diff options
authorDerrick Stolee <>2019-10-24 13:40:42 (GMT)
committerJunio C Hamano <>2019-10-25 02:19:16 (GMT)
commitcb99a34e23e32ca8e94bafaa9699cfd133a17fd3 (patch)
parente88aab917e0dc3e99af8fb0f3ecbef66ac3e49b6 (diff)
commit-graph: fix writing first commit-graph during fetch
The previous commit includes a failing test for an issue around fetch.writeCommitGraph and fetching in a repo with a submodule. Here, we fix that bug and set the test to "test_expect_success". The problem arises with this set of commands when the remote repo at <url> has a submodule. Note that --recurse-submodules is not needed to demonstrate the bug. $ git clone <url> test $ cd test $ git -c fetch.writeCommitGraph=true fetch origin Computing commit graph generation numbers: 100% (12/12), done. BUG: commit-graph.c:886: missing parent <hash1> for commit <hash2> Aborted (core dumped) As an initial fix, I converted the code in builtin/fetch.c that calls write_commit_graph_reachable() to instead launch a "git commit-graph write --reachable --split" process. That code worked, but is not how we want the feature to work long-term. That test did demonstrate that the issue must be something to do with internal state of the 'git fetch' process. The write_commit_graph() method in commit-graph.c ensures the commits we plan to write are "closed under reachability" using close_reachable(). This method walks from the input commits, and uses the UNINTERESTING flag to mark which commits have already been visited. This allows the walk to take O(N) time, where N is the number of commits, instead of O(P) time, where P is the number of paths. (The number of paths can be exponential in the number of commits.) However, the UNINTERESTING flag is used in lots of places in the codebase. This flag usually means some barrier to stop a commit walk, such as in revision-walking to compare histories. It is not often cleared after the walk completes because the starting points of those walks do not have the UNINTERESTING flag, and clear_commit_marks() would stop immediately. This is happening during a 'git fetch' call with a remote. The fetch negotiation is comparing the remote refs with the local refs and marking some commits as UNINTERESTING. I tested running clear_commit_marks_many() to clear the UNINTERESTING flag inside close_reachable(), but the tips did not have the flag, so that did nothing. It turns out that the calculate_changed_submodule_paths() method is at fault. Thanks, Peff, for pointing out this detail! More specifically, for each submodule, the collect_changed_submodules() runs a revision walk to essentially do file-history on the list of submodules. That revision walk marks commits UNININTERESTING if they are simplified away by not changing the submodule. Instead, I finally arrived on the conclusion that I should use a flag that is not used in any other part of the code. In commit-reach.c, a number of flags were defined for commit walk algorithms. The REACHABLE flag seemed like it made the most sense, and it seems it was not actually used in the file. The REACHABLE flag was used in early versions of commit-reach.c, but was removed by 4fbcca4 (commit-reach: make can_all_from_reach... linear, 2018-07-20). Add the REACHABLE flag to commit-graph.c and use it instead of UNINTERESTING in close_reachable(). This fixes the bug in manual testing. Reported-by: Johannes Schindelin <> Helped-by: Jeff King <> Helped-by: Szeder Gábor <> Signed-off-by: Derrick Stolee <> Signed-off-by: Junio C Hamano <>
4 files changed, 10 insertions, 7 deletions
diff --git a/commit-graph.c b/commit-graph.c
index 7854e49..a23b9d9 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -41,6 +41,9 @@
+ GRAPH_FANOUT_SIZE + the_hash_algo->rawsz)
+/* Remember to update object flag allocation in object.h */
+#define REACHABLE (1u<<15)
char *get_commit_graph_filename(const char *obj_dir)
char *filename = xstrfmt("%s/info/commit-graph", obj_dir);
@@ -1014,11 +1017,11 @@ static void add_missing_parents(struct write_commit_graph_context *ctx, struct c
struct commit_list *parent;
for (parent = commit->parents; parent; parent = parent->next) {
- if (!(parent->item->object.flags & UNINTERESTING)) {
+ if (!(parent->item->object.flags & REACHABLE)) {
ALLOC_GROW(ctx->oids.list, ctx-> + 1, ctx->oids.alloc);
oidcpy(&ctx->oids.list[ctx->], &(parent->item->object.oid));
- parent->item->object.flags |= UNINTERESTING;
+ parent->item->object.flags |= REACHABLE;
@@ -1036,7 +1039,7 @@ static void close_reachable(struct write_commit_graph_context *ctx)
display_progress(ctx->progress, i + 1);
commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
if (commit)
- commit->object.flags |= UNINTERESTING;
+ commit->object.flags |= REACHABLE;
@@ -1073,7 +1076,7 @@ static void close_reachable(struct write_commit_graph_context *ctx)
commit = lookup_commit(ctx->r, &ctx->oids.list[i]);
if (commit)
- commit->object.flags &= ~UNINTERESTING;
+ commit->object.flags &= ~REACHABLE;
diff --git a/commit-reach.c b/commit-reach.c
index 3ea1747..4ca7e70 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -10,7 +10,6 @@
#include "commit-reach.h"
/* Remember to update object flag allocation in object.h */
-#define REACHABLE (1u<<15)
#define PARENT1 (1u<<16)
#define PARENT2 (1u<<17)
#define STALE (1u<<18)
diff --git a/object.h b/object.h
index 0120892..25f5ab3 100644
--- a/object.h
+++ b/object.h
@@ -68,7 +68,8 @@ struct object_array {
* bisect.c: 16
* bundle.c: 16
* http-push.c: 16-----19
- * commit-reach.c: 15-------19
+ * commit-graph.c: 15
+ * commit-reach.c: 16-----19
* sha1-name.c: 20
* list-objects-filter.c: 21
* builtin/fsck.c: 0--3
diff --git a/t/ b/t/
index 404e900..8248923 100755
--- a/t/
+++ b/t/
@@ -583,7 +583,7 @@ test_expect_success 'fetch.writeCommitGraph' '
-test_expect_failure 'fetch.writeCommitGraph with submodules' '
+test_expect_success 'fetch.writeCommitGraph with submodules' '
git clone dups super &&
cd super &&