Bug 459002 - ConfigurationImpl should use ReentrantLock

In order to use the JVM deadlock detection mechanism, a
ReentrantLock should be used instead of a custom built locking
mechanism. This way the JVM can detect deadlocks based on this lock.

It also reduced the lines of code and uses something that is already
availabe at JVM level.

Change-Id: I8b1b4dde0e82e142e0383715c2020ce6e316b0fa
Signed-off-by: Jens Reimann <jens.reimann@ibh-systems.com>

1 files changed, 10 insertions, 38 deletions

diff --git a/bundles/org.eclipse.equinox.cm/src/org/eclipse/equinox/internal/cm/ConfigurationImpl.java b/bundles/org.eclipse.equinox.cm/src/org/eclipse/equinox/internal/cm/ConfigurationImpl.java
index 8c59be38d..489df3272 100644
--- a/bundles/org.eclipse.equinox.cm/src/org/eclipse/equinox/internal/cm/ConfigurationImpl.java
+++ b/bundles/org.eclipse.equinox.cm/src/org/eclipse/equinox/internal/cm/ConfigurationImpl.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2013 Cognos Incorporated, IBM Corporation and others.
+ * Copyright (c) 2005, 2015 Cognos Incorporated, IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -8,12 +8,14 @@
  * Contributors:
  *     Cognos Incorporated - initial API and implementation
  *     IBM Corporation - bug fixes and enhancements
+ *     IBH SYSTEMS GmbH - replace custom lock with a ReentrantLock, bug 459002
  *******************************************************************************/
 package org.eclipse.equinox.internal.cm;
 
 import java.io.IOException;
 import java.lang.reflect.Array;
 import java.util.*;
+import java.util.concurrent.locks.ReentrantLock;
 import org.osgi.framework.Bundle;
 import org.osgi.framework.Constants;
 import org.osgi.service.cm.*;
@@ -40,13 +42,10 @@ class ConfigurationImpl implements Configuration {
 	/** @GuardedBy this*/
 	private boolean bound = false;
 	/** @GuardedBy this*/
-	private int lockedCount = 0;
-	/** @GuardedBy this*/
-	private Thread lockHolder = null;
-	/** @GuardedBy this*/
 	private long changeCount;
 	/** @GuardedBy this*/
 	private Object storageToken;
+	private final ReentrantLock lock = new ReentrantLock();
 
 	public ConfigurationImpl(ConfigurationAdminFactory configurationAdminFactory, ConfigurationStore configurationStore, String factoryPid, String pid, String bundleLocation, boolean bind) {
 		this.configurationAdminFactory = configurationAdminFactory;
@@ -75,43 +74,16 @@ class ConfigurationImpl implements Configuration {
 		this.storageToken = storageToken;
 	}
 
-	synchronized void lock() {
-		Thread current = Thread.currentThread();
-		if (lockHolder != current) {
-			boolean interrupted = false;
-			try {
-				while (lockedCount != 0)
-					try {
-						wait();
-					} catch (InterruptedException e) {
-						// although we don't handle an interrupt we should still 
-						// save and restore the interrupt for others further up the stack
-						interrupted = true;
-					}
-			} finally {
-				if (interrupted)
-					current.interrupt(); // restore interrupted status
-			}
-		}
-		lockedCount++;
-		lockHolder = current;
+	void lock() {
+		lock.lock();
 	}
 
-	synchronized void unlock() {
-		Thread current = Thread.currentThread();
-		if (lockHolder != current)
-			throw new IllegalStateException("Thread not lock owner"); //$NON-NLS-1$
-
-		lockedCount--;
-		if (lockedCount == 0) {
-			lockHolder = null;
-			notify();
-		}
+	void unlock() {
+		lock.unlock();
 	}
 
-	synchronized void checkLocked() {
-		Thread current = Thread.currentThread();
-		if (lockHolder != current)
+	void checkLocked() {
+		if (!lock.isHeldByCurrentThread())
 			throw new IllegalStateException("Thread not lock owner"); //$NON-NLS-1$
 	}