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author | Patrick Steinhardt <ps@pks.im> | 2021-08-09 10:12:03 +0200 |
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committer | Junio C Hamano <gitster@pobox.com> | 2021-08-09 09:51:12 -0700 |
commit | f559d6d45e7e58ae1f922213948723de77ea77bd (patch) | |
tree | 5db9c2b4540075ffb8f27aaab1f5d4ba489ca9e8 /commit-graph.c | |
parent | 809ea28f809e52d3204b597637b2f5e072c140f8 (diff) | |
download | git-f559d6d45e7e58ae1f922213948723de77ea77bd.tar.gz |
revision: avoid hitting packfiles when commits are in commit-graph
When queueing references in git-rev-list(1), we try to optimize parsing
of commits via the commit-graph. To do so, we first look up the object's
type, and if it is a commit we call `repo_parse_commit()` instead of
`parse_object()`. This is quite inefficient though given that we're
always uncompressing the object header in order to determine the type.
Instead, we can opportunistically search the commit-graph for the object
ID: in case it's found, we know it's a commit and can directly fill in
the commit object without having to uncompress the object header.
Expose a new function `lookup_commit_in_graph()`, which tries to find a
commit in the commit-graph by ID, and convert `get_reference()` to use
this function. This provides a big performance win in cases where we
load references in a repository with lots of references pointing to
commits. The following has been executed in a real-world repository with
about 2.2 million refs:
Benchmark #1: HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev
Time (mean ± σ): 4.458 s ± 0.044 s [User: 4.115 s, System: 0.342 s]
Range (min … max): 4.409 s … 4.534 s 10 runs
Benchmark #2: HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev
Time (mean ± σ): 3.089 s ± 0.015 s [User: 2.768 s, System: 0.321 s]
Range (min … max): 3.061 s … 3.105 s 10 runs
Summary
'HEAD: rev-list --unsorted-input --objects --quiet --not --all --not $newrev' ran
1.44 ± 0.02 times faster than 'HEAD~: rev-list --unsorted-input --objects --quiet --not --all --not $newrev'
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'commit-graph.c')
-rw-r--r-- | commit-graph.c | 24 |
1 files changed, 24 insertions, 0 deletions
diff --git a/commit-graph.c b/commit-graph.c index 8c4c7262c8..00614acd65 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -891,6 +891,30 @@ static int find_commit_pos_in_graph(struct commit *item, struct commit_graph *g, } } +struct commit *lookup_commit_in_graph(struct repository *repo, const struct object_id *id) +{ + struct commit *commit; + uint32_t pos; + + if (!repo->objects->commit_graph) + return NULL; + if (!search_commit_pos_in_graph(id, repo->objects->commit_graph, &pos)) + return NULL; + if (!repo_has_object_file(repo, id)) + return NULL; + + commit = lookup_commit(repo, id); + if (!commit) + return NULL; + if (commit->object.parsed) + return commit; + + if (!fill_commit_in_graph(repo, commit, repo->objects->commit_graph, pos)) + return NULL; + + return commit; +} + static int parse_commit_in_graph_one(struct repository *r, struct commit_graph *g, struct commit *item) |