PHP shared memory cache

  function cache($key, $val=null, $expire=100) {      static $_caches = null;      static $_shm = null;      if ( null === $_shm ) $_shm = @shmop_open(ftok('mcache.solt'),              'c', 0755, config('cache.size', null, 10485760));      if ( null === $_caches && $_shm && ($size = intval(shmop_read($_shm, 0, 10))))          $_caches = $size ? @unserialize(@shmop_read($_shm, 10, $size)) : array();      if (($time = time()) && $val && $expire){          $_caches[$key] = array($time + intval($expire), $val);          if($_shm && ($size = @shmop_write($_shm, serialize(array_filter($_caches, function($  n)use($time){return $n[0] > $time;})), 10)))              @shmop_write($_shm, sprintf('%10d', $size), 0);          return $val;      }      return (isset($_caches[$key]) && $_caches[$key][0] > $time) ? $_caches[$key][1] : null;  }