/* * Copyright (c) Contributors, http://opensimulator.org/ * See CONTRIBUTORS.TXT for a full list of copyright holders. * * 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. * * 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. * * Neither the name of the OpenSimulator Project 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 DEVELOPERS ``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 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; using System.Collections.Generic; namespace OpenSim.Region.ClientStack.LindenUDP { /// <summary> /// A circular buffer and hashset for tracking incoming packet sequence /// numbers /// </summary> public sealed class IncomingPacketHistoryCollection { private readonly uint[] m_items; private HashSet<uint> m_hashSet; private int m_first; private int m_next; private int m_capacity; public IncomingPacketHistoryCollection(int capacity) { this.m_capacity = capacity; m_items = new uint[capacity]; m_hashSet = new HashSet<uint>(); } public bool TryEnqueue(uint ack) { lock (m_hashSet) { if (m_hashSet.Add(ack)) { m_items[m_next] = ack; m_next = (m_next + 1) % m_capacity; if (m_next == m_first) { m_hashSet.Remove(m_items[m_first]); m_first = (m_first + 1) % m_capacity; } return true; } } return false; } } }