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- // Provides an efficient blocking version of moodycamel::ConcurrentQueue.
- // ©2015-2016 Cameron Desrochers. Distributed under the terms of the simplified
- // BSD license, available at the top of concurrentqueue.h.
- // Uses Jeff Preshing's semaphore implementation (under the terms of its
- // separate zlib license, embedded below).
-
- #pragma once
-
- #include "concurrentqueue.h"
- #include <type_traits>
- #include <cerrno>
- #include <memory>
- #include <chrono>
- #include <ctime>
-
- #if defined(_WIN32)
- // Avoid including windows.h in a header; we only need a handful of
- // items, so we'll redeclare them here (this is relatively safe since
- // the API generally has to remain stable between Windows versions).
- // I know this is an ugly hack but it still beats polluting the global
- // namespace with thousands of generic names or adding a .cpp for nothing.
- extern "C" {
- struct _SECURITY_ATTRIBUTES;
- __declspec(dllimport) void* __stdcall CreateSemaphoreW(_SECURITY_ATTRIBUTES* lpSemaphoreAttributes, long lInitialCount, long lMaximumCount, const wchar_t* lpName);
- __declspec(dllimport) int __stdcall CloseHandle(void* hObject);
- __declspec(dllimport) unsigned long __stdcall WaitForSingleObject(void* hHandle, unsigned long dwMilliseconds);
- __declspec(dllimport) int __stdcall ReleaseSemaphore(void* hSemaphore, long lReleaseCount, long* lpPreviousCount);
- }
- #elif defined(__MACH__)
- #include <mach/mach.h>
- #elif defined(__unix__)
- #include <semaphore.h>
- #endif
-
- namespace moodycamel
- {
- namespace details
- {
- // Code in the mpmc_sema namespace below is an adaptation of Jeff Preshing's
- // portable + lightweight semaphore implementations, originally from
- // https://github.com/preshing/cpp11-on-multicore/blob/master/common/sema.h
- // LICENSE:
- // Copyright (c) 2015 Jeff Preshing
- //
- // This software is provided 'as-is', without any express or implied
- // warranty. In no event will the authors be held liable for any damages
- // arising from the use of this software.
- //
- // Permission is granted to anyone to use this software for any purpose,
- // including commercial applications, and to alter it and redistribute it
- // freely, subject to the following restrictions:
- //
- // 1. The origin of this software must not be misrepresented; you must not
- // claim that you wrote the original software. If you use this software
- // in a product, an acknowledgement in the product documentation would be
- // appreciated but is not required.
- // 2. Altered source versions must be plainly marked as such, and must not be
- // misrepresented as being the original software.
- // 3. This notice may not be removed or altered from any source distribution.
- namespace mpmc_sema
- {
- #if defined(_WIN32)
- class Semaphore
- {
- private:
- void* m_hSema;
-
- Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
- Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
-
- public:
- Semaphore(int initialCount = 0)
- {
- assert(initialCount >= 0);
- const long maxLong = 0x7fffffff;
- m_hSema = CreateSemaphoreW(nullptr, initialCount, maxLong, nullptr);
- }
-
- ~Semaphore()
- {
- CloseHandle(m_hSema);
- }
-
- void wait()
- {
- const unsigned long infinite = 0xffffffff;
- WaitForSingleObject(m_hSema, infinite);
- }
-
- bool try_wait()
- {
- const unsigned long RC_WAIT_TIMEOUT = 0x00000102;
- return WaitForSingleObject(m_hSema, 0) != RC_WAIT_TIMEOUT;
- }
-
- bool timed_wait(std::uint64_t usecs)
- {
- const unsigned long RC_WAIT_TIMEOUT = 0x00000102;
- return WaitForSingleObject(m_hSema, (unsigned long)(usecs / 1000)) != RC_WAIT_TIMEOUT;
- }
-
- void signal(int count = 1)
- {
- ReleaseSemaphore(m_hSema, count, nullptr);
- }
- };
- #elif defined(__MACH__)
