undef/git-commit-vandalism
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Do not write out new index if nothing has changed.

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The git-update-cache command, especially with --refresh, may not change
anything.  In such a case, writing 1.6MB of the same thing is a waste.

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Junio C Hamano 2005-05-05 15:29:06 -07:00
parent ed4eeaf203
commit c4b83e618f
1 changed files with 41 additions and 3 deletions
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44
update-cache.c
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@ -15,6 +15,12 @@
*/ */
static int allow_add = 0, allow_remove = 0, not_new = 0; static int allow_add = 0, allow_remove = 0, not_new = 0;
/*
* update-cache --refresh may not touch anything at all, in which case
* writing 1.6MB of the same thing is a waste.
*/
static int cache_changed = 0;
/* Three functions to allow overloaded pointer return; see linux/err.h */ /* Three functions to allow overloaded pointer return; see linux/err.h */
static inline void *ERR_PTR(long error) static inline void *ERR_PTR(long error)
{ {
@ -51,7 +57,7 @@ static void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
ce->ce_size = htonl(st->st_size); ce->ce_size = htonl(st->st_size);
} }
static int add_file_to_cache(char *path) static int add_file_to_cache_1(char *path)
{ {
int size, namelen; int size, namelen;
struct cache_entry *ce; struct cache_entry *ce;
@ -93,9 +99,35 @@ static int add_file_to_cache(char *path)
default: default:
return -1; return -1;
} }
if (!cache_changed) {
/* If we have not smudged the cache, be careful
* to keep it clean. Find out if we have a matching
* cache entry that add_cache_entry would replace with,
* and if it matches then do not bother calling it.
*/
int pos = cache_name_pos(ce->name, namelen);
if ((0 <= pos) &&
!memcmp(active_cache[pos], ce, sizeof(*ce))) {
free(ce);
/* magic to tell add_file_to_cache that
* we have not updated anything.
*/
return 999;
}
}
return add_cache_entry(ce, allow_add); return add_cache_entry(ce, allow_add);
} }
static int add_file_to_cache(char *path)
{
int ret = add_file_to_cache_1(path);
if (ret == 0)
cache_changed = 1;
else if (ret == 999)
ret = 0;
return ret;
}
static int match_data(int fd, void *buffer, unsigned long size) static int match_data(int fd, void *buffer, unsigned long size)
{ {
while (size) { while (size) {
@ -165,6 +197,7 @@ static struct cache_entry *refresh_entry(struct cache_entry *ce)
if (compare_data(ce, st.st_size)) if (compare_data(ce, st.st_size))
return ERR_PTR(-EINVAL); return ERR_PTR(-EINVAL);
cache_changed = 1;
size = ce_size(ce); size = ce_size(ce);
updated = xmalloc(size); updated = xmalloc(size);
memcpy(updated, ce, size); memcpy(updated, ce, size);
@ -245,6 +278,7 @@ static int add_cacheinfo(char *arg1, char *arg2, char *arg3)
if (!verify_path(arg3)) if (!verify_path(arg3))
return -1; return -1;
cache_changed = 1;
len = strlen(arg3); len = strlen(arg3);
size = cache_entry_size(len); size = cache_entry_size(len);
ce = xmalloc(size); ce = xmalloc(size);
@ -339,9 +373,13 @@ int main(int argc, char **argv)
if (add_file_to_cache(path)) if (add_file_to_cache(path))
die("Unable to add %s to database", path); die("Unable to add %s to database", path);
} }
if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
if (!cache_changed)
unlink(lockfile);
else if (write_cache(newfd, active_cache, active_nr) ||
rename(lockfile, indexfile))
die("Unable to write new cachefile"); die("Unable to write new cachefile");
lockfile_name = NULL; lockfile_name = NULL;
return has_errors; return has_errors ? 1 : 0;
} }