polybar/lib/concurrentqueue/include/moodycamel/blockingconcurrentqueue.h

982 lines
32 KiB
C++

// 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 = 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;
}
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, 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))
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))
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