From: Kyle Zhao <kylezhao@xxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxx/ Signed-off-by: Kyle Zhao <kylezhao@xxxxxxxxxxx> --- send-pack.c: add config push.useBitmaps This patch add config push.useBitmaps to prevent git push using bitmap. The origin discussion is here: https://lore.kernel.org/git/b940e705fbe9454685757f2e3055e2ce@xxxxxxxxxxx/ Thanks, -Kyle Changes since v1: * changed the commit message * modified and added missing \n to push.txt * used test_subcommand for test * modified "if" statement for "git_config_get_bool()" in send-pack.c Changes since v2: * enable 'push.useBitmaps" by default * fix nit in t/t5516-fetch-push.sh Changes since v3: * changed the commit message * s/no_use_bitmaps/disable_bitmaps in send-pack.h and send-pack.c * I modified the document about "push.useBitmaps". When it is true, Git will keep the historical behaviour. So I mainly introduced what happens when it set to false. * use test_config and test_unconfig for test. Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1263%2Fkeyu98%2Fkz%2Fpush-usebitmps-config-v4 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1263/keyu98/kz/push-usebitmps-config-v4 Pull-Request: https://github.com/gitgitgadget/git/pull/1263 Range-diff vs v3: 1: a523cb52542 ! 1: 9d35d926638 send-pack.c: add config push.useBitmaps @@ Metadata ## Commit message ## send-pack.c: add config push.useBitmaps - This allows you to disable bitmaps for "git push". Default is true. - 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" config option to disable reachability - bitmaps during "git push". This allows reachability bitmaps to still - be used in other areas, such as "git rev-list --use-bitmap-index". + 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@xxxxxxxxxxxxxxxxxxx/ @@ Documentation/config/push.txt: push.negotiate:: in common. + +push.useBitmaps:: -+ If this config and `pack.useBitmaps` are both `true`, then Git will -+ use reachability bitmaps during `git push`, if available. If set to -+ `false`, may improve push performance without affecting use of the -+ reachability bitmaps for other operations. Default is true. ++ 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. ## send-pack.c ## @@ send-pack.c: 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->no_use_bitmaps) ++ if (args->disable_bitmaps) + strvec_push(&po.args, "--no-use-bitmap-index"); po.in = -1; po.out = args->stateless_rpc ? -1 : fd; @@ send-pack.c: int send_pack(struct send_pack_args *args, get_commons_through_negotiation(args->url, remote_refs, &commons); + if (!git_config_get_bool("push.usebitmaps", &use_bitmaps)) -+ args->no_use_bitmaps = !use_bitmaps; ++ args->disable_bitmaps = !use_bitmaps; + git_config_get_bool("transfer.advertisesid", &advertise_sid); @@ send-pack.h: struct send_pack_args { stateless_rpc:1, - atomic:1; + atomic:1, -+ no_use_bitmaps:1; ++ disable_bitmaps:1; const struct string_list *push_options; }; @@ t/t5516-fetch-push.sh: test_expect_success 'push warns or fails when using usern +test_expect_success 'push with config push.useBitmaps' ' + mk_test testrepo heads/main && + git checkout main && ++ test_unconfig push.useBitmaps && + GIT_TRACE2_EVENT="$PWD/default" \ + git push testrepo main:test && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ + --thin --delta-base-offset -q <default && + -+ git config push.useBitmaps true && ++ test_config push.useBitmaps true && + GIT_TRACE2_EVENT="$PWD/true" \ + git push testrepo main:test2 && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ + --thin --delta-base-offset -q <true && + -+ git config push.useBitmaps false && ++ test_config push.useBitmaps false && + GIT_TRACE2_EVENT="$PWD/false" \ + git push testrepo main:test3 && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ 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 e32801e6c91..7386fea225a 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 bc0fcdbb000..662f7c2aeb9 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 e148fcd9609..7edb80596c7 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 dedca106a7a..b3734dd2fe9 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 <default && + + test_config push.useBitmaps true && + GIT_TRACE2_EVENT="$PWD/true" \ + git push testrepo main:test2 && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ + --thin --delta-base-offset -q <true && + + test_config push.useBitmaps false && + GIT_TRACE2_EVENT="$PWD/false" \ + git push testrepo main:test3 && + test_subcommand git pack-objects --all-progress-implied --revs --stdout \ + --thin --delta-base-offset -q --no-use-bitmap-index <false +' + test_done base-commit: 8168d5e9c23ed44ae3d604f392320d66556453c9 -- gitgitgadget
