1 files changed, 219 insertions, 0 deletions

diff --git a/OpenSim/Region/ClientStack/Linden/UDP/UnackedPacketCollection.cs b/OpenSim/Region/ClientStack/Linden/UDP/UnackedPacketCollection.cs
new file mode 100644
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+++ b/OpenSim/Region/ClientStack/Linden/UDP/UnackedPacketCollection.cs
@@ -0,0 +1,219 @@
+/*
+ * 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;
+using System.Net;
+using System.Threading;
+using OpenMetaverse;
+
+namespace OpenSim.Region.ClientStack.LindenUDP
+{
+    /// <summary>
+    /// Special collection that is optimized for tracking unacknowledged packets
+    /// </summary>
+    public sealed class UnackedPacketCollection
+    {
+        /// <summary>
+        /// Holds information about a pending acknowledgement
+        /// </summary>
+        private struct PendingAck
+        {
+            /// <summary>Sequence number of the packet to remove</summary>
+            public uint SequenceNumber;
+            /// <summary>Environment.TickCount value when the remove was queued.
+            /// This is used to update round-trip times for packets</summary>
+            public int RemoveTime;
+            /// <summary>Whether or not this acknowledgement was attached to a
+            /// resent packet. If so, round-trip time will not be calculated</summary>
+            public bool FromResend;
+
+            public PendingAck(uint sequenceNumber, int currentTime, bool fromResend)
+            {
+                SequenceNumber = sequenceNumber;
+                RemoveTime = currentTime;
+                FromResend = fromResend;
+            }
+        }
+
+        /// <summary>Holds the actual unacked packet data, sorted by sequence number</summary>
+        private Dictionary<uint, OutgoingPacket> m_packets = new Dictionary<uint, OutgoingPacket>();
+        /// <summary>Holds packets that need to be added to the unacknowledged list</summary>
+        private LocklessQueue<OutgoingPacket> m_pendingAdds = new LocklessQueue<OutgoingPacket>();
+        /// <summary>Holds information about pending acknowledgements</summary>
+        private LocklessQueue<PendingAck> m_pendingAcknowledgements = new LocklessQueue<PendingAck>();
+        /// <summary>Holds information about pending removals</summary>
+        private LocklessQueue<uint> m_pendingRemoves = new LocklessQueue<uint>();
+
+        /// <summary>
+        /// Add an unacked packet to the collection
+        /// </summary>
+        /// <param name="packet">Packet that is awaiting acknowledgement</param>
+        /// <returns>True if the packet was successfully added, false if the
+        /// packet already existed in the collection</returns>
+        /// <remarks>This does not immediately add the ACK to the collection,
+        /// it only queues it so it can be added in a thread-safe way later</remarks>
+        public void Add(OutgoingPacket packet)
+        {
+            m_pendingAdds.Enqueue(packet);
+            Interlocked.Add(ref packet.Client.UnackedBytes, packet.Buffer.DataLength);            
+        }
+
+        /// <summary>
+        /// Marks a packet as acknowledged
+        /// This method is used when an acknowledgement is received from the network for a previously
+        /// sent packet. Effects of removal this way are to update unacked byte count, adjust RTT
+        /// and increase throttle to the coresponding client.
+        /// </summary>
+        /// <param name="sequenceNumber">Sequence number of the packet to
+        /// acknowledge</param>
+        /// <param name="currentTime">Current value of Environment.TickCount</param>
+        /// <remarks>This does not immediately acknowledge the packet, it only
+        /// queues the ack so it can be handled in a thread-safe way later</remarks>
+        public void Acknowledge(uint sequenceNumber, int currentTime, bool fromResend)
+        {
+            m_pendingAcknowledgements.Enqueue(new PendingAck(sequenceNumber, currentTime, fromResend));
+        }
+
+        /// <summary>
+        /// Marks a packet as no longer needing acknowledgement without a received acknowledgement.
+        /// This method is called when a packet expires and we no longer need an acknowledgement.
+        /// When some reliable packet types expire, they are handled in a way other than simply 
+        /// resending them. The only effect of removal this way is to update unacked byte count.
