Fork UDPBase from libOMV into opensim

author: Melanie 2009-10-08 22:25:14 +0100
committer: Melanie 2009-10-08 22:25:14 +0100
commit: a0dd9f4bb4c1a88c2692066c54923c7f91429df5 (patch)
tree: 700b656c3662b62d73fe2c13894d1c57fab25197 /OpenSim
parent: Added guards against the exception reported: (diff)
download: opensim-SC_OLD-a0dd9f4bb4c1a88c2692066c54923c7f91429df5.zip
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2 files changed, 341 insertions, 1 deletions
diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
index 2c5ad85..1e6927f 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
@@ -87,7 +87,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
    /// The LLUDP server for a region. This handles incoming and outgoing
    /// packets for all UDP connections to the region
    /// </summary>
-    public class LLUDPServer : UDPBase
+    public class LLUDPServer : OpenSimUDPBase
    {
        private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
diff --git a/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs b/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs
new file mode 100644
index 0000000..aaefbc6
--- /dev/null
+++ b/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs
@@ -0,0 +1,340 @@
+/*
+ * Copyright (c) 2006, Clutch, Inc.
+ * Original Author: Jeff Cesnik
+ * 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;
+using System.Net;
+using System.Net.Sockets;
+using System.Threading;
+using OpenMetaverse;
+namespace OpenSim.Region.ClientStack.LindenUDP
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public abstract class OpenSimUDPBase
+    {
+        // these abstract methods must be implemented in a derived class to actually do
+        // something with the packets that are sent and received.
+        protected abstract void PacketReceived(UDPPacketBuffer buffer);
+        protected abstract void PacketSent(UDPPacketBuffer buffer, int bytesSent);
+        // the port to listen on
+        internal int udpPort;
+        // the UDP socket
+        private Socket udpSocket;
+        // the ReaderWriterLock is used solely for the purposes of shutdown (Stop()).
+        // since there are potentially many "reader" threads in the internal .NET IOCP
+        // thread pool, this is a cheaper synchronization primitive than using
+        // a Mutex object.  This allows many UDP socket "reads" concurrently - when
+        // Stop() is called, it attempts to obtain a writer lock which will then
+        // wait until all outstanding operations are completed before shutting down.
+        // this avoids the problem of closing the socket with outstanding operations
+        // and trying to catch the inevitable ObjectDisposedException.
+        private ReaderWriterLock rwLock = new ReaderWriterLock();
+        // number of outstanding operations.  This is a reference count
+        // which we use to ensure that the threads exit cleanly. Note that
+        // we need this because the threads will potentially still need to process
+        // data even after the socket is closed.
+        private int rwOperationCount = 0;
+        // the all important shutdownFlag.  This is synchronized through the ReaderWriterLock.
+        private volatile bool shutdownFlag = true;
+        // the remote endpoint to communicate with
+        protected IPEndPoint remoteEndPoint = null;
+        /// <summary>
+        /// Initialize the UDP packet handler in server mode
+        /// </summary>
+        /// <param name="port">Port to listening for incoming UDP packets on</param>
+        public OpenSimUDPBase(int port)
+        {
+            udpPort = port;
+        }
+        /// <summary>
+        /// Initialize the UDP packet handler in client mode
+        /// </summary>
+        /// <param name="endPoint">Remote UDP server to connect to</param>
+        public OpenSimUDPBase(IPEndPoint endPoint)
+        {
+            remoteEndPoint = endPoint;
+            udpPort = 0;
+        }
+        /// <summary>
+        /// 
+        /// </summary>
+        public void Start()
+        {
+            if (shutdownFlag)
+            {
+                if (remoteEndPoint == null)
+                {
+                    // Server mode
+                    // create and bind the socket
+                    IPEndPoint ipep = new IPEndPoint(Settings.BIND_ADDR, udpPort);
+                    udpSocket = new Socket(
+                        AddressFamily.InterNetwork,
+                        SocketType.Dgram,
+                        ProtocolType.Udp);
+                    udpSocket.Bind(ipep);
+                }
+                else
+                {
+                    // Client mode
+                    IPEndPoint ipep = new IPEndPoint(Settings.BIND_ADDR, udpPort);
+                    udpSocket = new Socket(
+                        AddressFamily.InterNetwork,
+                        SocketType.Dgram,
+                        ProtocolType.Udp);
+                    udpSocket.Bind(ipep);
+                    //udpSocket.Connect(remoteEndPoint);
+                }
+                // we're not shutting down, we're starting up
+                shutdownFlag = false;
+                // kick off an async receive.  The Start() method will return, the
+                // actual receives will occur asynchronously and will be caught in
+                // AsyncEndRecieve().
