583 lines
21 KiB
C++
583 lines
21 KiB
C++
// Provides an efficient blocking version of moodycamel::ConcurrentQueue.
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// ©2015-2020 Cameron Desrochers. Distributed under the terms of the simplified
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// BSD license, available at the top of concurrentqueue.h.
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// Also dual-licensed under the Boost Software License (see LICENSE.md)
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// Uses Jeff Preshing's semaphore implementation (under the terms of its
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// separate zlib license, see lightweightsemaphore.h).
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#pragma once
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#include "concurrentqueue.h"
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#include "lightweightsemaphore.h"
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#include <type_traits>
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#include <cerrno>
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#include <memory>
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#include <chrono>
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#include <ctime>
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namespace moodycamel
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{
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// This is a blocking version of the queue. It has an almost identical interface to
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// the normal non-blocking version, with the addition of various wait_dequeue() methods
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// and the removal of producer-specific dequeue methods.
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template<typename T, typename Traits = ConcurrentQueueDefaultTraits>
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class BlockingConcurrentQueue
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{
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private:
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typedef ::moodycamel::ConcurrentQueue<T, Traits> ConcurrentQueue;
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typedef ::moodycamel::LightweightSemaphore LightweightSemaphore;
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public:
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typedef typename ConcurrentQueue::producer_token_t producer_token_t;
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typedef typename ConcurrentQueue::consumer_token_t consumer_token_t;
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typedef typename ConcurrentQueue::index_t index_t;
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typedef typename ConcurrentQueue::size_t size_t;
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typedef typename std::make_signed<size_t>::type ssize_t;
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static const size_t BLOCK_SIZE = ConcurrentQueue::BLOCK_SIZE;
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static const size_t EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD = ConcurrentQueue::EXPLICIT_BLOCK_EMPTY_COUNTER_THRESHOLD;
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static const size_t EXPLICIT_INITIAL_INDEX_SIZE = ConcurrentQueue::EXPLICIT_INITIAL_INDEX_SIZE;
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static const size_t IMPLICIT_INITIAL_INDEX_SIZE = ConcurrentQueue::IMPLICIT_INITIAL_INDEX_SIZE;
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static const size_t INITIAL_IMPLICIT_PRODUCER_HASH_SIZE = ConcurrentQueue::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE;
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static const std::uint32_t EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE = ConcurrentQueue::EXPLICIT_CONSUMER_CONSUMPTION_QUOTA_BEFORE_ROTATE;
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static const size_t MAX_SUBQUEUE_SIZE = ConcurrentQueue::MAX_SUBQUEUE_SIZE;
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public:
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// Creates a queue with at least `capacity` element slots; note that the
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// actual number of elements that can be inserted without additional memory
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// allocation depends on the number of producers and the block size (e.g. if
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// the block size is equal to `capacity`, only a single block will be allocated
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// up-front, which means only a single producer will be able to enqueue elements
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// without an extra allocation -- blocks aren't shared between producers).
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// This method is not thread safe -- it is up to the user to ensure that the
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// queue is fully constructed before it starts being used by other threads (this
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// includes making the memory effects of construction visible, possibly with a
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// memory barrier).
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explicit BlockingConcurrentQueue(size_t capacity = 6 * BLOCK_SIZE)
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: inner(capacity), sema(create<LightweightSemaphore, ssize_t, int>(0, (int)Traits::MAX_SEMA_SPINS), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
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{
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assert(reinterpret_cast<ConcurrentQueue*>((BlockingConcurrentQueue*)1) == &((BlockingConcurrentQueue*)1)->inner && "BlockingConcurrentQueue must have ConcurrentQueue as its first member");
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if (!sema) {
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MOODYCAMEL_THROW(std::bad_alloc());
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}
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}
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BlockingConcurrentQueue(size_t minCapacity, size_t maxExplicitProducers, size_t maxImplicitProducers)
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: inner(minCapacity, maxExplicitProducers, maxImplicitProducers), sema(create<LightweightSemaphore, ssize_t, int>(0, (int)Traits::MAX_SEMA_SPINS), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
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{
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assert(reinterpret_cast<ConcurrentQueue*>((BlockingConcurrentQueue*)1) == &((BlockingConcurrentQueue*)1)->inner && "BlockingConcurrentQueue must have ConcurrentQueue as its first member");
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if (!sema) {
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MOODYCAMEL_THROW(std::bad_alloc());
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}
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}
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// Disable copying and copy assignment
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BlockingConcurrentQueue(BlockingConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION;
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BlockingConcurrentQueue& operator=(BlockingConcurrentQueue const&) MOODYCAMEL_DELETE_FUNCTION;
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// Moving is supported, but note that it is *not* a thread-safe operation.
