to the 'git
> pack-objects' child process, ensuring that we create a packfile
> containing all reachable objects.
> 
> In the world of multi-pack-index bitmaps, we no longer need to repack
> all objects into a single pack to have valid bitmaps. Thus, we should
> continue sending the '--honor-pack-keep' flag to 'git pack-objects'.
> 
> The fix is very simple: only disable the flag when writing bitmaps but
> also _not_ writing the multi-pack-index.
> 
> This opens the door to new repacking strategies that might want to keep
> some historical set of objects in a stable pack-file while only
> repacking more recent objects.

That all makes sense. Another way of thinking about it: we disable
--honor-pack-keep so we that keep packs do not interfere with writing a
pack bitmap. But with --write-midx, we skip the pack bitmap entirely.

In the end it's the same, but I wanted to emphasize that the important
hing is not so much that we are writing a midx bitmap as that we are
_not_ writing a pack bitmap. And that is what makes this OK to do (that
the repack code already disables the pack bitmap when writing a midx
one).

> diff --git a/builtin/repack.c b/builtin/repack.c
> index 9b0be6a6ab3..1f128b7c90b 100644
> --- a/builtin/repack.c
> +++ b/builtin/repack.c
> @@ -693,7 +693,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
>  		write_bitmaps = 0;
>  	}
>  	if (pack_kept_objects < 0)
> -		pack_kept_objects = write_bitmaps > 0;
> +		pack_kept_objects = write_bitmaps > 0 && !write_midx;

So the code change here looks good.

> diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
> index 0260ad6f0e0..8c4ba6500be 100755
> --- a/t/t7700-repack.sh
> +++ b/t/t7700-repack.sh
> @@ -372,4 +372,19 @@ test_expect_success '--write-midx with preferred bitmap tips' '
>  	)
>  '
>  
> +test_expect_success '--write-midx -b packs non-kept objects' '
> +	git init midx-kept &&
> +	test_when_finished "rm -fr midx-kept" &&
> +	(
> +		cd midx-kept &&
> +		test_commit_bulk 100 &&
> +		GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
> +			git repack --write-midx -a -b &&
> +		cat trace.txt | \
> +			grep \"event\":\"start\" | \
> +			grep pack-objects | \
> +			grep \"--honor-pack-keep\"
> +	)
> +'

This looks correct, though:

  - do we really need this separate repo directory? The test before it
    uses one, but only because it needs a very specific set of commits.
    There is a long-running "midx" directory we could use, though I
    think just the regular test repo would be fine, too.

  - likewise, do we need 100 commits? They are not too expensive these
    days with test_commit_bulk, but I think we don't even care about the
    repo contents at all.

  - there is no actual .keep file in your test. That's OK, as we are
    just checking the args passed to pack-objects.

  - useless use of cat. :) Also, you could probably do it all with one
    grep. This is bikeshedding, of course, but it's nice to keep process
    counts low in the test suite. Also, your middle grep is looser than
    the others (it doesn't check for surrounding quotes).

So something like this would work:

  test_expect_success '--write-midx -b packs non-kept objects' '
          GIT_TRACE2_EVENT="$(pwd)/midx-keep-bitmap.trace" \
                  git -C midx repack --write-midx -a -b &&
          grep "\"event\":\"start\".*\"pack-objects\".*\"--honor-pack-keep\"" \
                  midx-keep-bitmap.trace
  '

One could perhaps argue that the combined grep is less readable. If
that's a concern, I'd suggest wrapping it in a function like:

  # usage: check_trace2_arg <trace_file> <cmd> <arg>
  check_trace2_arg () {
	grep "\"event\":\"start\".*\"$2\".*\"$3\"" "$1"
  }

All just suggestions, of course. I'd be happy enough to see the patch go
in as-is.

-Peff

Re: [PATCH 1/2] repack: respect kept objects with '--write-midx -b'

[Derrick Stolee]

On 12/17/2021 12:24 PM, Jeff King wrote:
> On Fri, Dec 17, 2021 at 04:28:45PM +0000, Derrick Stolee via GitGitGadget wrote:

...