+                AsyncBeginReceive();
+            }
+        }
+        /// <summary>
+        /// 
+        /// </summary>
+        public void Stop()
+        {
+            if (!shutdownFlag)
+            {
+                // wait indefinitely for a writer lock.  Once this is called, the .NET runtime
+                // will deny any more reader locks, in effect blocking all other send/receive
+                // threads.  Once we have the lock, we set shutdownFlag to inform the other
+                // threads that the socket is closed.
+                rwLock.AcquireWriterLock(-1);
+                shutdownFlag = true;
+                udpSocket.Close();
+                rwLock.ReleaseWriterLock();
+                // wait for any pending operations to complete on other
+                // threads before exiting.
+                const int FORCE_STOP = 100;
+                int i = 0;
+                while (rwOperationCount > 0 && i < FORCE_STOP)
+                {
+                    Thread.Sleep(10);
+                    ++i;
+                }
+                if (i >= FORCE_STOP)
+                {
+                    Logger.Log("UDPBase.Stop() forced shutdown while waiting on pending operations",
+                        Helpers.LogLevel.Warning);
+                }
+            }
+        }
+        /// <summary>
+        /// 
+        /// </summary>
+        public bool IsRunning
+        {
+            get { return !shutdownFlag; }
+        }
+        private void AsyncBeginReceive()
+        {
+            // this method actually kicks off the async read on the socket.
+            // we aquire a reader lock here to ensure that no other thread
+            // is trying to set shutdownFlag and close the socket.
+            rwLock.AcquireReaderLock(-1);
+            if (!shutdownFlag)
+            {
+                // increment the count of pending operations
+                Interlocked.Increment(ref rwOperationCount);
+                // allocate a packet buffer
+                //WrappedObject<UDPPacketBuffer> wrappedBuffer = Pool.CheckOut();
+                UDPPacketBuffer buf = new UDPPacketBuffer();
+                try
+                {
+                    // kick off an async read
+                    udpSocket.BeginReceiveFrom(
+                        //wrappedBuffer.Instance.Data,
+                        buf.Data,
+                        0,
+                        UDPPacketBuffer.BUFFER_SIZE,
+                        SocketFlags.None,
+                        //ref wrappedBuffer.Instance.RemoteEndPoint,
+                        ref buf.RemoteEndPoint,
+                        new AsyncCallback(AsyncEndReceive),
+                        //wrappedBuffer);
+                        buf);
+                }
+                catch (SocketException)
+                {
+                    // something bad happened
+                    //Logger.Log(
+                    //    "A SocketException occurred in UDPServer.AsyncBeginReceive()", 
+                    //    Helpers.LogLevel.Error, se);
+                    // an error occurred, therefore the operation is void.  Decrement the reference count.
+                    Interlocked.Decrement(ref rwOperationCount);
+                }
+            }
+            // we're done with the socket for now, release the reader lock.
+            rwLock.ReleaseReaderLock();
+        }
+        private void AsyncEndReceive(IAsyncResult iar)
+        {
+            // Asynchronous receive operations will complete here through the call
+            // to AsyncBeginReceive
+            // aquire a reader lock
+            rwLock.AcquireReaderLock(-1);
+            if (!shutdownFlag)
+            {
+                // get the buffer that was created in AsyncBeginReceive
+                // this is the received data
+                //WrappedObject<UDPPacketBuffer> wrappedBuffer = (WrappedObject<UDPPacketBuffer>)iar.AsyncState;
+                //UDPPacketBuffer buffer = wrappedBuffer.Instance;
+                UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
+                try
+                {
+                    // get the length of data actually read from the socket, store it with the
+                    // buffer
+                    buffer.DataLength = udpSocket.EndReceiveFrom(iar, ref buffer.RemoteEndPoint);
+                    // this operation is now complete, decrement the reference count
+                    Interlocked.Decrement(ref rwOperationCount);
+                    // we're done with the socket, release the reader lock
+                    rwLock.ReleaseReaderLock();
+                    // call the abstract method PacketReceived(), passing the buffer that
+                    // has just been filled from the socket read.
