Home | History | Annotate | Download | only in exit 
      1 /* Copyright (C) 2003 Vladimir Roubtsov. All rights reserved.
      2  *
      3  * This program and the accompanying materials are made available under
      4  * the terms of the Common Public License v1.0 which accompanies this distribution,
      5  * and is available at http://www.eclipse.org/legal/cpl-v10.html
      6  *
      7  * $Id: ExitHookManager.java,v 1.1.1.1 2004/05/09 16:57:58 vlad_r Exp $
      8  */
      9 package com.vladium.util.exit;
     10 
     11 import java.util.HashMap;
     12 import java.util.Map;
     13 
     14 import com.vladium.util.IJREVersion;
     15 import com.vladium.util.Property;
     16 import com.vladium.emma.IAppConstants;
     17 
     18 // ----------------------------------------------------------------------------
     19 /**
     20  * @author Vlad Roubtsov, (C) 2003
     21  */
     22 public
     23 abstract class ExitHookManager implements IJREVersion
     24 {
     25     // public: ................................................................
     26 
     27     // TOTO: handle thread groups as well?
     28 
     29     public abstract boolean addExitHook (Runnable runnable);
     30     public abstract boolean removeExitHook (Runnable runnable);
     31 
     32     public static synchronized ExitHookManager getSingleton ()
     33     {
     34         if (s_singleton == null)
     35         {
     36             if (JRE_1_3_PLUS)
     37             {
     38                 s_singleton = new JRE13ExitHookManager ();
     39             }
     40             else
     41             {
     42                 throw new UnsupportedOperationException ("no shutdown hook manager available [JVM: " + Property.getSystemFingerprint () + "]");
     43             }
     44         }
     45 
     46         return s_singleton;
     47     }
     48 
     49     // protected: .............................................................
     50 
     51 
     52     protected ExitHookManager () {}
     53 
     54     // package: ...............................................................
     55 
     56     // private: ...............................................................
     57 
     58 
     59     private static final class JRE13ExitHookManager extends ExitHookManager
     60     {
     61         public synchronized boolean addExitHook (final Runnable runnable)
     62         {
     63             if ((runnable != null) && ! m_exitThreadMap.containsKey (runnable))
     64             {
     65                 final Thread exitThread = new Thread (runnable, IAppConstants.APP_NAME + " shutdown handler thread");
     66 
     67                 try
     68                 {
     69                     Runtime.getRuntime ().addShutdownHook (exitThread);
     70                     m_exitThreadMap.put (runnable, exitThread); // TODO: use identity here
     71 
     72                     return true;
     73                 }
     74                 catch (Exception e)
     75                 {
     76                     System.out.println ("exception caught while adding a shutdown hook:");
     77                     e.printStackTrace (System.out);
     78                 }
     79             }
     80 
     81             return false;
     82         }
     83 
     84         public synchronized boolean removeExitHook (final Runnable runnable)
     85         {
     86             if (runnable != null)
     87             {
     88                 final Thread exitThread = (Thread) m_exitThreadMap.get (runnable);  // TODO: use identity here
     89 
     90                 if (exitThread != null)
     91                 {
     92                     try
     93                     {
     94                         Runtime.getRuntime ().removeShutdownHook (exitThread);
     95                         m_exitThreadMap.remove (runnable);
     96 
     97                         return true;
     98                     }
     99                     catch (Exception e)
    100                     {
    101                         System.out.println ("exception caught while removing a shutdown hook:");
    102                         e.printStackTrace (System.out);
    103                     }
    104                 }
    105             }
    106 
    107             return false;
    108         }
    109 
    110         JRE13ExitHookManager ()
    111         {
    112             m_exitThreadMap = new HashMap ();
    113         }
    114 
    115 
    116         private final Map /* Runnable->Thread */ m_exitThreadMap;
    117 
    118     } // end of nested class
    119 
    120     private static ExitHookManager s_singleton;
    121 
    122 } // end of class
    123 // ----------------------------------------------------------------------------
    124