同步生产者，使用者和生产者队列

问题描述

我有一个生产者和一个消费者。生产者用对象填充其内部队列，消费者逐一地取得这些对象。我想要使​​cosumer与生产者同步，这样当没有对象准备就绪时，消费者阻塞，并且我想使生产者与自身同步，以便在队列满时停止产生（并且当有空间时再次启动） 。我怎么做？我可以使用 / p>

  @implementation生产者
 
  - （id）getNextObject {
 [objectsReady wait]; 
 id anObject = [[buffer objectAtIndex：0] retain]; 
 [buffer removeObjectAtIndex：0]; 
 [bufferFreeSlots signal]; 
 return [anObject autorelease]; 
} 
 
  - （void）decodeLoop {
 while（1）{
 [bufferFreeSlots wait]; 
 [buffer push：[self produceAnObject]]; 
 [objectsReady signal]; 
} 
} 
 
 @end 
  

bufferFreeSlots 初始化为最大队列大小。到目前为止，它似乎工作，但上帝知道这是一种信仰的行为，而不是一个坚定的信心。

I have a producer and a consumer. Producer fills its internal queue with objects, consumer takes these objects one by one. I want to synchronize the cosumer with the producer, so that the consumer blocks when there are no objects ready, and I want to synchronize the producer with itself, so that it stops producing when the queue is full (and starts again when there’s space). How do I do that? I was able to solve a simpler case without the queue using NSConditionalLock, but with the queue the problem looks more complex.

解决方案

I ended up using two semaphores, objectsReady and bufferFreeSlots:

@implementation Producer

- (id) getNextObject {
    [objectsReady wait];
    id anObject = [[buffer objectAtIndex:0] retain];
    [buffer removeObjectAtIndex:0];
    [bufferFreeSlots signal];
    return [anObject autorelease];
}

- (void) decodeLoop {
    while (1) {
        [bufferFreeSlots wait];
        [buffer push:[self produceAnObject]];
        [objectsReady signal];
    }
}

@end

The bufferFreeSlots is initialized to the maximum queue size. So far it seems to work, but God knows this is an act of faith, not a solid confidence.

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