ThreadLock 线程锁、同步一段代码

àì夳堔傛蜴生んèń 2023-10-17 06:28 2阅读 0赞

- (void)viewDidLoad
    {
        [super viewDidLoad];
        //NSLock 线程锁 用于锁定一个线程
        _lock = [[NSLock alloc]init];
        _ticketNumber = 100;
        [NSThread detachNewThreadSelector:@selector(buyTickets:) toTarget:self withObject:[NSNumber numberWithInt:50]];
        [NSThread detachNewThreadSelector:@selector(buyTickets:) toTarget:self withObject:[NSNumber numberWithInt:51]];
        //代码运行时间不可控，先后顺序不一定
        //[NSThread detachNewThreadSelector:@selector(printNumber) toTarget:self withObject:nil];
        //[self printNumber];
    }
    
    //- (void)printNumber
    //{
    //    for (int i = 0; i < 10; i++)
    //    {
    //        NSLog(@"%d",i);
    //    }
    //}
    
    - (void)buyTickets:(NSNumber *)number
    {
        //对当前线程加锁，当一个线程被加锁时，其他线程就暂时无法执行锁里面的这段代码
        //[_lock lock];
        //或者@synchronized同步限制，这段代码只能被同步执行，不能异步执行，和NSLock作用相同。
        @synchronized(self)
        {
            if (_ticketNumber >= number.integerValue)
            {
                NSLog(@"剩余%ld张票",_ticketNumber);
                _ticketNumber -= number.integerValue;
                NSLog(@"购买成功，还剩%ld张",_ticketNumber);
            }
            else
            {
                NSLog(@"剩余票数不足%ld张，无法购买",number.integerValue);
            }
        }
        //解锁，对于锁里面的这段代码，线程走完时必须解锁
        //[_lock unlock];
    }

输出结果如下：

![Center][]

[Center]: https://img-blog.csdn.net/20160704215540649?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center