From 0eeb077be7d526635995e17808927c94c70be665 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Tue, 9 Jun 2015 13:24:37 -0400 Subject: index-pack: avoid excessive re-reading of pack directory Since 45e8a74 (has_sha1_file: re-check pack directory before giving up, 2013-08-30), we spend extra effort for has_sha1_file to give the right answer when somebody else is repacking. Usually this effort does not matter, because after finding that the object does not exist, the next step is usually to die(). However, some code paths make a large number of has_sha1_file checks which are _not_ expected to return 1. The collision test in index-pack.c is such a case. On a local system, this can cause a performance slowdown of around 5%. But on a system with high-latency system calls (like NFS), it can be much worse. This patch introduces a "quick" flag to has_sha1_file which callers can use when they would prefer high performance at the cost of false negatives during repacks. There may be other code paths that can use this, but the index-pack one is the most obviously critical, so we'll start with switching that one. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- cache.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'cache.h') diff --git a/cache.h b/cache.h index f23fdbee96..3fb7570671 100644 --- a/cache.h +++ b/cache.h @@ -873,8 +873,17 @@ extern int has_sha1_pack(const unsigned char *sha1); * Return true iff we have an object named sha1, whether local or in * an alternate object database, and whether packed or loose. This * function does not respect replace references. + * + * If the QUICK flag is set, do not re-check the pack directory + * when we cannot find the object (this means we may give a false + * negative answer if another process is simultaneously repacking). */ -extern int has_sha1_file(const unsigned char *sha1); +#define HAS_SHA1_QUICK 0x1 +extern int has_sha1_file_with_flags(const unsigned char *sha1, int flags); +static inline int has_sha1_file(const unsigned char *sha1) +{ + return has_sha1_file_with_flags(sha1, 0); +} /* * Return true iff an alternate object database has a loose object -- cgit v1.2.3