Minor tree cache speedups

While I was looking at the conflict cleanup code, I looked over at
the tree cache code, since we clear the tree cache for each entry
that gets removed and there is some redundancy there.  I made some
small tweaks to avoid extra calls to strchr and strlen in a few
circumstances.

src/tree-cache.c

@@ -7,23 +7,16 @@
 
 #include "tree-cache.h"
 
-static git_tree_cache *find_child(const git_tree_cache *tree, const char *path)
+static git_tree_cache *find_child(
+	const git_tree_cache *tree, const char *path, const char *end)
 {
-	size_t i, dirlen;
-	const char *end;
-
-	end = strchr(path, '/');
-	if (end == NULL) {
-		end = strrchr(path, '\0');
-	}
-
-	dirlen = end - path;
+	size_t i, dirlen = end ? (size_t)(end - path) : strlen(path);
 
 	for (i = 0; i < tree->children_count; ++i) {
-		const char *childname = tree->children[i]->name;
+		git_tree_cache *child = tree->children[i];
 
-		if (strlen(childname) == dirlen && !memcmp(path, childname, dirlen))
-			return tree->children[i];
+		if (child->namelen == dirlen && !memcmp(path, child->name, dirlen))
+			return child;
 	}
 
 	return NULL;
@@ -44,7 +37,7 @@ void git_tree_cache_invalidate_path(git_tree_cache *tree, const char *path)
 		if (end == NULL) /* End of path */
 			break;
 
-		tree = find_child(tree, ptr);
+		tree = find_child(tree, ptr, end);
 		if (tree == NULL) /* We don't have that tree */
 			return;
 
@@ -64,10 +57,9 @@ const git_tree_cache *git_tree_cache_get(const git_tree_cache *tree, const char
 	while (1) {
 		end = strchr(ptr, '/');
 
-		tree = find_child(tree, ptr);
-		if (tree == NULL) { /* Can't find it */
+		tree = find_child(tree, ptr, end);
+		if (tree == NULL) /* Can't find it */
 			return NULL;
-		}
 
 		if (end == NULL || *end + 1 == '\0')
 			return tree;
@@ -100,6 +92,7 @@ static int read_tree_internal(git_tree_cache **out,
 	tree->parent = parent;
 
 	/* NUL-terminated tree name */
+	tree->namelen = name_len;
 	memcpy(tree->name, name_start, name_len);
 	tree->name[name_len] = '\0';
 

src/tree-cache.h

@@ -18,6 +18,7 @@ struct git_tree_cache {
 
 	ssize_t entries;
 	git_oid oid;
+	size_t namelen;
 	char name[GIT_FLEX_ARRAY];
 };