+                    PacketReceived(buffer);
+                }
+                catch (SocketException)
+                {
+                    // an error occurred, therefore the operation is void.  Decrement the reference count.
+                    Interlocked.Decrement(ref rwOperationCount);
+                    // we're done with the socket for now, release the reader lock.
+                    rwLock.ReleaseReaderLock();
+                }
+                finally
+                {
+                    // start another receive - this keeps the server going!
+                    AsyncBeginReceive();
+                    //wrappedBuffer.Dispose();
+                }
+            }
+            else
+            {
+                // nothing bad happened, but we are done with the operation
+                // decrement the reference count and release the reader lock
+                Interlocked.Decrement(ref rwOperationCount);
+                rwLock.ReleaseReaderLock();
+            }
+        }
+        public void AsyncBeginSend(UDPPacketBuffer buf)
+        {
+            rwLock.AcquireReaderLock(-1);
+            if (!shutdownFlag)
+            {
+                try
+                {
+                    Interlocked.Increment(ref rwOperationCount);
+                    udpSocket.BeginSendTo(
+                        buf.Data,
+                        0,
+                        buf.DataLength,
+                        SocketFlags.None,
+                        buf.RemoteEndPoint,
+                        new AsyncCallback(AsyncEndSend),
+                        buf);
+                }
+                catch (SocketException)
+                {
+                    //Logger.Log(
+                    //    "A SocketException occurred in UDPServer.AsyncBeginSend()",
+                    //    Helpers.LogLevel.Error, se);
+                }
+            }
+            rwLock.ReleaseReaderLock();
+        }
+        private void AsyncEndSend(IAsyncResult iar)
+        {
+            rwLock.AcquireReaderLock(-1);
+            if (!shutdownFlag)
+            {
+                UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
+                try
+                {
+                    int bytesSent = udpSocket.EndSendTo(iar);
+                    // note that call to the abstract PacketSent() method - we are passing the number
+                    // of bytes sent in a separate parameter, since we can't use buffer.DataLength which
+                    // is the number of bytes to send (or bytes received depending upon whether this
+                    // buffer was part of a send or a receive).
+                    PacketSent(buffer, bytesSent);
+                }
+                catch (SocketException)
+                {
+                    //Logger.Log(
+                    //    "A SocketException occurred in UDPServer.AsyncEndSend()",
+                    //    Helpers.LogLevel.Error, se);
+                }
+            }
+            Interlocked.Decrement(ref rwOperationCount);
+            rwLock.ReleaseReaderLock();
+        }
+    }
+}
author	Melanie	2009-10-08 22:25:14 +0100
committer	Melanie	2009-10-08 22:25:14 +0100
commit	a0dd9f4bb4c1a88c2692066c54923c7f91429df5 (patch)
tree	700b656c3662b62d73fe2c13894d1c57fab25197 /OpenSim
parent	Added guards against the exception reported: (diff)
download	opensim-SC_OLD-a0dd9f4bb4c1a88c2692066c54923c7f91429df5.zip opensim-SC_OLD-a0dd9f4bb4c1a88c2692066c54923c7f91429df5.tar.gz opensim-SC_OLD-a0dd9f4bb4c1a88c2692066c54923c7f91429df5.tar.bz2 opensim-SC_OLD-a0dd9f4bb4c1a88c2692066c54923c7f91429df5.tar.xz

diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs index 2c5ad85..1e6927f 100644 --- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs +++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
@@ -87,7 +87,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
87	/// The LLUDP server for a region. This handles incoming and outgoing	87	/// The LLUDP server for a region. This handles incoming and outgoing
88	/// packets for all UDP connections to the region	88	/// packets for all UDP connections to the region
89	/// </summary>	89	/// </summary>
90	public class LLUDPServer : UDPBase	90	public class LLUDPServer : OpenSimUDPBase
91	{	91	{
92	private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);	92	private static readonly ILog m_log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
93		93


diff --git a/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs b/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs new file mode 100644 index 0000000..aaefbc6 --- /dev/null +++ b/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs
@@ -0,0 +1,340 @@
		1	/*
		2	* Copyright (c) 2006, Clutch, Inc.
