StructuralJob


1   package org.oddjob.framework;
2   
3   
4   import java.util.Date  ;
5   
6   import org.apache.log4j.MDC;
7   import org.oddjob.Resetable;
8   import org.oddjob.Stateful;
9   import org.oddjob.Structural;
10  import org.oddjob.images.IconHelper;
11  import org.oddjob.logging.Log4jArchiver;
12  import org.oddjob.state.AbstractJobStateListener;
13  import org.oddjob.structural.StatefulChildHelper;
14  import org.oddjob.structural.StructuralListener;
15  import org.oddjob.util.OddjobLockedException;
16  
17  /**
18   * An abstract implementation of a job which provides commen functionality to
19   * concrete sub classes.
20   * 
21   * @author Rob Gordon
22   */
23  
24  public abstract class StructuralJob extends BasePrimary
25          implements 
26              Runnable  , Resetable, Stateful, Structural {
27  
28      /**
29       * Intended to be used by decendent classes to
30       * help implement Structural.
31       */
32      protected StatefulChildHelper childHelper;
33              
34      /** Use to suppress child state changes when executing. */ 
35      private volatile boolean executing;
36      
37      public StructuralJob() {
38          completeConstruction();
39      }
40      
41      /**
42       * Complete construction after constructor or 
43       * maybe one day deserialisation.
44       *
45       */
46      private void completeConstruction() {
47          childHelper = new StatefulChildHelper(this);
48          childHelper.addJobStateListener(new AbstractJobStateListener() {
49              protected void jobStateReady(Stateful source, Date   time) {
50                  if (!executing) {
51                      StructuralJob.super.setJobStateReady();
52                      logger().info("Job [" + StructuralJob.this 
53                              + "] Ready.");
54                  }
55              }
56              protected void jobStateComplete(Stateful source, Date   time) {
57                  if (!executing) {
58                      StructuralJob.super.setJobStateComplete();
59                      logger().info("Job [" + StructuralJob.this 
60                              + "] Complete.");
61                  }
62              }
63              protected void jobStateNotComplete(Stateful source, Date   time) {
64                  if (!executing) {
65                      StructuralJob.super.setJobStateNotComplete();
66                      logger().info("Job [" + StructuralJob.this 
67                              + "] Not Complete.");
68                  }
69              }
70              /* (non-Javadoc)
71               * @see org.oddjob.state.AbstractJobStateListener#jobStateException(org.oddjob.Stateful, java.util.Date, java.lang.Throwable)
72               */
73              protected void jobStateException(Stateful source, Date   time,
74                      Throwable   throwable) {
75                  if (!executing) {
76                      StructuralJob.super.setJobStateException(throwable);
77                      logger().warn("Job [" + StructuralJob.this 
78                              + "] Exception.", throwable);
79                  }
80              }
81          });
82      }
83      
84      
85      /*
86       *  (non-Javadoc)
87       * @see org.oddjob.framework.BaseComponent#independant()
88       */
89      protected boolean independant() {
90          return true;
91      }
92          
93      /**
94       * Execute this job.
95       * 
96       * @throws Exception If the unexpected occurs.
97       */
98      abstract protected void execute() throws Throwable  ;
99  
100     /**
101      * Implement the main execute method for a job. This surrounds the 
102      * doExecute method of the sub class and sets state for the job.
103      */
104     public final void run() throws OddjobLockedException {
105         lock.accquire("Job executing.");
106         String   oldMDC = (String  )MDC.get(Log4jArchiver.MDC);
107         try {
108             MDC.put(Log4jArchiver.MDC, getLogger());
109             if (!stateHandler.requestJobStateExecuting()) { 
110                 logger().debug("Can't execute job [" + this + "] because state is ["
111                         + stateHandler.getJobState() + "]");
112                 return;
113             }
114             iconHelper.changeIcon(IconHelper.EXECUTING);
115             executing = true;
116             
117             // runtime configuration.
118             if (!configure()) {
119                 executing = false;
120                 return;
121             }
122             
123             logger().info("Executing job [" + this + "]");
124             try {
125                 execute();
126                 // we ignore state while executing but now we need to update.
127                 // dependent on our child states.
128                 // synchronize so this updates before any child states trigger.
129                 synchronized (stateHandler) {
130                     executing = false;
131                     childHelper.refreshState();                 
132                 }
133             }
134             catch (Throwable   e) {
135                 executing = false;
136                 logger().warn("Job Exception in [" + this + "]", e);
137                 setJobStateException(e);
138             }   
139         }
140         finally {
141             if (oldMDC != null) {
142                 MDC.put(Log4jArchiver.MDC, oldMDC);
143             }
144             else {
145                 MDC.remove(Log4jArchiver.MDC);
146             }
147             lock.release();
148         }
149     }
150     
151     /**
152      * Implementation for a typical stop. Subclasses must implement 
153      * Stoppable to take advantage of it.
154      * <p>
155      * This stop implementation doesn't check that the job is 
156      * executing as stop messages must cascade down the hierarchy
157      * to manually started jobs.
158      */
159     public void stop() {
160         if (destroyed) {
161             throw new IllegalStateException  ("[" + this + "] destroyed");
162         }
163         logger().debug("Thread [" + Thread.currentThread().getName() 
164                 + "] requested [" + getName() + "] stop.");
165         
166         if (iconHelper.currentId()== IconHelper.EXECUTING) {
167             iconHelper.changeIcon(IconHelper.STOPPING);
168         }
169         
170         stop = true;
171         childHelper.stopChildren();
172         
173         synchronized (this) {
174             notifyAll();
175         }
176     }
177     
178     /**
179      * Perform a soft reset on the job.
180      */
181     public void softReset() {
182         lock.accquire("Soft Reset in progress.");
183         try {
184             childHelper.softResetChildren();
185             stop = false;
186         } finally { 
187             lock.release();
188         }
189     }
190     
191     /**
192      * Perform a hard reset on the job.
193      */
194     public void hardReset() {
195         lock.accquire("Hard Reset in progress.");
196         try {
197             childHelper.hardResetChildren();
198             stop = false;
199         } finally {
200             lock.release();
201         }
202     }
203 
204     /**
205      * Add a listener. The listener will immediately recieve add
206      * notifications for all existing children.
207      * 
208      * @param listener The listener.
209      */ 
210     public void addStructuralListener(StructuralListener listener) {
211         if (destroyed) {
212             throw new IllegalStateException  ("[" + this + "] destroyed");
213         }
214         childHelper.addStructuralListener(listener);
215     }
216     
217     /**
218      * Remove a listener.
219      * 
220      * @param listener The listner.
221      */
222     public void removeStructuralListener(StructuralListener listener) {
223         childHelper.removeStructuralListener(listener);
224     }   
225     
226     /**
227      * Destroy this component.
228      */
229     public void onDestroy() {
230         childHelper.destroyAll();
231     }
232         
233 }
234
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags