builtin/repo: add object counts in structure output

The amount of objects in a repository can provide insight regarding its
shape. To surface this information, use the path-walk API to count the
number of reachable objects in the repository by object type. All
regular references are used to determine the reachable set of objects.
The object counts are appended to the same table containing the
reference information.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: jltobler

Documentation/git-repo.adoc

@@ -49,6 +49,7 @@ supported:
 	following kinds of information are reported:
 +
 * Reference counts categorized by type
+* Reachable object counts categorized by type
 
 +
 The table output format may change and is not intended for machine parsing.

builtin/repo.c

@@ -3,9 +3,11 @@
 #include "builtin.h"
 #include "environment.h"
 #include "parse-options.h"
+#include "path-walk.h"
 #include "quote.h"
 #include "ref-filter.h"
 #include "refs.h"
+#include "revision.h"
 #include "strbuf.h"
 #include "string-list.h"
 #include "shallow.h"
@@ -167,6 +169,18 @@ struct ref_stats {
 	size_t others;
 };
 
+struct object_stats {
+	size_t tags;
+	size_t commits;
+	size_t trees;
+	size_t blobs;
+};
+
+struct repo_structure {
+	struct ref_stats refs;
+	struct object_stats objects;
+};
+
 struct stats_table {
 	struct string_list rows;
 
@@ -234,9 +248,17 @@ static inline size_t get_total_reference_count(struct ref_stats *stats)
 	return stats->branches + stats->remotes + stats->tags + stats->others;
 }
 
+static inline size_t get_total_object_count(struct object_stats *stats)
+{
+	return stats->tags + stats->commits + stats->trees + stats->blobs;
+}
+
 static void stats_table_setup_structure(struct stats_table *table,
-					struct ref_stats *refs)
+					struct repo_structure *stats)
 {
+	struct object_stats *objects = &stats->objects;
+	struct ref_stats *refs = &stats->refs;
+	size_t object_total;
 	size_t ref_total;
 
 	ref_total = get_total_reference_count(refs);
@@ -246,6 +268,15 @@ static void stats_table_setup_structure(struct stats_table *table,
 	stats_table_count_addf(table, refs->tags, "    * %s", _("Tags"));
 	stats_table_count_addf(table, refs->remotes, "    * %s", _("Remotes"));
 	stats_table_count_addf(table, refs->others, "    * %s", _("Others"));
+
+	object_total = get_total_object_count(objects);
+	stats_table_addf(table, "");
+	stats_table_addf(table, "* %s", _("Reachable objects"));
+	stats_table_count_addf(table, object_total, "  * %s", _("Count"));
+	stats_table_count_addf(table, objects->commits, "    * %s", _("Commits"));
+	stats_table_count_addf(table, objects->trees, "    * %s", _("Trees"));
+	stats_table_count_addf(table, objects->blobs, "    * %s", _("Blobs"));
+	stats_table_count_addf(table, objects->tags, "    * %s", _("Tags"));
 }
 
 static void stats_table_print_structure(const struct stats_table *table)
@@ -299,12 +330,18 @@ static void stats_table_clear(struct stats_table *table)
 	string_list_clear(&table->rows, 1);
 }
 
+struct count_references_data {
+	struct ref_stats *stats;
+	struct rev_info *revs;
+};
+
 static int count_references(const char *refname,
 			    const char *referent UNUSED,
-			    const struct object_id *oid UNUSED,
+			    const struct object_id *oid,
 			    int flags UNUSED, void *cb_data)
 {
-	struct ref_stats *stats = cb_data;
+	struct count_references_data *data = cb_data;
+	struct ref_stats *stats = data->stats;
 
 	switch (ref_kind_from_refname(refname)) {
 	case FILTER_REFS_BRANCHES:
@@ -323,13 +360,64 @@ static int count_references(const char *refname,
 		BUG("unexpected reference type");
 	}
 
