commit-graph: split up close_reachable() progress output

Amend the progress output added in 7b0f229222 ("commit-graph write:
add progress output", 2018-09-17) so that the total numbers it reports
aren't higher than the total number of commits anymore. See [1] for a
bug report pointing that out.

When I added this I wasn't intending to provide an accurate count, but
just have some progress output to show the user the command wasn't
hanging[2]. But since we are showing numbers, let's make them
accurate. The progress descriptions were suggested by Derrick Stolee
in [3].

As noted in [2] we are unlikely to show anything except the "Expanding
reachable..." message even on fairly large repositories such as
linux.git. On a test repository I have with north of 7 million commits
all of these are displayed. Two of them don't show up for long, but as
noted in [5] future-proofing this for if the loops become more
expensive in the future makes sense.

1. https://public-inbox.org/git/20181010203738.GE23446@szeder.dev/
2. https://public-inbox.org/git/87pnwhea8y.fsf@evledraar.gmail.com/
3. https://public-inbox.org/git/f7a0cbee-863c-61d3-4959-5cec8b43c705@gmail.com/
4. https://public-inbox.org/git/20181015160545.GG19800@szeder.dev/
5. https://public-inbox.org/git/87murle8da.fsf@evledraar.gmail.com/

Reported-by: SZEDER Gábor <szeder.dev@gmail.com>
Helped-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/commit-graph.c b/commit-graph.c
index 2a24eb8..7f3bb93 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -595,26 +595,29 @@ static void add_missing_parents(struct packed_oid_list *oids, struct commit *com
 
 static void close_reachable(struct packed_oid_list *oids, int report_progress)
 {
-	int i;
+	int i, j;
 	struct commit *commit;
 	struct progress *progress = NULL;
-	int j = 0;
 
 	if (report_progress)
 		progress = start_delayed_progress(
-			_("Annotating commits in commit graph"), 0);
+			_("Loading known commits in commit graph"), j = 0);
 	for (i = 0; i < oids->nr; i++) {
 		display_progress(progress, ++j);
 		commit = lookup_commit(the_repository, &oids->list[i]);
 		if (commit)
 			commit->object.flags |= UNINTERESTING;
 	}
+	stop_progress(&progress);
 
 	/*
 	 * As this loop runs, oids->nr may grow, but not more
 	 * than the number of missing commits in the reachable
 	 * closure.
 	 */
+	if (report_progress)
+		progress = start_delayed_progress(
+			_("Expanding reachable commits in commit graph"), j = 0);
 	for (i = 0; i < oids->nr; i++) {
 		display_progress(progress, ++j);
 		commit = lookup_commit(the_repository, &oids->list[i]);
@@ -622,7 +625,11 @@ static void close_reachable(struct packed_oid_list *oids, int report_progress)
 		if (commit && !parse_commit(commit))
 			add_missing_parents(oids, commit);
 	}
+	stop_progress(&progress);
 
+	if (report_progress)
+		progress = start_delayed_progress(
+			_("Clearing commit marks in commit graph"), j = 0);
 	for (i = 0; i < oids->nr; i++) {
 		display_progress(progress, ++j);
 		commit = lookup_commit(the_repository, &oids->list[i]);