[PATCH] Windows: Fix intermittent failures of t7701

[PATCH] Windows: Fix intermittent failures of t7701

[Johannes Sixt]

From: Johannes Sixt <j6t@kdbg.org>

The last test case checks whether unpacked objects receive the time stamp
of the pack file. Due to different implementations of stat(2) by MSYS and
our version in compat/mingw.c, the test fails in about half of the test
runs.

Note the following facts:

- The test uses perl's -M operator to compare the time stamps. Since we
  depend on MSYS perl, the result of this operator is based on MSYS's
  implementation of the stat(2) call.

- NTFS on Windows records fractional seconds.

- The MSYS implementation of stat(2) *rounds* fractional seconds to full
  seconds instead of truncating them. This becomes obvious by comparing the
  modification times reported by 'ls --full-time $f' and 'stat $f' for
  various files $f.

- Our implementation of stat(2) in compat/mingw.c *truncates* to full
  seconds.

The consequence of this is that

- add_packed_git() picks up truncated whole second modification times
  from the pack file time stamp, which is then used for the loose objects,
  while the pack file retains its time stamp in fractional seconds;

- but the test case compares the pack file's rounded modification times
  to the loose objects' truncated modification times.

And half of the time the rounded modification time is not the same as its
truncated modification time.

The fix is that we replace perl by 'test-chmtime -v +0', which prints the
truncated whole-second mtime without modifying it.

We want to catch failures of test-chmtime; but since it appears in a pipe,
we cannot access its exit code. Therefore, we at least make sure that it
prints time stamps of all files that are passed on its command line.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 t/t7701-repack-unpack-unreachable.sh |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/t/t7701-repack-unpack-unreachable.sh b/t/t7701-repack-unpack-unreachable.sh
index 63a8225..e6e9f99 100755
--- a/t/t7701-repack-unpack-unreachable.sh
+++ b/t/t7701-repack-unpack-unreachable.sh
@@ -50,12 +50,15 @@ test_expect_success '-A with -d option leaves unreachable objects unpacked' '

 compare_mtimes ()
 {
-	perl -e 'my $reference = shift;
-		 foreach my $file (@ARGV) {
-			exit(1) unless(-f $file && -M $file == -M $reference);
-		 }
-		 exit(0);
-		' -- "$@"
+	test-chmtime -v +0 "$@" |
+	{
+		read ref files &&
+		while read t name; do
+			test $ref = $t || break
+			files="$files $name"
+		done &&
+		test "$files" = "$*"
+	}
 }

 test_expect_success '-A without -d option leaves unreachable objects packed' '
-- 
1.6.1.1.1203.g5882

Re: [PATCH] Windows: Fix intermittent failures of t7701

[Johannes Schindelin]

Hi,

On Tue, 27 Jan 2009, Johannes Sixt wrote:

> We want to catch failures of test-chmtime; but since it appears in a 
> pipe, we cannot access its exit code. Therefore, we at least make sure 
> that it prints time stamps of all files that are passed on its command 
> line.

I use this trick in my valgrind series:

	($PROGRAM; echo $? > exit.code) | $OTHER_PROGRAM &&
	test 0 = "$(cat exit.code)"

Ciao,
Dscho

Re: [PATCH] Windows: Fix intermittent failures of t7701

[Jeff King]

On Tue, Jan 27, 2009 at 05:42:03PM +0100, Johannes Schindelin wrote:

> > We want to catch failures of test-chmtime; but since it appears in a 
> > pipe, we cannot access its exit code. Therefore, we at least make sure 
> > that it prints time stamps of all files that are passed on its command 
> > line.
> 
> I use this trick in my valgrind series:
> 
> 	($PROGRAM; echo $? > exit.code) | $OTHER_PROGRAM &&
> 	test 0 = "$(cat exit.code)"

Oh, that's far too readable. How about:

  exec 3>&1
  status=$( ( ($PROGRAM ; echo $? >&4) | $OTHER_PROGRAM >&3) 4>&1 )
  exec 3>&-

But seriously, I think if we are talking about tests, then

  $PROGRAM >output &&
  $OTHER_PROGRAM <output

is very clear to read, and as a bonus makes "output" accessible for
viewing when the test breaks. The downside is that it isn't very
efficient for a large output, but most of our test output is small (and
we don't care that much about efficiency).

Just my shell bikeshedding 2 cents. Feel free to ignore.

