perf(cli): apply bundle via git fetch + git merge --ff-only#317
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worstell wants to merge 1 commit into
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perf(cli): apply bundle via git fetch + git merge --ff-only#317worstell wants to merge 1 commit into
worstell wants to merge 1 commit into
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Replaces `git pull --ff-only <bundle> <branch>` in cachew git restore's bundle-apply path with an explicit `git fetch` + `git merge --ff-only FETCH_HEAD` pair. `git pull` runs two implicit subcommands that add no value for a one-shot bundle apply: - `git rev-list --objects --stdin --not --exclude-hidden=fetch --all` (connectivity check across all local refs) - `git maintenance run --auto` (background gc/repack heuristic) — can trigger surprise pack rewrites during a hot bootstrap path The new path also emits separate cachew.git_fetch_seconds and cachew.git_merge_seconds span attributes so future work can attribute bundle-apply cost between fetch vs working-tree update. Measured on a staging cachew-bench workstation against squareup/cash-server (5.5 GiB snapshot, 290 KiB bundle, 13 commits ahead): bundle-apply wall-clock improves ~300ms (14.95s -> 14.41s median over 3 runs). The cold `git merge` itself dominates bundle apply cost on a fresh extract; this PR is mainly about predictability and instrumentation, not raw wall-clock. Amp-Thread-ID: https://ampcode.com/threads/T-019e41af-0a15-718d-a9d8-e26df6071f9b Co-authored-by: Amp <amp@ampcode.com>
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Replaces
git pull --ff-only <bundle> <branch>in cachew git restore's bundle-apply path with an explicitgit fetch+git merge --ff-only FETCH_HEADpair.Why
git pullruns two implicit subcommands that add no value for a one-shot bundle apply:git rev-list --objects --stdin --not --exclude-hidden=fetch --all— connectivity check across all local refsgit maintenance run --auto— background gc/repack heuristic; can trigger surprise pack rewrites during a hot bootstrap pathObservability
Emits separate
cachew.git_fetch_secondsandcachew.git_merge_secondsspan attributes so future work can attribute bundle-apply cost between fetch vs working-tree update. Today the working-tree update (coldgit mergeon a fresh tar-extracted repo) dominates by ~30x.Measured impact
On a staging cachew-bench workstation against squareup/cash-server (5.5 GiB snapshot, 290 KiB bundle, 13 commits ahead):
~300 ms wall-clock; the rest is the cold
git mergeitself reading every stat-dirty index entry on the fresh extract. This PR is mainly about predictability and instrumentation — the headline cold-merge cost needs a separate (server-side) fix.