- //---------------------------------------------------------
- // Semaphore (Apple iOS and OSX)
- // Can't use POSIX semaphores due to http://lists.apple.com/archives/darwin-kernel/2009/Apr/msg00010.html
- //---------------------------------------------------------
- class Semaphore
- {
- private:
- semaphore_t m_sema;
-
- Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
- Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
-
- public:
- Semaphore(int initialCount = 0)
- {
- assert(initialCount >= 0);
- semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, initialCount);
- }
-
- ~Semaphore()
- {
- semaphore_destroy(mach_task_self(), m_sema);
- }
-
- void wait()
- {
- semaphore_wait(m_sema);
- }
-
- bool try_wait()
- {
- return timed_wait(0);
- }
-
- bool timed_wait(std::uint64_t timeout_usecs)
- {
- mach_timespec_t ts;
- ts.tv_sec = static_cast<unsigned int>(timeout_usecs / 1000000);
- ts.tv_nsec = (timeout_usecs % 1000000) * 1000;
-
- // added in OSX 10.10: https://developer.apple.com/library/prerelease/mac/documentation/General/Reference/APIDiffsMacOSX10_10SeedDiff/modules/Darwin.html
- kern_return_t rc = semaphore_timedwait(m_sema, ts);
-
- return rc != KERN_OPERATION_TIMED_OUT && rc != KERN_ABORTED;
- }
-
- void signal()
- {
- semaphore_signal(m_sema);
- }
-
- void signal(int count)
- {
- while (count-- > 0)
- {
- semaphore_signal(m_sema);
- }
- }
- };
- #elif defined(__unix__)
- //---------------------------------------------------------
- // Semaphore (POSIX, Linux)
- //---------------------------------------------------------
- class Semaphore
- {
- private:
- sem_t m_sema;
-
- Semaphore(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
- Semaphore& operator=(const Semaphore& other) MOODYCAMEL_DELETE_FUNCTION;
-
- public:
- Semaphore(int initialCount = 0)
- {
- assert(initialCount >= 0);
- sem_init(&m_sema, 0, static_cast<unsigned int>(initialCount));
- }
-
- ~Semaphore()
- {
- sem_destroy(&m_sema);
- }
-
- void wait()
- {
- // http://stackoverflow.com/questions/2013181/gdb-causes-sem-wait-to-fail-with-eintr-error
- int rc;
- do {
- rc = sem_wait(&m_sema);
- } while (rc == -1 && errno == EINTR);
- }
-
- bool try_wait()
- {
- int rc;
- do {
- rc = sem_trywait(&m_sema);
- } while (rc == -1 && errno == EINTR);
- return !(rc == -1 && errno == EAGAIN);
- }
-
- bool timed_wait(std::uint64_t usecs)
- {
- struct timespec ts;
- const int usecs_in_1_sec = 1000000;
- const int nsecs_in_1_sec = 1000000000;
- clock_gettime(CLOCK_REALTIME, &ts);
- ts.tv_sec += usecs / usecs_in_1_sec;
- ts.tv_nsec += (usecs % usecs_in_1_sec) * 1000;
- // sem_timedwait bombs if you have more than 1e9 in tv_nsec
- // so we have to clean things up before passing it in
- if (ts.tv_nsec >= nsecs_in_1_sec) {
- ts.tv_nsec -= nsecs_in_1_sec;
- ++ts.tv_sec;
- }
-
- int rc;
- do {
- rc = sem_timedwait(&m_sema, &ts);
- } while (rc == -1 && errno == EINTR);
- return !(rc == -1 && errno == ETIMEDOUT);
- }
-
- void signal()
- {
- sem_post(&m_sema);
- }
-
- void signal(int count)
- {
- while (count-- > 0)
- {
- sem_post(&m_sema);
- }
- }
- };
- #else
- #error Unsupported platform! (No semaphore wrapper available)
- #endif
-
- //---------------------------------------------------------
- // LightweightSemaphore
- //---------------------------------------------------------
- class LightweightSemaphore
- {
- public:
- typedef std::make_signed<std::size_t>::type ssize_t;
-
- private:
- std::atomic<ssize_t> m_count;
- Semaphore m_sema;
-
- bool waitWithPartialSpinning(std::int64_t timeout_usecs = -1)
- {
- ssize_t oldCount;
- // Is there a better way to set the initial spin count?
- // If we lower it to 1000, testBenaphore becomes 15x slower on my Core i7-5930K Windows PC,
- // as threads start hitting the kernel semaphore.
