diff mbox series

[v2,5/8] parallel-checkout: add tests related to path collisions

Message ID eae6d3a1c16e440f18fd60d69b061d15ffbfe8e7.1619818517.git.matheus.bernardino@usp.br (mailing list archive)
State Superseded
Headers show
Series Parallel Checkout (part 3) | expand

Commit Message

Matheus Tavares Bernardino April 30, 2021, 9:40 p.m. UTC
Add tests to confirm that path collisions are properly detected by
checkout workers, both to avoid race conditions and to report colliding
entries on clone.

Co-authored-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 parallel-checkout.c                     |   4 +
 t/lib-parallel-checkout.sh              |   4 +-
 t/t2081-parallel-checkout-collisions.sh | 162 ++++++++++++++++++++++++
 3 files changed, 168 insertions(+), 2 deletions(-)
 create mode 100755 t/t2081-parallel-checkout-collisions.sh

Comments

Torsten Bögershausen May 2, 2021, 7:59 a.m. UTC | #1
On Fri, Apr 30, 2021 at 06:40:32PM -0300, Matheus Tavares wrote:
> Add tests to confirm that path collisions are properly detected by
> checkout workers, both to avoid race conditions and to report colliding
> entries on clone.
>
> Co-authored-by: Jeff Hostetler <jeffhost@microsoft.com>
> Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
> ---
>  parallel-checkout.c                     |   4 +
>  t/lib-parallel-checkout.sh              |   4 +-
>  t/t2081-parallel-checkout-collisions.sh | 162 ++++++++++++++++++++++++
>  3 files changed, 168 insertions(+), 2 deletions(-)
>  create mode 100755 t/t2081-parallel-checkout-collisions.sh
>
> diff --git a/parallel-checkout.c b/parallel-checkout.c
> index 09e8b10a35..6fb3f1e6c9 100644
> --- a/parallel-checkout.c
> +++ b/parallel-checkout.c
> @@ -8,6 +8,7 @@
>  #include "sigchain.h"
>  #include "streaming.h"
>  #include "thread-utils.h"
> +#include "trace2.h"
>
>  struct pc_worker {
>  	struct child_process cp;
> @@ -326,6 +327,7 @@ void write_pc_item(struct parallel_checkout_item *pc_item,
>  	if (dir_sep && !has_dirs_only_path(path.buf, dir_sep - path.buf,
>  					   state->base_dir_len)) {
>  		pc_item->status = PC_ITEM_COLLIDED;
> +		trace2_data_string("pcheckout", NULL, "collision/dirname", path.buf);
>  		goto out;
>  	}
>
> @@ -341,6 +343,8 @@ void write_pc_item(struct parallel_checkout_item *pc_item,
>  			 * call should have already caught these cases.
>  			 */
>  			pc_item->status = PC_ITEM_COLLIDED;
> +			trace2_data_string("pcheckout", NULL,
> +					   "collision/basename", path.buf);
>  		} else {
>  			error_errno("failed to open file '%s'", path.buf);
>  			pc_item->status = PC_ITEM_FAILED;
> diff --git a/t/lib-parallel-checkout.sh b/t/lib-parallel-checkout.sh
> index f60b22ef34..d6740425b1 100644
> --- a/t/lib-parallel-checkout.sh
> +++ b/t/lib-parallel-checkout.sh
> @@ -22,12 +22,12 @@ test_checkout_workers () {
>
>  	local trace_file=trace-test-checkout-workers &&
>  	rm -f "$trace_file" &&
> -	GIT_TRACE2="$(pwd)/$trace_file" "$@" &&
> +	GIT_TRACE2="$(pwd)/$trace_file" "$@" 2>&8 &&
>
>  	local workers=$(grep "child_start\[..*\] git checkout--worker" "$trace_file" | wc -l) &&
>  	test $workers -eq $expected_workers &&
>  	rm "$trace_file"
> -}
> +} 8>&2 2>&4
>
>  # Verify that both the working tree and the index were created correctly
>  verify_checkout () {
> diff --git a/t/t2081-parallel-checkout-collisions.sh b/t/t2081-parallel-checkout-collisions.sh
> new file mode 100755
> index 0000000000..f6fcfc0c1e
> --- /dev/null
> +++ b/t/t2081-parallel-checkout-collisions.sh
> @@ -0,0 +1,162 @@
> +#!/bin/sh
> +
> +test_description="path collisions during parallel checkout
> +
> +Parallel checkout must detect path collisions to:
> +
> +1) Avoid racily writing to different paths that represent the same file on disk.
> +2) Report the colliding entries on clone.
> +
> +The tests in this file exercise parallel checkout's collision detection code in
> +both these mechanics.
> +"
> +
> +. ./test-lib.sh
> +. "$TEST_DIRECTORY/lib-parallel-checkout.sh"

