Advisory file locking

# streamWrapper::stream_lock

(PHP 5, PHP 7, PHP 8)

streamWrapper::stream_lock — Advisory file locking

### 说明

public function 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`).

### 参数

`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).
  It is also possible to have `LOCK_NB` added as a bitmask to one of the above operations, if the lock should not block during the locking attempt (not supported on Windows).

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 错误／异常

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

### 参见

- stream_set_blocking() - 为资源流设置阻塞或者阻塞模式
- flock() - 可移植的协同文件锁定

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