>> +test_expect_success '--write-midx -b packs non-kept objects' '
>> +	git init midx-kept &&
>> +	test_when_finished "rm -fr midx-kept" &&
>> +	(
>> +		cd midx-kept &&
>> +		test_commit_bulk 100 &&
>> +		GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
>> +			git repack --write-midx -a -b &&
>> +		cat trace.txt | \
>> +			grep \"event\":\"start\" | \
>> +			grep pack-objects | \
>> +			grep \"--honor-pack-keep\"
>> +	)
>> +'
> 
> This looks correct, though:
> 
>   - do we really need this separate repo directory? The test before it
>     uses one, but only because it needs a very specific set of commits.
>     There is a long-running "midx" directory we could use, though I
>     think just the regular test repo would be fine, too.
> 
>   - likewise, do we need 100 commits? They are not too expensive these
>     days with test_commit_bulk, but I think we don't even care about the
>     repo contents at all.
> 
>   - there is no actual .keep file in your test. That's OK, as we are
>     just checking the args passed to pack-objects.
> 
>   - useless use of cat. :) Also, you could probably do it all with one
>     grep. This is bikeshedding, of course, but it's nice to keep process
>     counts low in the test suite. Also, your middle grep is looser than
>     the others (it doesn't check for surrounding quotes).
> 
> So something like this would work:
> 
>   test_expect_success '--write-midx -b packs non-kept objects' '
>           GIT_TRACE2_EVENT="$(pwd)/midx-keep-bitmap.trace" \
>                   git -C midx repack --write-midx -a -b &&
>           grep "\"event\":\"start\".*\"pack-objects\".*\"--honor-pack-keep\"" \
>                   midx-keep-bitmap.trace
>   '
> 
> One could perhaps argue that the combined grep is less readable. If
> that's a concern, I'd suggest wrapping it in a function like:
> 
>   # usage: check_trace2_arg <trace_file> <cmd> <arg>
>   check_trace2_arg () {
> 	grep "\"event\":\"start\".*\"$2\".*\"$3\"" "$1"
>   }
> 
> All just suggestions, of course. I'd be happy enough to see the patch go
> in as-is.

Thanks for the suggestions. I decided to adapt the 'test_subcommand'
helper into a 'test_subcommand_inexact' helper. The existing helper
requires the full argument list in exact order, but the new one only
cares about the given arguments (in that relative order).

Thanks,
-Stolee

Re: [PATCH 1/2] repack: respect kept objects with '--write-midx -b'

[Jeff King]

On Mon, Dec 20, 2021 at 08:40:09AM -0500, Derrick Stolee wrote:

> > One could perhaps argue that the combined grep is less readable. If
> > that's a concern, I'd suggest wrapping it in a function like:
> > 
> >   # usage: check_trace2_arg <trace_file> <cmd> <arg>
> >   check_trace2_arg () {
> > 	grep "\"event\":\"start\".*\"$2\".*\"$3\"" "$1"
> >   }
> > 
> > All just suggestions, of course. I'd be happy enough to see the patch go
> > in as-is.
> 
> Thanks for the suggestions. I decided to adapt the 'test_subcommand'
> helper into a 'test_subcommand_inexact' helper. The existing helper
> requires the full argument list in exact order, but the new one only
> cares about the given arguments (in that relative order).

Heh, I should have looked to see if we had faced this problem before.
Extending that family of helpers is better still than my suggestion.

-Peff

Re: [PATCH 1/2] repack: respect kept objects with '--write-midx -b'

[Ævar Arnfjörð Bjarmason]

On Fri, Dec 17 2021, Derrick Stolee via GitGitGadget wrote:

> +test_expect_success '--write-midx -b packs non-kept objects' '
> +	git init midx-kept &&
> +	test_when_finished "rm -fr midx-kept" &&

Nit: Better the other way around, so we'll clean up things if "git init"
dies midway, but unlikely to ever happen here.

> +	(
> +		cd midx-kept &&
> +		test_commit_bulk 100 &&
> +		GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
> +			git repack --write-midx -a -b &&
> +		cat trace.txt | \
> +			grep \"event\":\"start\" | \

The "cat" here should go in favor of "grep <pat> trace.txt", and can't
this all be on one grep line with "." between the relevant parts you're
extracting out?

[PATCH 2/2] repack: make '--quiet' disable progress

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <dstolee@microsoft.com>

While testing some ideas in 'git repack', I ran it with '--quiet' and
discovered that some progress output was still shown. Specifically, the
output for writing the multi-pack-index showed the progress.

The 'show_progress' variable in cmd_repack() is initialized with
isatty(2) and is not modified at all by the '--quiet' flag. The
'--quiet' flag modifies the po_args.quiet option which is translated
into a '--quiet' flag for the 'git pack-objects' child process. However,
'show_progress' is used to directly send progress information to the
multi-pack-index writing logic which does not use a child process.

