This patch fixes the following issue:
When we found the commit in the graph in lookup_commit_in_graph(), but
the commit is missing from the repository, we will try
promisor_remote_get_direct() and then enter another loop.
Then we will go into an endless loop:
git fetch -> deref_without_lazy_fetch() ->
lookup_commit_in_graph() -> repo_has_object_file() ->
promisor_remote_get_direct() -> fetch_objects() ->
git fetch (a new loop round)
Changes since v2:
* Remove test_have_prereq() from ULIMIT_PROCESSES as
"run_with_limited_processses true" is enough.
* Teach run_with_limited_processses() to support dash and zsh.
* Skip the whole test file if ulimit is not avaliable.
* Minor grammar/comment etc. fixes throughout.
Han Xin (2):
test-lib.sh: add limited processes to test-lib
commit-graph.c: no lazy fetch in lookup_commit_in_graph()
commit-graph.c | 2 +-
t/t5329-no-lazy-fetch-with-commit-graph.sh | 53 ++++++++++++++++++++++
t/test-lib.sh | 16 +++++++
3 files changed, 70 insertions(+), 1 deletion(-)
create mode 100755 t/t5329-no-lazy-fetch-with-commit-graph.sh
Range-diff against v2:
1: 442a4c351d ! 1: ad0a539759 test-lib.sh: add limited processes to test-lib
@@ t/test-lib.sh: test_lazy_prereq ULIMIT_FILE_DESCRIPTORS '
'
+run_with_limited_processses () {
-+ (ulimit -u 512 && "$@")
++ # bash and ksh use "ulimit -u", dash uses "ulimit -p"
++ if test -n "$BASH_VERSION"
++ then
++ ulimit_max_process="-u"
++ elif test -n "$KSH_VERSION"
++ then
++ ulimit_max_process="-u"
++ fi
++ (ulimit ${ulimit_max_process-"-p"} 512 && "$@")
+}
+
+test_lazy_prereq ULIMIT_PROCESSES '
-+ test_have_prereq !HPPA,!MINGW,!CYGWIN &&
+ run_with_limited_processses true
+'
+
2: a7d456db9b ! 2: 3cdb1abd43 commit-graph.c: no lazy fetch in lookup_commit_in_graph()
@@ Metadata
## Commit message ##
commit-graph.c: no lazy fetch in lookup_commit_in_graph()
- If a commit is in the commit graph, we would expect the commit to also
- be present. So we should use has_object() instead of
- repo_has_object_file(), which will help us avoid getting into an endless
- loop of lazy fetch.
+ The commit-graph is used to opportunistically optimize accesses to
+ certain pieces of information on commit objects, and
+ lookup_commit_in_graph() tries to say "no" when the requested commit
+ does not locally exist by returning NULL, in which case the caller
+ can ask for (which may result in on-demand fetching from a promisor
+ remote) and parse the commit object itself.
- When we found the commit in the graph in lookup_commit_in_graph(), but
- the commit is missing from the repository, we will try
- promisor_remote_get_direct() and then enter another loop. While
- sometimes it will finally succeed because it cannot fork subprocess,
- it has exhausted the local process resources and can be harmful to the
- remote service.
+ However, it uses a wrong helper, repo_has_object_file(), to do so.
+ This helper not only checks if an object is mmediately available in
+ the local object store, but also tries to fetch from a promisor remote.
+ But the fetch machinery calls lookup_commit_in_graph(), thus causing an
+ infinite loop.
+
+ We should make lookup_commit_in_graph() expect that a commit given to it
+ can be legitimately missing from the local object store, by using the
+ has_object_file() helper instead.
Signed-off-by: Han Xin <hanxin.hx@xxxxxxxxxxxxx>
@@ t/t5329-no-lazy-fetch-with-commit-graph.sh (new)
+
+. ./test-lib.sh
+
++if ! test_have_prereq ULIMIT_PROCESSES
++then
++ skip_all='skipping tests for no lazy fetch with the commit-graph, ulimit processes not available'
++ test_done
++fi
++
+test_expect_success 'setup: prepare a repository with a commit' '
+ git init with-commit &&
+ test_commit -C with-commit the-commit &&
@@ t/t5329-no-lazy-fetch-with-commit-graph.sh (new)
+ # create a ref that points to the commit in alternates
+ git -C with-commit-graph update-ref refs/ref_to_the_commit "$oid" &&
+ # prepare some other objects to commit-graph
-+ test_commit -C with-commit-graph somthing &&
++ test_commit -C with-commit-graph something &&
+ git -c gc.writeCommitGraph=true -C with-commit-graph gc &&
+ test_path_is_file with-commit-graph/.git/objects/info/commit-graph
+'
@@ t/t5329-no-lazy-fetch-with-commit-graph.sh (new)
+ test_must_fail git -C with-commit-graph cat-file -e $oid
+'
+
-+test_expect_success 'setup: prepare another commit to fetch' '
-+ test_commit -C with-commit another-commit &&
++test_expect_success 'setup: prepare any commit to fetch' '
++ test_commit -C with-commit any-commit &&
+ anycommit=$(git -C with-commit rev-parse HEAD)
+'
+
-+test_expect_success ULIMIT_PROCESSES 'fetch any commit from promisor with the usage of the commit graph' '
++test_expect_success 'fetch any commit from promisor with the usage of the commit graph' '
+ git -C with-commit-graph remote add origin "$(pwd)/with-commit" &&
+ git -C with-commit-graph config remote.origin.promisor true &&
+ git -C with-commit-graph config remote.origin.partialclonefilter blob:none &&
--
2.36.1