- int spin = 10000;
- while (--spin >= 0)
- {
- oldCount = m_count.load(std::memory_order_relaxed);
- if ((oldCount > 0) && m_count.compare_exchange_strong(oldCount, oldCount - 1, std::memory_order_acquire, std::memory_order_relaxed))
- return true;
- std::atomic_signal_fence(std::memory_order_acquire); // Prevent the compiler from collapsing the loop.
- }
- oldCount = m_count.fetch_sub(1, std::memory_order_acquire);
- if (oldCount > 0)
- return true;
- if (timeout_usecs < 0)
- {
- m_sema.wait();
- return true;
- }
- if (m_sema.timed_wait((std::uint64_t)timeout_usecs))
- return true;
- // At this point, we've timed out waiting for the semaphore, but the
- // count is still decremented indicating we may still be waiting on
- // it. So we have to re-adjust the count, but only if the semaphore
- // wasn't signaled enough times for us too since then. If it was, we
- // need to release the semaphore too.
- while (true)
- {
- oldCount = m_count.load(std::memory_order_acquire);
- if (oldCount >= 0 && m_sema.try_wait())
- return true;
- if (oldCount < 0 && m_count.compare_exchange_strong(oldCount, oldCount + 1, std::memory_order_relaxed, std::memory_order_relaxed))
- return false;
- }
- }
-
- ssize_t waitManyWithPartialSpinning(ssize_t max, std::int64_t timeout_usecs = -1)
- {
- assert(max > 0);
- ssize_t oldCount;
- int spin = 10000;
- while (--spin >= 0)
- {
- oldCount = m_count.load(std::memory_order_relaxed);
- if (oldCount > 0)
- {
- ssize_t newCount = oldCount > max ? oldCount - max : 0;
- if (m_count.compare_exchange_strong(oldCount, newCount, std::memory_order_acquire, std::memory_order_relaxed))
- return oldCount - newCount;
- }
- std::atomic_signal_fence(std::memory_order_acquire);
- }
- oldCount = m_count.fetch_sub(1, std::memory_order_acquire);
- if (oldCount <= 0)
- {
- if (timeout_usecs < 0)
- m_sema.wait();
- else if (!m_sema.timed_wait((std::uint64_t)timeout_usecs))
- {
- while (true)
- {
- oldCount = m_count.load(std::memory_order_acquire);
- if (oldCount >= 0 && m_sema.try_wait())
- break;
- if (oldCount < 0 && m_count.compare_exchange_strong(oldCount, oldCount + 1, std::memory_order_relaxed, std::memory_order_relaxed))
- return 0;
- }
- }
- }
- if (max > 1)
- return 1 + tryWaitMany(max - 1);
- return 1;
- }
-
- public:
- LightweightSemaphore(ssize_t initialCount = 0) : m_count(initialCount)
- {
- assert(initialCount >= 0);
- }
-
- bool tryWait()
- {
- ssize_t oldCount = m_count.load(std::memory_order_relaxed);
- while (oldCount > 0)
- {
- if (m_count.compare_exchange_weak(oldCount, oldCount - 1, std::memory_order_acquire, std::memory_order_relaxed))
- return true;
- }
- return false;
- }
-
- void wait()
- {
- if (!tryWait())
- waitWithPartialSpinning();
- }
-
- bool wait(std::int64_t timeout_usecs)
- {
- return tryWait() || waitWithPartialSpinning(timeout_usecs);
- }
-
- // Acquires between 0 and (greedily) max, inclusive
- ssize_t tryWaitMany(ssize_t max)
- {
- assert(max >= 0);
- ssize_t oldCount = m_count.load(std::memory_order_relaxed);
- while (oldCount > 0)
- {
- ssize_t newCount = oldCount > max ? oldCount - max : 0;
- if (m_count.compare_exchange_weak(oldCount, newCount, std::memory_order_acquire, std::memory_order_relaxed))
- return oldCount - newCount;
- }
- return 0;
- }
-
- // Acquires at least one, and (greedily) at most max
- ssize_t waitMany(ssize_t max, std::int64_t timeout_usecs)
- {
- assert(max >= 0);
- ssize_t result = tryWaitMany(max);
- if (result == 0 && max > 0)
- result = waitManyWithPartialSpinning(max, timeout_usecs);
- return result;
- }
-
- ssize_t waitMany(ssize_t max)
- {
- ssize_t result = waitMany(max, -1);
- assert(result > 0);
- return result;
- }
-
- void signal(ssize_t count = 1)
- {
- assert(count >= 0);
- ssize_t oldCount = m_count.fetch_add(count, std::memory_order_release);
- ssize_t toRelease = -oldCount < count ? -oldCount : count;
- if (toRelease > 0)
- {
- m_sema.signal((int)toRelease);
- }
- }
-
- ssize_t availableApprox() const
- {
- ssize_t count = m_count.load(std::memory_order_relaxed);
- return count > 0 ? count : 0;
- }
- };
- } // end namespace mpmc_sema
- } // end namespace details
-
-
- // This is a blocking version of the queue. It has an almost identical interface to
- // the normal non-blocking version, with the addition of various wait_dequeue() methods
- // and the removal of producer-specific dequeue methods.
