Waits for an exclusive lock

# SyncMutex::lock

(PECL sync >= 1.0.0)

SyncMutex::lock — Waits for an exclusive lock

### 说明

public function SyncMutex::lock(int `$wait` = -1): bool

Obtains an exclusive lock on a SyncMutex object. If the lock is already acquired, then this increments an internal counter.

### 参数

`wait`
  The number of milliseconds to wait for the exclusive lock. A value of -1 is infinite.

### 返回值

成功时返回 `true`， 或者在失败时返回 `false`。

### 示例

示例 #1 SyncMutex::lock() example

    <?php
    $mutex = new SyncMutex("UniqueName");

    if (!$mutex->lock(3000))
    {
        echo "Unable to lock mutex.";

        exit();
    }

    /* ... */

    $mutex->unlock();
    ?>

### 参见

- SyncMutex::unlock() - Unlocks the mutex

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