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// Nobody can use the queue while it's being moved, and the memory effects
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// of that move must be propagated to other threads before they can use it.
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// Note: When a queue is moved, its tokens are still valid but can only be
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// used with the destination queue (i.e. semantically they are moved along
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// with the queue itself).
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BlockingConcurrentQueue(BlockingConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT
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: inner(std::move(other.inner)), sema(std::move(other.sema))
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{ }
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inline BlockingConcurrentQueue& operator=(BlockingConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT
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{
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return swap_internal(other);
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}
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// Swaps this queue's state with the other's. Not thread-safe.
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// Swapping two queues does not invalidate their tokens, however
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// the tokens that were created for one queue must be used with
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// only the swapped queue (i.e. the tokens are tied to the
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// queue's movable state, not the object itself).
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inline void swap(BlockingConcurrentQueue& other) MOODYCAMEL_NOEXCEPT
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{
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swap_internal(other);
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}
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private:
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BlockingConcurrentQueue& swap_internal(BlockingConcurrentQueue& other)
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{
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if (this == &other) {
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return *this;
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}
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inner.swap(other.inner);
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sema.swap(other.sema);
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return *this;
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}
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public:
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// Enqueues a single item (by copying it).
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// Allocates memory if required. Only fails if memory allocation fails (or implicit
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// production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0,
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// or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Thread-safe.
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inline bool enqueue(T const& item)
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{
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if ((details::likely)(inner.enqueue(item))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by moving it, if possible).
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// Allocates memory if required. Only fails if memory allocation fails (or implicit
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// production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0,
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// or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Thread-safe.
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inline bool enqueue(T&& item)
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{
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if ((details::likely)(inner.enqueue(std::move(item)))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by copying it) using an explicit producer token.
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// Allocates memory if required. Only fails if memory allocation fails (or
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// Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Thread-safe.
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inline bool enqueue(producer_token_t const& token, T const& item)
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{
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if ((details::likely)(inner.enqueue(token, item))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by moving it, if possible) using an explicit producer token.
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// Allocates memory if required. Only fails if memory allocation fails (or
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// Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Thread-safe.
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inline bool enqueue(producer_token_t const& token, T&& item)
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{
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if ((details::likely)(inner.enqueue(token, std::move(item)))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues several items.
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// Allocates memory if required. Only fails if memory allocation fails (or
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// implicit production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE
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// is 0, or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Note: Use std::make_move_iterator if the elements should be moved instead of copied.
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// Thread-safe.
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template<typename It>
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inline bool enqueue_bulk(It itemFirst, size_t count)
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{
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if ((details::likely)(inner.enqueue_bulk(std::forward<It>(itemFirst), count))) {
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sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
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return true;
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}
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return false;
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}
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// Enqueues several items using an explicit producer token.
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// Allocates memory if required. Only fails if memory allocation fails
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// (or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
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// Note: Use std::make_move_iterator if the elements should be moved
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// instead of copied.
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// Thread-safe.
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template<typename It>
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inline bool enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count)
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{
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if ((details::likely)(inner.enqueue_bulk(token, std::forward<It>(itemFirst), count))) {
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sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
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return true;
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}
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return false;
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}
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// Enqueues a single item (by copying it).
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// Does not allocate memory. Fails if not enough room to enqueue (or implicit
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// production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE
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// is 0).
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// Thread-safe.
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inline bool try_enqueue(T const& item)
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{
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if (inner.try_enqueue(item)) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by moving it, if possible).
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// Does not allocate memory (except for one-time implicit producer).
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// Fails if not enough room to enqueue (or implicit production is
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// disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0).
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// Thread-safe.
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inline bool try_enqueue(T&& item)
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{
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if (inner.try_enqueue(std::move(item))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by copying it) using an explicit producer token.