- template<typename T, typename Traits = ConcurrentQueueDefaultTraits>
- class BlockingConcurrentQueue
- {
- private:
- typedef ::moodycamel::ConcurrentQueue<T, Traits> ConcurrentQueue;
- typedef details::mpmc_sema::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>(), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
- {
- assert(reinterpret_cast<ConcurrentQueue*>((BlockingConcurrentQueue*)1) == &((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>(), &BlockingConcurrentQueue::template destroy<LightweightSemaphore>)
- {
- assert(reinterpret_cast<ConcurrentQueue*>((BlockingConcurrentQueue*)1) == &((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.
- // Note: When a queue is moved, its tokens are still valid but can only be
- // used with the destination queue (i.e. semantically they are moved along
- // with the queue itself).
- BlockingConcurrentQueue(BlockingConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT
- : inner(std::move(other.inner)), sema(std::move(other.sema))
- { }
-
- inline BlockingConcurrentQueue& operator=(BlockingConcurrentQueue&& other) MOODYCAMEL_NOEXCEPT
- {
- return swap_internal(other);
- }
-
- // Swaps this queue's state with the other's. Not thread-safe.
- // Swapping two queues does not invalidate their tokens, however
- // the tokens that were created for one queue must be used with
- // only the swapped queue (i.e. the tokens are tied to the
- // queue's movable state, not the object itself).
- inline void swap(BlockingConcurrentQueue& other) MOODYCAMEL_NOEXCEPT
- {
- swap_internal(other);
- }
-
- private:
- BlockingConcurrentQueue& swap_internal(BlockingConcurrentQueue& other)
- {
- if (this == &other) {
- return *this;
- }
-
- inner.swap(other.inner);
- sema.swap(other.sema);
- return *this;
- }
-
- public:
- // Enqueues a single item (by copying it).
- // Allocates memory if required. Only fails if memory allocation fails (or implicit
- // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0,
- // or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Thread-safe.
- inline bool enqueue(T const& item)
- {
- if ((details::likely)(inner.enqueue(item))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by moving it, if possible).
- // Allocates memory if required. Only fails if memory allocation fails (or implicit
- // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0,
- // or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Thread-safe.
- inline bool enqueue(T&& item)
- {
- if ((details::likely)(inner.enqueue(std::move(item)))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by copying it) using an explicit producer token.
- // Allocates memory if required. Only fails if memory allocation fails (or
- // Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Thread-safe.
- inline bool enqueue(producer_token_t const& token, T const& item)
- {
- if ((details::likely)(inner.enqueue(token, item))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by moving it, if possible) using an explicit producer token.
- // Allocates memory if required. Only fails if memory allocation fails (or
- // Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Thread-safe.
- inline bool enqueue(producer_token_t const& token, T&& item)
- {
- if ((details::likely)(inner.enqueue(token, std::move(item)))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues several items.
- // Allocates memory if required. Only fails if memory allocation fails (or
- // implicit production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE
- // is 0, or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Note: Use std::make_move_iterator if the elements should be moved instead of copied.
- // Thread-safe.
- template<typename It>
- inline bool enqueue_bulk(It itemFirst, size_t count)
- {
- if ((details::likely)(inner.enqueue_bulk(std::forward<It>(itemFirst), count))) {
- sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
- return true;
- }
- return false;
- }
-
- // Enqueues several items using an explicit producer token.
