ck_ht: Add ck_ht_stat function.

This can be used to expose certain performance metrics.

include/ck_ht.h

@@ -99,6 +99,11 @@ struct ck_ht {
 };
 typedef struct ck_ht ck_ht_t;
 
+struct ck_ht_stat {
+	uint64_t probe_maximum;
+	uint64_t n_entries;
+};
+
 struct ck_ht_iterator {
 	struct ck_ht_entry *current;
 	uint64_t offset;
@@ -237,6 +242,7 @@ ck_ht_entry_value_direct(ck_ht_entry_t *entry)
  */
 bool ck_ht_next(ck_ht_t *, ck_ht_iterator_t *, ck_ht_entry_t **entry);
 
+void ck_ht_stat(ck_ht_t *, struct ck_ht_stat *);
 void ck_ht_hash(ck_ht_hash_t *, ck_ht_t *, const void *, uint16_t);
 void ck_ht_hash_direct(ck_ht_hash_t *, ck_ht_t *, uintptr_t);
 bool ck_ht_init(ck_ht_t *, enum ck_ht_mode, ck_ht_hash_cb_t *, struct ck_malloc *, uint64_t, uint64_t);

regressions/ck_ht/benchmark/serial.c

@@ -176,6 +176,7 @@ main(int argc, char *argv[])
 	unsigned int d = 0;
 	uint64_t s, e, a, ri, si, ai, sr, rg, sg, ag, sd, ng;
 	char **t;
+	struct ck_ht_stat st;
 
 	r = 20;
 	s = 8;
@@ -218,9 +219,10 @@ main(int argc, char *argv[])
 
 	for (i = 0; i < keys_length; i++)
 		d += table_insert(keys[i]) == false;
+	ck_ht_stat(&ht, &st);
 
-	fprintf(stderr, "# %zu entries stored and %u duplicates.\n",
-	    table_count(), d);
+	fprintf(stderr, "# %zu entries stored, %u duplicates, %" PRIu64 " probe.\n",
+	    table_count(), d, st.probe_maximum);
 
 	fprintf(stderr, "#    reverse_insertion serial_insertion random_insertion serial_replace reverse_get serial_get random_get serial_remove negative_get\n\n");
 

src/ck_ht.c

@@ -74,6 +74,17 @@ struct ck_ht_map {
 	struct ck_ht_entry *entries;
 };
 
+void
+ck_ht_stat(struct ck_ht *table,
+	   struct ck_ht_stat *st)
+{
+	struct ck_ht_map *map = table->map;
+
+	st->n_entries = map->n_entries;
+	st->probe_maximum = map->probe_maximum;
+	return;
+}
+
 void
 ck_ht_hash(struct ck_ht_hash *h,
 	   struct ck_ht *table,