/// <summary>/// Connection对象  这个类是TcpConnection和 UDPConnnection连接类的父类/// Connection由以下五个文件组成 大家注意到每个类前面都有个 partial关键字/// ConnectionCreate.cs <1>/// ConnectionDelegatesHandlers.cs <2>/// ConnectionIncomingData.cs <3>/// ConnectionSendClose.cs <4>/// ConnectionStatic.cs  <5>/// </summary>/// 这部分负责接收数据，并交个networkcomms的优先级线程池处理public abstract partial class Connection{/// <summary>/// The <see cref="PacketBuilder"/> for this connection/// </summary>protected PacketBuilder packetBuilder;/// <summary>/// The current incoming data buffer/// </summary>protected byte[] dataBuffer;/// <summary>/// The total bytes read so far within dataBuffer/// </summary>protected int totalBytesRead;/// <summary>/// The thread listening for incoming data should we be using synchronous methods./// </summary>protected Thread incomingDataListenThread = null;/// <summary>/// A connection specific method which triggers any requisites for accepting incoming data/// </summary>protected abstract void StartIncomingDataListen();/// <summary>/// Attempts to use the data provided in packetBuilder to recreate something usefull. If we don't have enough data yet that value is set in packetBuilder./// </summary>/// <param name="packetBuilder">The <see cref="PacketBuilder"/> containing incoming cached data</param>protected void IncomingPacketHandleHandOff(PacketBuilder packetBuilder){try{if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... checking for completed packet with " + packetBuilder.TotalBytesCached.ToString() + " bytes read.");if (packetBuilder.TotalPartialPacketCount == 0)throw new Exception("Executing IncomingPacketHandleHandOff when no packets exist in packetbuilder.");//Loop until we are finished with this packetBuilderint loopCounter = 0;while (true){//If we have ended up with a null packet at the front, probably due to some form of concatentation we can pull it off here//It is possible we have concatenation of several null packets along with real data so we loop until the firstByte is greater than 0if (packetBuilder.FirstByte() == 0){if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... null packet removed in IncomingPacketHandleHandOff() from " + ConnectionInfo + ", loop index - " + loopCounter.ToString());packetBuilder.ClearNTopBytes(1);//Reset the expected bytes to 0 so that the next check starts from scratchpacketBuilder.TotalBytesExpected = 0;//If we have run out of data completely then we can return immediatelyif (packetBuilder.TotalBytesCached == 0) return;}else{//First determine the expected size of a header packetint packetHeaderSize = packetBuilder.FirstByte() + 1;//Do we have enough data to build a header?if (packetBuilder.TotalBytesCached < packetHeaderSize){if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... ... more data required for complete packet header.");//Set the expected number of bytes and then returnpacketBuilder.TotalBytesExpected = packetHeaderSize;return;}//We have enough for a header
                        PacketHeader topPacketHeader;using(MemoryStream headerStream = packetBuilder.ReadDataSection(1, packetHeaderSize - 1))topPacketHeader = new PacketHeader(headerStream, NetworkComms.InternalFixedSendReceiveOptions);//Idiot testif (topPacketHeader.PacketType == null)throw new SerialisationException("packetType value in packetHeader should never be null");//We can now use the header to establish if we have enough payload data//First case is when we have not yet received enough dataif (packetBuilder.TotalBytesCached < packetHeaderSize + topPacketHeader.PayloadPacketSize){if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... ... more data required for complete packet payload. Expecting " + (packetHeaderSize + topPacketHeader.PayloadPacketSize).ToString() + " total packet bytes.");//Set the expected number of bytes and then returnpacketBuilder.TotalBytesExpected = packetHeaderSize + topPacketHeader.PayloadPacketSize;return;}//Second case is we have enough dataelse if (packetBuilder.TotalBytesCached >= packetHeaderSize + topPacketHeader.PayloadPacketSize){//We can either have exactly the right amount or even more than we were expecting//We may have too much data if we are sending high quantities and the packets have been concatenated//no problem!!SendReceiveOptions incomingPacketSendReceiveOptions = IncomingPacketSendReceiveOptions(topPacketHeader);if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Debug("Received packet of type '" + topPacketHeader.PacketType + "' from " + ConnectionInfo + ", containing " + packetHeaderSize.ToString() + " header bytes and " + topPacketHeader.PayloadPacketSize.ToString() + " payload bytes.");//If this is a reserved packetType we call the method inline so that it gets dealt with immediatelybool isReservedType = false;foreach (var tName in NetworkComms.reservedPacketTypeNames){//isReservedType |= topPacketHeader.PacketType == tName;if (topPacketHeader.PacketType == tName){isReservedType = true;break;}}//Only reserved packet types get completed inlineif (isReservedType){
