commit-graph: close under reachability

Teach write_commit_graph() to walk all parents from the commits
discovered in packfiles. This prevents gaps given by loose objects or
previously-missed packfiles.

Also automatically add commits from the existing graph file, if it
exists.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit-graph.c b/commit-graph.c
index b1bd3a892d8992d9e0825ac5efcc9e542741ee8b..ea29c5c2d86ae69f7ea0a5ac1a5fb4dfafec9660 100644 (file)
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -367,6 +367,50 @@ static int add_packed_commits(const struct object_id *oid,
        return 0;
 }
 
+static void add_missing_parents(struct packed_oid_list *oids, struct commit *commit)
+{
+       struct commit_list *parent;
+       for (parent = commit->parents; parent; parent = parent->next) {
+               if (!(parent->item->object.flags & UNINTERESTING)) {
+                       ALLOC_GROW(oids->list, oids->nr + 1, oids->alloc);
+                       oidcpy(&oids->list[oids->nr], &(parent->item->object.oid));
+                       oids->nr++;
+                       parent->item->object.flags |= UNINTERESTING;
+               }
+       }
+}
+
+static void close_reachable(struct packed_oid_list *oids)
+{
+       int i;
+       struct commit *commit;
+
+       for (i = 0; i < oids->nr; i++) {
+               commit = lookup_commit(&oids->list[i]);
+               if (commit)
+                       commit->object.flags |= UNINTERESTING;
+       }
+
+       /*
+        * As this loop runs, oids->nr may grow, but not more
+        * than the number of missing commits in the reachable
+        * closure.
+        */
+       for (i = 0; i < oids->nr; i++) {
+               commit = lookup_commit(&oids->list[i]);
+
+               if (commit && !parse_commit(commit))
+                       add_missing_parents(oids, commit);
+       }
+
+       for (i = 0; i < oids->nr; i++) {
+               commit = lookup_commit(&oids->list[i]);
+
+               if (commit)
+                       commit->object.flags &= ~UNINTERESTING;
+       }
+}
+
 void write_commit_graph(const char *obj_dir)
 {
        struct packed_oid_list oids;
@@ -390,6 +434,7 @@ void write_commit_graph(const char *obj_dir)
        ALLOC_ARRAY(oids.list, oids.alloc);
 
        for_each_packed_object(add_packed_commits, &oids, 0);
+       close_reachable(&oids);
 
        QSORT(oids.list, oids.nr, commit_compare);