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perf: use git cat-file -e instead of git rev-list in _rev_exists #3601

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perf: use git cat-file -e instead of git rev-list in _rev_exists #3601

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perf: use git cat-file -e instead of git rev-list in _rev_exists 
Replace git rev-list --quiet with git cat-file -e for checking if a
revision exists. This changes the operation from O(commits) to O(1).

Benchmarks from a large monorepo:
- git rev-list --quiet <sha>: 5150ms
- git cat-file -e <sha>: 4ms

Both commands have the same semantics: return success if the revision
exists in the local repo, failure otherwise.
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@claude
claude committed Dec 24, 2025
commit 66d1c0707e4139e548ffe052f719486adb02c305
2 changes: 1 addition & 1 deletion pre_commit/commands/hook_impl.py
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Expand Up @@ -111,7 +111,7 @@ def _ns(


def _rev_exists(rev: str) -> bool:
return not subprocess.call(('git', 'rev-list', '--quiet', rev))
return subprocess.call(('git', 'cat-file', '-e', rev)) == 0


def _pre_push_ns(
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16 changes: 16 additions & 0 deletions tests/commands/hook_impl_test.py
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Expand Up @@ -91,6 +91,22 @@ def call(*_, **__):
call()


def test_rev_exists_with_existing_rev(tempdir_factory):
src = git_dir(tempdir_factory)
git_commit(cwd=src)
head = git.head_rev(src)
with cwd(src):
assert hook_impl._rev_exists(head) is True


def test_rev_exists_with_nonexistent_rev(tempdir_factory):
src = git_dir(tempdir_factory)
git_commit(cwd=src)
with cwd(src):
fake_sha = 'deadbeefdeadbeefdeadbeefdeadbeefdeadbeef'
assert hook_impl._rev_exists(fake_sha) is False


@pytest.mark.parametrize(
('hook_type', 'args'),
(
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