- // Allocates memory if required. Only fails if memory allocation fails
- // (or Traits::MAX_SUBQUEUE_SIZE has been defined and would be surpassed).
- // Note: Use std::make_move_iterator if the elements should be moved
- // instead of copied.
- // Thread-safe.
- template<typename It>
- inline bool enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count)
- {
- if ((details::likely)(inner.enqueue_bulk(token, std::forward<It>(itemFirst), count))) {
- sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by copying it).
- // Does not allocate memory. Fails if not enough room to enqueue (or implicit
- // production is disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE
- // is 0).
- // Thread-safe.
- inline bool try_enqueue(T const& item)
- {
- if (inner.try_enqueue(item)) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by moving it, if possible).
- // Does not allocate memory (except for one-time implicit producer).
- // Fails if not enough room to enqueue (or implicit production is
- // disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0).
- // Thread-safe.
- inline bool try_enqueue(T&& item)
- {
- if (inner.try_enqueue(std::move(item))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by copying it) using an explicit producer token.
- // Does not allocate memory. Fails if not enough room to enqueue.
- // Thread-safe.
- inline bool try_enqueue(producer_token_t const& token, T const& item)
- {
- if (inner.try_enqueue(token, item)) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues a single item (by moving it, if possible) using an explicit producer token.
- // Does not allocate memory. Fails if not enough room to enqueue.
- // Thread-safe.
- inline bool try_enqueue(producer_token_t const& token, T&& item)
- {
- if (inner.try_enqueue(token, std::move(item))) {
- sema->signal();
- return true;
- }
- return false;
- }
-
- // Enqueues several items.
- // Does not allocate memory (except for one-time implicit producer).
- // Fails if not enough room to enqueue (or implicit production is
- // disabled because Traits::INITIAL_IMPLICIT_PRODUCER_HASH_SIZE is 0).
- // Note: Use std::make_move_iterator if the elements should be moved
- // instead of copied.
- // Thread-safe.
- template<typename It>
- inline bool try_enqueue_bulk(It itemFirst, size_t count)
- {
- if (inner.try_enqueue_bulk(std::forward<It>(itemFirst), count)) {
- sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
- return true;
- }
- return false;
- }
-
- // Enqueues several items using an explicit producer token.
- // Does not allocate memory. Fails if not enough room to enqueue.
- // Note: Use std::make_move_iterator if the elements should be moved
- // instead of copied.
- // Thread-safe.
- template<typename It>
- inline bool try_enqueue_bulk(producer_token_t const& token, It itemFirst, size_t count)
- {
- if (inner.try_enqueue_bulk(token, std::forward<It>(itemFirst), count)) {
- sema->signal((LightweightSemaphore::ssize_t)(ssize_t)count);
- return true;
- }
- return false;
- }
-
-
- // Attempts to dequeue from the queue.
- // Returns false if all producer streams appeared empty at the time they
- // were checked (so, the queue is likely but not guaranteed to be empty).
- // Never allocates. Thread-safe.
- template<typename U>
- inline bool try_dequeue(U& item)
- {
- if (sema->tryWait()) {
- while (!inner.try_dequeue(item)) {
- continue;
- }
- return true;
- }
- return false;
- }
-
- // Attempts to dequeue from the queue using an explicit consumer token.
- // Returns false if all producer streams appeared empty at the time they
- // were checked (so, the queue is likely but not guaranteed to be empty).
- // Never allocates. Thread-safe.
- template<typename U>
- inline bool try_dequeue(consumer_token_t& token, U& item)
- {
- if (sema->tryWait()) {
- while (!inner.try_dequeue(token, item)) {
- continue;
- }
- return true;
- }
- return false;
- }
-
- // Attempts to dequeue several elements from the queue.
- // Returns the number of items actually dequeued.
- // Returns 0 if all producer streams appeared empty at the time they
- // were checked (so, the queue is likely but not guaranteed to be empty).
- // Never allocates. Thread-safe.
- template<typename It>
- inline size_t try_dequeue_bulk(It itemFirst, size_t max)
- {
- size_t count = 0;
- max = (size_t)sema->tryWaitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
- while (count != max) {
- count += inner.template try_dequeue_bulk<It&>(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.
