bml_realizer: bml_realizer/src/edu/wpi/hri/bml/net/PetriPart.java Source File

00001 /*
00002  * Software License Agreement (BSD License)
00003  *
00004  *  Copyright (c) 2010, Worcester Polytechnic Institute
00005  *  All rights reserved.
00006  *
00007  *  Redistribution and use in source and binary forms, with or without
00008  *  modification, are permitted provided that the following conditions
00009  *  are met:
00010  *
00011  *   * Redistributions of source code must retain the above copyright
00012  *     notice, this list of conditions and the following disclaimer.
00013  *   * Redistributions in binary form must reproduce the above
00014  *     copyright notice, this list of conditions and the following
00015  *     disclaimer in the documentation and/or other materials provided
00016  *     with the distribution.
00017  *   * Neither the name of Worcester Polytechnic Institute. nor the names
00018  *     of its contributors may be used to endorse or promote products
00019  *     derived from this software without specific prior written permission.
00020  *
00021  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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00023  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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00034 package edu.wpi.hri.bml.net;
00035 
00036 import java.util.List;
00037 import java.util.Set;
00038 
00039 import edu.wpi.hri.log.Logger;
00040 import edu.wpi.hri.log.Logger.Colors;
00041 import edu.wpi.hri.log.Logger.LoggerLevel;
00042 
00050 public abstract class PetriPart {
00051 
00052         protected final Logger logger;
00053         protected final Thread thread;
00054         private boolean success;
00055         protected boolean status;
00056 
00067         protected PetriPart(ThreadGroup group, Logger sublog, String name) {
00068                 this.logger = sublog.sub(Colors.PETRI_NET, name);
00069                 this.success = false;
00070                 this.status = true;
00071                 this.thread = new Thread(group, name) {
00072 
00073                         @Override
00074                         public void run() {
00075                                 // wait to hear the start of the execution of this part
00076                                 synchronized (thread) {
00077                                         logger.debug(LoggerLevel.BML_EXECUTION,
00078                                                         "Waiting for previous parts");
00079                                         do {
00080                                                 try {
00081                                                         thread.wait();
00082                                                 } catch (InterruptedException e) {
00083                                                 }
00084                                         } while (!shouldExecute());
00085                                 }
00086                                 logger.debug(LoggerLevel.BML_EXECUTION, "Executing ... ");
00087                                 // then execute the transition or place
00088                                 if (status) {
00089                                         try {
00090                                                 execute();
00091                                                 success = true;
00092                                         } catch (PetriException e) {
00093                                                 success = false;
00094                                         }
00095                                 }
00096                                 logger.debug(LoggerLevel.BML_EXECUTION,
00097                                                 "Completed with status [" + success + "]");
00098 
00099                                 // send the signals to the next parts so that they may begin
00100                                 sendTokens();
00101                         }
00102                 };
00103                 this.thread.start();
00104         }
00105 
00106         private final void receiveToken(PetriPart from, boolean status) {
00107                 this.status = this.status && status;
00108                 if (this.status) {
00109                         tokenFrom(from);
00110                 }
00111                 this.start();
00112         }
00113 
00114         private final boolean shouldExecute() {
00115                 return (!status) || checkRequirements();
00116         }
00117 
00125         protected abstract boolean checkRequirements();
00126 
00135         protected abstract void execute() throws PetriException;
00136 
00141         protected abstract void sendTokens();
00142 
00149         protected abstract void tokenFrom(PetriPart from);
00150 
00158         protected final void sendTokensTo(Set<? extends PetriPart> parts) {
00159                 logger.debug(LoggerLevel.BML_EXECUTION, "Sending all tokens ...");
00160                 for (PetriPart pp : parts) {
00161                         logger.debug(LoggerLevel.BML_EXECUTION, "Sent a token");
00162                         pp.receiveToken(this, success && status);
00163                 }
00164         }
00165 
00170         public void start() {
00171                 synchronized (thread) {
00172                         logger.debug(LoggerLevel.BML_EXECUTION,
00173                                         "Sending start notification");
00174                         thread.notifyAll();
00175                 }
00176         }
00177 
00181         public byte finish() {
00182                 try {
00183                         this.thread.join();
00184                 } catch (InterruptedException e) {
00185                 }
00186                 logger.debug(LoggerLevel.BML_EXECUTION, "Thread terminated");
00187                 return 1;
00188         }
00189 
00190         public abstract boolean existsCycle(List<PetriPart> beento);
00191 }