Coverage Report - org.mule.impl.ThreadSafeAccess
 
Classes in this File Line Coverage Branch Coverage Complexity
ThreadSafeAccess
N/A
N/A
1
 
 1  
 /*
 2  
  * $Id: ThreadSafeAccess.java 7976 2007-08-21 14:26:13Z dirk.olmes $
 3  
  * --------------------------------------------------------------------------------------
 4  
  * Copyright (c) MuleSource, Inc.  All rights reserved.  http://www.mulesource.com
 5  
  *
 6  
  * The software in this package is published under the terms of the CPAL v1.0
 7  
  * license, a copy of which has been included with this distribution in the
 8  
  * LICENSE.txt file.
 9  
  */
 10  
 
 11  
 package org.mule.impl;
 12  
 
 13  
 /**
 14  
  * Interface implemented by message-related objects that avoid exposing mutable data to multiple threads
 15  
  * by providing immutable copies.  This interface is optional - it is an implementation detail that is
 16  
  * tested for dynamically and used only if available.
 17  
  *
 18  
  * <p>To avoid "scribbling" where several threads change state within in a single method (typically
 19  
  * in inconsistent ways, causing subtle and intermittent errors) we use the following access policy for
 20  
  * message related objects:</p>
 21  
  *
 22  
  * <ul>
 23  
  *
 24  
  * <li>A new object is "unbound" and "mutable".</li>
 25  
  *
 26  
  * <li>An object is "bound" to the first thread that calls the object after it is created.</li>
 27  
  *
 28  
  * <li>A "mutable" object can be modified only by the thread to which it is bound.</li>
 29  
  *
 30  
  * <li>An object is "sealed" (no longer "mutable") when it is accessed by a thread other than the
 31  
  * thread to which it is "bound".  It is an error to attempt to change a "sealed" object.</li>
 32  
  *
 33  
  * </ul>
 34  
  *
 35  
  * <p>In practice this means that objects are initially mutable, but become immutable once they are
 36  
  * shared.</p>
 37  
  */
 38  
 public interface ThreadSafeAccess
 39  
 {
 40  
 
 41  
     /**
 42  
      * This method may be called before data in the object are accessed.  It should verify that the
 43  
      * access policy is followed correctly (if not, a runtime exception may be thrown).
 44  
      *
 45  
      * @param write True if the access will mutate values.
 46  
      */
 47  
     void assertAccess(boolean write);
 48  
 
 49  
     /**
 50  
      * This method should ONLY be used in the construction of composite ThreadSafeAccess instances.
 51  
      * For example, a ThreadSafeAccess UMOEvent contains a ThreadSafeAccess UMOMessageAdapter. During
 52  
      * the construction of the event, the message adapter may be bound to the contructing thread.
 53  
      * Calling this method releases that binding so that the event as a whole can be passed to a new
 54  
      * thread unbound.
 55  
      */
 56  
     void resetAccessControl();
 57  
 
 58  
     /**
 59  
      * @return A new instance of the implementing class, unbound to any thread and mutable.
 60  
      */
 61  
     ThreadSafeAccess newThreadCopy();
 62  
 
 63  
 }