The fix here is to modify 'show_progress' to be false if po_opts.quiet
is true, and isatty(2) otherwise. This new expectation simplifies a
later condition that checks both.

This is difficult to test because the isatty(2) already prevents the
progess indicators from appearing when we redirect stderr to a file.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/repack.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 1f128b7c90b..c393a5db774 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -612,7 +612,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	struct tempfile *refs_snapshot = NULL;
 	int i, ext, ret;
 	FILE *out;
-	int show_progress = isatty(2);
+	int show_progress;
 
 	/* variables to be filled by option parsing */
 	int pack_everything = 0;
@@ -725,6 +725,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 
 	prepare_pack_objects(&cmd, &po_args);
 
+	show_progress = !po_args.quiet && isatty(2);
+
 	strvec_push(&cmd.args, "--keep-true-parents");
 	if (!pack_kept_objects)
 		strvec_push(&cmd.args, "--honor-pack-keep");
@@ -926,7 +928,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			}
 			strbuf_release(&buf);
 		}
-		if (!po_args.quiet && show_progress)
+		if (show_progress)
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);
 
-- 
gitgitgadget

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Jeff King]

On Fri, Dec 17, 2021 at 04:28:46PM +0000, Derrick Stolee via GitGitGadget wrote:

> From: Derrick Stolee <dstolee@microsoft.com>
> 
> While testing some ideas in 'git repack', I ran it with '--quiet' and
> discovered that some progress output was still shown. Specifically, the
> output for writing the multi-pack-index showed the progress.
> 
> The 'show_progress' variable in cmd_repack() is initialized with
> isatty(2) and is not modified at all by the '--quiet' flag. The
> '--quiet' flag modifies the po_args.quiet option which is translated
> into a '--quiet' flag for the 'git pack-objects' child process. However,
> 'show_progress' is used to directly send progress information to the
> multi-pack-index writing logic which does not use a child process.
> 
> The fix here is to modify 'show_progress' to be false if po_opts.quiet
> is true, and isatty(2) otherwise. This new expectation simplifies a
> later condition that checks both.

Makes sense. I wondered if you might have to decide what to do with
"--progress --quiet", but we do not have an explicit progress option for
git-repack in the first place.

> This is difficult to test because the isatty(2) already prevents the
> progess indicators from appearing when we redirect stderr to a file.

You'd need test_terminal. Something like this:

diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 8c4ba6500b..b673c49650 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -5,6 +5,7 @@ test_description='git repack works correctly'
 . ./test-lib.sh
 . "${TEST_DIRECTORY}/lib-bitmap.sh"
 . "${TEST_DIRECTORY}/lib-midx.sh"
+. "${TEST_DIRECTORY}/lib-terminal.sh"
 
 commit_and_pack () {
 	test_commit "$@" 1>&2 &&
@@ -387,4 +388,10 @@ test_expect_success '--write-midx -b packs non-kept objects' '
 	)
 '
 
+test_expect_success TTY '--quiet disables progress' '
+	test_terminal env GIT_PROGRESS_DELAY=0 \
+		git -C midx repack -ad --quiet --write-midx 2>stderr &&
+	test_must_be_empty stderr
+'
+
 test_done

-Peff

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Derrick Stolee]

On 12/17/2021 1:10 PM, Jeff King wrote:
> On Fri, Dec 17, 2021 at 04:28:46PM +0000, Derrick Stolee via GitGitGadget wrote:

>> This is difficult to test because the isatty(2) already prevents the
>> progess indicators from appearing when we redirect stderr to a file.
> 
> You'd need test_terminal. Something like this:
> 
> diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
> index 8c4ba6500b..b673c49650 100755
> --- a/t/t7700-repack.sh
> +++ b/t/t7700-repack.sh
> @@ -5,6 +5,7 @@ test_description='git repack works correctly'
>  . ./test-lib.sh
>  . "${TEST_DIRECTORY}/lib-bitmap.sh"
>  . "${TEST_DIRECTORY}/lib-midx.sh"
> +. "${TEST_DIRECTORY}/lib-terminal.sh"
>  
>  commit_and_pack () {
>  	test_commit "$@" 1>&2 &&
> @@ -387,4 +388,10 @@ test_expect_success '--write-midx -b packs non-kept objects' '
>  	)
>  '
>  
> +test_expect_success TTY '--quiet disables progress' '
> +	test_terminal env GIT_PROGRESS_DELAY=0 \
> +		git -C midx repack -ad --quiet --write-midx 2>stderr &&
> +	test_must_be_empty stderr
> +'
> +
>  test_done

Thanks. I added this test.

