/*
* Created on 18-Sep-2004
* Created by Paul Gardner
* Copyright (C) 2004, 2005, 2006 Aelitis, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package org.gudy.azureus2.core3.util;
/**
* @author parg
*
*/
import java.util.*;
public class
AEMonitor
extends AEMonSem
{
private int dont_wait = 1;
private int nests = 0;
private int total_reserve = 0;
private int total_release = 1;
protected Thread owner;
protected Thread last_waiter;
public
AEMonitor(
String _name )
{
super( _name, true );
}
public void
enter()
{
// if ( DEBUG ){
//
// debugEntry();
// }
Thread current_thread = Thread.currentThread();
synchronized( this ){
entry_count++;
if ( owner == current_thread ){
nests++;
}else{
if ( dont_wait == 0 ){
try{
waiting++;
last_waiter = current_thread;
if ( waiting > 1 ){
// System.out.println( "AEMonitor: " + name + " contended" );
}
// we can get spurious wakeups (see Object javadoc) so we need to guard against
// their possibility
int spurious_count = 0;
while( true ){
wait();
if ( total_reserve == total_release ){
spurious_count++;
if ( spurious_count > 1024 ){
waiting--;
// Debug.out( "AEMonitor: spurious wakeup limit exceeded" );
throw( new Throwable( "die die die" ));
}else{
// Debug.out("AEMonitor: spurious wakeup, ignoring" );
}
}else{
break;
}
}
total_reserve++;
}catch( Throwable e ){
// we know here that someone's got a finally clause to do the
// balanced 'exit'. hence we should make it look as if we own it...
waiting--;
owner = current_thread;
// Debug.out( "**** monitor interrupted ****" );
throw( new RuntimeException("AEMonitor:interrupted" ));
}finally{
last_waiter = null;
}
}else{
total_reserve++;
dont_wait--;
}
owner = current_thread;
}
}
}
/*
* Try and obtain it
* @return true if got monitor, false otherwise
*/
public boolean
enter(
int max_millis )
{
// if ( DEBUG ){
//
// debugEntry();
// }
Thread current_thread = Thread.currentThread();
synchronized( this ){
entry_count++;
if ( owner == current_thread ){
nests++;
}else{
if ( dont_wait == 0 ){
try{
waiting++;
last_waiter = current_thread;
wait( max_millis );
if ( total_reserve == total_release ){
// failed to obtain it, so we need to mark ourselves as no
// longer waiting
waiting--;
return( false );
}
total_reserve++;
}catch( Throwable e ){
// we know here that someone's got a finally clause to do the
// balanced 'exit'. hence we should make it look as if we own it...
waiting--;
owner = current_thread;
// Debug.out( "**** monitor interrupted ****" );
throw( new RuntimeException("AEMonitor:interrupted" ));
}finally{
last_waiter = null;
}
}else{
total_reserve++;
dont_wait--;
}
owner = current_thread;
}
}
return( true );
}
public void
exit()
{
try{
synchronized( this ){
if ( nests > 0 ){
// if ( DEBUG ){
//
// if ( owner != Thread.currentThread()){
//
// Debug.out( "nested exit but current thread not owner");
// }
// }
nests--;
}else{
owner = null;
total_release++;
if ( waiting != 0 ){
waiting--;
notify();
}else{
dont_wait++;
if ( dont_wait > 1 ){
// Debug.out( "**** AEMonitor '" + name + "': multiple exit detected" );
}
}
}
}
}finally{
// if ( DEBUG ){
//
// debugExit();
// }
}
}
public boolean
isHeld()
{
return( owner == Thread.currentThread());
}
public boolean
hasWaiters()
{
synchronized( this ){
return( waiting > 0 );
}
}
public static Map
getSynchronisedMap(
Map m )
{
return( Collections.synchronizedMap(m));
}
}