多线程-读写锁

场景

  • 同一时间，只有一条线程进行写操作；
  • 同一时间，允许多条线程进行读操作；
  • 同一时间，不能既有写，又有读的操作

方案

  • pthread_rwlock
  • dispatch_barrirer_async

测试

  • pthread_rwlock
@interface pthread_rwlock_test()

@property(nonatomic,assign)pthread_rwlock_t rwlock;

@end

@implementation pthread_rwlock_test

- (instancetype)init
{
    self = [super init];
    if (self) {
        pthread_rwlock_init(&_rwlock, NULL);
    }
    
    return self;
}

- (void)test
{
    dispatch_queue_t queue = dispatch_get_global_queue(0, 0);
    
    for (int i = 0; i < 10; i++) {
        dispatch_async(queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"read-%d",i]];
            NSLog(@"%@",[NSThread currentThread].name);

            [self read];
        });
        
        dispatch_async(queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"write-%d",i]];
            NSLog(@"%@",[NSThread currentThread].name);

            [self write];
        });

    }
    
}

- (void)read
{
    pthread_rwlock_rdlock(&_rwlock);
    sleep(1);
    NSLog(@"%@",[NSThread currentThread]);
    pthread_rwlock_unlock(&_rwlock);

    
}

- (void)write
{
    pthread_rwlock_wrlock(&_rwlock);
    sleep(1);

    NSLog(@"%@",[NSThread currentThread]);
    pthread_rwlock_unlock(&_rwlock);

}


- (void)dealloc
{
    pthread_rwlock_destroy(&_rwlock);
}




@end


//log

2021-02-10 19:40:07.753335+0800 lock[63582:10634592] read-0
2021-02-10 19:40:07.753382+0800 lock[63582:10656695] write-0
2021-02-10 19:40:07.753453+0800 lock[63582:10656696] read-1
2021-02-10 19:40:07.753527+0800 lock[63582:10656697] write-1
2021-02-10 19:40:07.753760+0800 lock[63582:10656699] read-2
2021-02-10 19:40:07.753776+0800 lock[63582:10656700] read-3
2021-02-10 19:40:07.753769+0800 lock[63582:10656698] write-2
2021-02-10 19:40:07.755202+0800 lock[63582:10656701] write-3
2021-02-10 19:40:07.755232+0800 lock[63582:10656702] read-4
2021-02-10 19:40:07.755298+0800 lock[63582:10656703] write-4
2021-02-10 19:40:07.755371+0800 lock[63582:10656704] read-5
2021-02-10 19:40:07.759075+0800 lock[63582:10656705] write-5
2021-02-10 19:40:07.759091+0800 lock[63582:10656706] read-6
2021-02-10 19:40:07.759147+0800 lock[63582:10656708] read-7
2021-02-10 19:40:07.759183+0800 lock[63582:10656709] write-7
2021-02-10 19:40:07.759124+0800 lock[63582:10656707] write-6
2021-02-10 19:40:07.759239+0800 lock[63582:10656710] read-8
2021-02-10 19:40:07.766197+0800 lock[63582:10656711] write-8
2021-02-10 19:40:07.766304+0800 lock[63582:10656713] write-9
2021-02-10 19:40:07.766295+0800 lock[63582:10656712] read-9
2021-02-10 19:40:08.757851+0800 lock[63582:10634592] <NSThread: 0x6000012e92c0>{number = 19, name = read-0}
2021-02-10 19:40:09.762398+0800 lock[63582:10656695] <NSThread: 0x60000128fe80>{number = 36, name = write-0}
2021-02-10 19:40:10.764276+0800 lock[63582:10656696] <NSThread: 0x6000012e9300>{number = 37, name = read-1}
2021-02-10 19:40:11.764904+0800 lock[63582:10656697] <NSThread: 0x6000012ed340>{number = 38, name = write-1}
2021-02-10 19:40:12.769697+0800 lock[63582:10656699] <NSThread: 0x60000128ee80>{number = 39, name = read-2}
2021-02-10 19:40:13.770228+0800 lock[63582:10656698] <NSThread: 0x6000012eca00>{number = 40, name = write-2}
2021-02-10 19:40:14.773556+0800 lock[63582:10656700] <NSThread: 0x6000012f28c0>{number = 41, name = read-3}
2021-02-10 19:40:14.773556+0800 lock[63582:10656702] <NSThread: 0x6000012ec3c0>{number = 43, name = read-4}
2021-02-10 19:40:15.774997+0800 lock[63582:10656701] <NSThread: 0x60000128f980>{number = 42, name = write-3}
2021-02-10 19:40:16.780800+0800 lock[63582:10656704] <NSThread: 0x6000012ec900>{number = 45, name = read-5}
2021-02-10 19:40:17.785779+0800 lock[63582:10656703] <NSThread: 0x6000012ecb00>{number = 44, name = write-4}
2021-02-10 19:40:18.791448+0800 lock[63582:10656705] <NSThread: 0x60000128ef40>{number = 46, name = write-5}
2021-02-10 19:40:19.796147+0800 lock[63582:10656708] <NSThread: 0x6000012f2b00>{number = 49, name = read-7}
2021-02-10 19:40:19.796213+0800 lock[63582:10656706] <NSThread: 0x6000012f2a00>{number = 47, name = read-6}
2021-02-10 19:40:20.798082+0800 lock[63582:10656709] <NSThread: 0x6000012f2b80>{number = 50, name = write-7}
2021-02-10 19:40:21.802982+0800 lock[63582:10656707] <NSThread: 0x60000128f040>{number = 48, name = write-6}
2021-02-10 19:40:22.804432+0800 lock[63582:10656710] <NSThread: 0x6000012e80c0>{number = 51, name = read-8}
2021-02-10 19:40:23.809673+0800 lock[63582:10656713] <NSThread: 0x6000012ea080>{number = 54, name = write-9}
2021-02-10 19:40:24.811072+0800 lock[63582:10656711] <NSThread: 0x60000128e2c0>{number = 52, name = write-8}
2021-02-10 19:40:25.814991+0800 lock[63582:10656712] <NSThread: 0x6000012f2c80>{number = 53, name = read-9}
  • dispatch_barrier_async
@interface dispatch_barrier_async_test()

