php方法中的静态变量

class Counter {
    public static $count = 0;

    public function increment() {
        self::$count++;
    }

    public function getCount() {
        return self::$count;
    }
}

$counter1 = new Counter();
$counter1->increment();
echo $counter1->getCount(); // 输出 1

$counter2 = new Counter();
$counter2->increment();
echo $counter2->getCount(); // 输出 2

class Counter {
    private static $count = 0;
    private static $lock;

    public function __construct() {
        if (self::$lock === null) {
            self::$lock = new \Swoole\Lock(SWOOLE_MUTEX);
        }
    }

    public function increment() {
        self::$lock->lock();
        self::$count++;
        self::$lock->unlock();
    }

    public function getCount() {
        self::$lock->lock();
        $count = self::$count;
        self::$lock->unlock();
        return $count;
    }
}