decrement() публичный Метод

Note that, as per the Memcached specification: "If the item's value is not numeric, it is treated as if the value were 0. If the operation would decrease the value below 0, the new value will be 0."
См. ссылку: http://php.net/manual/memcached.decrement.php
public decrement ( string $key, integer $offset = 1 ) : integer | boolean
$key string Key of numeric cache item to decrement.
$offset integer Offset to decrement - defaults to `1`.
Результат integer | boolean The item's new value on successful decrement, else `false`.
Документация по классу Memcache
Пример #1
0
 public function testDecrementWithScope()
 {
     $adapter = new Memcache(array('scope' => 'primary'));
     $this->_conn->set('primary:key1', 1, 60);
     $this->_conn->set('key1', 1, 60);
     $adapter->decrement('key1');
     $expected = 1;
     $result = $this->_conn->get('key1');
     $this->assertEqual($expected, $result);
     $expected = 0;
     $result = $this->_conn->get('primary:key1');
     $this->assertEqual($expected, $result);
 }