[PATCH 8/9] grep: load file data after checking binary-ness

From: Jeff King <peff@peff.net>
Date: Feb 2, 2012, 08:21 UTC
Message-ID: <20120202082111.GH6786@sigill.intra.peff.net>
In-Reply-To: <20120202081747.GA10271@sigill.intra.peff.net>

Usually we load each file to grep into memory, check whether it's binary, and then either grep it (the default) or not (if "-I" was given).

In the "-I" case, we can skip loading the file entirely if it is marked as binary via gitattributes. On my giant 3-gigabyte media repository, doing "git grep -I foo" went from:

  real    0m0.712s
  user    0m0.044s
  sys     0m4.780s

to:

  real    0m0.026s
  user    0m0.016s
  sys     0m0.020s

Obviously this is an extreme example. The repo is almost entirely binary files, and you can see that we spent all of our time asking the kernel to read() the data. However, with a cold disk cache, even avoiding a few binary files can have an impact.

Signed-off-by: Jeff King <peff@peff.net>
---
 grep.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/grep.c b/grep.c
index a50d161..3821400 100644
--- a/grep.c
+++ b/grep.c
@@ -1019,9 +1019,6 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
 	}
 	opt->last_shown = 0;
 
-	if (grep_source_load(gs) < 0)
-		return 0;
-
 	switch (opt->binary) {
 	case GREP_BINARY_DEFAULT:
 		if (grep_source_is_binary(gs))
@@ -1042,6 +1039,9 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
 
 	try_lookahead = should_lookahead(opt);
 
+	if (grep_source_load(gs) < 0)
+		return 0;
+
 	bol = gs->buf;
 	left = gs->size;
 	while (left) {

-- 
1.7.9.3.gc3fce1.dirty