git-fetch-pack: Do not use git-rev-list

The code used to call git-rev-list to enumerate the local revisions. A
disadvantage of that method was that git-rev-list, lacking a control apart
from the command line, would happily enumerate ancestors of acknowledged
common commits, which was just taking unnecessary bandwidth.

Therefore, do not use git-rev-list on the fetching side, but rather
construct the list on the go. Send the revisions starting from the local
heads, ignoring the revisions known to be common.

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/fetch-pack.c b/fetch-pack.c
index 8566ab1..3a903c4 100644 (file)
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -13,18 +13,123 @@ static const char fetch_pack_usage[] =
 static const char *exec = "git-upload-pack";
 
 #define COMPLETE       (1U << 0)
+#define COMMON         (1U << 1)
+#define COMMON_REF     (1U << 2 | COMMON)
+#define SEEN           (1U << 3)
+#define POPPED         (1U << 4)
+
+static struct commit_list *rev_list = NULL;
+static struct commit_list *rev_list_end = NULL;
+static unsigned long non_common_revs = 0;
+
+static void rev_list_append(struct commit *commit, int mark)
+{
+       if (!(commit->object.flags & mark)) {
+               commit->object.flags |= mark;
+
+               if (rev_list == NULL) {
+                       commit_list_insert(commit, &rev_list);
+                       rev_list_end = rev_list;
+               } else {
+                       commit_list_insert(commit, &(rev_list_end->next));
+                       rev_list_end = rev_list_end->next;
+               }
+
+               if (!(commit->object.flags & COMMON))
+                       non_common_revs++;
+       }
+}
+
+static int rev_list_append_sha1(const char *path, const unsigned char *sha1)
+{
+       struct object *o = deref_tag(parse_object(sha1));
+
+       if (o->type == commit_type)
+               rev_list_append((struct commit *)o, SEEN);
+
+       return 0;
+}
+
+static void mark_common(struct commit *commit)
+{
+       if (commit != NULL && !(commit->object.flags & COMMON)) {
+               struct object *o = (struct object *)commit;
+               o->flags |= COMMON;
+               if (!(o->flags & SEEN))
+                       rev_list_append(commit, SEEN);
+               else {
+                       struct commit_list *parents;
+
+                       if (!(o->flags & POPPED))
+                               non_common_revs--;
+                       if (!o->parsed)
+                               parse_commit(commit);
+                       for (parents = commit->parents;
+                                       parents;
+                                       parents = parents->next)
+                               mark_common(parents->item);
+               }
+       }
+}
+
+/*
+  Get the next rev to send, ignoring the common.
+*/
+
+static const unsigned char* get_rev()
+{
+       struct commit *commit = NULL;
+
+       while (commit == NULL) {
+               unsigned int mark;
+               struct commit_list* parents;
+
+               if (rev_list == NULL || non_common_revs == 0)
+                       return NULL;
+
+               commit = rev_list->item;
+               if (!(commit->object.parsed))
+                       parse_commit(commit);
+               commit->object.flags |= POPPED;
+               if (!(commit->object.flags & COMMON))
+                       non_common_revs--;
+       
+               parents = commit->parents;
+
+               if (commit->object.flags & COMMON) {
+                       /* do not send "have", and ignore ancestors */
+                       commit = NULL;
+                       mark = COMMON | SEEN;
+               } else if (commit->object.flags & COMMON_REF)
+                       /* send "have", and ignore ancestors */
+                       mark = COMMON | SEEN;
+               else
+                       /* send "have", also for its ancestors */
+                       mark = SEEN;
+
+               while (parents) {
+                       if (mark & COMMON)
+                               mark_common(parents->item);
+                       else
+                               rev_list_append(parents->item, mark);
+                       parents = parents->next;
+               }
+
+               rev_list = rev_list->next;
+       }
+
+       return commit->object.sha1;
+}
 
 static int find_common(int fd[2], unsigned char *result_sha1,
                       struct ref *refs)
 {
        int fetching;
-       static char line[1000];
-       static char rev_command[1024];
-       int count = 0, flushes = 0, retval, rev_command_len;
-       FILE *revs;
+       int count = 0, flushes = 0, retval;
+       const unsigned char *sha1;
+
+       for_each_ref(rev_list_append_sha1);
 
-       strcpy(rev_command, "git-rev-list $(git-rev-parse --all)");
-       rev_command_len = strlen(rev_command);
        fetching = 0;
        for ( ; refs ; refs = refs->next) {
                unsigned char *remote = refs->old_sha1;
@@ -42,25 +147,15 @@ static int find_common(int fd[2], unsigned char *result_sha1,
                 */
                if (((o = lookup_object(remote)) != NULL) &&
                    (o->flags & COMPLETE)) {
-                       struct commit_list *p;
-                       struct commit *commit =
-                               (struct commit *) (o = deref_tag(o));
-                       if (!o)
-                               goto repair;
-                       if (o->type != commit_type)
-                               continue;
-                       p = commit->parents;
-                       while (p &&
-                              rev_command_len + 44 < sizeof(rev_command)) {
-                               snprintf(rev_command + rev_command_len, 44,
-                                        " ^%s",
-                                        sha1_to_hex(p->item->object.sha1));
-                               rev_command_len += 43;
-                               p = p->next;
-                       }
+                       o = deref_tag(o);
+
+                       if (o->type == commit_type)
+                               rev_list_append((struct commit *)o,
+                                               COMMON_REF | SEEN);
+
                        continue;
                }
-       repair:
+
                packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
                fetching++;
        }
@@ -68,16 +163,9 @@ static int find_common(int fd[2], unsigned char *result_sha1,
        if (!fetching)
                return 1;
 
-       revs = popen(rev_command, "r");
-       if (!revs)
-               die("unable to run 'git-rev-list'");
-
        flushes = 1;
        retval = -1;
-       while (fgets(line, sizeof(line), revs) != NULL) {
-               unsigned char sha1[20];
-               if (get_sha1_hex(line, sha1))
-                       die("git-fetch-pack: expected object name, got crud");
+       while ((sha1 = get_rev())) {
                packet_write(fd[1], "have %s\n", sha1_to_hex(sha1));
                if (verbose)
                        fprintf(stderr, "have %s\n", sha1_to_hex(sha1));
@@ -101,7 +189,6 @@ static int find_common(int fd[2], unsigned char *result_sha1,
                        flushes--;
                }
        }
-       pclose(revs);
        packet_write(fd[1], "done\n");
        if (verbose)
                fprintf(stderr, "done\n");