This method returns TRUE on custom wrappers by default if you don't implement the stream_lock() method inside the wrapper : http://php.net/manual/en/streamwrapper.stream-lock.php
(PHP 5 >= 5.3.0, PHP 7)
stream_supports_lock — Tells whether the stream supports locking
$stream
) : boolTells whether the stream supports locking through flock().
streamThe stream to check.
成功时返回 TRUE， 或者在失败时返回 FALSE。
This method returns TRUE on custom wrappers by default if you don't implement the stream_lock() method inside the wrapper : http://php.net/manual/en/streamwrapper.stream-lock.php