-
synchronized
static NSString* A = @"A";/** B锁 /
static NSString B = @"B";
dispatch_async(queue, ^{
// NSLog(@"%@",[self sourceOut]) ;
@synchronized(A){
NSLog(@"锁A0");
sleep(2);
@synchronized(B){
NSLog(@"锁B0");
}
}
});dispatch_async(queue, ^{
@synchronized(B){
NSLog(@"锁B1");@synchronized(A){ NSLog(@"锁A1"); } }});
打印：2018-04-06 15:35:56.206903+0800 COCOCOCO[13309:566143] 锁A0
2018-04-06 15:35:56.206939+0800 COCOCOCO[13309:566145] 锁B1
- NSLock
[self.lock lock];
[self.lock lock];//由于当前线程加锁，现在再次加同样的锁，需等待当前线程解锁，把当前线程挂起，不能解锁
[_lock unlock];
[_lock unlock];
- 递归锁。 核心：允许同一个线程对一把锁进行重复加锁。 如果不是同一线程那么将死锁
-
(void)__initMutexLock:(pthread_mutex_t *)mutex{
// 递归锁：允许同一个线程对一把锁进行重复加锁// 初始化属性
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
// 初始化锁
pthread_mutex_init(mutex, &attr);
// 销毁属性
pthread_mutexattr_destroy(&attr);
}
-
(void)viewDidLoad {
[super viewDidLoad];[self __initMutexLock:&_MutexLock];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
pthread_mutex_lock(&_MutexLock);
NSLog(@"加锁 %s =11111== %@",func, [NSThread currentThread]);dispatch_sync(dispatch_get_main_queue(), ^{ pthread_mutex_lock(&_MutexLock); NSLog(@"加锁 %s =22222== %@",__func__, [NSThread currentThread]); NSLog(@"解锁 %s ==2222222= %@",__func__, [NSThread currentThread]); pthread_mutex_unlock(&_MutexLock); }); NSLog(@"解锁 %s ==11111111= %@",__func__, [NSThread currentThread]); pthread_mutex_unlock(&_MutexLock);});
}
2020-12-30 19:34:27.331898+0800 iOS-LockDemo[19500:315177] 加锁 -[ViewController viewDidLoad]_block_invoke =11111== <NSThread: 0x600002d107c0>{number = 5, name = (null)}
