[PATCH v3 7/7] builtin/repo: add progress meter for stats

[Justin Tobler <jltobler@gmail.com>]

When using the stats subcommand for git-repo(1), evaluating a repository
may take some time depending on its shape. Add a progress meter to
provide feedback to the user about what is happening. The progress meter
is enabled by default when the command is executed from a tty. It can
also be explicitly enabled/disabled via the --[no-]progress option.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
---
 builtin/repo.c        | 47 +++++++++++++++++++++++++++++++++++++------
 t/t1901-repo-stats.sh | 20 ++++++++++++++++++
 2 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/builtin/repo.c b/builtin/repo.c
index e8a02c950b..e553d7aa28 100644
--- a/builtin/repo.c
+++ b/builtin/repo.c
@@ -4,6 +4,7 @@
 #include "environment.h"
 #include "parse-options.h"
 #include "path-walk.h"
+#include "progress.h"
 #include "quote.h"
 #include "ref-filter.h"
 #include "refs.h"
@@ -358,8 +359,15 @@ static void stats_keyvalue_print(struct repo_stats *stats, char key_delim,
 	fflush(stdout);
 }
 
-static void stats_count_references(struct ref_stats *stats, struct ref_array *refs)
+static void stats_count_references(struct ref_stats *stats, struct ref_array *refs,
+				   struct repository *repo, int show_progress)
 {
+	struct progress *progress = NULL;
+
+	if (show_progress)
+		progress = start_delayed_progress(repo, _("Counting references"),
+						  refs->nr);
+
 	for (int i = 0; i < refs->nr; i++) {
 		struct ref_array_item *ref = refs->items[i];
 
@@ -379,13 +387,24 @@ static void stats_count_references(struct ref_stats *stats, struct ref_array *re
 		default:
 			BUG("unexpected reference type");
 		}
+
+		display_progress(progress, i + 1);
 	}
+
+	stop_progress(&progress);
 }
 
+struct count_objects_data {
+	struct object_stats *stats;
+	struct progress *progress;
+};
+
 static int count_objects(const char *path UNUSED, struct oid_array *oids,
 			 enum object_type type, void *cb_data)
 {
-	struct object_stats *stats = cb_data;
+	struct count_objects_data *data = cb_data;
+	struct object_stats *stats = data->stats;
+	size_t object_count;
 
 	switch (type) {
 	case OBJ_TAG:
@@ -404,17 +423,24 @@ static int count_objects(const char *path UNUSED, struct oid_array *oids,
 		BUG("invalid object type");
 	}
 
+	object_count = get_total_object_count(stats);
+	display_progress(data->progress, object_count);
+
 	return 0;
 }
 
 static void stats_count_objects(struct object_stats *stats,
-				struct ref_array *refs, struct rev_info *revs)
+				struct ref_array *refs, struct rev_info *revs,
+				struct repository *repo, int show_progress)
 {
 	struct path_walk_info info = PATH_WALK_INFO_INIT;
+	struct count_objects_data data = {
+		.stats = stats,
+	};
 
 	info.revs = revs;
 	info.path_fn = count_objects;
-	info.path_fn_data = stats;
+	info.path_fn_data = &data;
 
 	for (int i = 0; i < refs->nr; i++) {
 		struct ref_array_item *ref = refs->items[i];
@@ -431,8 +457,12 @@ static void stats_count_objects(struct object_stats *stats,
 		}
 	}
 
+	if (show_progress)
+		data.progress = start_delayed_progress(repo, _("Counting objects"), 0);
+
 	walk_objects_by_path(&info);
 	path_walk_info_clear(&info);
+	stop_progress(&data.progress);
 }
 
 static int cmd_repo_stats(int argc, const char **argv, const char *prefix,
@@ -446,10 +476,12 @@ static int cmd_repo_stats(int argc, const char **argv, const char *prefix,
 	struct repo_stats stats = { 0 };
 	struct ref_array refs = { 0 };
 	struct rev_info revs;
+	int show_progress = -1;
 	struct option options[] = {
 		OPT_CALLBACK_F(0, "format", &format, N_("format"),
 			       N_("output format"),
 			       PARSE_OPT_NONEG, parse_format_cb),
+		OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
 		OPT_END()
 	};
 
@@ -461,8 +493,11 @@ static int cmd_repo_stats(int argc, const char **argv, const char *prefix,
 	if (filter_refs(&refs, &filter, FILTER_REFS_REGULAR))
 		die(_("unable to filter refs"));
 
-	stats_count_references(&stats.refs, &refs);
-	stats_count_objects(&stats.objects, &refs, &revs);
+	if (show_progress < 0)
+		show_progress = isatty(2);
+
+	stats_count_references(&stats.refs, &refs, repo, show_progress);
+	stats_count_objects(&stats.objects, &refs, &revs, repo, show_progress);
 
 	switch (format) {
 	case FORMAT_TABLE:
diff --git a/t/t1901-repo-stats.sh b/t/t1901-repo-stats.sh
index 2409edae4f..03d6db479f 100755
--- a/t/t1901-repo-stats.sh
+++ b/t/t1901-repo-stats.sh
@@ -106,4 +106,24 @@ test_expect_success 'keyvalue and nul format' '
 	)
 '
 
+test_expect_success 'progress meter option' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit foo &&
+
+		GIT_PROGRESS_DELAY=0 git repo stats --progress >out 2>err &&
+
+		test_file_not_empty out &&
+		test_grep "Counting references: 100% (2/2), done." err &&
+		test_grep "Counting objects: 3, done." err &&
+
+		GIT_PROGRESS_DELAY=0 git repo stats --no-progress >out 2>err &&
+
+		test_file_not_empty out &&
+		test_line_count = 0 err
+	)
+'
+
 test_done
-- 
2.51.0.193.g4975ec3473b