commit-graph: refactor preparing commit graph

Two functions in the code (1) check if the repository is configured for
commit graphs, (2) call prepare_commit_graph(), and (3) check if the
graph exists. Move (1) and (3) into prepare_commit_graph(), reducing
duplication of code.

Signed-off-by: Jonathan Tan <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: jonathantanmy

commit-graph.c

@@ -200,22 +200,33 @@ static void prepare_commit_graph_one(const char *obj_dir)
 }
 
 static int prepare_commit_graph_run_once = 0;
-static void prepare_commit_graph(void)
+
+/*
+ * Return 1 if commit_graph is non-NULL, and 0 otherwise.
+ *
+ * On the first invocation, this function attemps to load the commit
+ * graph if the_repository is configured to have one.
+ */
+static int prepare_commit_graph(void)
 {
 	struct alternate_object_database *alt;
 	char *obj_dir;
 
 	if (prepare_commit_graph_run_once)
-		return;
+		return !!commit_graph;
 	prepare_commit_graph_run_once = 1;
 
+	if (!core_commit_graph)
+		return 0;
+
 	obj_dir = get_object_directory();
 	prepare_commit_graph_one(obj_dir);
 	prepare_alt_odb(the_repository);
 	for (alt = the_repository->objects->alt_odb_list;
 	     !commit_graph && alt;
 	     alt = alt->next)
 		prepare_commit_graph_one(alt->path);
+	return !!commit_graph;
 }
 
 static void close_commit_graph(void)
@@ -337,22 +348,17 @@ static int parse_commit_in_graph_one(struct commit_graph *g, struct commit *item
 
 int parse_commit_in_graph(struct commit *item)
 {
-	if (!core_commit_graph)
+	if (!prepare_commit_graph())
 		return 0;
-
-	prepare_commit_graph();
-	if (commit_graph)
-		return parse_commit_in_graph_one(commit_graph, item);
-	return 0;
+	return parse_commit_in_graph_one(commit_graph, item);
 }
 
 void load_commit_graph_info(struct commit *item)
 {
 	uint32_t pos;
-	if (!core_commit_graph)
+	if (!prepare_commit_graph())
 		return;
-	prepare_commit_graph();
-	if (commit_graph && find_commit_in_graph(item, commit_graph, &pos))
+	if (find_commit_in_graph(item, commit_graph, &pos))
 		fill_commit_graph_info(item, commit_graph, pos);
 }