		3	* Original Author: Jeff Cesnik
		4	* All rights reserved.
		5	*
		6	* - Redistribution and use in source and binary forms, with or without
		7	* modification, are permitted provided that the following conditions are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright notice, this
		10	* list of conditions and the following disclaimer.
		11	* - Neither the name of the openmetaverse.org nor the names
		12	* of its contributors may be used to endorse or promote products derived from
		13	* this software without specific prior written permission.
		14	*
		15	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
		16	* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
		17	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
		18	* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
		19	* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
		20	* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
		21	* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
		22	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
		23	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
		24	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
		25	* POSSIBILITY OF SUCH DAMAGE.
		26	*/
		27
		28	using System;
		29	using System.Net;
		30	using System.Net.Sockets;
		31	using System.Threading;
		32	using OpenMetaverse;
		33
		34	namespace OpenSim.Region.ClientStack.LindenUDP
		35	{
		36	/// <summary>
		37	///
		38	/// </summary>
		39	public abstract class OpenSimUDPBase
		40	{
		41	// these abstract methods must be implemented in a derived class to actually do
		42	// something with the packets that are sent and received.
		43	protected abstract void PacketReceived(UDPPacketBuffer buffer);
		44	protected abstract void PacketSent(UDPPacketBuffer buffer, int bytesSent);
		45
		46	// the port to listen on
		47	internal int udpPort;
		48
		49	// the UDP socket
		50	private Socket udpSocket;
		51
		52	// the ReaderWriterLock is used solely for the purposes of shutdown (Stop()).
		53	// since there are potentially many "reader" threads in the internal .NET IOCP
		54	// thread pool, this is a cheaper synchronization primitive than using
		55	// a Mutex object. This allows many UDP socket "reads" concurrently - when
		56	// Stop() is called, it attempts to obtain a writer lock which will then
		57	// wait until all outstanding operations are completed before shutting down.
		58	// this avoids the problem of closing the socket with outstanding operations
		59	// and trying to catch the inevitable ObjectDisposedException.
		60	private ReaderWriterLock rwLock = new ReaderWriterLock();
		61
		62	// number of outstanding operations. This is a reference count
		63	// which we use to ensure that the threads exit cleanly. Note that
		64	// we need this because the threads will potentially still need to process
		65	// data even after the socket is closed.
		66	private int rwOperationCount = 0;
		67
		68	// the all important shutdownFlag. This is synchronized through the ReaderWriterLock.
		69	private volatile bool shutdownFlag = true;
		70
		71	// the remote endpoint to communicate with
		72	protected IPEndPoint remoteEndPoint = null;
		73
		74
		75	/// <summary>
		76	/// Initialize the UDP packet handler in server mode
		77	/// </summary>
		78	/// <param name="port">Port to listening for incoming UDP packets on</param>
		79	public OpenSimUDPBase(int port)
		80	{
		81	udpPort = port;
		82	}
		83
		84	/// <summary>
		85	/// Initialize the UDP packet handler in client mode
		86	/// </summary>
		87	/// <param name="endPoint">Remote UDP server to connect to</param>
		88	public OpenSimUDPBase(IPEndPoint endPoint)
		89	{
		90	remoteEndPoint = endPoint;
		91	udpPort = 0;
		92	}
		93
		94	/// <summary>
		95	///
		96	/// </summary>
		97	public void Start()
		98	{
		99	if (shutdownFlag)
		100	{
		101	if (remoteEndPoint == null)
		102	{
		103	// Server mode
		104
		105	// create and bind the socket
		106	IPEndPoint ipep = new IPEndPoint(Settings.BIND_ADDR, udpPort);
		107	udpSocket = new Socket(
		108	AddressFamily.InterNetwork,
		109	SocketType.Dgram,
		110	ProtocolType.Udp);
		111	udpSocket.Bind(ipep);
		112	}
		113	else
		114	{
		115	// Client mode
		116	IPEndPoint ipep = new IPEndPoint(Settings.BIND_ADDR, udpPort);
		117	udpSocket = new Socket(
		118	AddressFamily.InterNetwork,
		119	SocketType.Dgram,
		120	ProtocolType.Udp);
		121	udpSocket.Bind(ipep);
		122	//udpSocket.Connect(remoteEndPoint);
		123	}
		124
		125	// we're not shutting down, we're starting up
		126	shutdownFlag = false;
		127
		128	// kick off an async receive. The Start() method will return, the
		129	// actual receives will occur asynchronously and will be caught in
		130	// AsyncEndRecieve().