@property(nonatomic,strong)dispatch_queue_t queue;

@end

@implementation dispatch_barrier_async_test

- (instancetype)init
{
    self = [super init];
    if (self) {
        self.queue = dispatch_queue_create("com.bien.dispatch.barrier", DISPATCH_QUEUE_CONCURRENT);
    }
    
    return self;
}

- (void)other_test
{
    for (int i = 0; i < 10; i++) {
        dispatch_async(self.queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"read-%d",i]];
            NSLog(@"%@",[NSThread currentThread].name);

            [self read];
        });
        
        dispatch_async(self.queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"read-%d",i]];
            //NSLog(@"%@",[NSThread currentThread].name);

            [self read];
        });

        dispatch_async(self.queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"read-%d",i]];
            //NSLog(@"%@",[NSThread currentThread].name);

            [self read];
        });

        
        dispatch_barrier_async(self.queue, ^{
            [[NSThread currentThread] setName:[NSString stringWithFormat:@"write-%d",i]];
           // NSLog(@"%@",[NSThread currentThread].name);

            [self write];
        });

        
    }
    

}

- (void)read
{
    sleep(1);
    NSLog(@"%@",[NSThread currentThread]);
    
}


- (void)write
{
 
    sleep(1);
    NSLog(@"%@",[NSThread currentThread]);
    
}

@end

//log
2021-02-10 19:45:32.501298+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = read-0}
2021-02-10 19:45:32.501298+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-0}
2021-02-10 19:45:32.501298+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-0}
2021-02-10 19:45:33.503124+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = write-0}
2021-02-10 19:45:34.507568+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = read-1}
2021-02-10 19:45:34.507568+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-1}
2021-02-10 19:45:34.507586+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-1}
2021-02-10 19:45:35.509629+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = write-1}
2021-02-10 19:45:36.514013+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-2}
2021-02-10 19:45:36.514013+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = read-2}
2021-02-10 19:45:36.514013+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-2}
2021-02-10 19:45:37.519743+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = write-2}
2021-02-10 19:45:38.522475+0800 lock[64070:10659436] <NSThread: 0x60000371c480>{number = 6, name = read-3}
2021-02-10 19:45:38.522475+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-3}
2021-02-10 19:45:38.522475+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-3}
2021-02-10 19:45:39.525170+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = write-3}
2021-02-10 19:45:40.529765+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-4}
2021-02-10 19:45:40.529765+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-4}
2021-02-10 19:45:40.529765+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-4}
2021-02-10 19:45:41.532054+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = write-4}
2021-02-10 19:45:42.533763+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-5}
2021-02-10 19:45:42.533763+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-5}
2021-02-10 19:45:42.533762+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-5}
2021-02-10 19:45:43.535208+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = write-5}
2021-02-10 19:45:44.540031+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-6}
2021-02-10 19:45:44.540032+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-6}
2021-02-10 19:45:44.540032+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-6}
2021-02-10 19:45:45.542095+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = write-6}
2021-02-10 19:45:46.543757+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-7}
2021-02-10 19:45:46.543786+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-7}
2021-02-10 19:45:46.543757+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-7}
2021-02-10 19:45:47.545658+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = write-7}
2021-02-10 19:45:48.547210+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-8}
2021-02-10 19:45:48.547211+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-8}
2021-02-10 19:45:48.547211+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-8}
2021-02-10 19:45:49.549645+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = write-8}
2021-02-10 19:45:50.551015+0800 lock[64070:10659441] <NSThread: 0x600003715d40>{number = 3, name = read-9}
2021-02-10 19:45:50.551144+0800 lock[64070:10659443] <NSThread: 0x6000037114c0>{number = 7, name = read-9}
2021-02-10 19:45:50.551174+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = read-9}
2021-02-10 19:45:51.551950+0800 lock[64070:10659537] <NSThread: 0x60000371f200>{number = 8, name = write-9}
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