-Peff

Re: [PATCH] Windows: Fix intermittent failures of t7701

[Johannes Schindelin]

Hi,

On Tue, 27 Jan 2009, Jeff King wrote:

> On Tue, Jan 27, 2009 at 05:42:03PM +0100, Johannes Schindelin wrote:
> 
> > > We want to catch failures of test-chmtime; but since it appears in a 
> > > pipe, we cannot access its exit code. Therefore, we at least make sure 
> > > that it prints time stamps of all files that are passed on its command 
> > > line.
> > 
> > I use this trick in my valgrind series:
> > 
> > 	($PROGRAM; echo $? > exit.code) | $OTHER_PROGRAM &&
> > 	test 0 = "$(cat exit.code)"
> 
> Oh, that's far too readable. How about:
> 
>   exec 3>&1
>   status=$( ( ($PROGRAM ; echo $? >&4) | $OTHER_PROGRAM >&3) 4>&1 )
>   exec 3>&-
> 
> But seriously, I think if we are talking about tests, then
> 
>   $PROGRAM >output &&
>   $OTHER_PROGRAM <output
> 
> is very clear to read, and as a bonus makes "output" accessible for
> viewing when the test breaks.

The real problem is that in my case, OTHER_PROGRAM=tee.

But you're right, Hannes was talking about tests, where it might 
even make sense to have a record of what was passed between the 
two programs.

Ciao,
Dscho

Re: [PATCH] Windows: Fix intermittent failures of t7701

[Johannes Sixt]

Johannes Schindelin schrieb:
> I use this trick in my valgrind series:
> 
> 	($PROGRAM; echo $? > exit.code) | $OTHER_PROGRAM &&
> 	test 0 = "$(cat exit.code)"

Ah, using a file as temporary storage? Why not simply

	$PROGRAM > data &&
	$OTHER_PROGRAM < data

Hm? ;)

-- Hannes

Re: [PATCH] Windows: Fix intermittent failures of t7701

[Junio C Hamano]

Johannes Sixt <j.sixt@viscovery.net> writes:

> Johannes Schindelin schrieb:
>> I use this trick in my valgrind series:
>> 
>> 	($PROGRAM; echo $? > exit.code) | $OTHER_PROGRAM &&
>> 	test 0 = "$(cat exit.code)"
>
> Ah, using a file as temporary storage? Why not simply
>
> 	$PROGRAM > data &&
> 	$OTHER_PROGRAM < data
>
> Hm? ;)

Because too much cleverness often blinds clever minds.

Care to reroll with the simpler, dumber but clearer version?

[PATCH v2] Windows: Fix intermittent failures of t7701

[Johannes Sixt]

From: Johannes Sixt <j6t@kdbg.org>

The last test case checks whether unpacked objects receive the time stamp
of the pack file. Due to different implementations of stat(2) by MSYS and
our version in compat/mingw.c, the test fails in about half of the test
runs.

Note the following facts:

- The test uses perl's -M operator to compare the time stamps. Since we
  depend on MSYS perl, the result of this operator is based on MSYS's
  implementation of the stat(2) call.

- NTFS on Windows records fractional seconds.

- The MSYS implementation of stat(2) *rounds* fractional seconds to full
  seconds instead of truncating them. This becomes obvious by comparing the
  modification times reported by 'ls --full-time $f' and 'stat $f' for
  various files $f.

- Our implementation of stat(2) in compat/mingw.c *truncates* to full
  seconds.

The consequence of this is that

- add_packed_git() picks up a truncated whole second modification time
  from the pack file time stamp, which is then used for the loose objects,
  while the pack file retains its time stamp in fractional seconds;

- but the test case compared the pack file's rounded modification times
  to the loose objects' truncated modification times.

And half of the time the rounded modification time is not the same as its
truncated modification time.

The fix is that we replace perl by 'test-chmtime -v +0', which prints the
truncated whole-second mtime without modifying it.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
Junio C Hamano schrieb:
> Care to reroll with the simpler, dumber but clearer version?

OK. This time I use an intermediate file and dquotes around $t.

-- Hannes

 t/t7701-repack-unpack-unreachable.sh |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/t/t7701-repack-unpack-unreachable.sh b/t/t7701-repack-unpack-unreachable.sh
index 63a8225..5babdf2 100755
--- a/t/t7701-repack-unpack-unreachable.sh
+++ b/t/t7701-repack-unpack-unreachable.sh
@@ -50,12 +50,10 @@ test_expect_success '-A with -d option leaves unreachable objects unpacked' '

 compare_mtimes ()
 {
-	perl -e 'my $reference = shift;
-		 foreach my $file (@ARGV) {
-			exit(1) unless(-f $file && -M $file == -M $reference);
-		 }
-		 exit(0);
-		' -- "$@"
+	read tref rest &&
+	while read t rest; do
+		test "$tref" = "$t" || break
+	done
 }

 test_expect_success '-A without -d option leaves unreachable objects packed' '
@@ -87,7 +85,9 @@ test_expect_success 'unpacked objects receive timestamp of pack file' '
 	tmppack=".git/objects/pack/tmp_pack" &&
 	ln "$packfile" "$tmppack" &&
 	git repack -A -l -d &&
-	compare_mtimes "$tmppack" "$fsha1path" "$csha1path" "$tsha1path"
+	test-chmtime -v +0 "$tmppack" "$fsha1path" "$csha1path" "$tsha1path" \
+		> mtimes &&
+	compare_mtimes < mtimes
 '

 test_done
-- 
1.6.1.1.1203.g5882