corrade-vassal – Rev 1
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/*
* Copyright (c) 2006-2014, openmetaverse.org
* All rights reserved.
*
* - Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
* - Neither the name of the openmetaverse.org nor the names
* of its contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 THE COPYRIGHT OWNER 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.
*/
using System;
namespace OpenMetaverse
{
public class CircularQueue<T>
{
public readonly T[] Items;
int first;
int next;
int capacity;
object syncRoot;
public int First { get { return first; } }
public int Next { get { return next; } }
public CircularQueue(int capacity)
{
this.capacity = capacity;
Items = new T[capacity];
syncRoot = new object();
}
/// <summary>
/// Copy constructor
/// </summary>
/// <param name="queue">Circular queue to copy</param>
public CircularQueue(CircularQueue<T> queue)
{
lock (queue.syncRoot)
{
capacity = queue.capacity;
Items = new T[capacity];
syncRoot = new object();
for (int i = 0; i < capacity; i++)
Items[i] = queue.Items[i];
first = queue.first;
next = queue.next;
}
}
public void Clear()
{
lock (syncRoot)
{
// Explicitly remove references to help garbage collection
for (int i = 0; i < capacity; i++)
Items[i] = default(T);
first = next;
}
}
public void Enqueue(T value)
{
lock (syncRoot)
{
Items[next] = value;
next = (next + 1) % capacity;
if (next == first) first = (first + 1) % capacity;
}
}
public T Dequeue()
{
lock (syncRoot)
{
T value = Items[first];
Items[first] = default(T);
if (first != next)
first = (first + 1) % capacity;
return value;
}
}
public T DequeueLast()
{
lock (syncRoot)
{
// If the next element is right behind the first element (queue is full),
// back up the first element by one
int firstTest = first - 1;
if (firstTest < 0) firstTest = capacity - 1;
if (firstTest == next)
{
--next;
if (next < 0) next = capacity - 1;
--first;
if (first < 0) first = capacity - 1;
}
else if (first != next)
{
--next;
if (next < 0) next = capacity - 1;
}
T value = Items[next];
Items[next] = default(T);
return value;
}
}
}
}