When first running the test, it failed because I didn't have the
IO::Pty Perl module installed. I'm not sure why I don't fail with
other tests that use test_terminal. If someone knows more about
what is going on, then maybe we need to expand the TTY prereq?

Thanks,
-Stolee

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Jeff King]

On Mon, Dec 20, 2021 at 08:37:52AM -0500, Derrick Stolee wrote:

> > +test_expect_success TTY '--quiet disables progress' '
> > +	test_terminal env GIT_PROGRESS_DELAY=0 \
> > +		git -C midx repack -ad --quiet --write-midx 2>stderr &&
> > +	test_must_be_empty stderr
> > +'
> > +
> >  test_done
> 
> Thanks. I added this test.
> 
> When first running the test, it failed because I didn't have the
> IO::Pty Perl module installed. I'm not sure why I don't fail with
> other tests that use test_terminal. If someone knows more about
> what is going on, then maybe we need to expand the TTY prereq?

Weird. I uninstalled IO::Pty, and get:

  checking prerequisite: TTY
  
  [...prereq code...]

  
  + perl /home/peff/compile/git/t/test-terminal.perl sh -c test -t 1 && test -t 2
  + command /usr/bin/perl /home/peff/compile/git/t/test-terminal.perl sh -c test -t 1 && test -t 2
  Can't locate IO/Pty.pm in @INC (you may need to install the IO::Pty module) (@INC contains: [...etc...]
  BEGIN failed--compilation aborted at /home/peff/compile/git/t/test-terminal.perl line 5.
  prerequisite TTY not satisfied
  ok 25 # skip --quiet disables progress (missing TTY)

What does running with "-x -i" say for the prereq?

-Peff

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Derrick Stolee]

On 12/20/2021 8:49 AM, Jeff King wrote:
> On Mon, Dec 20, 2021 at 08:37:52AM -0500, Derrick Stolee wrote:
> 
>>> +test_expect_success TTY '--quiet disables progress' '
>>> +	test_terminal env GIT_PROGRESS_DELAY=0 \
>>> +		git -C midx repack -ad --quiet --write-midx 2>stderr &&
>>> +	test_must_be_empty stderr
>>> +'
>>> +
>>>  test_done
>>
>> Thanks. I added this test.
>>
>> When first running the test, it failed because I didn't have the
>> IO::Pty Perl module installed. I'm not sure why I don't fail with
>> other tests that use test_terminal. If someone knows more about
>> what is going on, then maybe we need to expand the TTY prereq?
> 
> Weird. I uninstalled IO::Pty, and get:
> 
>   checking prerequisite: TTY
>   
>   [...prereq code...]
> 
>   
>   + perl /home/peff/compile/git/t/test-terminal.perl sh -c test -t 1 && test -t 2
>   + command /usr/bin/perl /home/peff/compile/git/t/test-terminal.perl sh -c test -t 1 && test -t 2
>   Can't locate IO/Pty.pm in @INC (you may need to install the IO::Pty module) (@INC contains: [...etc...]
>   BEGIN failed--compilation aborted at /home/peff/compile/git/t/test-terminal.perl line 5.
>   prerequisite TTY not satisfied
>   ok 25 # skip --quiet disables progress (missing TTY)
> 
> What does running with "-x -i" say for the prereq?

Ok, I got this same error and misread it as an error. The prereq
is working just fine. Thanks for checking.

-Stolee

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Ævar Arnfjörð Bjarmason]

On Fri, Dec 17 2021, Derrick Stolee via GitGitGadget wrote:

