+struct pbase_tree_cache {
+ unsigned char sha1[20];
+ int ref;
+ int temporary;
+ void *tree_data;
+ unsigned long tree_size;
+};
+
+static struct pbase_tree_cache *(pbase_tree_cache[256]);
+static int pbase_tree_cache_ix(const unsigned char *sha1)
+{
+ return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
+}
+static int pbase_tree_cache_ix_incr(int ix)
+{
+ return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
+}
+
+static struct pbase_tree {
+ struct pbase_tree *next;
+ /* This is a phony "cache" entry; we are not
+ * going to evict it nor find it through _get()
+ * mechanism -- this is for the toplevel node that
+ * would almost always change with any commit.
+ */
+ struct pbase_tree_cache pcache;
+} *pbase_tree;
+
+static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
+{
+ struct pbase_tree_cache *ent, *nent;
+ void *data;
+ unsigned long size;
+ char type[20];
+ int neigh;
+ int my_ix = pbase_tree_cache_ix(sha1);
+ int available_ix = -1;
+
+ /* pbase-tree-cache acts as a limited hashtable.
+ * your object will be found at your index or within a few
+ * slots after that slot if it is cached.
+ */
+ for (neigh = 0; neigh < 8; neigh++) {
+ ent = pbase_tree_cache[my_ix];
+ if (ent && !memcmp(ent->sha1, sha1, 20)) {
+ ent->ref++;
+ return ent;
+ }
+ else if (((available_ix < 0) && (!ent || !ent->ref)) ||
+ ((0 <= available_ix) &&
+ (!ent && pbase_tree_cache[available_ix])))
+ available_ix = my_ix;
+ if (!ent)
+ break;
+ my_ix = pbase_tree_cache_ix_incr(my_ix);
+ }
+
+ /* Did not find one. Either we got a bogus request or
+ * we need to read and perhaps cache.
+ */
+ data = read_sha1_file(sha1, type, &size);
+ if (!data)
+ return NULL;
+ if (strcmp(type, tree_type)) {
+ free(data);
+ return NULL;
+ }
+
+ /* We need to either cache or return a throwaway copy */
+
+ if (available_ix < 0)
+ ent = NULL;
+ else {
+ ent = pbase_tree_cache[available_ix];
+ my_ix = available_ix;
+ }
+
+ if (!ent) {
+ nent = xmalloc(sizeof(*nent));
+ nent->temporary = (available_ix < 0);
+ }
+ else {
+ /* evict and reuse */
+ free(ent->tree_data);
+ nent = ent;
+ }
+ memcpy(nent->sha1, sha1, 20);
+ nent->tree_data = data;
+ nent->tree_size = size;
+ nent->ref = 1;
+ if (!nent->temporary)
+ pbase_tree_cache[my_ix] = nent;
+ return nent;
+}
+
+static void pbase_tree_put(struct pbase_tree_cache *cache)
+{
+ if (!cache->temporary) {
+ cache->ref--;
+ return;
+ }
+ free(cache->tree_data);
+ free(cache);
+}
+
+static int name_cmp_len(const char *name)
+{
+ int i;
+ for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
+ ;
+ return i;
+}
+
+static void add_pbase_object(struct tree_desc *tree,
+ struct name_path *up,
+ const char *name,
+ int cmplen)