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Revision 5bdbaaa4e9dd901dd2907b53bbecfdf3eac9276b authored by Linus Torvalds on 15 September 2005, 22:14:29 UTC, committed by Junio C Hamano on 15 September 2005, 23:19:44 UTC 
[PATCH] Re-organize "git-rev-list --objects" logic
 
The logic to calculate the full object list used to be very inter-twined
with the logic that looked up the commits.

For no good reason - it's actually a lot simpler to just do that logic
as a separate pass.

This improves performance a bit, and uses slightly less memory in my
tests, but more importantly it makes the code simpler to work with and
follow what it does.

The performance win is less than I had hoped for, but I get:

Before:

	[torvalds@g5 linux]$ /usr/bin/time git-rev-list --objects v2.6.12..HEAD | wc -l
	13.64user 0.42system 0:14.13elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
	0inputs+0outputs (0major+47947minor)pagefaults 0swaps
	58945

After:

	[torvalds@g5 linux]$ /usr/bin/time git-rev-list --objects v2.6.12..HEAD | wc -l
	11.80user 0.36system 0:12.16elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k
	0inputs+0outputs (0major+42684minor)pagefaults 0swaps
	58945

ie it improved by 2 seconds, and took a 5000+ fewer pages (hey, that's
20MB out of 174MB to go). And got the same number of objects (in theory,
the more expensive one might find some more shared objects to avoid. In
practice it obviously doesn't).

I know how to make it use _lots_ less memory, which will probably speed it
up. But that's for another time, and I'd prefer to see this go in first.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
1 parent 5098baf
Raw File
refs.h 
#ifndef REFS_H
#define REFS_H

/*
 * Calls the specified function for each ref file until it returns nonzero,
 * and returns the value
 */
extern int head_ref(int (*fn)(const char *path, const unsigned char *sha1));
extern int for_each_ref(int (*fn)(const char *path, const unsigned char *sha1));

/** Reads the refs file specified into sha1 **/
extern int get_ref_sha1(const char *ref, unsigned char *sha1);

/** Locks ref and returns the fd to give to write_ref_sha1() if the ref
 * has the given value currently; otherwise, returns -1.
 **/
extern int lock_ref_sha1(const char *ref, const unsigned char *old_sha1);

/** Writes sha1 into the refs file specified, locked with the given fd. **/
extern int write_ref_sha1(const char *ref, int fd, const unsigned char *sha1);

/** Writes sha1 into the refs file specified. **/
extern int write_ref_sha1_unlocked(const char *ref, const unsigned char *sha1);

/** Returns 0 if target has the right format for a ref. **/
extern int check_ref_format(const char *target);

#endif /* REFS_H */
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