[PATCH nd/threaded-index-pack] index-pack: disable threading if NO_PREAD is defined

[PATCH nd/threaded-index-pack] index-pack: disable threading if NO_PREAD is defined

[Nguyễn Thái Ngọc Duy]

NO_PREAD simulates pread() as a sequence of seek, read, seek in
compat/pread.c. The simulation is not thread-safe because another
thread could move the file offset away in the middle of pread
operation. Do not allow threading in that case.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/index-pack.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 847dbb3..c1c3c81 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -39,6 +39,11 @@ struct base_data {
 	int ofs_first, ofs_last;
 };
 
+#if !defined(NO_PTHREADS) && defined(NO_PREAD)
+/* NO_PREAD uses compat/pread.c, which is not thread-safe. Disable threading. */
+#define NO_PTHREADS
+#endif
+
 struct thread_local {
 #ifndef NO_PTHREADS
 	pthread_t thread;
-- 
1.7.8.36.g69ee2

Re: [PATCH nd/threaded-index-pack] index-pack: disable threading if NO_PREAD is defined

[Junio C Hamano]

Thanks; will queue.

Re: [PATCH nd/threaded-index-pack] index-pack: disable threading if NO_PREAD is defined

[Johannes Sixt]

Am 4/19/2012 16:05, schrieb Nguyễn Thái Ngọc Duy:
> NO_PREAD simulates pread() as a sequence of seek, read, seek in
> compat/pread.c. The simulation is not thread-safe because another
> thread could move the file offset away in the middle of pread
> operation. Do not allow threading in that case.

Unsurprisingly, this fixes the breakage for me.

I used the attached patch to keep t9300 running when the breakage
was detected.

--- 8< ---
From: Johannes Sixt <j6t@kdbg.org>
Subject: [PATCH] t9300-fast-import: avoid 'exit' in test_expect_success snippets

Exiting from a for-loop early using '|| break' does not propagate the
failure code, and for this reason, the tests used just 'exit'. But this
ends the test script with 'FATAL: Unexpected exit code 1' in the case of
a failed test.

Fix this by moving the loop into a shell function, from which we can
simply return early.

While at it, modernize the style of the affected test cases.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
 t/t9300-fast-import.sh |   88 +++++++++++++++++++++++++++++-------------------
 1 file changed, 54 insertions(+), 34 deletions(-)

diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index 0f5b5e5..8d7be67 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -24,6 +24,13 @@ head_c () {
 	' - "$1"
 }
 
+verify_packs () {
+	for p in .git/objects/pack/*.pack
+	do
+		git verify-pack "$@" "$p" || return
+	done
+}
+
 file2_data='file2
 second line of EOF'
 
@@ -105,9 +112,10 @@ test_expect_success \
     'A: create pack from stdin' \
     'git fast-import --export-marks=marks.out <input &&
 	 git whatchanged master'
-test_expect_success \
-	'A: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'A: verify pack' '
+	verify_packs
+'
 
 cat >expect <<EOF
 author $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
@@ -252,9 +260,11 @@ test_expect_success \
 	'A: verify marks import does not crash' \
 	'git fast-import --import-marks=marks.out <input &&
 	 git whatchanged verify--import-marks'
-test_expect_success \
-	'A: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'A: verify pack' '
+	verify_packs
+'
+
 cat >expect <<EOF
 :000000 100755 0000000000000000000000000000000000000000 7123f7f44e39be127c5eb701e5968176ee9d78b1 A	copy-of-file2
 EOF
@@ -514,9 +524,11 @@ test_expect_success \
     'C: incremental import create pack from stdin' \
     'git fast-import <input &&
 	 git whatchanged branch'
-test_expect_success \
-	'C: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'C: verify pack' '
+	verify_packs
+'
+
 test_expect_success \
 	'C: validate reuse existing blob' \
 	'test $newf = `git rev-parse --verify branch:file2/newf` &&
@@ -572,9 +584,10 @@ test_expect_success \
     'D: inline data in commit' \
     'git fast-import <input &&
 	 git whatchanged branch'
-test_expect_success \
-	'D: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'D: verify pack' '
+	verify_packs
+'
 
