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84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
/*
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* This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef MPSCQueue_h__
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#define MPSCQueue_h__
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#include <atomic>
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#include <utility>
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// C++ implementation of Dmitry Vyukov's lock free MPSC queue
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// http://www.1024cores.net/home/lock-free-algorithms/queues/non-intrusive-mpsc-node-based-queue
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template<typename T>
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class MPSCQueue
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{
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public:
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MPSCQueue() : _head(new Node()), _tail(_head.load(std::memory_order_relaxed))
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{
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Node* front = _head.load(std::memory_order_relaxed);
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front->Next.store(nullptr, std::memory_order_relaxed);
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}
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~MPSCQueue()
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{
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T* output;
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while (this->Dequeue(output))
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;
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Node* front = _head.load(std::memory_order_relaxed);
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delete front;
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}
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void Enqueue(T* input)
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{
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Node* node = new Node(input);
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Node* prevHead = _head.exchange(node, std::memory_order_acq_rel);
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prevHead->Next.store(node, std::memory_order_release);
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}
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bool Dequeue(T*& result)
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{
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Node* tail = _tail.load(std::memory_order_relaxed);
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Node* next = tail->Next.load(std::memory_order_acquire);
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if (!next)
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return false;
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result = next->Data;
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_tail.store(next, std::memory_order_release);
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delete tail;
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return true;
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}
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private:
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struct Node
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{
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Node() = default;
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explicit Node(T* data) : Data(data) { Next.store(nullptr, std::memory_order_relaxed); }
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T* Data;
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std::atomic<Node*> Next;
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};
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std::atomic<Node*> _head;
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std::atomic<Node*> _tail;
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MPSCQueue(MPSCQueue const&) = delete;
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MPSCQueue& operator=(MPSCQueue const&) = delete;
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};
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#endif // MPSCQueue_h__
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