#if WINDOWS_PHONEvar priority = QueueItemPriority.Normal;
#elsevar priority = (QueueItemPriority)Thread.CurrentThread.Priority;
#endifPriorityQueueItem item = new PriorityQueueItem(priority, this, topPacketHeader, packetBuilder.ReadDataSection(packetHeaderSize, topPacketHeader.PayloadPacketSize), incomingPacketSendReceiveOptions);if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... handling packet type '" + topPacketHeader.PacketType + "' inline. Loop index - " + loopCounter.ToString());NetworkComms.CompleteIncomingItemTask(item);}else{QueueItemPriority itemPriority = (incomingPacketSendReceiveOptions.Options.ContainsKey("ReceiveHandlePriority") ? (QueueItemPriority)Enum.Parse(typeof(QueueItemPriority), incomingPacketSendReceiveOptions.Options["ReceiveHandlePriority"]) : QueueItemPriority.Normal);PriorityQueueItem item = new PriorityQueueItem(itemPriority, this, topPacketHeader, packetBuilder.ReadDataSection(packetHeaderSize, topPacketHeader.PayloadPacketSize), incomingPacketSendReceiveOptions);//QueueItemPriority.Highest is the only priority that is executed inline
#if !WINDOWS_PHONEif (itemPriority == QueueItemPriority.Highest){if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... handling packet type '" + topPacketHeader.PacketType + "' with priority HIGHEST inline. Loop index - " + loopCounter.ToString());NetworkComms.CompleteIncomingItemTask(item);}else{int threadId = NetworkComms.CommsThreadPool.EnqueueItem(item.Priority, NetworkComms.CompleteIncomingItemTask, item);if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... added completed " + item.PacketHeader.PacketType + " packet to thread pool (Q:" + NetworkComms.CommsThreadPool.QueueCount.ToString() + ", T:" + NetworkComms.CommsThreadPool.CurrentNumTotalThreads.ToString() + ", I:" + NetworkComms.CommsThreadPool.CurrentNumIdleThreads.ToString() + ") with priority " + itemPriority.ToString() + (threadId > 0 ? ". Selected threadId=" + threadId.ToString() : "") + ". Loop index=" + loopCounter.ToString() + ".");}
#elseint threadId = NetworkComms.CommsThreadPool.EnqueueItem(item.Priority, NetworkComms.CompleteIncomingItemTask, item);if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace(" ... added completed " + item.PacketHeader.PacketType + " packet to thread pool (Q:" + NetworkComms.CommsThreadPool.QueueCount.ToString() + ", T:" + NetworkComms.CommsThreadPool.CurrentNumTotalThreads.ToString() + ", I:" + NetworkComms.CommsThreadPool.CurrentNumIdleThreads.ToString() + ") with priority " + itemPriority.ToString() + (threadId > 0 ? ". Selected threadId=" + threadId.ToString() : "") + ". Loop index=" + loopCounter.ToString() + ".");
#endif}//We clear the bytes we have just handed offif (NetworkComms.LoggingEnabled) NetworkComms.Logger.Trace("Removing " + (packetHeaderSize + topPacketHeader.PayloadPacketSize).ToString() + " bytes from incoming packet buffer from connection with " + ConnectionInfo +".");packetBuilder.ClearNTopBytes(packetHeaderSize + topPacketHeader.PayloadPacketSize);//Reset the expected bytes to 0 so that the next check starts from scratchpacketBuilder.TotalBytesExpected = 0;//If we have run out of data completely then we can return immediatelyif (packetBuilder.TotalBytesCached == 0) return;}elsethrow new CommunicationException("This should be impossible!");}loopCounter++;}}catch (Exception ex){//Any error, throw an exception.if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Fatal("A fatal exception occured in IncomingPacketHandleHandOff(), connection with " + ConnectionInfo + " be closed. See log file for more information.");NetworkComms.LogError(ex, "CommsError");CloseConnection(true, 45);}}/// <summary>/// Handle an incoming CheckSumFailResend packet type/// </summary>/// <param name="packetDataSection"></param>internal void CheckSumFailResendHandler(MemoryStream packetDataSection){//If we have been asked to resend a packet then we just go through the list and resend it.
            SentPacket packetToReSend;lock (sentPacketsLocker){string checkSumRequested = NetworkComms.InternalFixedSendReceiveOptions.DataSerializer.DeserialiseDataObject<string>(packetDataSection, NetworkComms.InternalFixedSendReceiveOptions.DataProcessors, NetworkComms.InternalFixedSendReceiveOptions.Options);if (sentPackets.ContainsKey(checkSumRequested))packetToReSend = sentPackets[checkSumRequested];elsethrow new CheckSumException("There was no packet sent with a matching check sum");}//If we have already tried resending the packet 10 times something has gone horribly wrongif (packetToReSend.SendCount > 10) throw new CheckSumException("Packet sent resulted in a catastropic checksum check exception.");if (NetworkComms.LoggingEnabled) NetworkComms.Logger.Warn(" ... resending packet due to MD5 mismatch.");//Increment send count and then resend
            packetToReSend.IncrementSendCount();SendPacket(packetToReSend.Packet);}}