fetch-pack: avoid quadratic behavior in remove_duplicates

diff --git a/builtin/fetch-pack.c b/builtin/fetch-pack.c
index 10db15b18403f01b9ee5db27b37d1e0cdbb2abb1..e101842627d47f6e368201cd1d01690be016342e 100644 (file)
--- a/builtin/fetch-pack.c
+++ b/builtin/fetch-pack.c
@@ -834,21 +834,12 @@ static int remove_duplicates(int nr_heads, char **heads)
 {
        int src, dst;
 
-       for (src = dst = 0; src < nr_heads; src++) {
-               /* If heads[src] is different from any of
-                * heads[0..dst], push it in.
-                */
-               int i;
-               for (i = 0; i < dst; i++) {
-                       if (!strcmp(heads[i], heads[src]))
-                               break;
-               }
-               if (i < dst)
-                       continue;
-               if (src != dst)
-                       heads[dst] = heads[src];
-               dst++;
-       }
+       if (!nr_heads)
+               return 0;
+
+       for (src = dst = 1; src < nr_heads; src++)
+               if (strcmp(heads[src], heads[dst-1]))
+                       heads[dst++] = heads[src];
        return dst;
 }
 
@@ -1057,6 +1048,11 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
        return ret;
 }
 
+static int compare_heads(const void *a, const void *b)
+{
+       return strcmp(*(const char **)a, *(const char **)b);
+}
+
 struct ref *fetch_pack(struct fetch_pack_args *my_args,
                       int fd[], struct child_process *conn,
                       const struct ref *ref,
@@ -1076,8 +1072,11 @@ struct ref *fetch_pack(struct fetch_pack_args *my_args,
                        st.st_mtime = 0;
        }
 
-       if (heads && nr_heads)
+       if (heads && nr_heads) {
                nr_heads = remove_duplicates(nr_heads, heads);
+               qsort(heads, nr_heads, sizeof(*heads), compare_heads);
+       }
+
        if (!ref) {
                packet_flush(fd[1]);
                die("no matching remote head");