Download commit pack even when commit exists as loose object#1995
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tyrielv wants to merge 1 commit into
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Download commit pack even when commit exists as loose object#1995tyrielv wants to merge 1 commit into
tyrielv wants to merge 1 commit into
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When TryDownloadCommit finds the commit via CommitAndRootTreeExists, it now checks whether the commit is a loose object. Loose commits (e.g., from a prior 'git show' or 'git log' in a mounted enlistment) do not include reachable trees. Skipping the download in this case causes 'git checkout -f' to fail with 'unable to read tree', followed by an expensive fallback that re-downloads and retries checkout. If the commit is in a pack file (prefetch or commit pack), trees are included by the GVFS protocol, so the download can safely be skipped. Added GitRepo.LooseObjectExists() to check whether a SHA exists as a loose object file in the shared cache or local object store. Assisted-by: Claude Opus 4.6 Signed-off-by: Tyrie Vella <tyrielv@gmail.com>
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Summary
Fixes the worst-case clone performance when a commit exists as a loose object in the shared cache (e.g., from a prior
git showorgit login a mounted enlistment).Before:
TryDownloadCommitchecksCommitAndRootTreeExists- if the commit and root tree exist (even as loose objects), the commit+trees pack download is skipped.git checkout -fthen fails withunable to read treebecause subtrees are missing, triggering an expensive fallback: re-download the pack + retry checkout. On a large repo this wastes ~60 seconds.After:
TryDownloadCommitadditionally checks whether the commit is a loose object via the newGitRepo.LooseObjectExists()method. If the commit is loose, the pack is downloaded proactively. If the commit is in a pack file, trees are included by the GVFS protocol, so the download is safely skipped.Changes
CommitAndRootTreeExistsreturns true, checkLooseObjectExistsbefore skipping downloadLooseObjectExistsmethod - fast filesystem check for loose object filesPerformance Impact (large repo)