+/* global storage */
+static struct commit_graph *commit_graph = NULL;
+
+static void prepare_commit_graph_one(const char *obj_dir)
+{
+ char *graph_name;
+
+ if (commit_graph)
+ return;
+
+ graph_name = get_commit_graph_filename(obj_dir);
+ commit_graph = load_commit_graph_one(graph_name);
+
+ FREE_AND_NULL(graph_name);
+}
+
+static int prepare_commit_graph_run_once = 0;
+static void prepare_commit_graph(void)
+{
+ struct alternate_object_database *alt;
+ char *obj_dir;
+
+ if (prepare_commit_graph_run_once)
+ return;
+ prepare_commit_graph_run_once = 1;
+
+ obj_dir = get_object_directory();
+ prepare_commit_graph_one(obj_dir);
+ prepare_alt_odb();
+ for (alt = alt_odb_list; !commit_graph && alt; alt = alt->next)
+ prepare_commit_graph_one(alt->path);
+}
+
+static void close_commit_graph(void)
+{
+ if (!commit_graph)
+ return;
+
+ if (commit_graph->graph_fd >= 0) {
+ munmap((void *)commit_graph->data, commit_graph->data_len);
+ commit_graph->data = NULL;
+ close(commit_graph->graph_fd);
+ }
+
+ FREE_AND_NULL(commit_graph);
+}
+
+static int bsearch_graph(struct commit_graph *g, struct object_id *oid, uint32_t *pos)
+{
+ return bsearch_hash(oid->hash, g->chunk_oid_fanout,
+ g->chunk_oid_lookup, g->hash_len, pos);
+}
+
+static struct commit_list **insert_parent_or_die(struct commit_graph *g,
+ uint64_t pos,
+ struct commit_list **pptr)
+{
+ struct commit *c;
+ struct object_id oid;
+ hashcpy(oid.hash, g->chunk_oid_lookup + g->hash_len * pos);
+ c = lookup_commit(&oid);
+ if (!c)
+ die("could not find commit %s", oid_to_hex(&oid));
+ c->graph_pos = pos;
+ return &commit_list_insert(c, pptr)->next;
+}
+
+static int fill_commit_in_graph(struct commit *item, struct commit_graph *g, uint32_t pos)
+{
+ struct object_id oid;
+ uint32_t edge_value;
+ uint32_t *parent_data_ptr;
+ uint64_t date_low, date_high;
+ struct commit_list **pptr;
+ const unsigned char *commit_data = g->chunk_commit_data + (g->hash_len + 16) * pos;
+
+ item->object.parsed = 1;
+ item->graph_pos = pos;
+
+ hashcpy(oid.hash, commit_data);
+ item->tree = lookup_tree(&oid);
+
+ date_high = get_be32(commit_data + g->hash_len + 8) & 0x3;
+ date_low = get_be32(commit_data + g->hash_len + 12);
+ item->date = (timestamp_t)((date_high << 32) | date_low);
+
+ pptr = &item->parents;
+
+ edge_value = get_be32(commit_data + g->hash_len);
+ if (edge_value == GRAPH_PARENT_NONE)
+ return 1;
+ pptr = insert_parent_or_die(g, edge_value, pptr);
+
+ edge_value = get_be32(commit_data + g->hash_len + 4);
+ if (edge_value == GRAPH_PARENT_NONE)
+ return 1;
+ if (!(edge_value & GRAPH_OCTOPUS_EDGES_NEEDED)) {
+ pptr = insert_parent_or_die(g, edge_value, pptr);
+ return 1;
+ }
+
+ parent_data_ptr = (uint32_t*)(g->chunk_large_edges +
+ 4 * (uint64_t)(edge_value & GRAPH_EDGE_LAST_MASK));
+ do {
+ edge_value = get_be32(parent_data_ptr);
+ pptr = insert_parent_or_die(g,
+ edge_value & GRAPH_EDGE_LAST_MASK,
+ pptr);
+ parent_data_ptr++;
+ } while (!(edge_value & GRAPH_LAST_EDGE));
+
+ return 1;
+}
+
+int parse_commit_in_graph(struct commit *item)
+{
+ if (!core_commit_graph)
+ return 0;
+ if (item->object.parsed)
+ return 1;
+
+ prepare_commit_graph();
+ if (commit_graph) {
+ uint32_t pos;
+ int found;
+ if (item->graph_pos != COMMIT_NOT_FROM_GRAPH) {
+ pos = item->graph_pos;
+ found = 1;
+ } else {
+ found = bsearch_graph(commit_graph, &(item->object.oid), &pos);
+ }
+
+ if (found)
+ return fill_commit_in_graph(item, commit_graph, pos);
+ }
+
+ return 0;
+}
+