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| author |  René Scharfe <l.s.r@web.de> | 2020-02-04 22:24:24 +0100 |
|---|---|---|
| committer |  Junio C Hamano <gitster@pobox.com> | 2020-02-05 10:24:15 -0800 |
| commit | 1c56fc208400011b196f571041a0bc694fc9637c (patch) | |
| tree | 22ec3e5b7dfdbc75309d9deca1bb9d46fc70de5d /builtin/name-rev.c | |
| parent | name-rev: factor out get_parent_name() (diff) | |
| download | tgif-1c56fc208400011b196f571041a0bc694fc9637c.tar.xz | |
name-rev: pre-size buffer in get_parent_name()
We can calculate the size of new name easily and precisely. Open-code
the xstrfmt() calls and grow the buffers as needed before filling them.
This provides a surprisingly large benefit when working with the
Chromium repository; here are the numbers measured using hyperfine
before:
Benchmark #1: ./git -C ../chromium/src name-rev --all
Time (mean ± σ): 5.822 s ± 0.013 s [User: 5.304 s, System: 0.516 s]
Range (min … max): 5.803 s … 5.837 s 10 runs
... and with this patch:
Benchmark #1: ./git -C ../chromium/src name-rev --all
Time (mean ± σ): 1.527 s ± 0.003 s [User: 1.015 s, System: 0.511 s]
Range (min … max): 1.524 s … 1.535 s 10 runs
Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'builtin/name-rev.c')
| -rw-r--r-- | builtin/name-rev.c | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/builtin/name-rev.c b/builtin/name-rev.c index 6701fb1569..793356edd1 100644 --- a/builtin/name-rev.c +++ b/builtin/name-rev.c @@ -103,15 +103,23 @@ static struct rev_name *create_or_update_name(struct commit *commit, static char *get_parent_name(const struct rev_name *name, int parent_number) { + struct strbuf sb = STRBUF_INIT; size_t len; strip_suffix(name->tip_name, "^0", &len); - if (name->generation > 0) - return xstrfmt("%.*s~%d^%d", (int)len, name->tip_name, - name->generation, parent_number); - else - return xstrfmt("%.*s^%d", (int)len, name->tip_name, - parent_number); + if (name->generation > 0) { + strbuf_grow(&sb, len + + 1 + decimal_width(name->generation) + + 1 + decimal_width(parent_number)); + strbuf_addf(&sb, "%.*s~%d^%d", (int)len, name->tip_name, + name->generation, parent_number); + } else { + strbuf_grow(&sb, len + + 1 + decimal_width(parent_number)); + strbuf_addf(&sb, "%.*s^%d", (int)len, name->tip_name, + parent_number); + } + return strbuf_detach(&sb, NULL); } static void name_rev(struct commit *start_commit, |