		131	AsyncBeginReceive();
		132	}
		133	}
		134
		135	/// <summary>
		136	///
		137	/// </summary>
		138	public void Stop()
		139	{
		140	if (!shutdownFlag)
		141	{
		142	// wait indefinitely for a writer lock. Once this is called, the .NET runtime
		143	// will deny any more reader locks, in effect blocking all other send/receive
		144	// threads. Once we have the lock, we set shutdownFlag to inform the other
		145	// threads that the socket is closed.
		146	rwLock.AcquireWriterLock(-1);
		147	shutdownFlag = true;
		148	udpSocket.Close();
		149	rwLock.ReleaseWriterLock();
		150
		151	// wait for any pending operations to complete on other
		152	// threads before exiting.
		153	const int FORCE_STOP = 100;
		154	int i = 0;
		155	while (rwOperationCount > 0 && i < FORCE_STOP)
		156	{
		157	Thread.Sleep(10);
		158	++i;
		159	}
		160
		161	if (i >= FORCE_STOP)
		162	{
		163	Logger.Log("UDPBase.Stop() forced shutdown while waiting on pending operations",
		164	Helpers.LogLevel.Warning);
		165	}
		166	}
		167	}
		168
		169	/// <summary>
		170	///
		171	/// </summary>
		172	public bool IsRunning
		173	{
		174	get { return !shutdownFlag; }
		175	}
		176
		177	private void AsyncBeginReceive()
		178	{
		179	// this method actually kicks off the async read on the socket.
		180	// we aquire a reader lock here to ensure that no other thread
		181	// is trying to set shutdownFlag and close the socket.
		182	rwLock.AcquireReaderLock(-1);
		183
		184	if (!shutdownFlag)
		185	{
		186	// increment the count of pending operations
		187	Interlocked.Increment(ref rwOperationCount);
		188
		189	// allocate a packet buffer
		190	//WrappedObject<UDPPacketBuffer> wrappedBuffer = Pool.CheckOut();
		191	UDPPacketBuffer buf = new UDPPacketBuffer();
		192
		193	try
		194	{
		195	// kick off an async read
		196	udpSocket.BeginReceiveFrom(
		197	//wrappedBuffer.Instance.Data,
		198	buf.Data,
		199	0,
		200	UDPPacketBuffer.BUFFER_SIZE,
		201	SocketFlags.None,
		202	//ref wrappedBuffer.Instance.RemoteEndPoint,
		203	ref buf.RemoteEndPoint,
		204	new AsyncCallback(AsyncEndReceive),
		205	//wrappedBuffer);
		206	buf);
		207	}
		208	catch (SocketException)
		209	{
		210	// something bad happened
		211	//Logger.Log(
		212	// "A SocketException occurred in UDPServer.AsyncBeginReceive()",
		213	// Helpers.LogLevel.Error, se);
		214
		215	// an error occurred, therefore the operation is void. Decrement the reference count.
		216	Interlocked.Decrement(ref rwOperationCount);
		217	}
		218	}
		219
		220	// we're done with the socket for now, release the reader lock.