 cat >expect <<EOF
 :000000 100755 0000000000000000000000000000000000000000 35a59026a33beac1569b1c7f66f3090ce9c09afc A	newdir/exec.sh
@@ -618,9 +631,10 @@ test_expect_success 'E: rfc2822 date, --date-format=raw' '
 test_expect_success \
     'E: rfc2822 date, --date-format=rfc2822' \
     'git fast-import --date-format=rfc2822 <input'
-test_expect_success \
-	'E: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'E: verify pack' '
+	verify_packs
+'
 
 cat >expect <<EOF
 author $GIT_AUTHOR_NAME <$GIT_AUTHOR_EMAIL> 1170778938 -0500
@@ -669,9 +683,10 @@ test_expect_success \
 		fi
 	 fi
 	'
-test_expect_success \
-	'F: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'F: verify pack' '
+	verify_packs
+'
 
 cat >expect <<EOF
 tree `git rev-parse branch~1^{tree}`
@@ -705,9 +720,11 @@ INPUT_END
 test_expect_success \
     'G: non-fast-forward update forced' \
     'git fast-import --force <input'
-test_expect_success \
-	'G: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'G: verify pack' '
+	verify_packs
+'
+
 test_expect_success \
 	'G: branch changed, but logged' \
 	'test $old_branch != `git rev-parse --verify branch^0` &&
@@ -742,9 +759,10 @@ test_expect_success \
     'H: deletall, add 1' \
     'git fast-import <input &&
 	 git whatchanged H'
-test_expect_success \
-	'H: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'H: verify pack' '
+	verify_packs
+'
 
 cat >expect <<EOF
 :100755 000000 f1fb5da718392694d0076d677d6d0e364c79b0bc 0000000000000000000000000000000000000000 D	file2/newf
@@ -1857,9 +1875,10 @@ test_expect_success \
 	'Q: commit notes' \
 	'git fast-import <input &&
 	 git whatchanged notes-test'
-test_expect_success \
-	'Q: verify pack' \
-	'for p in .git/objects/pack/*.pack;do git verify-pack $p||exit;done'
+
+test_expect_success 'Q: verify pack' '
+	verify_packs
+'
 
 commit1=$(git rev-parse notes-test~2)
 commit2=$(git rev-parse notes-test^)
@@ -2616,13 +2635,14 @@ test_expect_success \
 	'R: blob bigger than threshold' \
 	'test_create_repo R &&
 	 git --git-dir=R/.git fast-import --big-file-threshold=1 <input'
-test_expect_success \
-	'R: verify created pack' \
-	': >verify &&
-	 for p in R/.git/objects/pack/*.pack;
-	 do
-	   git verify-pack -v $p >>verify || exit;
-	 done'
+
+test_expect_success 'R: verify created pack' '
+	(
+		cd R &&
+		verify_packs -v > ../verify
+	)
+'
+
 test_expect_success \
 	'R: verify written objects' \
 	'git --git-dir=R/.git cat-file blob big-file:big1 >actual &&
-- 
1.7.10.1386.g7bd022

Re: [PATCH nd/threaded-index-pack] index-pack: disable threading if NO_PREAD is defined

[Junio C Hamano]

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

> Am 4/19/2012 16:05, schrieb Nguyễn Thái Ngọc Duy:
>> NO_PREAD simulates pread() as a sequence of seek, read, seek in
>> compat/pread.c. The simulation is not thread-safe because another
>> thread could move the file offset away in the middle of pread
>> operation. Do not allow threading in that case.
>
> Unsurprisingly, this fixes the breakage for me.
>
> I used the attached patch to keep t9300 running when the breakage
> was detected.
>
> --- 8< ---
> From: Johannes Sixt <j6t@kdbg.org>
> Subject: [PATCH] t9300-fast-import: avoid 'exit' in test_expect_success snippets
>
> Exiting from a for-loop early using '|| break' does not propagate the
> failure code, and for this reason, the tests used just 'exit'. But this
> ends the test script with 'FATAL: Unexpected exit code 1' in the case of
> a failed test.
>
> Fix this by moving the loop into a shell function, from which we can
> simply return early.

Makes sense.  If the original were written more readably, I may have
suggested to run the entire for loop in a subshell, but a helper
function is equally readable and with many identical checks, it is the
right way to do this.

Thanks.