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// Does not allocate memory. Fails if not enough room to enqueue.
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// Thread-safe.
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inline bool try_enqueue(producer_token_t const& token, T const& item)
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{
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if (inner.try_enqueue(token, item)) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues a single item (by moving it, if possible) using an explicit producer token.
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// Does not allocate memory. Fails if not enough room to enqueue.
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// Thread-safe.
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inline bool try_enqueue(producer_token_t const& token, T&& item)
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{
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if (inner.try_enqueue(token, std::move(item))) {
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sema->signal();
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return true;
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}
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return false;
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}
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// Enqueues several items.
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// Does not allocate memory (except for one-time implicit producer).
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// Fails if not enough room to enqueue (or implicit production is
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// disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0).
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// Note: Use std::make_move_iterator if the elements should be moved
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// instead of copied.
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// Thread-safe.
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template<typename It>
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inline bool try_enqueue_bulk(It itemFirst, size_t count)
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{
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if (inner.try_enqueue_bulk(std::forward<It>(itemFirst), count)) {
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sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
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return true;
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}
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return false;
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}
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// Enqueues several items using an explicit producer token.
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// Does not allocate memory. Fails if not enough room to enqueue.
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// Note: Use std::make_move_iterator if the elements should be moved
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// instead of copied.
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// Thread-safe.
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template<typename It>
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inline bool try_enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count)
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{
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if (inner.try_enqueue_bulk(token, std::forward<It>(itemFirst), count)) {
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sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
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return true;
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}
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return false;
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}
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// Attempts to dequeue from the queue.
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// Returns false if all producer streams appeared empty at the time they
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// were checked (so, the queue is likely but not guaranteed to be empty).
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// Never allocates. Thread-safe.
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template<typename U>
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inline bool try_dequeue(U& item)
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{
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if (sema->tryWait()) {
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while (!inner.try_dequeue(item)) {
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continue;
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}
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return true;
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}
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return false;
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}
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// Attempts to dequeue from the queue using an explicit consumer token.
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// Returns false if all producer streams appeared empty at the time they
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// were checked (so, the queue is likely but not guaranteed to be empty).
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// Never allocates. Thread-safe.
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template<typename U>
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inline bool try_dequeue(consumer_token_t& token, U& item)
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{
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if (sema->tryWait()) {
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while (!inner.try_dequeue(token, item)) {
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continue;
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}
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return true;
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}
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return false;
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}
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// Attempts to dequeue several elements from the queue.
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// Returns the number of items actually dequeued.
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// Returns 0 if all producer streams appeared empty at the time they
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// were checked (so, the queue is likely but not guaranteed to be empty).
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// Never allocates. Thread-safe.
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template<typename It>
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inline size_t try_dequeue_bulk(It itemFirst, size_t max)
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{
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size_t count = 0;
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max = (size_t)sema->tryWaitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
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while (count != max) {
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count += inner.template try_dequeue_bulk<It&>(itemFirst, max - count);
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}
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return count;
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}
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// Attempts to dequeue several elements from the queue using an explicit consumer token.
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// Returns the number of items actually dequeued.
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// Returns 0 if all producer streams appeared empty at the time they
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// were checked (so, the queue is likely but not guaranteed to be empty).
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// Never allocates. Thread-safe.
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template<typename It>
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inline size_t try_dequeue_bulk(consumer_token_t& token, It itemFirst, size_t max)
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{
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size_t count = 0;
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max = (size_t)sema->tryWaitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
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while (count != max) {
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count += inner.template try_dequeue_bulk<It&>(token, itemFirst, max - count);
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}
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return count;
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}
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// Blocks the current thread until there's something to dequeue, then
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// dequeues it.
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// Never allocates. Thread-safe.
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template<typename U>
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inline void wait_dequeue(U& item)
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{
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while (!sema->wait()) {
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continue;
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}
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while (!inner.try_dequeue(item)) {
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continue;
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}
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}
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// Blocks the current thread until either there's something to dequeue
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// or the timeout (specified in microseconds) expires. Returns false
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// without setting `item` if the timeout expires, otherwise assigns
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// to `item` and returns true.
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// Using a negative timeout indicates an indefinite timeout,
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// and is thus functionally equivalent to calling wait_dequeue.
