1 files changed, 136 insertions, 0 deletions
diff --git a/java/src/TimedWait.java b/java/src/TimedWait.java
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+++ b/java/src/TimedWait.java
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+/*************************************************
+ *
+ * = PACKAGE
+ *    ACE.ASX
+ *
+ * = FILENAME
+ *    TimedWait.java
+ *
+ *@author Prashant Jain and Doug Schmidt
+ *
+ *************************************************/
+package ACE.ASX;
+
+import ACE.Reactor.*;
+
+public abstract class TimedWait
+{
+  /**
+   * Default Constructor. Sets "this" to be used for the delegation of
+   * the wait() call to. 
+   */
+  public TimedWait ()
+  {
+    object_ = this;
+  }
+
+  /**
+   * Constructor. Allows subclasses to supply us with an Object that
+   * is delegated the wait() call.
+   *@param obj The Object that is delegated the wait() call.
+   */
+  public TimedWait (Object obj)
+  {
+    object_ = obj;
+  }
+
+  /**
+   * Hook method that needs to be implemented by subclasses.
+   */
+  public abstract boolean condition ();
+
+  /**
+   * Wait until condition becomes true. Note that the method
+   * blocks. Also note that this method is final to ensure that no one
+   * overrides it. 
+   * IMPORTANT: This method assumes it is called with the object_'s
+   * monitor lock already held.
+   */
+  public final void timedWait () throws InterruptedException
+  {
+    // Acquire the monitor lock.
+    if (!condition ()) 
+      {
+	// Only attempt to perform the wait if the condition isn't
+	// true initially.
+	for (;;) 
+	  {
+	    // Wait until we are notified.
+	    object_.wait ();
+
+	  // Recheck the condition.
+	  if (condition ()) 
+	    break; // Condition became true.
+	  // else we were falsely notified so go back into wait
+	  }
+      }
+  }
+
+  /**
+   * Template Method that implements the actual timed wait. Note that
+   * this method is final to ensure that no one overrides it. 
+   * IMPORTANT: This method assumes it is called with the object_'s
+   * monitor lock already held.
+   *@param tv Amount of time to do wait for.
+   */
+  public final void timedWait (TimeValue tv)
+    throws InterruptedException,
+           TimeoutException 
+  {
+    // Acquire the monitor lock.
+    if (!condition ()) 
+      {
+	// Only attempt to perform the timed wait if the condition isn't
+	// true initially.
+	long start = System.currentTimeMillis ();
+	long waitTime = tv.getMilliTime ();
+
+	for (;;) {
+	  // Wait until we are notified.
+	  object_.wait (waitTime);
+
+	  // Recheck the condition.
+	  if (!condition ()) {
+	    long now = System.currentTimeMillis ();
+	    long timeSoFar = now - start;
+
+	    // Timed out!
+	    if (timeSoFar >= tv.getMilliTime ()) 
+	      throw new TimeoutException ();
+	    else 
+	      // We still have some time left to wait, so adjust the
+	      // wait_time.
+	      waitTime = tv.getMilliTime () - timeSoFar; 
+	  }
+	  else
+	    break;  // Condition became true.
+	}
+      }
+  }
+
+  /**
+   * Notify any one thread waiting on the object_.  
+   * IMPORTANT: This method assumes it is called with the object_'s
+   * monitor lock already held.
+   */
+  public final void signal () {
+    object_.notify ();
+  }
+
+  /**
+   * Notify all threads waiting on the object_.  
+   * IMPORTANT: This method assumes it is called with the object_'s
+   * monitor lock already held.
+   */
+  public final void broadcast () {
+    object_.notifyAll ();
+  }
+
+  /** 
+   * The object we delegate to. If a subclass gives us a particular
+   * object,  we use that to delegate to, otherwise, we ``delegate''
+   * to ourself (i.e., this).
+   */
+  protected Object object_;
+
+}