upload-pack: stop the other side when they have more roots than we do.
[git/git.git] / upload-pack.c
index 35c7ecb..e8f4be3 100644 (file)
 
 static const char upload_pack_usage[] = "git-upload-pack [--strict] [--timeout=nn] <dir>";
 
-#define THEY_HAVE (1U << 0)
-#define OUR_REF (1U << 1)
-#define WANTED (1U << 2)
+/* bits #0..7 in revision.h, #8..10 in commit.c */
+#define THEY_HAVE      (1u << 11)
+#define OUR_REF                (1u << 12)
+#define WANTED         (1u << 13)
+#define COMMON_KNOWN   (1u << 14)
+#define REACHABLE      (1u << 15)
+
+static unsigned long oldest_have = 0;
+
 static int multi_ack = 0, nr_our_refs = 0;
 static int use_thin_pack = 0;
 static struct object_array have_obj;
@@ -323,11 +329,12 @@ static void create_pack_file(void)
 static int got_sha1(char *hex, unsigned char *sha1)
 {
        struct object *o;
+       int we_knew_they_have = 0;
 
        if (get_sha1_hex(hex, sha1))
                die("git-upload-pack: expected SHA1 object, got '%s'", hex);
        if (!has_sha1_file(sha1))
-               return 0;
+               return -1;
 
        o = lookup_object(sha1);
        if (!(o && o->parsed))
@@ -336,15 +343,84 @@ static int got_sha1(char *hex, unsigned char *sha1)
                die("oops (%s)", sha1_to_hex(sha1));
        if (o->type == OBJ_COMMIT) {
                struct commit_list *parents;
+               struct commit *commit = (struct commit *)o;
                if (o->flags & THEY_HAVE)
-                       return 0;
-               o->flags |= THEY_HAVE;
-               for (parents = ((struct commit*)o)->parents;
+                       we_knew_they_have = 1;
+               else
+                       o->flags |= THEY_HAVE;
+               if (!oldest_have || (commit->date < oldest_have))
+                       oldest_have = commit->date;
+               for (parents = commit->parents;
                     parents;
                     parents = parents->next)
                        parents->item->object.flags |= THEY_HAVE;
        }
-       add_object_array(o, NULL, &have_obj);
+       if (!we_knew_they_have) {
+               add_object_array(o, NULL, &have_obj);
+               return 1;
+       }
+       return 0;
+}
+
+static int reachable(struct commit *want)
+{
+       struct commit_list *work = NULL;
+
+       insert_by_date(want, &work);
+       while (work) {
+               struct commit_list *list = work->next;
+               struct commit *commit = work->item;
+               free(work);
+               work = list;
+
+               if (commit->object.flags & THEY_HAVE) {
+                       want->object.flags |= COMMON_KNOWN;
+                       break;
+               }
+               if (!commit->object.parsed)
+                       parse_object(commit->object.sha1);
+               if (commit->object.flags & REACHABLE)
+                       continue;
+               commit->object.flags |= REACHABLE;
+               if (commit->date < oldest_have)
+                       continue;
+               for (list = commit->parents; list; list = list->next) {
+                       struct commit *parent = list->item;
+                       if (!(parent->object.flags & REACHABLE))
+                               insert_by_date(parent, &work);
+               }
+       }
+       want->object.flags |= REACHABLE;
+       clear_commit_marks(want, REACHABLE);
+       free_commit_list(work);
+       return (want->object.flags & COMMON_KNOWN);
+}
+
+static int ok_to_give_up(void)
+{
+       int i;
+
+       if (!have_obj.nr)
+               return 0;
+
+       for (i = 0; i < want_obj.nr; i++) {
+               struct object *want = want_obj.objects[i].item;
+
+               if (want->flags & COMMON_KNOWN)
+                       continue;
+               want = deref_tag(want, "a want line", 0);
+               if (!want || want->type != OBJ_COMMIT) {
+                       /* no way to tell if this is reachable by
+                        * looking at the ancestry chain alone, so
+                        * leave a note to ourselves not to worry about
+                        * this object anymore.
+                        */
+                       want_obj.objects[i].item->flags |= COMMON_KNOWN;
+                       continue;
+               }
+               if (!reachable((struct commit *)want))
+                       return 0;
+       }
        return 1;
 }
 
@@ -369,7 +445,13 @@ static int get_common_commits(void)
                }
                len = strip(line, len);
                if (!strncmp(line, "have ", 5)) {
-                       if (got_sha1(line+5, sha1)) {
+                       switch (got_sha1(line+5, sha1)) {
+                       case -1: /* they have what we do not */
+                               if (multi_ack && ok_to_give_up())
+                                       packet_write(1, "ACK %s continue\n",
+                                                    sha1_to_hex(sha1));
+                               break;
+                       default:
                                memcpy(hex, sha1_to_hex(sha1), 41);
                                if (multi_ack) {
                                        const char *msg = "ACK %s continue\n";
@@ -378,6 +460,7 @@ static int get_common_commits(void)
                                }
                                else if (have_obj.nr == 1)
                                        packet_write(1, "ACK %s\n", hex);
+                               break;
                        }
                        continue;
                }