Why this $TEST_DIRECTORY ?
Aren't all files under the t/ directory, where test-lib.sh is as well ?
(The $TEST_DIRECTORY macro is used at different places, so I may have missed
something)

> +
> +TEST_ROOT="$PWD"
> +
> +test_expect_success CASE_INSENSITIVE_FS 'setup' '
> +	empty_oid=$(git hash-object -w --stdin </dev/null) &&
> +	cat >objs <<-EOF &&
> +	100644 $empty_oid	FILE_X
> +	100644 $empty_oid	FILE_x
> +	100644 $empty_oid	file_X
> +	100644 $empty_oid	file_x
> +	EOF
> +	git update-index --index-info <objs &&
> +	git commit -m "colliding files" &&
> +	git tag basename_collision &&
> +
> +	write_script "$TEST_ROOT"/logger_script <<-\EOF
> +	echo "$@" >>filter.log
> +	EOF
> +'
> +
> +test_workers_in_event_trace ()
> +{
> +	test $1 -eq $(grep ".event.:.child_start..*checkout--worker" $2 | wc -l)
> +}
> +
> +test_expect_success CASE_INSENSITIVE_FS 'worker detects basename collision' '
> +	GIT_TRACE2_EVENT="$(pwd)/trace" git \
> +		-c checkout.workers=2 -c checkout.thresholdForParallelism=0 \
> +		checkout . &&
> +
> +	test_workers_in_event_trace 2 trace &&
> +	collisions=$(grep -i "category.:.pcheckout.,.key.:.collision/basename.,.value.:.file_x.}" trace | wc -l) &&
> +	test $collisions -eq 3
> +'
> +
> +test_expect_success CASE_INSENSITIVE_FS 'worker detects dirname collision' '
> +	test_config filter.logger.smudge "\"$TEST_ROOT/logger_script\" %f" &&
> +	empty_oid=$(git hash-object -w --stdin </dev/null) &&
> +
> +	# By setting a filter command to "a", we make it ineligible for parallel
> +	# checkout, and thus it is checked out *first*. This way we can ensure
> +	# that "A/B" and "A/C" will both collide with the regular file "a".
> +	#
> +	attr_oid=$(echo "a filter=logger" | git hash-object -w --stdin) &&
> +
> +	cat >objs <<-EOF &&
> +	100644 $empty_oid	A/B
> +	100644 $empty_oid	A/C
> +	100644 $empty_oid	a
> +	100644 $attr_oid	.gitattributes
> +	EOF
> +	git rm -rf . &&
> +	git update-index --index-info <objs &&
> +
> +	rm -f trace filter.log &&
> +	GIT_TRACE2_EVENT="$(pwd)/trace" git \
> +		-c checkout.workers=2 -c checkout.thresholdForParallelism=0 \
> +		checkout . &&
> +
> +	# Check that "a" (and only "a") was filtered
> +	echo a >expected.log &&
> +	test_cmp filter.log expected.log &&
> +
> +	# Check that it used the right number of workers and detected the collisions
> +	test_workers_in_event_trace 2 trace &&
> +	grep "category.:.pcheckout.,.key.:.collision/dirname.,.value.:.A/B.}" trace &&
> +	grep "category.:.pcheckout.,.key.:.collision/dirname.,.value.:.A/C.}" trace
> +'
> +
> +test_expect_success SYMLINKS,CASE_INSENSITIVE_FS 'do not follow symlinks colliding with leading dir' '
> +	empty_oid=$(git hash-object -w --stdin </dev/null) &&
> +	symlink_oid=$(echo "./e" | git hash-object -w --stdin) &&
> +	mkdir e &&
> +
> +	cat >objs <<-EOF &&
> +	120000 $symlink_oid	D
> +	100644 $empty_oid	d/x
> +	100644 $empty_oid	e/y
> +	EOF
> +	git rm -rf . &&
> +	git update-index --index-info <objs &&
> +
> +	set_checkout_config 2 0 &&
> +	test_checkout_workers 2 git checkout . &&
> +	test_path_is_dir e &&
> +	test_path_is_missing e/x
> +'
> +
> +# The two following tests check that parallel checkout correctly reports
> +# colliding entries on clone. The sequential code detects a collision by
> +# calling lstat() before trying to open(O_CREAT) a file. (Note that this only
