Advisory file locking

# streamWrapper::stream_lock

(PHP 5, PHP 7, PHP 8)

streamWrapper::stream_lock — Advisory file locking

### Description

public streamWrapper::stream_lock(int `$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`).

### Parameters

`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)

### Return Values

Returns `true` on success or `false` on failure.

### Errors/Exceptions

Emits `E_WARNING` if call to this method fails (i.e. not implemented).

### See Also

- stream_set_blocking() - Set blocking/non-blocking mode on a stream
- flock() - Portable advisory file locking

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