salad: add LIGHT(count) method

This commit adds a function that retrieves the number of records stored
in a light hash table and makes light users use it instead of accessing
the light count directly. This gives us more freedom of refactoring the
light internals without modifying the code using it.

Needed for #7192

NO_DOC=refactoring
NO_TEST=refactoring
NO_CHANGELOG=refactoring

src/box/memtx_hash.cc

@@ -269,7 +269,7 @@ memtx_hash_index_size(struct index *base)
 	struct memtx_hash_index *index = (struct memtx_hash_index *)base;
 	struct space *space = space_by_id(base->def->space_id);
 	/* Substract invisible count. */
-	return index->hash_table.count -
+	return light_index_count(&index->hash_table) -
 	       memtx_tx_index_invisible_count(in_txn(), space, base);
 }
 
@@ -288,7 +288,7 @@ memtx_hash_index_random(struct index *base, uint32_t rnd, struct tuple **result)
 	struct light_index_core *hash_table = &index->hash_table;
 
 	*result = NULL;
-	if (hash_table->count == 0)
+	if (light_index_count(hash_table) == 0)
 		return 0;
 	rnd %= (hash_table->table_size);
 	while (!light_index_pos_valid(hash_table, rnd)) {
@@ -358,7 +358,8 @@ memtx_hash_index_replace(struct index *base, struct tuple *old_tuple,
 		});
 
 		if (pos == light_index_end) {
-			diag_set(OutOfMemory, (ssize_t)hash_table->count,
+			diag_set(OutOfMemory,
+				 (ssize_t)light_index_count(hash_table),
 				 "hash_table", "key");
 			return -1;
 		}

src/lib/salad/light.h

@@ -206,6 +206,14 @@ LIGHT(create)(struct LIGHT(core) *ht, size_t extent_size,
 static inline void
 LIGHT(destroy)(struct LIGHT(core) *ht);
 
+/**
+ * @brief Number of records stored in hash table
+ * @param ht - pointer to a hash table struct
+ * @return number of records
+ */
+static inline uint32_t
+LIGHT(count)(struct LIGHT(core) *ht);
+
 /**
  * @brief Find a record with given hash and value
  * @param ht - pointer to a hash table struct
@@ -372,6 +380,17 @@ LIGHT(destroy)(struct LIGHT(core) *ht)
 	matras_destroy(&ht->mtable);
 }
 
+/**
+ * @brief Number of records stored in hash table
+ * @param ht - pointer to a hash table struct
+ * @return number of records
+ */
+static inline uint32_t
+LIGHT(count)(struct LIGHT(core) *ht)
+{
+	return ht->count;
+}
+
 /**
  * Find a slot (index in the hash table), where an item with
  * given hash should be placed.

test/unit/light.cc

@@ -96,7 +96,7 @@ simple_test()
 				light_delete(&ht, fnd);
 			}
 
-			if (count != ht.count)
+			if (count != light_count(&ht))
 				fail("count check failed!", "true");
 
 			bool identical = true;
@@ -160,7 +160,7 @@ collision_test()
 				light_delete(&ht, fnd);
 			}
 
-			if (count != ht.count)
+			if (count != light_count(&ht))
 				fail("count check failed!", "true");
 
 			bool identical = true;