> From: Derrick Stolee <dstolee@microsoft.com>
>
> While testing some ideas in 'git repack', I ran it with '--quiet' and
> discovered that some progress output was still shown. Specifically, the
> output for writing the multi-pack-index showed the progress.
>
> The 'show_progress' variable in cmd_repack() is initialized with
> isatty(2) and is not modified at all by the '--quiet' flag. The
> '--quiet' flag modifies the po_args.quiet option which is translated
> into a '--quiet' flag for the 'git pack-objects' child process. However,
> 'show_progress' is used to directly send progress information to the
> multi-pack-index writing logic which does not use a child process.
>
> The fix here is to modify 'show_progress' to be false if po_opts.quiet
> is true, and isatty(2) otherwise. This new expectation simplifies a
> later condition that checks both.
>
> This is difficult to test because the isatty(2) already prevents the
> progess indicators from appearing when we redirect stderr to a file.
>
> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
> ---
>  builtin/repack.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/builtin/repack.c b/builtin/repack.c
> index 1f128b7c90b..c393a5db774 100644
> --- a/builtin/repack.c
> +++ b/builtin/repack.c
> @@ -612,7 +612,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
>  	struct tempfile *refs_snapshot = NULL;
>  	int i, ext, ret;
>  	FILE *out;
> -	int show_progress = isatty(2);
> +	int show_progress;
>  
>  	/* variables to be filled by option parsing */
>  	int pack_everything = 0;
> @@ -725,6 +725,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
>  
>  	prepare_pack_objects(&cmd, &po_args);
>  
> +	show_progress = !po_args.quiet && isatty(2);
> +
>  	strvec_push(&cmd.args, "--keep-true-parents");
>  	if (!pack_kept_objects)
>  		strvec_push(&cmd.args, "--honor-pack-keep");
> @@ -926,7 +928,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
>  			}
>  			strbuf_release(&buf);
>  		}
> -		if (!po_args.quiet && show_progress)
> +		if (show_progress)
>  			opts |= PRUNE_PACKED_VERBOSE;
>  		prune_packed_objects(opts);

This seems like a good change, but the documentation could really use an
update (also before this change). It just says about -q:

    Pass the -q option to git pack-objects. See git-pack-objects(1).

But do various things in "git-repack" itself differently if it's
supplied.

Re: [PATCH 2/2] repack: make '--quiet' disable progress

[Derrick Stolee]

On 12/18/2021 4:55 AM, Ævar Arnfjörð Bjarmason wrote:
> This seems like a good change, but the documentation could really use an
> update (also before this change). It just says about -q:
> 
>     Pass the -q option to git pack-objects. See git-pack-objects(1).
> 
> But do various things in "git-repack" itself differently if it's
> supplied.

Good point. I will update the docs.

Thanks,
-Stolee

[PATCH v2 0/2] Two small 'git repack' fixes

[Derrick Stolee via GitGitGadget]

I was experimenting with some ideas in 'git repack' and discovered these two
bugs.

The first is a "real" bug in that it repacks much more data than is
necessary when repacking with '--write-midx -b' and there exists a .keep
pack. The fix is simple, which is to change a condition that was added for
the '-b' case before '--write-midx' existed.

The second is a UX bug in that '--quiet' did not disable all progress, at
least when stderr was interactive.


Updates in v2
=============

Thanks for the quick review!

 * Test for --honor-pack-keep is cleaner with a reusable helper.
 * TTY test is added.
 * Docs are updated.

Thanks, -Stolee

Derrick Stolee (2):
  repack: respect kept objects with '--write-midx -b'
  repack: make '--quiet' disable progress

 Documentation/git-repack.txt |  5 +++--
 builtin/repack.c             |  8 +++++---
 t/t7700-repack.sh            | 13 +++++++++++++
 t/test-lib-functions.sh      | 34 ++++++++++++++++++++++++++++++++++
 4 files changed, 55 insertions(+), 5 deletions(-)


base-commit: 69a9c10c95e28df457e33b3c7400b16caf2e2962
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1098%2Fderrickstolee%2Frepack-fixes-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1098/derrickstolee/repack-fixes-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1098

Range-diff vs v1:

 1:  1ed91f6d255 ! 1:  747328a4dd6 repack: respect kept objects with '--write-midx -b'
     @@ Commit message
          some historical set of objects in a stable pack-file while only
          repacking more recent objects.
      