> +# works for clone.) Then, to find the pair of a colliding item k, it searches
> +# cache_entry[0, k-1]. This is not sufficient in parallel checkout because:
> +#
> +# - A colliding file may be created between the lstat() and open() calls;
> +# - A colliding entry might appear in the second half of the cache_entry array.
> +#
> +test_expect_success CASE_INSENSITIVE_FS 'collision report on clone (w/ racy file creation)' '
> +	git reset --hard basename_collision &&
> +	set_checkout_config 2 0 &&
> +	test_checkout_workers 2 git clone . clone-repo 2>stderr &&
> +
> +	grep FILE_X stderr &&
> +	grep FILE_x stderr &&
> +	grep file_X stderr &&
> +	grep file_x stderr &&
> +	grep "the following paths have collided" stderr
> +'
> +
> +# This test ensures that the collision report code is correctly looking for
> +# colliding peers in the second half of the cache_entry array. This is done by
> +# defining a smudge command for the *last* array entry, which makes it
> +# non-eligible for parallel-checkout. Thus, it is checked out *first*, before
> +# spawning the workers.
> +#
> +# Note: this test doesn't work on Windows because, on this system, the
> +# collision report code uses strcmp() to find the colliding pairs when
> +# core.ignoreCase is false. And we need this setting for this test so that only
> +# 'file_x' matches the pattern of the filter attribute. But the test works on
> +# OSX, where the colliding pairs are found using inode.
> +#
> +test_expect_success CASE_INSENSITIVE_FS,!MINGW,!CYGWIN \
> +	'collision report on clone (w/ colliding peer after the detected entry)' '
> +
> +	test_config_global filter.logger.smudge "\"$TEST_ROOT/logger_script\" %f" &&
> +	git reset --hard basename_collision &&
> +	echo "file_x filter=logger" >.gitattributes &&
> +	git add .gitattributes &&
> +	git commit -m "filter for file_x" &&
> +
> +	rm -rf clone-repo &&
> +	set_checkout_config 2 0 &&
> +	test_checkout_workers 2 \
> +		git -c core.ignoreCase=false clone . clone-repo 2>stderr &&
> +
> +	grep FILE_X stderr &&
> +	grep FILE_x stderr &&
> +	grep file_X stderr &&
> +	grep file_x stderr &&
> +	grep "the following paths have collided" stderr &&
> +
> +	# Check that only "file_x" was filtered
> +	echo file_x >expected.log &&
> +	test_cmp clone-repo/filter.log expected.log
> +'
> +
> +test_done
> --
> 2.30.1
>
Matheus Tavares Bernardino May 3, 2021, 2:58 p.m. UTC | #2
On Sun, May 2, 2021 at 4:59 AM Torsten Bögershausen <tboegi@web.de> wrote:
>
> On Fri, Apr 30, 2021 at 06:40:32PM -0300, Matheus Tavares wrote:
> >
> > diff --git a/t/t2081-parallel-checkout-collisions.sh b/t/t2081-parallel-checkout-collisions.sh
> > new file mode 100755
> > index 0000000000..f6fcfc0c1e
> > --- /dev/null
> > +++ b/t/t2081-parallel-checkout-collisions.sh
> > @@ -0,0 +1,162 @@
> > +#!/bin/sh
> > +
> > +test_description="path collisions during parallel checkout
> > +
> > +Parallel checkout must detect path collisions to:
> > +
> > +1) Avoid racily writing to different paths that represent the same file on disk.
> > +2) Report the colliding entries on clone.
> > +
> > +The tests in this file exercise parallel checkout's collision detection code in
> > +both these mechanics.
> > +"
> > +
> > +. ./test-lib.sh
> > +. "$TEST_DIRECTORY/lib-parallel-checkout.sh"
>
> Why this $TEST_DIRECTORY ?
> Aren't all files under the t/ directory, where test-lib.sh is as well ?

