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Fix for bug #2944, reported by David Holmes <dholmes@dltech.com.au>

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2003-10-21  Sascha Brawer  <brawer@dandelis.ch>

	Fix for bug #2944, reported by David Holmes <dholmes@dltech.com.au>
        * java/util/logging/ErrorManager.java (everUsed): Made volatile.
        (error): Synchronize on instance, not class.

From-SVN: r72750
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Sascha Brawer 2003-10-21 15:25:46 +02:00 committed by Michael Koch
parent 63d8374488
commit 75a5a481c2
2 changed files with 24 additions and 3 deletions
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6
libjava/ChangeLog
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@ -1,3 +1,9 @@
2003-10-21 Sascha Brawer <brawer@dandelis.ch>
Fix for bug #2944, reported by David Holmes <dholmes@dltech.com.au>
* java/util/logging/ErrorManager.java (everUsed): Made volatile.
(error): Synchronize on instance, not class.
2003-10-21 Mark Wielaard <mark@klomp.org>
Reported by M.Negovanovic

21
libjava/java/util/logging/ErrorManager.java
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@ -2,7 +2,7 @@
-- a class for dealing with errors that a Handler encounters
during logging
Copyright (C) 2002 Free Software Foundation, Inc.
Copyright (C) 2002, 2003 Free Software Foundation, Inc.
This file is part of GNU Classpath.
@ -100,7 +100,16 @@ public class ErrorManager
public static final int FORMAT_FAILURE = 5;
private boolean everUsed = false;
/**
* Indicates whether the {@link #error} method of this ErrorManager
* has ever been used.
*
* Declared volatile in order to correctly support the
* double-checked locking idiom (once the revised Java Memory Model
* gets adopted); see Classpath bug #2944.
*/
private volatile boolean everUsed = false;
public ErrorManager()
{
@ -125,13 +134,19 @@ public class ErrorManager
if (everUsed)
return;
synchronized (ErrorManager.class)
synchronized (this)
{
/* The double check is intentional. If the first check was
* omitted, the monitor would have to be entered every time
* error() method was called. If the second check was
* omitted, the code below could be executed by multiple
* threads simultaneously.
*
* This is the 'double-checked locking' idiom, which is broken
* with the current version of the Java memory model. However,
* we assume that JVMs will have adopted a revised version of
* the Java Memory Model by the time GNU Classpath gains
* widespread acceptance. See Classpath bug #2944.
*/
if (everUsed)
return;