Portable file locking

# SplFileObject::flock

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

SplFileObject::flock — Portable file locking

### 说明

public function SplFileObject::flock(int `$operation`, int `&$wouldBlock` = `null`): bool

Locks or unlocks the file in the same portable way as flock().

### 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 add `LOCK_NB` as a bitmask to one of the above operations, if flock() should not block during the locking attempt.

`wouldBlock`

  Set to `true` if the lock would block (EWOULDBLOCK errno condition).

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 示例

示例 #1 SplFileObject::flock() example

    <?php
    $file = new SplFileObject("/tmp/lock.txt", "w");
    if ($file->flock(LOCK_EX)) { // do an exclusive lock
        $file->ftruncate(0);     // truncate file
        $file->fwrite("Write something here\n");
        $file->flock(LOCK_UN);   // release the lock
    } else {
        echo "Couldn't get the lock!";
    }
    ?>

### 参见

- flock() - 可移植的协同文件锁定

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