From 16c4fa26b99e6f6c24dc93575ffa884c13b1fe5f Mon Sep 17 00:00:00 2001 From: Patrick Steinhardt Date: Thu, 31 Jul 2025 16:56:54 +0200 Subject: builtin/remote: only iterate through refs that are to be renamed MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When renaming a remote we also need to rename all references accordingly. But while we only need to rename references that are contained in the "refs/remotes/$OLDNAME/" namespace, we end up using `refs_for_each_rawref()` that iterates through _all_ references. We know to exit early in the callback in case we see an irrelevant reference, but ultimately this is still a waste of compute as we knowingly iterate through references that we won't ever care about. Improve this by using `refs_for_each_rawref_in()`, which knows to only iterate through (potentially broken) references in a given prefix. The following benchmark renames a remote with a single reference in a repository that has 100k unrelated references. This shows a sizeable improvement with the "files" backend: Benchmark 1: rename remote (refformat = files, revision = HEAD~) Time (mean ± σ): 42.6 ms ± 0.9 ms [User: 29.1 ms, System: 8.4 ms] Range (min … max): 40.1 ms … 43.3 ms 10 runs Benchmark 2: rename remote (refformat = files, revision = HEAD) Time (mean ± σ): 31.7 ms ± 4.0 ms [User: 19.6 ms, System: 6.9 ms] Range (min … max): 27.1 ms … 36.0 ms 10 runs Summary rename remote (refformat = files, revision = HEAD) ran 1.35 ± 0.17 times faster than rename remote (refformat = files, revision = HEAD~) The "reftable" backend shows roughly the same absolute improvement, but given that it's already significantly faster than the "files" backend this translates to a much larger relative improvement: Benchmark 1: rename remote (refformat = reftable, revision = HEAD~) Time (mean ± σ): 18.2 ms ± 0.5 ms [User: 12.7 ms, System: 3.0 ms] Range (min … max): 17.3 ms … 21.4 ms 110 runs Benchmark 2: rename remote (refformat = reftable, revision = HEAD) Time (mean ± σ): 8.8 ms ± 0.5 ms [User: 3.8 ms, System: 2.9 ms] Range (min … max): 7.5 ms … 9.9 ms 167 runs Summary rename remote (refformat = reftable, revision = HEAD) ran 2.07 ± 0.12 times faster than rename remote (refformat = reftable, revision = HEAD~) Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano --- refs.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'refs.h') diff --git a/refs.h b/refs.h index 0bf50ce25c..19fb1d924a 100644 --- a/refs.h +++ b/refs.h @@ -428,6 +428,8 @@ int refs_for_each_namespaced_ref(struct ref_store *refs, /* can be used to learn about broken ref and symref */ int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data); +int refs_for_each_rawref_in(struct ref_store *refs, const char *prefix, + each_ref_fn fn, void *cb_data); /* * Iterates over all refs including root refs, i.e. pseudorefs and HEAD. -- cgit v1.3