@matheusbsbs / matheus-bagliano / commits / ee1c6c34ac

sha1_file: only freshen packs once per run

Since 33d4221 (write_sha1_file: freshen existing objects, 2014-10-15), we update the mtime of existing objects that we would have written out (had they not existed). For the common case in which many objects are packed, we may update the mtime on a single packfile repeatedly. This can result in a noticeable performance problem if calling utime() is expensive (e.g., because your storage is on NFS). We can fix this by keeping a per-pack flag that lets us freshen only once per program invocation. An alternative would be to keep the packed_git.mtime flag up to date as we freshen, and freshen only once every N seconds. In practice, it's not worth the complexity. We are racing against prune expiration times here, which inherently must be set to accomodate reasonable program running times (because they really care about the time between an object being written and it becoming referenced, and the latter is typically the last step a program takes). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Apr 20, 2015 at 15:55 UTC ee1c6c34ac64c1e10b17a50710ea7002b7e7241f

2 files changed +9 -1

cache.h

@@ -1168,6 +1168,7 @@ extern struct packed_git {

1168 int pack_fd;

1169 unsigned pack_local:1,

1170 pack_keep:1,

1171 + freshened:1,

1172 do_not_close:1;

1173 unsigned char sha1[20];

1174 /* something like ".git/objects/pack/xxxxx.pack" */

sha1_file.c

+8 -1

@@ -2999,7 +2999,14 @@ static int freshen_loose_object(const unsigned char *sha1)

2999 static int freshen_packed_object(const unsigned char *sha1)

3000 {

3001 struct pack_entry e;

3002 - return find_pack_entry(sha1, &e) && freshen_file(e.p->pack_name);

3002 + if (!find_pack_entry(sha1, &e))

3003 + return 0;

3004 + if (e.p->freshened)

3005 + return 1;

3006 + if (!freshen_file(e.p->pack_name))

3007 + return 0;

3008 + e.p->freshened = 1;

3009 + return 1;

3010 }

3011

3012 int write_sha1_file(const void *buf, unsigned long len, const char *type, unsigned char *returnsha1)