[PATCH 7/7] merge: allow to use only the fp-only merge bases
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Oct 19, 2016, 04:23 UTC
- Message-ID
- <20161019042345.29766-8-gitster@pobox.com>
- In-Reply-To
- <20161019042345.29766-1-gitster@pobox.com>
Teach "git merge" a new option "--fp-base-only" that tells it to consider only merge bases that are on the first-parent chain.
This speeds up back-merges needed in the topic branch workflow. The merge of 'master' back into 'next' used as an example in the RFD article <xmqqmvi2sj8f.fsf@gitster.mtv.corp.google.com>, i.e.
git checkout 4868def05e && git merge 659889482a
in our history takes about 1.22-1.33 seconds without the series, while running the latter "git merge" with the "--fp-base-only" option takes about 0.54-0.59 seconds.
Signed-off-by: Junio C Hamano <gitster@pobox.com> --- Documentation/merge-options.txt | 9 +++++++++ builtin/merge.c | 15 ++++++++++++--- 2 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt index 5b4a62e936..7927f069e4 100644 --- a/Documentation/merge-options.txt +++ b/Documentation/merge-options.txt @@ -116,6 +116,15 @@ ifndef::git-pull[] Note that not all merge strategies may support progress reporting. +--fp-base-only:: + Instead of using all merge bases when computing the + three-way merge result, use only the merge bases on the + first-parent chain of the commits being merged. This + experimental feature is meant to be used when merging an + older integration branch back to a newer integration branch + in the topic-branch workflow. + + endif::git-pull[] --allow-unrelated-histories:: diff --git a/builtin/merge.c b/builtin/merge.c index 0ae099f746..a38b878e61 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -88,6 +88,8 @@ enum ff_type { static enum ff_type fast_forward = FF_ALLOW; +static int fp_base_only; + static int option_parse_message(const struct option *opt, const char *arg, int unset) { @@ -210,6 +212,8 @@ static struct option builtin_merge_options[] = { { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL, N_("abort if fast-forward is not possible"), PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY }, + OPT_BOOL(0, "fp-base-only", &fp_base_only, + N_("use only merge bases on first-parent chain")), OPT_RERERE_AUTOUPDATE(&allow_rerere_auto), OPT_BOOL(0, "verify-signatures", &verify_signatures, N_("verify that the named commit has a valid GPG signature")), @@ -1340,9 +1344,14 @@ int cmd_merge(int argc, const char **argv, const char *prefix) if (!remoteheads) ; /* already up-to-date */ - else if (!remoteheads->next) - common = get_merge_bases(head_commit, remoteheads->item); - else { + else if (!remoteheads->next) { + unsigned flags = MB_POSTCLEAN; + if (fp_base_only) + flags |= MB_FPCHAIN; + common = get_merge_bases_opt(head_commit, + 1, &remoteheads->item, + flags); + } else { struct commit_list *list = remoteheads; commit_list_insert(head_commit, &list); common = get_octopus_merge_bases(list);
-- 2.10.1-631-gb2c64dcf30