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authorJeff King <peff@peff.net>2015-04-16 05:01:38 -0400
committerJunio C Hamano <gitster@pobox.com>2015-04-16 08:15:05 -0700
commit0cc30e0e842a25846e76e09f62a1d425a25ee556 (patch)
treeaa967acf53f4e40271e0b36ab2d188d16eb6973e /config.mak.uname
parentf80c153bea4e0ea86f5b6d32e77df0b69501ee18 (diff)
downloadgit-0cc30e0e842a25846e76e09f62a1d425a25ee556.tar.gz
strbuf_getwholeline: use getdelim if it is available
We spend a lot of time in strbuf_getwholeline in a tight loop reading characters from a stdio handle into a buffer. The libc getdelim() function can do this for us with less overhead. It's in POSIX.1-2008, and was a GNU extension before that. Therefore we can't rely on it, but can fall back to the existing getc loop when it is not available. The HAVE_GETDELIM knob is turned on automatically for Linux, where we have glibc. We don't need to set any new feature-test macros, because we already define _GNU_SOURCE. Other systems that implement getdelim may need to other macros (probably _POSIX_C_SOURCE >= 200809L), but we can address that along with setting the Makefile knob after testing the feature on those systems. Running "git rev-parse refs/heads/does-not-exist" on a repo with an extremely large (1.6GB) packed-refs file went from (best-of-5): real 0m8.601s user 0m8.084s sys 0m0.524s to: real 0m6.768s user 0m6.340s sys 0m0.432s for a wall-clock speedup of 21%. Based on a patch from Rasmus Villemoes <rv@rasmusvillemoes.dk>. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'config.mak.uname')
-rw-r--r--config.mak.uname1
1 files changed, 1 insertions, 0 deletions
diff --git a/config.mak.uname b/config.mak.uname
index f4e77cb9e5..d26665fa54 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -36,6 +36,7 @@ ifeq ($(uname_S),Linux)
HAVE_DEV_TTY = YesPlease
HAVE_CLOCK_GETTIME = YesPlease
HAVE_CLOCK_MONOTONIC = YesPlease
+ HAVE_GETDELIM = YesPlease
endif
ifeq ($(uname_S),GNU/kFreeBSD)
HAVE_ALLOCA_H = YesPlease