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SocketListener.d

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00001 /*******************************************************************************
00002 
00003         @file SocketListener.d
00004         
00005         Copyright (C) 2004 Kris Bell
00006         
00007         This software is provided 'as-is', without any express or implied
00008         warranty. In no event will the authors be held liable for damages
00009         of any kind arising from the use of this software.
00010         
00011         Permission is hereby granted to anyone to use this software for any 
00012         purpose, including commercial applications, and to alter it and/or 
00013         redistribute it freely, subject to the following restrictions:
00014         
00015         1. The origin of this software must not be misrepresented; you must 
00016            not claim that you wrote the original software. If you use this 
00017            software in a product, an acknowledgment within documentation of 
00018            said product would be appreciated but is not required.
00019 
00020         2. Altered source versions must be plainly marked as such, and must 
00021            not be misrepresented as being the original software.
00022 
00023         3. This notice may not be removed or altered from any distribution
00024            of the source.
00025 
00026 
00027                         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
00028 
00029 
00030         @version        Initial version, June 2004      
00031         @author         Kris
00032 
00033 
00034 *******************************************************************************/
00035 
00036 module mango.io.SocketListener;
00037 
00038 private import  std.thread;
00039 
00040 private import  mango.io.Socket;
00041 
00042 private import  mango.io.model.IBuffer,
00043                 mango.io.model.IWriter;
00044 
00045 /******************************************************************************
00046 
00047         Abstract class to asynchronously listen for incoming data on a 
00048         socket. This can be used with DatagramSocket & MulticastSocket, 
00049         and might possibly be useful with a basic SocketConduit also.
00050         Note that DatagramSocket must first be bound to a local network
00051         address via bind(), and MulticastSocket should first be made a 
00052         member of a multicast group via its join() method. Note also
00053         that the underlying thread is not started by the constructor;
00054         you should do that manually via the start() method.
00055 
00056 ******************************************************************************/
00057 
00058 //version = AltListener;
00059 
00060 version (AltListener)
00061          alias Object FOO;
00062         else
00063          alias Thread FOO;
00064 
00065 class SocketListener : FOO, IListener
00066 {
00067         private bool                    quit;
00068         private IBuffer                 buffer;
00069         private ISocketReader           reader;
00070         private int                     limit = 3;
00071 
00072         /**********************************************************************
00073                
00074                 Construct a listener with the requisite arguments. The
00075                 specified buffer is populated via the provided instance
00076                 of ISocketReader before being passed to the notify()
00077                 method. All arguments are required.
00078 
00079         **********************************************************************/
00080 
00081         this (ISocketReader reader, IBuffer buffer)
00082         in {
00083            assert (reader);
00084            assert (buffer);
00085            }
00086         body
00087         {
00088                 this.buffer = buffer;
00089                 this.reader = reader;
00090                 version (AltListener)
00091                         {
00092                         Thread t = new Thread (&run);
00093                         t.start();
00094                         }
00095         }
00096 
00097         version (AltListener)
00098                  void start(){}
00099 
00100         /***********************************************************************
00101                 
00102                 Notification callback invoked whenever the listener has
00103                 anything to report. The buffer will have whatever content
00104                 was available from the read() operation
00105 
00106         ***********************************************************************/
00107 
00108         abstract void notify (IBuffer buffer);
00109 
00110         /***********************************************************************
00111 
00112                 Handle error conditions from the listener thread.
00113 
00114         ***********************************************************************/
00115 
00116         abstract void exception (char[] msg);
00117 
00118         /**********************************************************************
00119              
00120                 Cancel this listener. The thread will quit only after the 
00121                 current read() request responds, or is interrrupted.
00122 
00123         **********************************************************************/
00124 
00125         void cancel ()
00126         {
00127                 quit = true;
00128         }
00129 
00130         /**********************************************************************
00131              
00132                 Set the maximum contiguous number of exceptions this 
00133                 listener will survive. Setting a limit of zero will 
00134                 not survive any errors at all, whereas a limit of two
00135                 will survive as long as two consecutive errors don't 
00136                 arrive back to back.
00137 
00138         **********************************************************************/
00139 
00140         void setErrorLimit (ushort limit)
00141         {
00142                 this.limit = limit + 1;
00143         }
00144 
00145         /**********************************************************************
00146 
00147                 Execution of this thread is typically stalled on the
00148                 read() method belonging to the ISocketReader specified
00149                 during construction. You can invoke cancel() to indicate
00150                 execution should not proceed further, but that will not
00151                 actually interrupt a blocked read() operation.
00152 
00153                 Note that exceptions are all directed towards the handler
00154                 implemented by the class instance. 
00155 
00156         **********************************************************************/
00157 
00158         int run ()
00159         {
00160                 int lives = limit;
00161 
00162                 while (lives > 0)
00163                        try {
00164                            // start with a clean slate
00165                            buffer.clear ();
00166 
00167                            // wait for incoming content
00168                            reader.read (buffer);
00169 
00170                            // time to quit? Note that a v0.95 compiler bug 
00171                            // prohibits 'break' from exiting the try{} block
00172                            if (quit || Socket.isCancelled ())
00173                                lives = 0;
00174                            else
00175                               {
00176                               // invoke callback                        
00177                               notify (buffer);
00178                               lives = limit;
00179                               }
00180                            } catch (Object x)
00181                                     // time to quit?
00182                                     if (quit || Socket.isCancelled ())
00183                                         break;
00184                                     else
00185                                        {
00186                                        exception (x.toString);
00187                                        if (--lives == 0)
00188                                            exception ("listener thread aborting");
00189                                        }
00190                 version (TraceLinux)
00191                         {
00192                         printf ("SocketListener exiting\n");
00193                         }
00194                 return 0;
00195         }
00196 }
00197 
00198 
00199 

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