Good point. From what I understand, the reason why we need the macro
here is that, when running the test with --root=<path>, the trash dir
might actually be at a path outside `t/`. So the test can't rely on
`./` to read files from `t/`. We don't need the macro for
`test-lib.sh` because the working dir is only changed after it is
sourced (by `test-lib.sh` itself).
diff mbox series

Patch

diff --git a/parallel-checkout.c b/parallel-checkout.c
index 09e8b10a35..6fb3f1e6c9 100644
--- a/parallel-checkout.c
+++ b/parallel-checkout.c
@@ -8,6 +8,7 @@ 
 #include "sigchain.h"
 #include "streaming.h"
 #include "thread-utils.h"
+#include "trace2.h"
 
 struct pc_worker {
 	struct child_process cp;
@@ -326,6 +327,7 @@  void write_pc_item(struct parallel_checkout_item *pc_item,
 	if (dir_sep && !has_dirs_only_path(path.buf, dir_sep - path.buf,
 					   state->base_dir_len)) {
 		pc_item->status = PC_ITEM_COLLIDED;
+		trace2_data_string("pcheckout", NULL, "collision/dirname", path.buf);
 		goto out;
 	}
 
@@ -341,6 +343,8 @@  void write_pc_item(struct parallel_checkout_item *pc_item,
 			 * call should have already caught these cases.
 			 */
 			pc_item->status = PC_ITEM_COLLIDED;
+			trace2_data_string("pcheckout", NULL,
+					   "collision/basename", path.buf);
 		} else {
 			error_errno("failed to open file '%s'", path.buf);
 			pc_item->status = PC_ITEM_FAILED;
diff --git a/t/lib-parallel-checkout.sh b/t/lib-parallel-checkout.sh
index f60b22ef34..d6740425b1 100644
--- a/t/lib-parallel-checkout.sh
+++ b/t/lib-parallel-checkout.sh
@@ -22,12 +22,12 @@  test_checkout_workers () {
 
 	local trace_file=trace-test-checkout-workers &&
 	rm -f "$trace_file" &&
-	GIT_TRACE2="$(pwd)/$trace_file" "$@" &&
+	GIT_TRACE2="$(pwd)/$trace_file" "$@" 2>&8 &&
 
 	local workers=$(grep "child_start\[..*\] git checkout--worker" "$trace_file" | wc -l) &&
 	test $workers -eq $expected_workers &&
 	rm "$trace_file"
-}
+} 8>&2 2>&4
 
