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authorLibravatar Jonathan Tan <jonathantanmy@google.com>2018-12-04 14:42:38 -0800
committerLibravatar Junio C Hamano <gitster@pobox.com>2018-12-28 10:39:48 -0800
commitec0c5798ee9376382d44163d38156fd47e8001c2 (patch)
tree6eb02499090c12f98f23fbfe2ce5b8a2c5a74a86 /t/t4013/diff.diff-tree_--pretty_--root_--patch-with-raw_initial
parentt/helper/test-repository: celebrate independence from the_repository (diff)
downloadtgif-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/t4013/diff.diff-tree_--pretty_--root_--patch-with-raw_initial')
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