互斥锁
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@property(nonatomic, assign) init tickets;
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
self.tickets = 20;
NSThread * t1 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTickets) object:nil];
[t1 start];
NSThread * t2 = [[NSThread alloc] initWithTarget:self selector:@selector(saleTickets) object:nil];
[t2 start];
}
- (void)saleTickets {
while(YES) {
[NSThread sleepForTimeInterval: 1.0];
// 互斥锁可以让锁内代码同一时间只被一条线程运行
@synchronized(self) {
if(self.tickets > 0) {
self.tickets--;
NSLog(@"剩下%d张票", self.tickets);
} else {
NSLog(@"卖完了");
break;
}
}
}
}
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自旋锁
原子属性内部的锁
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| @property(atomic, assign) init tickets;
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相同点与不同的
相同点
不同点
- 自旋锁读取时不会锁
- 线程被互斥锁锁在外面，线程会进入休眠状态，等待锁打开后被唤醒
- 线程被自旋锁锁在外面，线程会进入死循环状态等待开锁
RunLoop
主线程默认开启RunLoop，子线程默认关闭，需要手动开启
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| @interface ViewController()
@property(assign, nonatomic, getter=isFinished)BOOL finished
@end
- (void)viewDidLoad {
[super viewDidLoad];
// 先执行demo
NSThread * t1 = [[NSThread alloc] initWithTarget:self selector:@selector(demo) object:nil];
[t1 start];
self.finished = NO;
// 然后执行otherMethod
// 如果不设置t1的RunLoop，执行完demo是不会执行otherMethod的
[self performSelector:@selector(otherMethod) onThread:t1 withObject:nil waitUntilDone:NO];
}
- (void)demo {
NSLog(@"before");
while(!self.isFinished) {
// 开启RunLoop查询当前线程有没有事件
[[NsRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0.1]];
NSLog(@"after");
}
}
- (void)otherMethod {
NSLog(@"otherMethod function");
// 执行完第二个方法后设置为YES
self.finished = YES;
}
// 另一种方式 一般不用 很难停下来
[[NSRunLoop currentRunLoop] run];
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RunLoopMode
NSDefaultRunLoop 时钟、网络事件模式，操作UI界面会停止执行，执行会非常耗时NSRunLoopCommonModes 用户交互模式
