builtin/repo: find tree with most entries

The size of a tree object usually corresponds with the number of entries
it has. While iterating through objects in the repository for
git-repo-structure, identify the tree with the most entries and display
it in the output.

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

Author: jltobler

builtin/repo.c

@@ -16,6 +16,8 @@
 #include "strbuf.h"
 #include "string-list.h"
 #include "shallow.h"
+#include "tree.h"
+#include "tree-walk.h"
 #include "utf8.h"
 
 static const char *const repo_usage[] = {
@@ -211,6 +213,7 @@ struct largest_objects {
 	struct object_data blob_size;
 
 	struct object_data parent_count;
+	struct object_data tree_entries;
 };
 
 struct ref_stats {
@@ -458,6 +461,10 @@ static void stats_table_setup_structure(struct stats_table *table,
 				     &objects->largest.tree_size.oid,
 				     objects->largest.tree_size.value,
 				     "    * %s", _("Maximum size"));
+	stats_table_object_count_addf(table,
+				      &objects->largest.tree_entries.oid,
+				      objects->largest.tree_entries.value,
+				      "    * %s", _("Maximum entries"));
 	stats_table_addf(table, "  * %s", _("Blobs"));
 	stats_table_object_size_addf(table,
 				     &objects->largest.blob_size.oid,
@@ -619,6 +626,10 @@ static void structure_keyvalue_print(struct repo_structure *stats,
 	       (uintmax_t)stats->objects.largest.parent_count.value, value_delim);
 	printf("objects.commits.max_parents_oid%c%s%c", key_delim,
 	       oid_to_hex(&stats->objects.largest.parent_count.oid), value_delim);
+	printf("objects.trees.max_entries%c%" PRIuMAX "%c", key_delim,
+	       (uintmax_t)stats->objects.largest.tree_entries.value, value_delim);
+	printf("objects.trees.max_entries_oid%c%s%c", key_delim,
+	       oid_to_hex(&stats->objects.largest.tree_entries.oid), value_delim);
 
 	fflush(stdout);
 }
@@ -697,6 +708,20 @@ static void check_largest(struct object_data *data, struct object_id *oid,
 	}
 }
 
+static size_t count_tree_entries(struct object *obj)
+{
+	struct tree *t = object_as_type(obj, OBJ_TREE, 0);
+	struct name_entry entry;
+	struct tree_desc desc;
+	size_t count = 0;
+
+	init_tree_desc(&desc, &t->object.oid, t->buffer, t->size);
+	while (tree_entry(&desc, &entry))
+		count++;
+
+	return count;
+}
+
 static int count_objects(const char *path UNUSED, struct oid_array *oids,
 			 enum object_type type, void *cb_data)
 {
@@ -749,6 +774,8 @@ static int count_objects(const char *path UNUSED, struct oid_array *oids,
 			stats->disk_sizes.trees += disk;
 			check_largest(&stats->largest.tree_size, &oids->oid[i],
 				      inflated);
+			check_largest(&stats->largest.tree_entries, &oids->oid[i],
+				      count_tree_entries(obj));
 			break;
 		case OBJ_BLOB:
 			stats->type_counts.blobs++;

t/t1901-repo-structure.sh

@@ -59,6 +59,7 @@ test_expect_success 'empty repository' '
 		|     * Maximum parents     |    0   |
 		|   * Trees                 |        |
 		|     * Maximum size        |    0 B |
+		|     * Maximum entries     |    0   |
 		|   * Blobs                 |        |
 		|     * Maximum size        |    0 B |
 		|   * Tags                  |        |
@@ -122,16 +123,18 @@ test_expect_success SHA1 'repository with references and objects' '
 		|     * Maximum parents [2] |      1     |
 		|   * Trees                 |            |
 		|     * Maximum size    [3] |  32.29 KiB |
+		|     * Maximum entries [4] |   1.01 k   |
 		|   * Blobs                 |            |
-		|     * Maximum size    [4] |     13 B   |
+		|     * Maximum size    [5] |     13 B   |
 		|   * Tags                  |            |
-		|     * Maximum size    [5] |    132 B   |
+		|     * Maximum size    [6] |    132 B   |
 
 		[1] 0dc91eb18580102a3a216c8bfecedeba2b9f9b9a
 		[2] 0dc91eb18580102a3a216c8bfecedeba2b9f9b9a
 		[3] 60665251ab71dbd8c18d9bf2174f4ee0d58aa06c
-		[4] 97d808e45116bf02103490294d3d46dad7a2ac62
-		[5] 4dae4f5954f5e6feb3577cfb1b181daa3fd3afd2
+		[4] 60665251ab71dbd8c18d9bf2174f4ee0d58aa06c
+		[5] 97d808e45116bf02103490294d3d46dad7a2ac62
+		[6] 4dae4f5954f5e6feb3577cfb1b181daa3fd3afd2
 		EOF
 
 		git repo structure >out 2>err &&
@@ -176,6 +179,8 @@ test_expect_success SHA1 'keyvalue and nul format' '
 		objects.tags.max_size_oid=1ee0f2b16ea37d895dbe9dbd76cd2ac70446176c
 		objects.commits.max_parents=1
 		objects.commits.max_parents_oid=de3508174b5c2ace6993da67cae9be9069e2df39
+		objects.trees.max_entries=42
+		objects.trees.max_entries_oid=09931deea9d81ec21300d3e13c74412f32eacec5
 		EOF
 
 		git repo structure --format=keyvalue >out 2>err &&