protected function readData() {
		$used = $this->readSize();
		return 0 === $used ? array() : json_decode($this->read(self::SHM_DATA_OFFSET, $used), true);
	}
protected function readData() {
		$used = $this->readSize();
		return 0 === $used ? array() : json_decode($this->read(self::SHM_DATA_OFFSET, $used), true);
	}
protected function readData ( ) { $ used = $ this -> readSize ( ) ; return 0 === $ used ? array ( ) : json_decode ( $ this -> read ( self :: SHM_DATA_OFFSET , $ used ) , true ) ; }
Read data from shm segment
@param string $key
@return string
Read data from shm segment