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// Never allocates. Thread-safe.
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template<typename U>
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inline bool wait_dequeue_timed(U& item, std::int64_t timeout_usecs)
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{
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if (!sema->wait(timeout_usecs)) {
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return false;
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}
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while (!inner.try_dequeue(item)) {
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continue;
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}
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return true;
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}
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// Blocks the current thread until either there's something to dequeue
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// or the timeout expires. Returns false without setting `item` if the
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// timeout expires, otherwise assigns to `item` and returns true.
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// Never allocates. Thread-safe.
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template<typename U, typename Rep, typename Period>
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inline bool wait_dequeue_timed(U& item, std::chrono::duration<Rep, Period> const& timeout)
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{
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return wait_dequeue_timed(item, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
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}
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// Blocks the current thread until there's something to dequeue, then
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// dequeues it using an explicit consumer token.
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// Never allocates. Thread-safe.
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template<typename U>
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inline void wait_dequeue(consumer_token_t& token, U& item)
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{
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while (!sema->wait()) {
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continue;
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}
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while (!inner.try_dequeue(token, item)) {
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continue;
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}
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}
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// Blocks the current thread until either there's something to dequeue
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// or the timeout (specified in microseconds) expires. Returns false
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// without setting `item` if the timeout expires, otherwise assigns
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// to `item` and returns true.
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// Using a negative timeout indicates an indefinite timeout,
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// and is thus functionally equivalent to calling wait_dequeue.
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// Never allocates. Thread-safe.
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template<typename U>
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inline bool wait_dequeue_timed(consumer_token_t& token, U& item, std::int64_t timeout_usecs)
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{
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if (!sema->wait(timeout_usecs)) {
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return false;
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}
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while (!inner.try_dequeue(token, item)) {
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continue;
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}
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return true;
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}
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// Blocks the current thread until either there's something to dequeue
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// or the timeout expires. Returns false without setting `item` if the
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// timeout expires, otherwise assigns to `item` and returns true.
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// Never allocates. Thread-safe.
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template<typename U, typename Rep, typename Period>
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inline bool wait_dequeue_timed(consumer_token_t& token, U& item, std::chrono::duration<Rep, Period> const& timeout)
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{
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return wait_dequeue_timed(token, item, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
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}
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// Attempts to dequeue several elements from the queue.
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// Returns the number of items actually dequeued, which will
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// always be at least one (this method blocks until the queue
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// is non-empty) and at most max.
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// Never allocates. Thread-safe.
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template<typename It>
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inline size_t wait_dequeue_bulk(It itemFirst, size_t max)
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{
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size_t count = 0;
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max = (size_t)sema->waitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
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while (count != max) {
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count += inner.template try_dequeue_bulk<It&>(itemFirst, max - count);
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}
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return count;
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}
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// Attempts to dequeue several elements from the queue.
|
|
// Returns the number of items actually dequeued, which can
|
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// be 0 if the timeout expires while waiting for elements,
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// and at most max.
|
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// Using a negative timeout indicates an indefinite timeout,
|
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// and is thus functionally equivalent to calling wait_dequeue_bulk.
|
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// Never allocates. Thread-safe.
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template<typename It>
|
|
inline size_t wait_dequeue_bulk_timed(It itemFirst, size_t max, std::int64_t timeout_usecs)
|
|
{
|
|
size_t count = 0;
|
|
max = (size_t)sema->waitMany((LightweightSemaphore::ssize_t)(ssize_t)max, timeout_usecs);
|
|
while (count != max) {
|
|
count += inner.template try_dequeue_bulk<It&>(itemFirst, max - count);
|
|
}
|
|
return count;
|
|
}
|
|
|
|
// Attempts to dequeue several elements from the queue.
|
|
// Returns the number of items actually dequeued, which can
|
|
// be 0 if the timeout expires while waiting for elements,
|
|
// and at most max.
|
|
// Never allocates. Thread-safe.
|
|
template<typename It, typename Rep, typename Period>
|
|
inline size_t wait_dequeue_bulk_timed(It itemFirst, size_t max, std::chrono::duration<Rep, Period> const& timeout)
|
|
{
|
|
return wait_dequeue_bulk_timed<It&>(itemFirst, max, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
|
|
}
|
|
|
|
// Attempts to dequeue several elements from the queue using an explicit consumer token.
