commit-graph.c: avoid duplicated progress output during verify

When `git commit-graph verify` was taught how to verify commit-graph
chains in 3da4b60 (commit-graph: verify chains with --shallow mode,
2019-06-18), it produced one line of progress per layer of the
commit-graph chain.

    $ git.compile commit-graph verify
    Verifying commits in commit graph: 100% (4356/4356), done.
    Verifying commits in commit graph: 100% (131912/131912), done.

This could be somewhat confusing to users, who may wonder why there are
multiple occurrences of "Verifying commits in commit graph".

There are likely good arguments on whether or not there should be
one line of progress output per commit-graph layer. On the one hand, the
existing output shows us verifying each individual layer of the chain.
But on the other hand, the fact that a commit-graph may be stored among
multiple layers is an implementation detail that the caller need not be
aware of.

Clarify this by showing a single progress meter regardless of the number
of layers in the commit-graph chain. After this patch, the output
reflects the logical contents of a commit-graph chain, instead of
showing one line of output per commit-graph layer:

    $ git.compile commit-graph verify
    Verifying commits in commit graph: 100% (136268/136268), done.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Acked-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: ttaylorr

commit-graph.c

@@ -2545,7 +2545,8 @@ static int commit_graph_checksum_valid(struct commit_graph *g)
 
 static int verify_one_commit_graph(struct repository *r,
 				   struct commit_graph *g,
-				   struct progress *progress)
+				   struct progress *progress,
+				   uint64_t *seen)
 {
 	uint32_t i, cur_fanout_pos = 0;
 	struct object_id prev_oid, cur_oid;
@@ -2606,7 +2607,7 @@ static int verify_one_commit_graph(struct repository *r,
 		timestamp_t max_generation = 0;
 		timestamp_t generation;
 
-		display_progress(progress, i + 1);
+		display_progress(progress, ++(*seen));
 		oidread(&cur_oid, g->chunk_oid_lookup + g->hash_len * i);
 
 		graph_commit = lookup_commit(r, &cur_oid);
@@ -2695,26 +2696,32 @@ static int verify_one_commit_graph(struct repository *r,
 
 int verify_commit_graph(struct repository *r, struct commit_graph *g, int flags)
 {
+	struct progress *progress = NULL;
 	int local_error = 0;
+	uint64_t seen = 0;
 
 	if (!g) {
 		graph_report("no commit-graph file loaded");
 		return 1;
 	}
 
-	for (; g; g = g->base_graph) {
-		struct progress *progress = NULL;
-		if (flags & COMMIT_GRAPH_WRITE_PROGRESS)
-			progress = start_progress(_("Verifying commits in commit graph"),
-						g->num_commits);
+	if (flags & COMMIT_GRAPH_WRITE_PROGRESS) {
+		uint64_t total = g->num_commits;
+		if (!(flags & COMMIT_GRAPH_VERIFY_SHALLOW))
+			total += g->num_commits_in_base;
+
+		progress = start_progress(_("Verifying commits in commit graph"),
+					  total);
+	}
 
-		local_error |= verify_one_commit_graph(r, g, progress);
+	for (; g; g = g->base_graph) {
+		local_error |= verify_one_commit_graph(r, g, progress, &seen);
 		if (flags & COMMIT_GRAPH_VERIFY_SHALLOW)
 			break;
-
-		stop_progress(&progress);
 	}
 
+	stop_progress(&progress);
+
 	return local_error;
 }
 

t/t5324-split-commit-graph.sh

@@ -351,7 +351,8 @@ test_expect_success 'add octopus merge' '
 	git branch merge/octopus &&
 	git commit-graph write --reachable --split &&
 	git commit-graph verify --progress 2>err &&
-	test_line_count = 3 err &&
+	test_line_count = 1 err &&
+	grep "Verifying commits in commit graph: 100% (18/18)" err &&
 	test_i18ngrep ! warning err &&
 	test_line_count = 3 $graphdir/commit-graph-chain
 '