commit-graph: allow cross-alternate chains
In an environment like a fork network, it is helpful to have a
commit-graph chain that spans both the base repo and the fork repo. The
fork is usually a small set of data on top of the large repo, but
sometimes the fork is much larger. For example, git-for-windows/git has
almost double the number of commits as git/git because it rebases its
commits on every major version update.
To allow cross-alternate commit-graph chains, we need a few pieces:
1. When looking for a graph-{hash}.graph file, check all alternates.
2. When merging commit-graph chains, do not merge across alternates.
3. When writing a new commit-graph chain based on a commit-graph file
in another object directory, do not allow success if the base file
has of the name "commit-graph" instead of
"commit-graphs/graph-{hash}.graph".
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/commit-graph.h b/commit-graph.h
index c321834..802d352 100644
--- a/commit-graph.h
+++ b/commit-graph.h
@@ -48,6 +48,7 @@ struct commit_graph {
uint32_t num_commits;
struct object_id oid;
char *filename;
+ const char *obj_dir;
uint32_t num_commits_in_base;
struct commit_graph *base_graph;
