commit-graph verify: add progress output

For the reasons explained in the "commit-graph write: add progress
output" commit leading up to this one, emit progress on "commit-graph
verify". Since e0fd51e ("fsck: verify commit-graph", 2018-06-27)
"git fsck" has called this command if core.commitGraph=true, but
there's been no progress output to indicate that anything was
different. Now there is (on my tiny dotfiles.git repository):

    $ git -c core.commitGraph=true -C ~/ fsck
    Checking object directories: 100% (256/256), done.
    Checking objects: 100% (2821/2821), done.
    dangling blob 5b8bbdb9b788ed90459f505b0934619c17cc605b
    Verifying commits in commit graph: 100% (867/867), done.

And on a larger repository, such as the 2015-04-03-1M-git.git test
repository:

    $ time git -c core.commitGraph=true -C ~/g/2015-04-03-1M-git/ commit-graph verify
    Verifying commits in commit graph: 100% (1000447/1000447), done.
    real    0m7.813s
    [...]

Since the "commit-graph verify" subcommand is never called from "git
gc", we don't have to worry about passing some some "report_progress"
progress variable around for this codepath.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

commit-graph.c

@@ -922,6 +922,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
 	int generation_zero = 0;
 	struct hashfile *f;
 	int devnull;
+	struct progress *progress = NULL;
 
 	if (!g) {
 		graph_report("no commit-graph file loaded");
@@ -989,11 +990,14 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
 	if (verify_commit_graph_error & ~VERIFY_COMMIT_GRAPH_ERROR_HASH)
 		return verify_commit_graph_error;
 
+	progress = start_progress(_("Verifying commits in commit graph"),
+				  g->num_commits);
 	for (i = 0; i < g->num_commits; i++) {
 		struct commit *graph_commit, *odb_commit;
 		struct commit_list *graph_parents, *odb_parents;
 		uint32_t max_generation = 0;
 
+		display_progress(progress, i + 1);
 		hashcpy(cur_oid.hash, g->chunk_oid_lookup + g->hash_len * i);
 
 		graph_commit = lookup_commit(r, &cur_oid);
@@ -1070,6 +1074,7 @@ int verify_commit_graph(struct repository *r, struct commit_graph *g)
 				     graph_commit->date,
 				     odb_commit->date);
 	}
+	stop_progress(&progress);
 
 	return verify_commit_graph_error;
 }