+        /// </summary>
+        /// <param name="sequenceNumber">Sequence number of the packet to
+        /// acknowledge</param>
+        /// <remarks>The does not immediately remove the packet, it only queues the removal
+        /// so it can be handled in a thread safe way later</remarks>
+        public void Remove(uint sequenceNumber)
+        {
+            m_pendingRemoves.Enqueue(sequenceNumber);
+        }
+
+        /// <summary>
+        /// Returns a list of all of the packets with a TickCount older than
+        /// the specified timeout
+        /// </summary>
+        /// <param name="timeoutMS">Number of ticks (milliseconds) before a
+        /// packet is considered expired</param>
+        /// <returns>A list of all expired packets according to the given
+        /// expiration timeout</returns>
+        /// <remarks>This function is not thread safe, and cannot be called
+        /// multiple times concurrently</remarks>
+        public List<OutgoingPacket> GetExpiredPackets(int timeoutMS)
+        {
+            ProcessQueues();
+
+            List<OutgoingPacket> expiredPackets = null;
+
+            if (m_packets.Count > 0)
+            {
+                int now = Environment.TickCount & Int32.MaxValue;
+
+                foreach (OutgoingPacket packet in m_packets.Values)
+                {
+                    // TickCount of zero means a packet is in the resend queue 
+                    // but hasn't actually been sent over the wire yet
+                    if (packet.TickCount == 0)
+                        continue;
+
+                    if (now - packet.TickCount >= timeoutMS)
+                    {
+                        if (expiredPackets == null)
+                            expiredPackets = new List<OutgoingPacket>();
+
+                        // The TickCount will be set to the current time when the packet
+                        // is actually sent out again
+                        packet.TickCount = 0;
+
+                        // As with other network applications, assume that an expired packet is
+                        // an indication of some network problem, slow transmission
+                        packet.Client.FlowThrottle.ExpirePackets(1);
+                        
+                        expiredPackets.Add(packet);
+                    }
+                }
+            }
+
+            return expiredPackets;
+        }
+
+        private void ProcessQueues()
+        {
+            // Process all the pending adds
+            OutgoingPacket pendingAdd;
+            while (m_pendingAdds.TryDequeue(out pendingAdd))
+                if (pendingAdd != null)
+                    m_packets[pendingAdd.SequenceNumber] = pendingAdd;
+            
+            // Process all the pending removes, including updating statistics and round-trip times
+            PendingAck pendingAcknowledgement;
+            while (m_pendingAcknowledgements.TryDequeue(out pendingAcknowledgement))
+            {
+                OutgoingPacket ackedPacket;
+                if (m_packets.TryGetValue(pendingAcknowledgement.SequenceNumber, out ackedPacket))
+                {
+                    if (ackedPacket != null)
+                    {
+                        m_packets.Remove(pendingAcknowledgement.SequenceNumber);
+
+                        // As with other network applications, assume that an acknowledged packet is an
+                        // indication that the network can handle a little more load, speed up the transmission
+                        ackedPacket.Client.FlowThrottle.AcknowledgePackets(ackedPacket.Buffer.DataLength);
+
+                        // Update stats
+                        Interlocked.Add(ref ackedPacket.Client.UnackedBytes, -ackedPacket.Buffer.DataLength);
+
+                        if (!pendingAcknowledgement.FromResend)
+                        {
+                            // Calculate the round-trip time for this packet and its ACK
+                            int rtt = pendingAcknowledgement.RemoveTime - ackedPacket.TickCount;
+                            if (rtt > 0)
+                                ackedPacket.Client.UpdateRoundTrip(rtt);
+                        }
+                    }
+                }
+            }
+
+            uint pendingRemove;
+            while(m_pendingRemoves.TryDequeue(out pendingRemove))
+            {
+                OutgoingPacket removedPacket;
+                if (m_packets.TryGetValue(pendingRemove, out removedPacket))
+                {
+                    if (removedPacket != null)
+                    {
+                        m_packets.Remove(pendingRemove);
+
+                        // Update stats
+                        Interlocked.Add(ref removedPacket.Client.UnackedBytes, -removedPacket.Buffer.DataLength);
+                    }
+                }
+            }
+        }
+    }
+}