Class BlockingConcurrentQueue

blockingconcurrentqueue.h:25–583

// and the removal of producer-specific dequeue methods.
template<typename T, typename Traits = ConcurrentQueueDefaultTraits>
class BlockingConcurrentQueue
{
private:
	typedef ::moodycamel::ConcurrentQueue<T, Traits> ConcurrentQueue;
	typedef ::moodycamel::LightweightSemaphore LightweightSemaphore;

public:
	typedef typename ConcurrentQueue::producer_token_t producer_token_t;
	typedef typename ConcurrentQueue::consumer_token_t consumer_token_t;
	
	typedef typename ConcurrentQueue::index_t index_t;
	typedef typename ConcurrentQueue::size_t size_t;
	typedef typename std::make_signed<size_t>::type ssize_t;
	
	static const size_t BLOCK_SIZE = ConcurrentQueue::BLOCK_SIZE;
	static const size_t EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD = ConcurrentQueue::EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD;
	static const size_t EXPLICIT_INITIAL_INDEX_SIZE = ConcurrentQueue::EXPLICIT_INITIAL_INDEX_SIZE;
	static const size_t IMPLICIT_INITIAL_INDEX_SIZE = ConcurrentQueue::IMPLICIT_INITIAL_INDEX_SIZE;
	static const size_t INITIAL_IMPLICIT_PRODUCER_HASH_SIZE = ConcurrentQueue::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE;
	static const std::uint32_t EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE = ConcurrentQueue::EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE;
	static const size_t MAX_SUBQUEUE_SIZE = ConcurrentQueue::MAX_SUBQUEUE_SIZE;
	
public:
	// Creates a queue with at least `capacity` element slots; note that the
	// actual number of elements that can be inserted without additional memory
	// allocation depends on the number of producers and the block size (e.g. if
	// the block size is equal to `capacity`, only a single block will be allocated
	// up-front, which means only a single producer will be able to enqueue elements
	// without an extra allocation -- blocks aren't shared between producers).
	// This method is not thread safe -- it is up to the user to ensure that the
	// queue is fully constructed before it starts being used by other threads (this
	// includes making the memory effects of construction visible, possibly with a
	// memory barrier).
	explicit BlockingConcurrentQueue(size_t capacity = 6 * BLOCK_SIZE)
		: inner(capacity), sema(create<LightweightSemaphore, ssize_t, int>(0, static_cast<int>(Traits::MAX_SEMA_SPINS)), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
	{
		assert(reinterpret_cast<ConcurrentQueue*>(reinterpret_cast<BlockingConcurrentQueue*>(1)) == &(reinterpret_cast<BlockingConcurrentQueue*>(1))->inner && "BlockingConcurrentQueue must have ConcurrentQueue as its first member");
		if (!sema) {
			MOODYCAMEL_THROW(std::bad_alloc());
		}
	}
	
	BlockingConcurrentQueue(size_t minCapacity, size_t maxExplicitProducers, size_t maxImplicitProducers)
		: inner(minCapacity, maxExplicitProducers, maxImplicitProducers), sema(create<LightweightSemaphore, ssize_t, int>(0, static_cast<int>(Traits::MAX_SEMA_SPINS)), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
	{
		assert(reinterpret_cast<ConcurrentQueue*>(reinterpret_cast<BlockingConcurrentQueue*>(1)) == &(reinterpret_cast<BlockingConcurrentQueue*>(1))->inner && "BlockingConcurrentQueue must have ConcurrentQueue as its first member");
		if (!sema) {
			MOODYCAMEL_THROW(std::bad_alloc());
		}
	}
	
	// Disable copying and copy assignment
	BlockingConcurrentQueue(BlockingConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION;
	BlockingConcurrentQueue& operator=(BlockingConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION;
	
	// Moving is supported, but note that it is *not* a thread-safe operation.
	// Nobody can use the queue while it's being moved, and the memory effects
	// of that move must be propagated to other threads before they can use it.