development/git
development/git
1
0
Fork 0
mirror of https://github.com/git/git synced 2024-08-27 19:49:21 +00:00
Code Issues Packages Projects Releases Wiki Activity

Use binary searching on large buckets in git-describe.

Browse source 
If a project has a really huge number of tags (such as several
thousand tags) then we are likely to have nearly a hundred tags in
some buckets.  Scanning those buckets as linked lists could take
a large amount of time if done repeatedly during history traversal.

Since we are searching for a unique commit SHA1 we can sort all
tags by commit SHA1 and perform a binary search within the bucket.
Once we identify a particular tag as matching this commit we walk
backwards within the bucket matches to make sure we pick up the
highest priority tag for that commit, as the binary search may
have landed us in the middle of a set of tags which point at the
same commit.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Shawn O. Pearce 2007-01-13 17:29:00 -05:00 committed by Junio C Hamano
parent c3e3cd4bf8
commit 910c0d7b5e
1 changed files with 20 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

27
builtin-describe.c
View file

@ -23,14 +23,24 @@ static struct commit_name {
static struct commit_name *match(struct commit *cmit)
{
unsigned char m = cmit->object.sha1[0];
unsigned int i = names[m];
struct commit_name **p = name_array[m];
unsigned char level0 = cmit->object.sha1[0];
struct commit_name **p = name_array[level0];
unsigned int hi = names[level0];
unsigned int lo = 0;
while (i-- > 0) {
struct commit_name *n = *p++;
if (n->commit == cmit)
return n;
while (lo < hi) {
unsigned int mi = (lo + hi) / 2;
int cmp = hashcmp(p[mi]->commit->object.sha1,
cmit->object.sha1);
if (!cmp) {
while (mi && p[mi - 1]->commit == cmit)
mi--;
return p[mi];
}
if (cmp > 0)
hi = mi;
else
lo = mi+1;
}
return NULL;
}
@ -95,7 +105,10 @@ static int compare_names(const void *_a, const void *_b)
struct commit_name *b = *(struct commit_name **)_b;
unsigned long a_date = a->commit->date;
unsigned long b_date = b->commit->date;
int cmp = hashcmp(a->commit->object.sha1, b->commit->object.sha1);
if (cmp)
return cmp;
if (a->prio != b->prio)
return b->prio - a->prio;
return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;