From 61fa30972c45e73d39c81d27af9eeacbda7531c9 Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Tue, 25 Apr 2006 17:40:02 -0700 Subject: [PATCH] cache-tree: sort the subtree entries. 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 --- cache-tree.c | 92 +++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 66 insertions(+), 26 deletions(-) diff --git a/cache-tree.c b/cache-tree.c index 2146723e9..d8438d67d 100644 --- a/cache-tree.c +++ b/cache-tree.c @@ -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"); -- 2.30.2