write_index(): update index_state->timestamp after flushing to disk

Since this timestamp is used to check for racy-clean files, it is important to keep it uptodate. For the 'git checkout' command without the '-q' option, this make a huge difference. Before, each and every file which was updated, was racy-clean after the call to unpack_trees() and write_index() but before the GIT process ended. And because of the call to show_local_changes() in builtin-checkout.c, we ended up reading those files back into memory, doing a SHA1 to check if the files was really different from the index. And, of course, no file was different. With this fix, 'git checkout' without the '-q' option should now be almost as fast as with the '-q' option, but not quite, as we still do some few lstat(2) calls more without the '-q' option. Below is some average numbers for 10 checkout's to v2.6.27 and 10 to v2.6.25 of the Linux kernel, to show the difference: before (git version 1.6.2.rc1.256.g58a87): 7.860 user 2.427 sys 19.465 real 52.8% CPU faults: 0 major 95331 minor after: 6.184 user 2.160 sys 17.619 real 47.4% CPU faults: 0 major 38994 minor Signed-off-by: Kjetil Barvik <barvik@broadpark.no> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Kjetil Barvik committed Feb 23, 2009 at 19:02 UTC e1afca4fd3e7cb4000874e991277f10119de4ad2

2 files changed +11 -3

cache.h

+1 -1

@@ -430,7 +430,7 @@ extern int read_index_preload(struct index_state *, const char **pathspec);

430 extern int read_index_from(struct index_state *, const char *path);

431 extern int is_index_unborn(struct index_state *);

432 extern int read_index_unmerged(struct index_state *);

433 -extern int write_index(const struct index_state *, int newfd);

433 +extern int write_index(struct index_state *, int newfd);

434 extern int discard_index(struct index_state *);

435 extern int unmerged_index(const struct index_state *);

436 extern int verify_path(const char *path);

read-cache.c

+10 -2

@@ -1528,13 +1528,14 @@ static int ce_write_entry(git_SHA_CTX *c, int fd, struct cache_entry *ce)

1528 return ce_write(c, fd, ondisk, size);

1529 }

1530

1531 -int write_index(const struct index_state *istate, int newfd)

1531 +int write_index(struct index_state *istate, int newfd)

1532 {

1533 git_SHA_CTX c;

1534 struct cache_header hdr;

1535 int i, err, removed, extended;

1536 struct cache_entry **cache = istate->cache;

1537 int entries = istate->cache_nr;

1538 + struct stat st;

1539

1540 for (i = removed = extended = 0; i < entries; i++) {

1541 if (cache[i]->ce_flags & CE_REMOVE)

@@ -1578,7 +1579,14 @@ int write_index(const struct index_state *istate, int newfd)

1579 if (err)

1580 return -1;

1581 }

1581 - return ce_flush(&c, newfd);

1582 +

1583 + if (ce_flush(&c, newfd) || fstat(newfd, &st))

1584 + return -1;

1585 + istate->timestamp.sec = (unsigned int)st.st_ctime;

1586 +#ifdef USE_NSEC

1587 + istate->timestamp.nsec = (unsigned int)st.st_ctim.tv_nsec;

1588 +#endif

1589 + return 0;

1590 }

1591

1592 /*