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cache-tree: sort the subtree entries.

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Not that this makes practical performance difference; the kernel tree
for example has 200 or so directories that have subdirectory, and the
largest ones have 57 of them (fs and drivers).  With a test to apply
600 patches with git-apply and git-write-tree, this did not make more
than one per-cent of a difference, but it is a good cleanup.

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Junio C Hamano 2006-04-25 17:40:02 -07:00
parent 53dc3f3e80
commit 61fa30972c
1 changed files with 66 additions and 26 deletions
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92
cache-tree.c
View file

@ -19,38 +19,75 @@ void cache_tree_free(struct cache_tree **it_p)
if (!it)
return;
for (i = 0; i < it->subtree_nr; i++)
cache_tree_free(&it->down[i]->cache_tree);
if (it->down[i])
cache_tree_free(&it->down[i]->cache_tree);
free(it->down);
free(it);
*it_p = NULL;
}
static int subtree_name_cmp(const char *one, int onelen,
const char *two, int twolen)
{
if (onelen < twolen)
return -1;
if (twolen < onelen)
return 1;
return memcmp(one, two, onelen);
}
static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
{
struct cache_tree_sub **down = it->down;
int lo, hi;
lo = 0;
hi = it->subtree_nr;
while (lo < hi) {
int mi = (lo + hi) / 2;
struct cache_tree_sub *mdl = down[mi];
int cmp = subtree_name_cmp(path, pathlen,
mdl->name, mdl->namelen);
if (!cmp)
return mi;
if (cmp < 0)
hi = mi;
else
lo = mi + 1;
}
return -lo-1;
}
static struct cache_tree_sub *find_subtree(struct cache_tree *it,
const char *path,
int pathlen,
int create)
{
int i;
struct cache_tree_sub *down;
for (i = 0; i < it->subtree_nr; i++) {
down = it->down[i];
if (down->namelen == pathlen &&
!memcmp(down->name, path, pathlen))
return down;
}
int pos = subtree_pos(it, path, pathlen);
if (0 <= pos)
return it->down[pos];
if (!create)
return NULL;
pos = -pos-1;
if (it->subtree_alloc <= it->subtree_nr) {
it->subtree_alloc = alloc_nr(it->subtree_alloc);
it->down = xrealloc(it->down, it->subtree_alloc *
sizeof(*it->down));
}
it->subtree_nr++;
down = xmalloc(sizeof(*down) + pathlen + 1);
down->cache_tree = NULL; /* cache_tree(); */
down->cache_tree = NULL;
down->namelen = pathlen;
memcpy(down->name, path, pathlen);
down->name[pathlen] = 0; /* not strictly needed */
it->down[it->subtree_nr++] = down;
down->name[pathlen] = 0;
if (pos < it->subtree_nr)
memmove(it->down + pos + 1,
it->down + pos,
sizeof(down) * (it->subtree_nr - pos - 1));
it->down[pos] = down;
return down;
}
@ -72,25 +109,21 @@ void cache_tree_invalidate_path(struct cache_tree *it, const char *path)
slash = strchr(path, '/');
it->entry_count = -1;
if (!slash) {
int i;
int pos;
namelen = strlen(path);
for (i = 0; i < it->subtree_nr; i++) {
if (it->down[i]->namelen == namelen &&
!memcmp(it->down[i]->name, path, namelen))
break;
}
if (i < it->subtree_nr) {
cache_tree_free(&it->down[i]->cache_tree);
free(it->down[i]);
pos = subtree_pos(it, path, namelen);
if (0 <= pos) {
cache_tree_free(&it->down[pos]->cache_tree);
free(it->down[pos]);
/* 0 1 2 3 4 5
* ^ ^subtree_nr = 6
* i
* pos
* move 4 and 5 up one place (2 entries)
* 2 = 6 - 3 - 1 = subtree_nr - i - 1
* 2 = 6 - 3 - 1 = subtree_nr - pos - 1
*/
memmove(it->down+i, it->down+i+1,
memmove(it->down+pos, it->down+pos+1,
sizeof(struct cache_tree_sub *) *
(it->subtree_nr - i - 1));
(it->subtree_nr - pos - 1));
it->subtree_nr--;
}
return;
@ -364,6 +397,12 @@ static void *write_one(struct cache_tree *it,
}
for (i = 0; i < it->subtree_nr; i++) {
struct cache_tree_sub *down = it->down[i];
if (i) {
struct cache_tree_sub *prev = it->down[i-1];
if (subtree_name_cmp(down->name, down->namelen,
prev->name, prev->namelen) <= 0)
die("fatal - unsorted cache subtree");
}
buffer = write_one(down->cache_tree, down->name, down->namelen,
buffer, size, offset);
}
@ -435,14 +474,15 @@ static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
for (i = 0; i < subtree_nr; i++) {
/* read each subtree */
struct cache_tree *sub;
struct cache_tree_sub *subtree;
const char *name = buf;
int namelen;
sub = read_one(&buf, &size);
if (!sub)
goto free_return;
namelen = strlen(name);
it->down[i] = find_subtree(it, name, namelen, 1);
it->down[i]->cache_tree = sub;
subtree = find_subtree(it, name, namelen, 1);
subtree->cache_tree = sub;
}
if (subtree_nr != it->subtree_nr)
die("cache-tree: internal error");