# swoole_lock::trylock
函数原型：
~~~
$lock->trylock();
~~~
加锁操作。与lock方法不同的是，trylock()不会阻塞，它会立即返回。当返回false时表示抢锁失败，有其他进程持有锁。返回true时表示加锁成功，此时可以修改共享变量。
> SWOOlE_SEM 信号量没有trylock方法
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