|
|
// Returns the number of items actually dequeued, which will
|
|
// always be at least one (this method blocks until the queue
|
|
// is non-empty) and at most max.
|
|
// Never allocates. Thread-safe.
|
|
template<typename It>
|
|
inline size_t wait_dequeue_bulk(consumer_token_t& token, It itemFirst, size_t max)
|
|
{
|
|
size_t count = 0;
|
|
max = (size_t)sema->waitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
|
|
while (count != max) {
|
|
count += inner.template try_dequeue_bulk<It&>(token, itemFirst, max - count);
|
|
}
|
|
return count;
|
|
}
|
|
|
|
// Attempts to dequeue several elements from the queue using an explicit consumer token.
|
|
// Returns the number of items actually dequeued, which can
|
|
// be 0 if the timeout expires while waiting for elements,
|
|
// and at most max.
|
|
// Using a negative timeout indicates an indefinite timeout,
|
|
// and is thus functionally equivalent to calling wait_dequeue_bulk.
|
|
// Never allocates. Thread-safe.
|
|
template<typename It>
|
|
inline size_t wait_dequeue_bulk_timed(consumer_token_t& token, It itemFirst, size_t max, std::int64_t timeout_usecs)
|
|
{
|
|
size_t count = 0;
|
|
max = (size_t)sema->waitMany((LightweightSemaphore::ssize_t)(ssize_t)max, timeout_usecs);
|
|
while (count != max) {
|
|
count += inner.template try_dequeue_bulk<It&>(token, itemFirst, max - count);
|
|
}
|
|
return count;
|
|
}
|
|
|
|
// Attempts to dequeue several elements from the queue using an explicit consumer token.
|
|
// Returns the number of items actually dequeued, which can
|
|
// be 0 if the timeout expires while waiting for elements,
|
|
// and at most max.
|
|
// Never allocates. Thread-safe.
|
|
template<typename It, typename Rep, typename Period>
|
|
inline size_t wait_dequeue_bulk_timed(consumer_token_t& token, It itemFirst, size_t max, std::chrono::duration<Rep, Period> const& timeout)
|
|
{
|
|
return wait_dequeue_bulk_timed<It&>(token, itemFirst, max, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
|
|
}
|
|
|
|
|
|
// Returns an estimate of the total number of elements currently in the queue. This
|
|
// estimate is only accurate if the queue has completely stabilized before it is called
|
|
// (i.e. all enqueue and dequeue operations have completed and their memory effects are
|
|
// visible on the calling thread, and no further operations start while this method is
|
|
// being called).
|
|
// Thread-safe.
|
|
inline size_t size_approx() const
|
|
{
|
|
return (size_t)sema->availableApprox();
|
|
}
|
|
|
|
|
|
// Returns true if the underlying atomic variables used by
|
|
// the queue are lock-free (they should be on most platforms).
|
|
// Thread-safe.
|
|
static constexpr bool is_lock_free()
|
|
{
|
|
return ConcurrentQueue::is_lock_free();
|
|
}
|
|
|
|
|
|
private:
|
|
template<typename U, typename A1, typename A2>
|
|
static inline U* create(A1&& a1, A2&& a2)
|
|
{
|
|
void* p = (Traits::malloc)(sizeof(U));
|
|
return p != nullptr ? new (p) U(std::forward<A1>(a1), std::forward<A2>(a2)) : nullptr;
|
|
}
|
|
|
|
template<typename U>
|
|
static inline void destroy(U* p)
|
|
{
|
|
if (p != nullptr) {
|
|
p->~U();
|
|
}
|
|
(Traits::free)(p);
|
|
}
|
|
|
|
private:
|
|
ConcurrentQueue inner;
|
|
std::unique_ptr<LightweightSemaphore, void (*)(LightweightSemaphore*)> sema;
|
|
};
|
|
|
|
|
|
template<typename T, typename Traits>
|
|
inline void swap(BlockingConcurrentQueue<T, Traits>& a, BlockingConcurrentQueue<T, Traits>& b) MOODYCAMEL_NOEXCEPT
|
|
{
|
|
a.swap(b);
|
|
}
|
|
|
|
} // end namespace moodycamel
|