     +    To test, create a new 'test_subcommand_inexact' helper that is more
     +    flexible than 'test_subcommand'. This allows us to look for the
     +    --honor-pack-keep flag without over-indexing on the exact set of
     +    arguments.
     +
          Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
      
       ## builtin/repack.c ##
     @@ t/t7700-repack.sh: test_expect_success '--write-midx with preferred bitmap tips'
       '
       
      +test_expect_success '--write-midx -b packs non-kept objects' '
     -+	git init midx-kept &&
     -+	test_when_finished "rm -fr midx-kept" &&
     -+	(
     -+		cd midx-kept &&
     -+		test_commit_bulk 100 &&
     -+		GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
     -+			git repack --write-midx -a -b &&
     -+		cat trace.txt | \
     -+			grep \"event\":\"start\" | \
     -+			grep pack-objects | \
     -+			grep \"--honor-pack-keep\"
     -+	)
     ++	GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
     ++		git repack --write-midx -a -b &&
     ++	test_subcommand_inexact git pack-objects --honor-pack-keep <trace.txt
      +'
      +
       test_done
     +
     + ## t/test-lib-functions.sh ##
     +@@ t/test-lib-functions.sh: test_subcommand () {
     + 	fi
     + }
     + 
     ++# Check that the given command was invoked as part of the
     ++# trace2-format trace on stdin, but without an exact set of
     ++# arguments.
     ++#
     ++#	test_subcommand [!] <command> <args>... < <trace>
     ++#
     ++# For example, to look for an invocation of "git pack-objects"
     ++# with the "--honor-pack-keep" argument, use
     ++#
     ++#	GIT_TRACE2_EVENT=event.log git repack ... &&
     ++#	test_subcommand git pack-objects --honor-pack-keep <event.log
     ++#
     ++# If the first parameter passed is !, this instead checks that
     ++# the given command was not called.
     ++#
     ++test_subcommand_inexact () {
     ++	local negate=
     ++	if test "$1" = "!"
     ++	then
     ++		negate=t
     ++		shift
     ++	fi
     ++
     ++	local expr=$(printf '"%s".*' "$@")
     ++	expr="${expr%,}"
     ++
     ++	if test -n "$negate"
     ++	then
     ++		! grep "\"event\":\"child_start\".*\[$expr\]"
     ++	else
     ++		grep "\"event\":\"child_start\".*\[$expr\]"
     ++	fi
     ++}
     ++
     + # Check that the given command was invoked as part of the
     + # trace2-format trace on stdin.
     + #
 2:  3eff83d9ae1 ! 2:  41260bf0829 repack: make '--quiet' disable progress
     @@ Commit message
          is true, and isatty(2) otherwise. This new expectation simplifies a
          later condition that checks both.
      
     -    This is difficult to test because the isatty(2) already prevents the
     -    progess indicators from appearing when we redirect stderr to a file.
     +    Update the documentation to make it clear that '-q' will disable all
     +    progress in addition to ensuring the 'git pack-objects' child process
     +    will receive the flag.
      
     +    Use 'test_terminal' to check that this works to get around the isatty(2)
     +    check.
     +
     +    Helped-by: Jeff King <peff@peff.net>
          Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
      
     + ## Documentation/git-repack.txt ##
     +@@ Documentation/git-repack.txt: to the new separate pack will be written.
     + 	linkgit:git-pack-objects[1].
     + 
     + -q::
     +-	Pass the `-q` option to 'git pack-objects'. See
     +-	linkgit:git-pack-objects[1].
     ++--quiet::
     ++	Show no progress over the standard error stream and pass the `-q`
     ++	option to 'git pack-objects'. See linkgit:git-pack-objects[1].
     + 
     + -n::
     + 	Do not update the server information with
     +
       ## builtin/repack.c ##
      @@ builtin/repack.c: int cmd_repack(int argc, const char **argv, const char *prefix)
       	struct tempfile *refs_snapshot = NULL;
     @@ builtin/repack.c: int cmd_repack(int argc, const char **argv, const char *prefix
       			opts |= PRUNE_PACKED_VERBOSE;
       		prune_packed_objects(opts);
       
     +
     + ## t/t7700-repack.sh ##
     +@@ t/t7700-repack.sh: test_description='git repack works correctly'
     + . ./test-lib.sh
     + . "${TEST_DIRECTORY}/lib-bitmap.sh"
     + . "${TEST_DIRECTORY}/lib-midx.sh"
     ++. "${TEST_DIRECTORY}/lib-terminal.sh"
     + 
     + commit_and_pack () {
     + 	test_commit "$@" 1>&2 &&
     +@@ t/t7700-repack.sh: test_expect_success '--write-midx -b packs non-kept objects' '
     + 	test_subcommand_inexact git pack-objects --honor-pack-keep <trace.txt
     + '
     + 
     ++test_expect_success TTY '--quiet disables progress' '
     ++	test_terminal env GIT_PROGRESS_DELAY=0 \
     ++		git -C midx repack -ad --quiet --write-midx 2>stderr &&
     ++	test_must_be_empty stderr
     ++'
     ++
     + test_done

-- 
gitgitgadget

[PATCH v2 1/2] repack: respect kept objects with '--write-midx -b'

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <dstolee@microsoft.com>

Historically, we needed a single packfile in order to have reachability
bitmaps. This introduced logic that when 'git repack' had a '-b' option
that we should stop sending the '--honor-pack-keep' option to the 'git
pack-objects' child process, ensuring that we create a packfile
containing all reachable objects.

