aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/OpenSim/Region/ClientStack/LindenUDP/OpenSimUDPBase.cs
blob: aaefbc6ce3746d2fc271ebfe5c01b883b362189b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
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();
        }
    }
}