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mpmc_bounded_queue.h
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mpmc_bounded_queue.h
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#pragma once
#include "core/concurrency.h"
#include "core/debug.h"
namespace Core
{
/* Multi-producer/multi-consumer bounded queue.
* Copyright (c) 2010-2011, Dmitry Vyukov. All rights reserved.
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list
* of conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
* THIS SOFTWARE IS PROVIDED BY DMITRY VYUKOV "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* DMITRY VYUKOV OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
* The views and conclusions contained in the software and documentation are those of the authors and should not be interpreted
* as representing official policies, either expressed or implied, of Dmitry Vyukov.
* http://www.1024cores.net/home/lock-free-algorithms/queues/bounded-mpmc-queue
*/
template<typename TYPE>
class MPMCBoundedQueue
{
public:
MPMCBoundedQueue() = default;
MPMCBoundedQueue(i32 size)
: buffer_(new Cell[size])
, bufferMask_(size - 1)
{
DBG_ASSERT((size >= 2) && ((size & (size - 1)) == 0));
Core::Barrier();
for(i32 i = 0; i != size; i += 1)
buffer_[i].sequence_ = i;
enqueuePos_ = 0;
dequeuePos_ = 0;
}
MPMCBoundedQueue(MPMCBoundedQueue&& other)
{
using std::swap;
swap(buffer_, other.buffer_);
swap(bufferMask_, other.bufferMask_);
swap(enqueuePos_, other.enqueuePos_);
swap(dequeuePos_, other.dequeuePos_);
}
MPMCBoundedQueue& operator=(MPMCBoundedQueue&& other)
{
using std::swap;
swap(buffer_, other.buffer_);
swap(bufferMask_, other.bufferMask_);
swap(enqueuePos_, other.enqueuePos_);
swap(dequeuePos_, other.dequeuePos_);
return *this;
}
~MPMCBoundedQueue() { delete[] buffer_; }
/**
* Enqueue data.
* @return Successfully queued.
*/
bool Enqueue(const TYPE& data)
{
Cell* cell = nullptr;
i32 pos = Core::AtomicCmpExchg(&enqueuePos_, 0, 0);
for(;;)
{
cell = &buffer_[pos & bufferMask_];
i32 seq = Core::AtomicCmpExchgAcq(&cell->sequence_, 0, 0);
i32 dif = seq - pos;
if(dif == 0)
{
if(Core::AtomicCmpExchg(&enqueuePos_, pos + 1, pos) == pos)
break;
}
else if(dif < 0)
return false;
else
pos = Core::AtomicCmpExchg(&enqueuePos_, 0, 0);
}
cell->data_ = data;
Core::Barrier();
cell->sequence_ = pos + 1;
return true;
}
/**
* Dequeue data.
* @return Successfully dequeued.
*/
bool Dequeue(TYPE& data)
{
Cell* cell = nullptr;
i32 pos = Core::AtomicCmpExchg(&dequeuePos_, 0, 0);
for(;;)
{
cell = &buffer_[pos & bufferMask_];
i32 seq = Core::AtomicCmpExchgAcq(&cell->sequence_, 0, 0);
i32 dif = seq - (pos + 1);
if(dif == 0)
{
if(Core::AtomicCmpExchg(&dequeuePos_, pos + 1, pos) == pos)
break;
}
else if(dif < 0)
return false;
else
pos = Core::AtomicCmpExchg(&dequeuePos_, 0, 0);
}
data = cell->data_;
Core::Barrier();
cell->sequence_ = pos + bufferMask_ + 1;
return true;
}
private:
struct Cell
{
volatile i32 sequence_ = 0;
TYPE data_ = TYPE();
};
typedef char CacheLinePad[CACHE_LINE_SIZE];
CacheLinePad pad0_ = {0};
Cell* buffer_ = nullptr;
i32 bufferMask_ = 0;
CacheLinePad pad1_ = {0};
volatile i32 enqueuePos_ = 0;
CacheLinePad pad2_ = {0};
volatile i32 dequeuePos_ = 0;
CacheLinePad pad3_ = {0};
MPMCBoundedQueue(const MPMCBoundedQueue&) = delete;
void operator=(const MPMCBoundedQueue&) = delete;
};
} // namespace Core