In the world of multi-pack-index bitmaps, we no longer need to repack
all objects into a single pack to have valid bitmaps. Thus, we should
continue sending the '--honor-pack-keep' flag to 'git pack-objects'.

The fix is very simple: only disable the flag when writing bitmaps but
also _not_ writing the multi-pack-index.

This opens the door to new repacking strategies that might want to keep
some historical set of objects in a stable pack-file while only
repacking more recent objects.

To test, create a new 'test_subcommand_inexact' helper that is more
flexible than 'test_subcommand'. This allows us to look for the
--honor-pack-keep flag without over-indexing on the exact set of
arguments.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/repack.c        |  2 +-
 t/t7700-repack.sh       |  6 ++++++
 t/test-lib-functions.sh | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 9b0be6a6ab3..1f128b7c90b 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -693,7 +693,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		write_bitmaps = 0;
 	}
 	if (pack_kept_objects < 0)
-		pack_kept_objects = write_bitmaps > 0;
+		pack_kept_objects = write_bitmaps > 0 && !write_midx;
 
 	if (write_bitmaps && !(pack_everything & ALL_INTO_ONE) && !write_midx)
 		die(_(incremental_bitmap_conflict_error));
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 0260ad6f0e0..63c9a247f57 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -372,4 +372,10 @@ test_expect_success '--write-midx with preferred bitmap tips' '
 	)
 '
 
+test_expect_success '--write-midx -b packs non-kept objects' '
+	GIT_TRACE2_EVENT="$(pwd)/trace.txt" \
+		git repack --write-midx -a -b &&
+	test_subcommand_inexact git pack-objects --honor-pack-keep <trace.txt
+'
+
 test_done
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 389153e5916..c3d38aaccbd 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -1759,6 +1759,40 @@ test_subcommand () {
 	fi
 }
 
+# Check that the given command was invoked as part of the
+# trace2-format trace on stdin, but without an exact set of
+# arguments.
+#
+#	test_subcommand [!] <command> <args>... < <trace>
+#
+# For example, to look for an invocation of "git pack-objects"
+# with the "--honor-pack-keep" argument, use
+#
+#	GIT_TRACE2_EVENT=event.log git repack ... &&
+#	test_subcommand git pack-objects --honor-pack-keep <event.log
+#
+# If the first parameter passed is !, this instead checks that
+# the given command was not called.
+#
+test_subcommand_inexact () {
+	local negate=
+	if test "$1" = "!"
+	then
+		negate=t
+		shift
+	fi
+
+	local expr=$(printf '"%s".*' "$@")
+	expr="${expr%,}"
+
+	if test -n "$negate"
+	then
+		! grep "\"event\":\"child_start\".*\[$expr\]"
+	else
+		grep "\"event\":\"child_start\".*\[$expr\]"
+	fi
+}
+
 # Check that the given command was invoked as part of the
 # trace2-format trace on stdin.
 #
-- 
gitgitgadget

[PATCH v2 2/2] repack: make '--quiet' disable progress

[Derrick Stolee via GitGitGadget]

From: Derrick Stolee <dstolee@microsoft.com>

While testing some ideas in 'git repack', I ran it with '--quiet' and
discovered that some progress output was still shown. Specifically, the
output for writing the multi-pack-index showed the progress.

The 'show_progress' variable in cmd_repack() is initialized with
isatty(2) and is not modified at all by the '--quiet' flag. The
'--quiet' flag modifies the po_args.quiet option which is translated
into a '--quiet' flag for the 'git pack-objects' child process. However,
'show_progress' is used to directly send progress information to the
multi-pack-index writing logic which does not use a child process.

The fix here is to modify 'show_progress' to be false if po_opts.quiet
is true, and isatty(2) otherwise. This new expectation simplifies a
later condition that checks both.

Update the documentation to make it clear that '-q' will disable all
progress in addition to ensuring the 'git pack-objects' child process
will receive the flag.

