252 lines
11 KiB
C#
252 lines
11 KiB
C#
/*
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* Copyright (c) Contributors, http://opensimulator.org/
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* See CONTRIBUTORS.TXT for a full list of copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the OpenSimulator Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``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 THE CONTRIBUTORS 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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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 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 THIS
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* SOFTWARE, 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.Collections.Generic;
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using System.Net;
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using System.Threading;
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using OpenMetaverse;
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//using System.Reflection;
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//using log4net;
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namespace OpenSim.Region.ClientStack.LindenUDP
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{
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/// <summary>
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/// Special collection that is optimized for tracking unacknowledged packets
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/// </summary>
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public sealed class UnackedPacketCollection
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{
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/// <summary>
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/// Holds information about a pending acknowledgement
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/// </summary>
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private struct PendingAck
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{
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/// <summary>Sequence number of the packet to remove</summary>
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public uint SequenceNumber;
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/// <summary>Environment.TickCount value when the remove was queued.
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/// This is used to update round-trip times for packets</summary>
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public int RemoveTime;
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/// <summary>Whether or not this acknowledgement was attached to a
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/// resent packet. If so, round-trip time will not be calculated</summary>
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public bool FromResend;
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public PendingAck(uint sequenceNumber, int currentTime, bool fromResend)
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{
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SequenceNumber = sequenceNumber;
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RemoveTime = currentTime;
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FromResend = fromResend;
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}
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}
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//private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
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/// <summary>Holds the actual unacked packet data, sorted by sequence number</summary>
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private Dictionary<uint, OutgoingPacket> m_packets = new Dictionary<uint, OutgoingPacket>();
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/// <summary>Holds packets that need to be added to the unacknowledged list</summary>
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private LocklessQueue<OutgoingPacket> m_pendingAdds = new LocklessQueue<OutgoingPacket>();
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/// <summary>Holds information about pending acknowledgements</summary>
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private LocklessQueue<PendingAck> m_pendingAcknowledgements = new LocklessQueue<PendingAck>();
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/// <summary>Holds information about pending removals</summary>
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private LocklessQueue<uint> m_pendingRemoves = new LocklessQueue<uint>();
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public void Clear()
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{
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m_packets.Clear();
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m_pendingAdds = null;
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m_pendingAcknowledgements = null;
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m_pendingRemoves = null;
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}
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/// <summary>
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/// Add an unacked packet to the collection
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/// </summary>
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/// <param name="packet">Packet that is awaiting acknowledgement</param>
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/// <returns>True if the packet was successfully added, false if the
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/// packet already existed in the collection</returns>
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/// <remarks>This does not immediately add the ACK to the collection,
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/// it only queues it so it can be added in a thread-safe way later</remarks>
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public void Add(OutgoingPacket packet)
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{
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m_pendingAdds.Enqueue(packet);
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Interlocked.Add(ref packet.Client.UnackedBytes, packet.Buffer.DataLength);
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}
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/// <summary>
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/// Marks a packet as acknowledged
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/// This method is used when an acknowledgement is received from the network for a previously
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/// sent packet. Effects of removal this way are to update unacked byte count, adjust RTT
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/// and increase throttle to the coresponding client.
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/// </summary>
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/// <param name="sequenceNumber">Sequence number of the packet to
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/// acknowledge</param>
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/// <param name="currentTime">Current value of Environment.TickCount</param>
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/// <remarks>This does not immediately acknowledge the packet, it only
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/// queues the ack so it can be handled in a thread-safe way later</remarks>
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public void Acknowledge(uint sequenceNumber, int currentTime, bool fromResend)
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{
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m_pendingAcknowledgements.Enqueue(new PendingAck(sequenceNumber, currentTime, fromResend));
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}
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/// <summary>
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/// Marks a packet as no longer needing acknowledgement without a received acknowledgement.
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/// This method is called when a packet expires and we no longer need an acknowledgement.
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/// When some reliable packet types expire, they are handled in a way other than simply
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/// resending them. The only effect of removal this way is to update unacked byte count.