+	/*
+	 * While iterating through references for counting, also add OIDs in
+	 * preparation for the path walk.
+	 */
+	add_pending_oid(data->revs, NULL, oid, 0);
+
 	return 0;
 }
 
 static void structure_count_references(struct ref_stats *stats,
+				       struct rev_info *revs,
 				       struct repository *repo)
 {
-	refs_for_each_ref(get_main_ref_store(repo), count_references, &stats);
+	struct count_references_data data = {
+		.stats = stats,
+		.revs = revs,
+	};
+
+	refs_for_each_ref(get_main_ref_store(repo), count_references, &data);
+}
+
+
+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;
+
+	switch (type) {
+	case OBJ_TAG:
+		stats->tags += oids->nr;
+		break;
+	case OBJ_COMMIT:
+		stats->commits += oids->nr;
+		break;
+	case OBJ_TREE:
+		stats->trees += oids->nr;
+		break;
+	case OBJ_BLOB:
+		stats->blobs += oids->nr;
+		break;
+	default:
+		BUG("invalid object type");
+	}
+
+	return 0;
+}
+
+static void structure_count_objects(struct object_stats *stats,
+				    struct rev_info *revs)
+{
+	struct path_walk_info info = PATH_WALK_INFO_INIT;
+
+	info.revs = revs;
+	info.path_fn = count_objects;
+	info.path_fn_data = stats;
+
+	walk_objects_by_path(&info);
+	path_walk_info_clear(&info);
 }
 
 static int cmd_repo_structure(int argc, const char **argv, const char *prefix,
@@ -338,19 +426,24 @@ static int cmd_repo_structure(int argc, const char **argv, const char *prefix,
 	struct stats_table table = {
 		.rows = STRING_LIST_INIT_DUP,
 	};
-	struct ref_stats stats = { 0 };
+	struct repo_structure stats = { 0 };
+	struct rev_info revs;
 	struct option options[] = { 0 };
 
 	argc = parse_options(argc, argv, prefix, options, repo_usage, 0);
 	if (argc)
 		usage(_("too many arguments"));
 
-	structure_count_references(&stats, repo);
+	repo_init_revisions(repo, &revs, prefix);
+
+	structure_count_references(&stats.refs, &revs, repo);
+	structure_count_objects(&stats.objects, &revs);
 
 	stats_table_setup_structure(&table, &stats);
 	stats_table_print_structure(&table);
 
 	stats_table_clear(&table);
+	release_revisions(&revs);
 
 	return 0;
 }

t/t1901-repo-structure.sh

@@ -18,6 +18,13 @@ test_expect_success 'empty repository' '
 		|     * Tags           |     0 |
 		|     * Remotes        |     0 |
 		|     * Others         |     0 |
+		|                      |       |
+		| * Reachable objects  |       |
+		|   * Count            |     0 |
+		|     * Commits        |     0 |
+		|     * Trees          |     0 |
+		|     * Blobs          |     0 |
+		|     * Tags           |     0 |
 		EOF
 
 		git repo structure >out 2>err &&
@@ -27,17 +34,18 @@ test_expect_success 'empty repository' '
 	)
 '
 
-test_expect_success 'repository with references' '
+test_expect_success 'repository with references and objects' '
 	test_when_finished "rm -rf repo" &&
 	git init repo &&
 	(
 		cd repo &&
-		git commit --allow-empty -m init &&
+		test_commit_bulk 42 &&
 		git tag -a foo -m bar &&
 
 		oid="$(git rev-parse HEAD)" &&
 		git update-ref refs/remotes/origin/foo "$oid" &&
 
+		# Also creates a commit, tree, and blob.
 		git notes add -m foo &&
 
 		cat >expect <<-\EOF &&
@@ -49,6 +57,13 @@ test_expect_success 'repository with references' '
 		|     * Tags           |     1 |
 		|     * Remotes        |     1 |
 		|     * Others         |     1 |
+		|                      |       |
+		| * Reachable objects  |       |
+		|   * Count            |   130 |
+		|     * Commits        |    43 |
+		|     * Trees          |    43 |
+		|     * Blobs          |    43 |
+		|     * Tags           |     1 |
 		EOF
 
 		git repo structure >out 2>err &&