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author | Jonathan Tan <jonathantanmy@google.com> | 2018-12-04 14:42:38 -0800 |
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committer | Junio C Hamano <gitster@pobox.com> | 2018-12-28 10:39:48 -0800 |
commit | ec0c5798ee9376382d44163d38156fd47e8001c2 (patch) | |
tree | 6eb02499090c12f98f23fbfe2ce5b8a2c5a74a86 /t/t4135/diff-with backslash.diff | |
parent | t/helper/test-repository: celebrate independence from the_repository (diff) | |
download | tgif-ec0c5798ee9376382d44163d38156fd47e8001c2.tar.xz |
revision: use commit graph in get_reference()
When fetching into a repository, a connectivity check is first made by
check_exist_and_connected() in builtin/fetch.c that runs:
git rev-list --objects --stdin --not --all --quiet <(list of objects)
If the client repository has many refs, this command can be slow,
regardless of the nature of the server repository or what is being
fetched. A profiler reveals that most of the time is spent in
setup_revisions() (approx. 60/63), and of the time spent in
setup_revisions(), most of it is spent in parse_object() (approx.
49/60). This is because setup_revisions() parses the target of every ref
(from "--all"), and parse_object() reads the buffer of the object.
Reading the buffer is unnecessary if the repository has a commit graph
and if the ref points to a commit (which is typically the case). This
patch uses the commit graph wherever possible; on my computer, when I
run the above command with a list of 1 object on a many-ref repository,
I get a speedup from 1.8s to 1.0s.
Another way to accomplish this effect would be to modify parse_object()
to use the commit graph if possible; however, I did not want to change
parse_object()'s current behavior of always checking the object
signature of the returned object.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 't/t4135/diff-with backslash.diff')
0 files changed, 0 insertions, 0 deletions