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/// </summary>
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/// <param name="sequenceNumber">Sequence number of the packet to
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/// acknowledge</param>
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/// <remarks>The does not immediately remove the packet, it only queues the removal
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/// so it can be handled in a thread safe way later</remarks>
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public void Remove(uint sequenceNumber)
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{
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m_pendingRemoves.Enqueue(sequenceNumber);
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}
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/// <summary>
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/// Returns a list of all of the packets with a TickCount older than
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/// the specified timeout
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/// </summary>
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/// <remarks>
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/// This function is not thread safe, and cannot be called
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/// multiple times concurrently
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/// </remarks>
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/// <param name="timeoutMS">Number of ticks (milliseconds) before a
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/// packet is considered expired
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/// </param>
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/// <returns>
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/// A list of all expired packets according to the given
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/// expiration timeout
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/// </returns>
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public List<OutgoingPacket> GetExpiredPackets(int timeoutMS)
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{
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ProcessQueues();
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List<OutgoingPacket> expiredPackets = null;
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if (m_packets.Count > 0)
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{
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int now = Environment.TickCount & Int32.MaxValue;
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foreach (OutgoingPacket packet in m_packets.Values)
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{
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// TickCount of zero means a packet is in the resend queue
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// but hasn't actually been sent over the wire yet
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if (packet.TickCount == 0)
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continue;
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if (now - packet.TickCount >= timeoutMS)
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{
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if (expiredPackets == null)
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expiredPackets = new List<OutgoingPacket>();
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// The TickCount will be set to the current time when the packet
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// is actually sent out again
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packet.TickCount = 0;
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// As with other network applications, assume that an expired packet is
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// an indication of some network problem, slow transmission
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packet.Client.FlowThrottle.ExpirePackets(1);
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expiredPackets.Add(packet);
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}
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}
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}
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// if (expiredPackets != null)
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// m_log.DebugFormat("[UNACKED PACKET COLLECTION]: Found {0} expired packets on timeout of {1}", expiredPackets.Count, timeoutMS);
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return expiredPackets;
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}
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private void ProcessQueues()
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{
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// Process all the pending adds
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OutgoingPacket pendingAdd;
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while (m_pendingAdds.TryDequeue(out pendingAdd))
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if (pendingAdd != null)
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m_packets[pendingAdd.SequenceNumber] = pendingAdd;
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// Process all the pending removes, including updating statistics and round-trip times
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PendingAck pendingAcknowledgement;
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while (m_pendingAcknowledgements.TryDequeue(out pendingAcknowledgement))
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{
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//m_log.DebugFormat("[UNACKED PACKET COLLECTION]: Processing ack {0}", pendingAcknowledgement.SequenceNumber);
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OutgoingPacket ackedPacket;
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if (m_packets.TryGetValue(pendingAcknowledgement.SequenceNumber, out ackedPacket))
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{
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if (ackedPacket != null)
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{
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m_packets.Remove(pendingAcknowledgement.SequenceNumber);
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// As with other network applications, assume that an acknowledged packet is an
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// indication that the network can handle a little more load, speed up the transmission
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ackedPacket.Client.FlowThrottle.AcknowledgePackets(1);
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// Update stats
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Interlocked.Add(ref ackedPacket.Client.UnackedBytes, -ackedPacket.Buffer.DataLength);
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if (!pendingAcknowledgement.FromResend)
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{
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// Calculate the round-trip time for this packet and its ACK
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int rtt = pendingAcknowledgement.RemoveTime - ackedPacket.TickCount;
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if (rtt > 0)
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ackedPacket.Client.UpdateRoundTrip(rtt);
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}
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}
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else
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{
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// m_log.WarnFormat("[UNACKED PACKET COLLECTION]: found null packet for sequence number {0} to ack",
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// pendingAcknowledgement.SequenceNumber);
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}
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}
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else
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{
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// m_log.WarnFormat("[UNACKED PACKET COLLECTION]: Could not find packet with sequence number {0} to ack",
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// pendingAcknowledgement.SequenceNumber);
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}
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}
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uint pendingRemove;
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while(m_pendingRemoves.TryDequeue(out pendingRemove))
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{
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OutgoingPacket removedPacket;
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if (m_packets.TryGetValue(pendingRemove, out removedPacket))
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{
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if (removedPacket != null)
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{
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m_packets.Remove(pendingRemove);
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// Update stats
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Interlocked.Add(ref removedPacket.Client.UnackedBytes, -removedPacket.Buffer.DataLength);
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}
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}
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}
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}
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}
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} |