streamWrapper::stream_lock — Advisory file locking
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)
Returns TRUE on success or FALSE on failure.
Emits E_WARNING if call to this method fails (i.e. not implemented).