81 lines
3.1 KiB
C#
81 lines
3.1 KiB
C#
/******************************************************************************
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* Spine Runtimes License Agreement
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* Last updated July 28, 2023. Replaces all prior versions.
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*
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* Copyright (c) 2013-2026, Esoteric Software LLC
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*
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* Integration of the Spine Runtimes into software or otherwise creating
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* derivative works of the Spine Runtimes is permitted under the terms and
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* conditions of Section 2 of the Spine Editor License Agreement:
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* http://esotericsoftware.com/spine-editor-license
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*
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* Otherwise, it is permitted to integrate the Spine Runtimes into software or
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* otherwise create derivative works of the Spine Runtimes (collectively,
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* "Products"), provided that each user of the Products must obtain their own
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* Spine Editor license and redistribution of the Products in any form must
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* include this license and copyright notice.
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*
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* THE SPINE RUNTIMES ARE PROVIDED BY ESOTERIC SOFTWARE LLC "AS IS" AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL ESOTERIC SOFTWARE LLC BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES,
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* BUSINESS INTERRUPTION, OR LOSS OF USE, DATA, OR PROFITS) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THE
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* SPINE RUNTIMES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*****************************************************************************/
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using System;
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using System.Threading;
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/// <summary>
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/// A generic lock-free single-producer single-consumer queue.
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/// </summary>
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public class LockFreeSPSCQueue<T> {
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private readonly int capacity;
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private readonly T[] circularBuffer;
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private int headIndex;
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private int tailIndex;
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public LockFreeSPSCQueue (int allocatedCapacity) {
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capacity = allocatedCapacity;
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circularBuffer = new T[allocatedCapacity];
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headIndex = tailIndex = 0;
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}
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/// <summary>Enqueues an item if there is space available.</summary>
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/// <returns>True if the item was successfully enqueued, false otherwise.</returns>
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public bool Enqueue (T item) {
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int head = Thread.VolatileRead(ref headIndex);
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int nextHead = (head + 1) % capacity;
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if (nextHead == Thread.VolatileRead(ref tailIndex))
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return false; // queue is full
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circularBuffer[head] = item;
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Thread.VolatileWrite(ref headIndex, nextHead);
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return true;
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}
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/// <summary>
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/// Dequeues an item unless the queue is empty.
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/// </summary>
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/// <param name="item">The dequeued item, or the default element if empty.</param>
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/// <returns>True if the item was successfully dequeued, false otherwise.</returns>
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public bool Dequeue (out T item) {
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int tail = Thread.VolatileRead(ref tailIndex);
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if (tail == Thread.VolatileRead(ref headIndex)) {
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item = default(T); // queue is empty
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return false;
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}
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item = circularBuffer[tail];
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int nextTail = (tail + 1) % capacity;
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Thread.VolatileWrite(ref tailIndex, nextTail);
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return true;
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}
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}
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