hash: add API to query the key count

Add a new function, rte_hash_count, to return the number of keys that
are currently stored in the hash table. Corresponding test functions are
added into hash_test and hash_multiwriter test.

Signed-off-by: Yipeng Wang <yipeng1.wang@intel.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>

lib/librte_hash/rte_cuckoo_hash.c

@@ -369,6 +369,30 @@ rte_hash_secondary_hash(const hash_sig_t primary_hash)
 	return primary_hash ^ ((tag + 1) * alt_bits_xor);
 }
 
+int32_t
+rte_hash_count(const struct rte_hash *h)
+{
+	uint32_t tot_ring_cnt, cached_cnt = 0;
+	uint32_t i, ret;
+
+	if (h == NULL)
+		return -EINVAL;
+
+	if (h->multi_writer_support) {
+		tot_ring_cnt = h->entries + (RTE_MAX_LCORE - 1) *
+					(LCORE_CACHE_SIZE - 1);
+		for (i = 0; i < RTE_MAX_LCORE; i++)
+			cached_cnt += h->local_free_slots[i].len;
+
+		ret = tot_ring_cnt - rte_ring_count(h->free_slots) -
+								cached_cnt;
+	} else {
+		tot_ring_cnt = h->entries;
+		ret = tot_ring_cnt - rte_ring_count(h->free_slots);
+	}
+	return ret;
+}
+
 /* Read write locks implemented using rte_rwlock */
 static inline void
 __hash_rw_writer_lock(const struct rte_hash *h)

lib/librte_hash/rte_hash.h

@@ -126,6 +126,17 @@ rte_hash_free(struct rte_hash *h);
 void
 rte_hash_reset(struct rte_hash *h);
 
+/**
+ * Return the number of keys in the hash table
+ * @param h
+ *  Hash table to query from
+ * @return
+ *   - -EINVAL if parameters are invalid
+ *   - A value indicating how many keys were inserted in the table.
+ */
+int32_t
+rte_hash_count(const struct rte_hash *h);
+
 /**
  * Add a key-value pair to an existing hash table.
  * This operation is not multi-thread safe

lib/librte_hash/rte_hash_version.map

@@ -45,3 +45,11 @@ DPDK_16.07 {
 	rte_hash_get_key_with_position;
 
 } DPDK_2.2;
+
+
+DPDK_18.08 {
+	global:
+
+	rte_hash_count;
+
+} DPDK_16.07;

test/test/test_hash.c

@@ -1103,6 +1103,7 @@ static int test_average_table_utilization(void)
 	unsigned i, j;
 	unsigned added_keys, average_keys_added = 0;
 	int ret;
+	unsigned int cnt;
 
 	printf("\n# Running test to determine average utilization"
 	       "\n  before adding elements begins to fail\n");
@@ -1121,13 +1122,24 @@ static int test_average_table_utilization(void)
 			for (i = 0; i < ut_params.key_len; i++)
 				simple_key[i] = rte_rand() % 255;
 			ret = rte_hash_add_key(handle, simple_key);
+			if (ret < 0)
+				break;
 		}
+
 		if (ret != -ENOSPC) {
 			printf("Unexpected error when adding keys\n");
 			rte_hash_free(handle);
 			return -1;
 		}
 
+		cnt = rte_hash_count(handle);
+		if (cnt != added_keys) {
+			printf("rte_hash_count returned wrong value %u, %u,"
+					"%u\n", j, added_keys, cnt);
+			rte_hash_free(handle);
+			return -1;
+		}
+
 		average_keys_added += added_keys;
 
 		/* Reset the table */

test/test/test_hash_multiwriter.c

@@ -116,6 +116,7 @@ test_hash_multiwriter(void)
 
 	uint32_t duplicated_keys = 0;
 	uint32_t lost_keys = 0;
+	uint32_t count;
 
 	snprintf(name, 32, "test%u", calledCount++);
 	hash_params.name = name;
@@ -163,6 +164,13 @@ test_hash_multiwriter(void)
 				 NULL, CALL_MASTER);
 	rte_eal_mp_wait_lcore();
 
+	count = rte_hash_count(handle);
+	if (count != rounded_nb_total_tsx_insertion) {
+		printf("rte_hash_count returned wrong value %u, %d\n",
+				rounded_nb_total_tsx_insertion, count);
+		goto err3;
+	}
+
 	while (rte_hash_iterate(handle, &next_key, &next_data, &iter) >= 0) {
 		/* Search for the key in the list of keys added .*/
 		i = *(const uint32_t *)next_key;