(PHP 5, PHP 7)
streamWrapper::stream_lock — Advisory file locking
$operation
) : bool
This method is called in response to flock(), when
file_put_contents() (when flags
contains LOCK_EX),
stream_set_blocking() and when closing the stream
(LOCK_UN).
operation
operation is one of the following:
LOCK_SH to acquire a shared lock (reader).
LOCK_EX to acquire an exclusive lock (writer).
LOCK_UN to release a lock (shared or exclusive).
LOCK_NB if you don't want
flock() to block while locking.
(not supported on Windows)
成功时返回 TRUE， 或者在失败时返回 FALSE。
Emits E_WARNING if call to this method fails (i.e. not implemented).