- // Returns 0 if all producer streams appeared empty at the time they
- // were checked (so, the queue is likely but not guaranteed to be empty).
- // Never allocates. Thread-safe.
- template<typename It>
- inline size_t try_dequeue_bulk(consumer_token_t& token, It itemFirst, size_t max)
- {
- size_t count = 0;
- max = (size_t)sema->tryWaitMany((LightweightSemaphore::ssize_t)(ssize_t)max);
- while (count != max) {
- count += inner.template try_dequeue_bulk<It&>(token, itemFirst, max - count);
- }
- return count;
- }
-
-
-
- // Blocks the current thread until there's something to dequeue, then
- // dequeues it.
- // Never allocates. Thread-safe.
- template<typename U>
- inline void wait_dequeue(U& item)
- {
- sema->wait();
- while (!inner.try_dequeue(item)) {
- continue;
- }
- }
-
- // Blocks the current thread until either there's something to dequeue
- // or the timeout (specified in microseconds) expires. Returns false
- // without setting `item` if the timeout expires, otherwise assigns
- // to `item` and returns true.
- // Using a negative timeout indicates an indefinite timeout,
- // and is thus functionally equivalent to calling wait_dequeue.
- // Never allocates. Thread-safe.
- template<typename U>
- inline bool wait_dequeue_timed(U& item, std::int64_t timeout_usecs)
- {
- if (!sema->wait(timeout_usecs)) {
- return false;
- }
- while (!inner.try_dequeue(item)) {
- continue;
- }
- return true;
- }
-
- // Blocks the current thread until either there's something to dequeue
- // or the timeout expires. Returns false without setting `item` if the
- // timeout expires, otherwise assigns to `item` and returns true.
- // Never allocates. Thread-safe.
- template<typename U, typename Rep, typename Period>
- inline bool wait_dequeue_timed(U& item, std::chrono::duration<Rep, Period> const& timeout)
- {
- return wait_dequeue_timed(item, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
- }
-
- // Blocks the current thread until there's something to dequeue, then
- // dequeues it using an explicit consumer token.
- // Never allocates. Thread-safe.
- template<typename U>
- inline void wait_dequeue(consumer_token_t& token, U& item)
- {
- sema->wait();
- while (!inner.try_dequeue(token, item)) {
- continue;
- }
- }
-
- // Blocks the current thread until either there's something to dequeue
- // or the timeout (specified in microseconds) expires. Returns false
- // without setting `item` if the timeout expires, otherwise assigns
- // to `item` and returns true.
- // Using a negative timeout indicates an indefinite timeout,
- // and is thus functionally equivalent to calling wait_dequeue.
- // Never allocates. Thread-safe.
- template<typename U>
- inline bool wait_dequeue_timed(consumer_token_t& token, U& item, std::int64_t timeout_usecs)
- {
- if (!sema->wait(timeout_usecs)) {
- return false;
- }
- while (!inner.try_dequeue(token, item)) {
- continue;
- }
- return true;
- }
-
- // Blocks the current thread until either there's something to dequeue
- // or the timeout expires. Returns false without setting `item` if the
- // timeout expires, otherwise assigns to `item` and returns true.
- // Never allocates. Thread-safe.
- template<typename U, typename Rep, typename Period>
- inline bool wait_dequeue_timed(consumer_token_t& token, U& item, std::chrono::duration<Rep, Period> const& timeout)
- {
- return wait_dequeue_timed(token, item, std::chrono::duration_cast<std::chrono::microseconds>(timeout).count());
- }
-
- // Attempts to dequeue several elements from the queue.
- // 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(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&>(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.
- // 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(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 bool is_lock_free()
- {
- return ConcurrentQueue::is_lock_free();
- }
-
-
- private:
- template<typename U>
- static inline U* create()
- {
- auto p = (Traits::malloc)(sizeof(U));
- return p != nullptr ? new (p) U : nullptr;
- }
-
- template<typename U, typename A1>
- static inline U* create(A1&& a1)
- {
- auto p = (Traits::malloc)(sizeof(U));
- return p != nullptr ? new (p) U(std::forward<A1>(a1)) : 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
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