 # Verify that both the working tree and the index were created correctly
 verify_checkout () {
diff --git a/t/t2081-parallel-checkout-collisions.sh b/t/t2081-parallel-checkout-collisions.sh
new file mode 100755
index 0000000000..f6fcfc0c1e
--- /dev/null
+++ b/t/t2081-parallel-checkout-collisions.sh
@@ -0,0 +1,162 @@ 
+#!/bin/sh
+
+test_description="path collisions during parallel checkout
+
+Parallel checkout must detect path collisions to:
+
+1) Avoid racily writing to different paths that represent the same file on disk.
+2) Report the colliding entries on clone.
+
+The tests in this file exercise parallel checkout's collision detection code in
+both these mechanics.
+"
+
+. ./test-lib.sh
+. "$TEST_DIRECTORY/lib-parallel-checkout.sh"
+
+TEST_ROOT="$PWD"
+
+test_expect_success CASE_INSENSITIVE_FS 'setup' '
+	empty_oid=$(git hash-object -w --stdin </dev/null) &&
+	cat >objs <<-EOF &&
+	100644 $empty_oid	FILE_X
+	100644 $empty_oid	FILE_x
+	100644 $empty_oid	file_X
+	100644 $empty_oid	file_x
+	EOF
+	git update-index --index-info <objs &&
+	git commit -m "colliding files" &&
+	git tag basename_collision &&
+
+	write_script "$TEST_ROOT"/logger_script <<-\EOF
+	echo "$@" >>filter.log
+	EOF
+'
+
+test_workers_in_event_trace ()
+{
+	test $1 -eq $(grep ".event.:.child_start..*checkout--worker" $2 | wc -l)
+}
+
+test_expect_success CASE_INSENSITIVE_FS 'worker detects basename collision' '
+	GIT_TRACE2_EVENT="$(pwd)/trace" git \
+		-c checkout.workers=2 -c checkout.thresholdForParallelism=0 \
+		checkout . &&
+
+	test_workers_in_event_trace 2 trace &&
+	collisions=$(grep -i "category.:.pcheckout.,.key.:.collision/basename.,.value.:.file_x.}" trace | wc -l) &&
+	test $collisions -eq 3
+'
+
+test_expect_success CASE_INSENSITIVE_FS 'worker detects dirname collision' '
+	test_config filter.logger.smudge "\"$TEST_ROOT/logger_script\" %f" &&
+	empty_oid=$(git hash-object -w --stdin </dev/null) &&
+
+	# By setting a filter command to "a", we make it ineligible for parallel
+	# checkout, and thus it is checked out *first*. This way we can ensure
+	# that "A/B" and "A/C" will both collide with the regular file "a".
+	#
+	attr_oid=$(echo "a filter=logger" | git hash-object -w --stdin) &&
+
+	cat >objs <<-EOF &&
+	100644 $empty_oid	A/B
+	100644 $empty_oid	A/C
+	100644 $empty_oid	a
+	100644 $attr_oid	.gitattributes
+	EOF
+	git rm -rf . &&
+	git update-index --index-info <objs &&
+
+	rm -f trace filter.log &&
+	GIT_TRACE2_EVENT="$(pwd)/trace" git \
+		-c checkout.workers=2 -c checkout.thresholdForParallelism=0 \
+		checkout . &&
+
+	# Check that "a" (and only "a") was filtered
+	echo a >expected.log &&
+	test_cmp filter.log expected.log &&
+
+	# Check that it used the right number of workers and detected the collisions
+	test_workers_in_event_trace 2 trace &&
+	grep "category.:.pcheckout.,.key.:.collision/dirname.,.value.:.A/B.}" trace &&
+	grep "category.:.pcheckout.,.key.:.collision/dirname.,.value.:.A/C.}" trace
+'
+
+test_expect_success SYMLINKS,CASE_INSENSITIVE_FS 'do not follow symlinks colliding with leading dir' '
+	empty_oid=$(git hash-object -w --stdin </dev/null) &&
+	symlink_oid=$(echo "./e" | git hash-object -w --stdin) &&
+	mkdir e &&
+
+	cat >objs <<-EOF &&
+	120000 $symlink_oid	D
+	100644 $empty_oid	d/x
+	100644 $empty_oid	e/y
+	EOF
+	git rm -rf . &&
+	git update-index --index-info <objs &&
+
+	set_checkout_config 2 0 &&
+	test_checkout_workers 2 git checkout . &&
+	test_path_is_dir e &&
+	test_path_is_missing e/x
+'
+
+# The two following tests check that parallel checkout correctly reports
+# colliding entries on clone. The sequential code detects a collision by
+# calling lstat() before trying to open(O_CREAT) a file. (Note that this only
+# works for clone.) Then, to find the pair of a colliding item k, it searches
+# cache_entry[0, k-1]. This is not sufficient in parallel checkout because:
+#
+# - A colliding file may be created between the lstat() and open() calls;
+# - A colliding entry might appear in the second half of the cache_entry array.
+#
+test_expect_success CASE_INSENSITIVE_FS 'collision report on clone (w/ racy file creation)' '
+	git reset --hard basename_collision &&
+	set_checkout_config 2 0 &&
+	test_checkout_workers 2 git clone . clone-repo 2>stderr &&
+
+	grep FILE_X stderr &&
+	grep FILE_x stderr &&
+	grep file_X stderr &&
+	grep file_x stderr &&
+	grep "the following paths have collided" stderr
+'
+
+# This test ensures that the collision report code is correctly looking for
+# colliding peers in the second half of the cache_entry array. This is done by
+# defining a smudge command for the *last* array entry, which makes it
+# non-eligible for parallel-checkout. Thus, it is checked out *first*, before
+# spawning the workers.
+#
+# Note: this test doesn't work on Windows because, on this system, the
+# collision report code uses strcmp() to find the colliding pairs when
+# core.ignoreCase is false. And we need this setting for this test so that only
+# 'file_x' matches the pattern of the filter attribute. But the test works on
+# OSX, where the colliding pairs are found using inode.
+#
+test_expect_success CASE_INSENSITIVE_FS,!MINGW,!CYGWIN \
+	'collision report on clone (w/ colliding peer after the detected entry)' '
+
+	test_config_global filter.logger.smudge "\"$TEST_ROOT/logger_script\" %f" &&
+	git reset --hard basename_collision &&
+	echo "file_x filter=logger" >.gitattributes &&
+	git add .gitattributes &&
+	git commit -m "filter for file_x" &&
+
+	rm -rf clone-repo &&
+	set_checkout_config 2 0 &&
+	test_checkout_workers 2 \
+		git -c core.ignoreCase=false clone . clone-repo 2>stderr &&
+
+	grep FILE_X stderr &&
+	grep FILE_x stderr &&
+	grep file_X stderr &&
+	grep file_x stderr &&
+	grep "the following paths have collided" stderr &&
+
+	# Check that only "file_x" was filtered
+	echo file_x >expected.log &&
+	test_cmp clone-repo/filter.log expected.log
+'
+
+test_done