+
+/* Adjusts 'hmap' to compensate for 'old_node' having moved position in memory
+ * to 'node' (e.g. due to realloc()). */
+void
+hmap_node_moved(struct hmap *hmap,
+ struct hmap_node *old_node, struct hmap_node *node)
+{
+ struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
+ while (*bucket != old_node) {
+ bucket = &(*bucket)->next;
+ }
+ *bucket = node;
+}
+
+/* Chooses and returns a randomly selected node from 'hmap', which must not be
+ * empty.
+ *
+ * I wouldn't depend on this algorithm to be fair, since I haven't analyzed it.
+ * But it does at least ensure that any node in 'hmap' can be chosen. */
+struct hmap_node *
+hmap_random_node(const struct hmap *hmap)
+{
+ struct hmap_node *bucket, *node;
+ size_t n, i;
+
+ /* Choose a random non-empty bucket. */
+ for (i = random_uint32(); ; i++) {
+ bucket = hmap->buckets[i & hmap->mask];
+ if (bucket) {
+ break;
+ }
+ }
+
+ /* Count nodes in bucket. */
+ n = 0;
+ for (node = bucket; node; node = node->next) {
+ n++;
+ }
+
+ /* Choose random node from bucket. */
+ i = random_range(n);
+ for (node = bucket; i-- > 0; node = node->next) {
+ continue;
+ }
+ return node;
+}