文件锁
最后更新于：2022-04-02 04:27:58
## 文件锁
### 锁可重入性：
1. 进程内可重入
2. 子进程内可重入
```php
$fp = fopen('./s-lock.lock', 'r');
if (flock($fp, LOCK_EX | LOCK_NB))
echo 'lock ok 1' . PHP_EOL;
if (flock($fp, LOCK_EX | LOCK_NB))
echo 'lock ok 2' . PHP_EOL; // 同一个进程内可重入
$r = pcntl_fork();
if ($r > 0) {
if (flock($fp, LOCK_EX | LOCK_NB))
echo 'lock ok 3' . PHP_EOL;
} elseif ($r == 0) {
if (flock($fp, LOCK_EX | LOCK_NB))
echo 'lock ok 4' . PHP_EOL;
if (flock($fp, LOCK_EX | LOCK_NB))
echo 'lock ok 5' . PHP_EOL;
} else {
echo 'fork fail';
}
sleep(5);
```
~~~shell
$: php test.php
lock ok 1
lock ok 2
lock ok 3
lock ok 4
lock ok 5
~~~
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