hashmap: introduce hashmap_free_entries

`hashmap_free_entries' behaves like `container_of' and passes
the offset of the hashmap_entry struct to the internal
`hashmap_free_' function, allowing the function to free any
struct pointer regardless of where the hashmap_entry field
is located.

`hashmap_free' no longer takes any arguments aside from
the hashmap itself.

Signed-off-by: Eric Wong <[email protected]>
Reviewed-by: Derrick Stolee <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Eric Wong

blame.c

@@ -433,7 +433,7 @@ static void get_fingerprint(struct fingerprint *result,
 
 static void free_fingerprint(struct fingerprint *f)
 {
-	hashmap_free(&f->map, 0);
+	hashmap_free(&f->map);
 	free(f->entries);
 }
 

builtin/fetch.c

@@ -366,7 +366,7 @@ static void find_non_local_tags(const struct ref *refs,
 		item = refname_hash_add(&remote_refs, ref->name, &ref->old_oid);
 		string_list_insert(&remote_refs_list, ref->name);
 	}
-	hashmap_free(&existing_refs, 1);
+	hashmap_free_entries(&existing_refs, struct refname_hash_entry, ent);
 
 	/*
 	 * We may have a final lightweight tag that needs to be
@@ -401,7 +401,7 @@ static void find_non_local_tags(const struct ref *refs,
 		**tail = rm;
 		*tail = &rm->next;
 	}
-	hashmap_free(&remote_refs, 1);
+	hashmap_free_entries(&remote_refs, struct refname_hash_entry, ent);
 	string_list_clear(&remote_refs_list, 0);
 }
 
@@ -530,7 +530,7 @@ static struct ref *get_ref_map(struct remote *remote,
 			}
 		}
 	}
-	hashmap_free(&existing_refs, 1);
+	hashmap_free_entries(&existing_refs, struct refname_hash_entry, ent);
 
 	return ref_map;
 }

config.c

@@ -1948,7 +1948,7 @@ void git_configset_clear(struct config_set *cs)
 		free(entry->key);
 		string_list_clear(&entry->value_list, 1);
 	}
-	hashmap_free(&cs->config_hash, 1);
+	hashmap_free_entries(&cs->config_hash, struct config_set_element, ent);
 	cs->hash_initialized = 0;
 	free(cs->list.items);
 	cs->list.nr = 0;

diff.c

@@ -6236,8 +6236,10 @@ static void diff_flush_patch_all_file_pairs(struct diff_options *o)
 			if (o->color_moved == COLOR_MOVED_ZEBRA_DIM)
 				dim_moved_lines(o);
 
-			hashmap_free(&add_lines, 1);
-			hashmap_free(&del_lines, 1);
+			hashmap_free_entries(&add_lines, struct moved_entry,
+						ent);
+			hashmap_free_entries(&del_lines, struct moved_entry,
+						ent);
 		}
 
 		for (i = 0; i < esm.nr; i++)

diffcore-rename.c

@@ -358,7 +358,7 @@ static int find_exact_renames(struct diff_options *options)
 		renames += find_identical_files(&file_table, i, options);
 
 	/* Free the hash data structure and entries */
-	hashmap_free(&file_table, 1);
+	hashmap_free_entries(&file_table, struct file_similarity, entry);
 
 	return renames;
 }

hashmap.c

@@ -171,16 +171,21 @@ void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
 	map->do_count_items = 1;
 }
 
-void hashmap_free(struct hashmap *map, int free_entries)
+void hashmap_free_(struct hashmap *map, ssize_t entry_offset)
 {
 	if (!map || !map->table)
 		return;
-	if (free_entries) {
+	if (entry_offset >= 0) { /* called by hashmap_free_entries */
 		struct hashmap_iter iter;
 		struct hashmap_entry *e;
+
 		hashmap_iter_init(map, &iter);
 		while ((e = hashmap_iter_next(&iter)))
-			free(e);
+			/*
+			 * like container_of, but using caller-calculated
+			 * offset (caller being hashmap_free_entries)
+			 */
+			free((char *)e - entry_offset);
 	}
 	free(map->table);
 	memset(map, 0, sizeof(*map));

hashmap.h

@@ -96,7 +96,7 @@
  *         }
  *
  *         if (!strcmp("end", action)) {
- *             hashmap_free(&map, 1);
+ *             hashmap_free_entries(&map, struct long2string, ent);
  *             break;
  *         }
  *     }
@@ -232,13 +232,20 @@ void hashmap_init(struct hashmap *map,
 			 const void *equals_function_data,
 			 size_t initial_size);
 
+/* internal function for freeing hashmap */
+void hashmap_free_(struct hashmap *map, ssize_t offset);
+
 /*
- * Frees a hashmap structure and allocated memory.
- *
- * If `free_entries` is true, each hashmap_entry in the map is freed as well
- * using stdlibs free().
+ * Frees a hashmap structure and allocated memory, leaves entries undisturbed
+ */
+#define hashmap_free(map) hashmap_free_(map, -1)
+
+/*
+ * Frees @map and all entries.  @type is the struct type of the entry
+ * where @member is the hashmap_entry struct used to associate with @map
  */
-void hashmap_free(struct hashmap *map, int free_entries);
+#define hashmap_free_entries(map, type, member) \
+	hashmap_free_(map, offsetof(type, member));
 
 /* hashmap_entry functions */
 

merge-recursive.c

@@ -2633,7 +2633,7 @@ static struct string_list *get_renames(struct merge_options *opt,
 		free(e->target_file);
 		string_list_clear(&e->source_files, 0);
 	}
-	hashmap_free(&collisions, 1);
+	hashmap_free_entries(&collisions, struct collision_entry, ent);
 	return renames;
 }
 
@@ -2853,7 +2853,7 @@ static void initial_cleanup_rename(struct diff_queue_struct *pairs,
 		strbuf_release(&e->new_dir);
 		/* possible_new_dirs already cleared in get_directory_renames */
 	}
-	hashmap_free(dir_renames, 1);
+	hashmap_free_entries(dir_renames, struct dir_rename_entry, ent);
 	free(dir_renames);
 
 	free(pairs->queue);
@@ -3482,7 +3482,8 @@ int merge_trees(struct merge_options *opt,
 		string_list_clear(entries, 1);
 		free(entries);
 
-		hashmap_free(&opt->current_file_dir_set, 1);
+		hashmap_free_entries(&opt->current_file_dir_set,
+					struct path_hashmap_entry, e);
 
 		if (clean < 0) {
 			unpack_trees_finish(opt);

name-hash.c

@@ -728,6 +728,6 @@ void free_name_hash(struct index_state *istate)
 		return;
 	istate->name_hash_initialized = 0;
 
-	hashmap_free(&istate->name_hash, 0);
-	hashmap_free(&istate->dir_hash, 1);
+	hashmap_free(&istate->name_hash);
+	hashmap_free_entries(&istate->dir_hash, struct dir_entry, ent);
 }

oidmap.c

@@ -25,7 +25,9 @@ void oidmap_free(struct oidmap *map, int free_entries)
 {
 	if (!map)
 		return;
-	hashmap_free(&map->map, free_entries);
+
+	/* TODO: make oidmap itself not depend on struct layouts */
+	hashmap_free_(&map->map, free_entries ? 0 : -1);
 }
 
 void *oidmap_get(const struct oidmap *map, const struct object_id *key)