Use 'test_terminal' to check that this works to get around the isatty(2)
check.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 Documentation/git-repack.txt | 5 +++--
 builtin/repack.c             | 6 ++++--
 t/t7700-repack.sh            | 7 +++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-repack.txt b/Documentation/git-repack.txt
index 7183fb498f4..ee30edc178a 100644
--- a/Documentation/git-repack.txt
+++ b/Documentation/git-repack.txt
@@ -76,8 +76,9 @@ to the new separate pack will be written.
 	linkgit:git-pack-objects[1].
 
 -q::
-	Pass the `-q` option to 'git pack-objects'. See
-	linkgit:git-pack-objects[1].
+--quiet::
+	Show no progress over the standard error stream and pass the `-q`
+	option to 'git pack-objects'. See linkgit:git-pack-objects[1].
 
 -n::
 	Do not update the server information with
diff --git a/builtin/repack.c b/builtin/repack.c
index 1f128b7c90b..c393a5db774 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -612,7 +612,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	struct tempfile *refs_snapshot = NULL;
 	int i, ext, ret;
 	FILE *out;
-	int show_progress = isatty(2);
+	int show_progress;
 
 	/* variables to be filled by option parsing */
 	int pack_everything = 0;
@@ -725,6 +725,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 
 	prepare_pack_objects(&cmd, &po_args);
 
+	show_progress = !po_args.quiet && isatty(2);
+
 	strvec_push(&cmd.args, "--keep-true-parents");
 	if (!pack_kept_objects)
 		strvec_push(&cmd.args, "--honor-pack-keep");
@@ -926,7 +928,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			}
 			strbuf_release(&buf);
 		}
-		if (!po_args.quiet && show_progress)
+		if (show_progress)
 			opts |= PRUNE_PACKED_VERBOSE;
 		prune_packed_objects(opts);
 
diff --git a/t/t7700-repack.sh b/t/t7700-repack.sh
index 63c9a247f57..fe2b493d0ee 100755
--- a/t/t7700-repack.sh
+++ b/t/t7700-repack.sh
@@ -5,6 +5,7 @@ test_description='git repack works correctly'
 . ./test-lib.sh
 . "${TEST_DIRECTORY}/lib-bitmap.sh"
 . "${TEST_DIRECTORY}/lib-midx.sh"
+. "${TEST_DIRECTORY}/lib-terminal.sh"
 
 commit_and_pack () {
 	test_commit "$@" 1>&2 &&
@@ -378,4 +379,10 @@ test_expect_success '--write-midx -b packs non-kept objects' '
 	test_subcommand_inexact git pack-objects --honor-pack-keep <trace.txt
 '
 
+test_expect_success TTY '--quiet disables progress' '
+	test_terminal env GIT_PROGRESS_DELAY=0 \
+		git -C midx repack -ad --quiet --write-midx 2>stderr &&
+	test_must_be_empty stderr
+'
+
 test_done
-- 
gitgitgadget

Re: [PATCH v2 0/2] Two small 'git repack' fixes

[Ævar Arnfjörð Bjarmason]

On Mon, Dec 20 2021, Derrick Stolee via GitGitGadget wrote:

> I was experimenting with some ideas in 'git repack' and discovered these two
> bugs.

This iteration looks good to me.

>      + ## Documentation/git-repack.txt ##
>      +@@ Documentation/git-repack.txt: to the new separate pack will be written.
>      + 	linkgit:git-pack-objects[1].
>      + 
>      + -q::
>      +-	Pass the `-q` option to 'git pack-objects'. See
>      +-	linkgit:git-pack-objects[1].
>      ++--quiet::
>      ++	Show no progress over the standard error stream and pass the `-q`
>      ++	option to 'git pack-objects'. See linkgit:git-pack-objects[1].
>      + 
>      + -n::
>      + 	Do not update the server information with
>      +

Nit: I think the addition of --quiet here is good, but also wouldn't
mind a prep change to add it as a separate step.

FWIW it appears to have been an unintended/hidden effect of a1bbc6c0176
(repack: rewrite the shell script in C, 2013-09-15), i.e. we started
using OPT__QUIET() which added "--quiet", but the shellscript just
supported -q.

Here we update the docs, but the SYNOPSIS stillj just lists -q.

I think all of that's fine & this v2 is good enough. Just braindumping
notes/observations while reading along/checking the v1->v2 diff.