-/* Search. */
-#define HMAP_FOR_EACH_WITH_HASH(NODE, STRUCT, MEMBER, HASH, HMAP) \
- for ((NODE) = CONTAINER_OF(hmap_first_with_hash(HMAP, HASH), \
- STRUCT, MEMBER); \
- &(NODE)->MEMBER != NULL; \
- (NODE) = CONTAINER_OF(hmap_next_with_hash(&(NODE)->MEMBER), \
- STRUCT, MEMBER))
+struct hmap_node *hmap_random_node(const struct hmap *);
+
+/* Search.
+ *
+ * HMAP_FOR_EACH_WITH_HASH iterates NODE over all of the nodes in HMAP that
+ * have hash value equal to HASH. HMAP_FOR_EACH_IN_BUCKET iterates NODE over
+ * all of the nodes in HMAP that would fall in the same bucket as HASH. MEMBER
+ * must be the name of the 'struct hmap_node' member within NODE.
+ *
+ * These macros may be used interchangeably to search for a particular value in
+ * an hmap, see, e.g. shash_find() for an example. Usually, using
+ * HMAP_FOR_EACH_WITH_HASH provides an optimization, because comparing a hash
+ * value is usually cheaper than comparing an entire hash map key. But for
+ * simple hash map keys, it makes sense to use HMAP_FOR_EACH_IN_BUCKET because
+ * it avoids doing two comparisons when a single simple comparison suffices.
+ *
+ * The loop should not change NODE to point to a different node or insert or
+ * delete nodes in HMAP (unless it "break"s out of the loop to terminate
+ * iteration).
+ *
+ * HASH is only evaluated once.
+ */
+#define HMAP_FOR_EACH_WITH_HASH(NODE, MEMBER, HASH, HMAP) \
+ for (ASSIGN_CONTAINER(NODE, hmap_first_with_hash(HMAP, HASH), MEMBER); \
+ NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
+ ASSIGN_CONTAINER(NODE, hmap_next_with_hash(&(NODE)->MEMBER), \
+ MEMBER))
+#define HMAP_FOR_EACH_IN_BUCKET(NODE, MEMBER, HASH, HMAP) \
+ for (ASSIGN_CONTAINER(NODE, hmap_first_in_bucket(HMAP, HASH), MEMBER); \
+ NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER); \
+ ASSIGN_CONTAINER(NODE, hmap_next_in_bucket(&(NODE)->MEMBER), MEMBER))