		221	rwLock.ReleaseReaderLock();
		222	}
		223
		224	private void AsyncEndReceive(IAsyncResult iar)
		225	{
		226	// Asynchronous receive operations will complete here through the call
		227	// to AsyncBeginReceive
		228
		229	// aquire a reader lock
		230	rwLock.AcquireReaderLock(-1);
		231
		232	if (!shutdownFlag)
		233	{
		234	// get the buffer that was created in AsyncBeginReceive
		235	// this is the received data
		236	//WrappedObject<UDPPacketBuffer> wrappedBuffer = (WrappedObject<UDPPacketBuffer>)iar.AsyncState;
		237	//UDPPacketBuffer buffer = wrappedBuffer.Instance;
		238	UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
		239
		240	try
		241	{
		242	// get the length of data actually read from the socket, store it with the
		243	// buffer
		244	buffer.DataLength = udpSocket.EndReceiveFrom(iar, ref buffer.RemoteEndPoint);
		245
		246	// this operation is now complete, decrement the reference count
		247	Interlocked.Decrement(ref rwOperationCount);
		248
		249	// we're done with the socket, release the reader lock
		250	rwLock.ReleaseReaderLock();
		251
		252	// call the abstract method PacketReceived(), passing the buffer that
		253	// has just been filled from the socket read.
		254	PacketReceived(buffer);
		255	}
		256	catch (SocketException)
		257	{
		258	// an error occurred, therefore the operation is void. Decrement the reference count.
		259	Interlocked.Decrement(ref rwOperationCount);
		260
		261	// we're done with the socket for now, release the reader lock.
		262	rwLock.ReleaseReaderLock();
		263	}
		264	finally
		265	{
		266	// start another receive - this keeps the server going!
		267	AsyncBeginReceive();
		268
		269	//wrappedBuffer.Dispose();
		270	}
		271	}
		272	else
		273	{
		274	// nothing bad happened, but we are done with the operation
		275	// decrement the reference count and release the reader lock
		276	Interlocked.Decrement(ref rwOperationCount);
		277	rwLock.ReleaseReaderLock();
		278	}
		279	}
		280
		281	public void AsyncBeginSend(UDPPacketBuffer buf)
		282	{
		283	rwLock.AcquireReaderLock(-1);
		284
		285	if (!shutdownFlag)
		286	{
		287	try
		288	{
		289	Interlocked.Increment(ref rwOperationCount);
		290	udpSocket.BeginSendTo(
		291	buf.Data,
		292	0,
		293	buf.DataLength,
		294	SocketFlags.None,
		295	buf.RemoteEndPoint,
		296	new AsyncCallback(AsyncEndSend),
		297	buf);
		298	}
		299	catch (SocketException)
		300	{
		301	//Logger.Log(
		302	// "A SocketException occurred in UDPServer.AsyncBeginSend()",
		303	// Helpers.LogLevel.Error, se);
		304	}
		305	}
		306
		307	rwLock.ReleaseReaderLock();
		308	}
		309
		310	private void AsyncEndSend(IAsyncResult iar)
		311	{
		312	rwLock.AcquireReaderLock(-1);
		313
		314	if (!shutdownFlag)
		315	{
		316	UDPPacketBuffer buffer = (UDPPacketBuffer)iar.AsyncState;
		317
		318	try
		319	{
		320	int bytesSent = udpSocket.EndSendTo(iar);
		321
		322	// note that call to the abstract PacketSent() method - we are passing the number
		323	// of bytes sent in a separate parameter, since we can't use buffer.DataLength which
		324	// is the number of bytes to send (or bytes received depending upon whether this
		325	// buffer was part of a send or a receive).
		326	PacketSent(buffer, bytesSent);
		327	}
		328	catch (SocketException)
		329	{
		330	//Logger.Log(
		331	// "A SocketException occurred in UDPServer.AsyncEndSend()",
		332	// Helpers.LogLevel.Error, se);
		333	}
		334	}
		335
		336	Interlocked.Decrement(ref rwOperationCount);
		337	rwLock.ReleaseReaderLock();
		338	}
		339	}
		340	}