@matheusbsbs / matheus-bagliano / commits / 3a1ea94a49

commit-graph.c: no lazy fetch in lookup_commit_in_graph()

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. 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@bytedance.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Han Xin committed Jul 1, 2022 at 09:34 UTC 3a1ea94a491e3e0bcbc2d55b4cfb0b9eacace608
2 files changed +71 -1
commit-graph.c
+1 -1
index 2b52818731..2dd9bcc7ea 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -907,7 +907,7 @@ struct commit *lookup_commit_in_graph(struct repository *repo, const struct obje return NULL; if (!search_commit_pos_in_graph(id, repo->objects->commit_graph, &pos)) return NULL; - if (!repo_has_object_file(repo, id)) + if (!has_object(repo, id, 0)) return NULL; commit = lookup_commit(repo, id);
t/t5330-no-lazy-fetch-with-commit-graph.sh
+70
new file mode 100755 index 0000000000..be33334229 --- /dev/null +++ b/t/t5330-no-lazy-fetch-with-commit-graph.sh @@ -0,0 +1,70 @@ +#!/bin/sh + +test_description='test for no lazy fetch with the commit-graph' + +. ./test-lib.sh + +run_with_limited_processses () { + # 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 ' + run_with_limited_processses true +' + +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 && + oid=$(git -C with-commit rev-parse HEAD) +' + +test_expect_success 'setup: prepare a repository with commit-graph contains the commit' ' + git init with-commit-graph && + echo "$(pwd)/with-commit/.git/objects" \ + >with-commit-graph/.git/objects/info/alternates && + # 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 something && + git -c gc.writeCommitGraph=true -C with-commit-graph gc && + test_path_is_file with-commit-graph/.git/objects/info/commit-graph +' + +test_expect_success 'setup: change the alternates to what without the commit' ' + git init --bare without-commit && + git -C with-commit-graph cat-file -e $oid && + echo "$(pwd)/without-commit/objects" \ + >with-commit-graph/.git/objects/info/alternates && + test_must_fail git -C with-commit-graph cat-file -e $oid +' + +test_expect_success 'fetch any commit from promisor with the usage of the commit graph' ' + # setup promisor and prepare any commit to fetch + git -C with-commit-graph remote add origin "$(pwd)/with-commit" && + git -C with-commit-graph config remote.origin.promisor true && + git -C with-commit-graph config remote.origin.partialclonefilter blob:none && + test_commit -C with-commit any-commit && + anycommit=$(git -C with-commit rev-parse HEAD) && + + run_with_limited_processses env GIT_TRACE="$(pwd)/trace.txt" \ + git -C with-commit-graph fetch origin $anycommit 2>err && + ! grep "fatal: promisor-remote: unable to fork off fetch subprocess" err && + grep "git fetch origin" trace.txt >actual && + test_line_count = 1 actual +' + +test_done