From 82f67ee13fb25ebed1cd722c83de49a1ac588429 Mon Sep 17 00:00:00 2001 From: Kyle Zhao Date: Fri, 17 Jun 2022 19:06:19 +0000 Subject: [PATCH] send-pack.c: add config push.useBitmaps Reachability bitmaps are designed to speed up the "counting objects" phase of generating a pack during a clone or fetch. They are not optimized for Git clients sending a small topic branch via "git push". In some cases (see [1]), using reachability bitmaps during "git push" can cause significant performance regressions. Add a new "push.useBitmaps" configuration variable to allow users to tell "git push" not to use bitmaps. We already have "pack.bitmaps" that controls the use of bitmaps, but a separate configuration variable allows the reachability bitmaps to still be used in other areas, such as "git upload-pack", while disabling it only for "git push". [1]: https://lore.kernel.org/git/87zhoz8b9o.fsf@evledraar.gmail.com/ Signed-off-by: Kyle Zhao Signed-off-by: Junio C Hamano --- Documentation/config/push.txt | 5 +++++ send-pack.c | 6 ++++++ send-pack.h | 3 ++- t/t5516-fetch-push.sh | 22 ++++++++++++++++++++++ 4 files changed, 35 insertions(+), 1 deletion(-) diff --git a/Documentation/config/push.txt b/Documentation/config/push.txt index e32801e6c9..7386fea225 100644 --- a/Documentation/config/push.txt +++ b/Documentation/config/push.txt @@ -137,3 +137,8 @@ push.negotiate:: server attempt to find commits in common. If "false", Git will rely solely on the server's ref advertisement to find commits in common. + +push.useBitmaps:: + If set to "false", disable use of bitmaps for "git push" even if + `pack.useBitmaps` is "true", without preventing other git operations + from using bitmaps. Default is true. diff --git a/send-pack.c b/send-pack.c index bc0fcdbb00..662f7c2aeb 100644 --- a/send-pack.c +++ b/send-pack.c @@ -84,6 +84,8 @@ static int pack_objects(int fd, struct ref *refs, struct oid_array *advertised, strvec_push(&po.args, "--progress"); if (is_repository_shallow(the_repository)) strvec_push(&po.args, "--shallow"); + if (args->disable_bitmaps) + strvec_push(&po.args, "--no-use-bitmap-index"); po.in = -1; po.out = args->stateless_rpc ? -1 : fd; po.git_cmd = 1; @@ -487,6 +489,7 @@ int send_pack(struct send_pack_args *args, struct async demux; const char *push_cert_nonce = NULL; struct packet_reader reader; + int use_bitmaps; if (!remote_refs) { fprintf(stderr, "No refs in common and none specified; doing nothing.\n" @@ -498,6 +501,9 @@ int send_pack(struct send_pack_args *args, if (push_negotiate) get_commons_through_negotiation(args->url, remote_refs, &commons); + if (!git_config_get_bool("push.usebitmaps", &use_bitmaps)) + args->disable_bitmaps = !use_bitmaps; + git_config_get_bool("transfer.advertisesid", &advertise_sid); /* Does the other end support the reporting? */ diff --git a/send-pack.h b/send-pack.h index e148fcd960..7edb80596c 100644 --- a/send-pack.h +++ b/send-pack.h @@ -26,7 +26,8 @@ struct send_pack_args { /* One of the SEND_PACK_PUSH_CERT_* constants. */ push_cert:2, stateless_rpc:1, - atomic:1; + atomic:1, + disable_bitmaps:1; const struct string_list *push_options; }; diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh index dedca106a7..b3734dd2fe 100755 --- a/t/t5516-fetch-push.sh +++ b/t/t5516-fetch-push.sh @@ -1865,4 +1865,26 @@ test_expect_success 'push warns or fails when using username:password' ' test_line_count = 1 warnings ' +test_expect_success 'push with config push.useBitmaps' ' + mk_test testrepo heads/main && + git checkout main && + test_unconfig push.useBitmaps && + GIT_TRACE2_EVENT="$PWD/default" \ + git push testrepo main:test && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ + --thin --delta-base-offset -q