队列barrier

最新推荐文章于 2024-11-01 18:42:05 发布

jks456

最新推荐文章于 2024-11-01 18:42:05 发布

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CC 4.0 BY-SA版权

本文链接：https://blog.youkuaiyun.com/jks456/article/details/51644320

本文介绍了一种使用GCD实现线程安全的NSMutableDictionary的方法。通过创建并发队列和使用dispatch_semaphore来确保多线程环境下对字典进行读写操作的安全性。

NSMutableDictionary

- (void)testMutableDictionaryThreadSafe {dispatch_semaphore_t sema = dispatch_semaphore_create(0);dispatch_async(concurrent_queue, ^{

for (int index = 0; index<1000 ; index++) {dict[@(index)] = @(index);

}

          dispatch_semaphore_signal(sema);
      });

dispatch_async(concurrent_queue, ^{
for (int index = 0; index<1000 ; index++) {

dict[@(index)] = @(0);}

          dispatch_semaphore_signal(sema);
      });

      dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
      dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);

      NSLog(@"dict is %@", dict);
  }

NSMutableDictionary gcd NSMutableDictionary

serial queue + dispatch_async

dispatch_async ,

concurrent queue + dispatch_async

dispatch_barrier_async dispatch_barrier_async dispatch_barrier_async

barrier barrier concurrent queue

typedef void (^ThreadSafeDictionaryBlock)(ThreadSafeDictionary*dict, NSString *key, id object);

@interface ThreadSafeDictionary (){

      dispatch_queue_t concurrentQueue;
  }

  @end
  @implementation ThreadSafeDictionary

- (id)init{

if (self = [super init]) {
concurrentQueue = dispatch_queue_create("www.reviewcode

  .cn", DISPATCH_QUEUE_CONCURRENT);
      }

return self;}

- (void)objectForKey:(id)aKey block:(ThreadSafeDictionaryBlock)block
{

id key = [aKey copy];
__weak __typeof__(self) weakSelf = self;dispatch_async(concurrentQueue, ^{

ThreadSafeDictionary *strongSelf = weakSelf;if (!strongSelf)

return;
id object = [self objectForKey:key];block(self, key, object);

});}

- (void)setObject:(id)object forKey:(NSString *)key block:(ThreadSafeDictionaryBlock)block
{