commit-graph.c: show progress of finding reachable commits

When 'git commit-graph write --reachable' is invoked, the commit-graph
machinery calls 'for_each_ref()' to discover the set of reachable
commits.

Right now the 'add_ref_to_set' callback is not doing anything other than
adding an OID to the set of known-reachable OIDs. In a subsequent
commit, 'add_ref_to_set' will presumptively peel references. This
operation should be fast for repositories with an up-to-date
'$GIT_DIR/packed-refs', but may be slow in the general case.

So that it doesn't appear that 'git commit-graph write' is idling with
'--reachable' in the slow case, add a progress meter to provide some
output in the meantime.

In general, we don't expect a progress meter to appear at all, since
peeling references with a 'packed-refs' file is quick. If it's slow and
we do show a progress meter, the subsequent 'fill_oids_from_commits()'
will be fast, since all of the calls to
'lookup_commit_reference_gently()' will be no-ops.

Both progress meters are delayed, so it is unlikely that more than one
will appear. In either case, this intermediate state will go away in a
handful of patches, at which point there will be at most one progress
meter.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/commit-graph.c b/commit-graph.c
index 00da281f390eba0a73bb6a08221b039d3c242af8..bd421c4f06381f7effc53dd9548c7d792a523d38 100644 (file)
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1320,6 +1320,7 @@ static void compute_bloom_filters(struct write_commit_graph_context *ctx)
 
 struct refs_cb_data {
        struct oidset *commits;
+       struct progress *progress;
 };
 
 static int add_ref_to_set(const char *refname,
@@ -1329,6 +1330,9 @@ static int add_ref_to_set(const char *refname,
        struct refs_cb_data *data = (struct refs_cb_data *)cb_data;
 
        oidset_insert(data->commits, oid);
+
+       display_progress(data->progress, oidset_size(data->commits));
+
        return 0;
 }
 
@@ -1342,12 +1346,17 @@ int write_commit_graph_reachable(struct object_directory *odb,
 
        memset(&data, 0, sizeof(data));
        data.commits = &commits;
+       if (flags & COMMIT_GRAPH_WRITE_PROGRESS)
+               data.progress = start_delayed_progress(
+                       _("Collecting referenced commits"), 0);
 
        for_each_ref(add_ref_to_set, &data);
        result = write_commit_graph(odb, NULL, &commits,
                                    flags, split_opts);
 
        oidset_clear(&commits);
+       if (data.progress)
+               stop_progress(&data.progress);
        return result;
 }