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Posted to commits@jackrabbit.apache.org by ck...@apache.org on 2012/06/27 15:47:45 UTC
svn commit: r1354499 - in
/jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal:
AbstractJournal.java JournalLock.java
Author: ckoell
Date: Wed Jun 27 13:47:44 2012
New Revision: 1354499
URL: http://svn.apache.org/viewvc?rev=1354499&view=rev
Log:
JCR-3354 The ReadWriteLock in AbstractJournal can create a Deadlock in XA Environment
Added:
jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java (with props)
Modified:
jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/AbstractJournal.java
Modified: jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/AbstractJournal.java
URL: http://svn.apache.org/viewvc/jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/AbstractJournal.java?rev=1354499&r1=1354498&r2=1354499&view=diff
==============================================================================
--- jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/AbstractJournal.java (original)
+++ jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/AbstractJournal.java Wed Jun 27 13:47:44 2012
@@ -30,7 +30,6 @@ import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import EDU.oswego.cs.dl.util.concurrent.ReadWriteLock;
-import EDU.oswego.cs.dl.util.concurrent.ReentrantWriterPreferenceReadWriteLock;
/**
* Base journal implementation.
@@ -71,7 +70,7 @@ public abstract class AbstractJournal im
* Journal lock, allowing multiple readers (synchronizing their contents)
* but only one writer (appending a new entry).
*/
- private final ReadWriteLock rwLock = new ReentrantWriterPreferenceReadWriteLock();
+ private final ReadWriteLock rwLock = new JournalLock();
/**
* The path of the local revision file on disk. Configurable through the repository.xml.
Added: jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java
URL: http://svn.apache.org/viewvc/jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java?rev=1354499&view=auto
==============================================================================
--- jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java (added)
+++ jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java Wed Jun 27 13:47:44 2012
@@ -0,0 +1,130 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.core.journal;
+
+import static org.apache.jackrabbit.core.TransactionContext.getCurrentThreadId;
+import static org.apache.jackrabbit.core.TransactionContext.isSameThreadId;
+import EDU.oswego.cs.dl.util.concurrent.ReentrantWriterPreferenceReadWriteLock;
+
+/**
+ * A reentrant read-write lock used by the Journal for synchronization.
+ * Unlike a normal reentrant lock, this one allows the lock
+ * to be re-entered not just by a thread that's already holding the lock but
+ * by any thread within the same transaction.
+ */
+public class JournalLock extends ReentrantWriterPreferenceReadWriteLock {
+
+ private Object activeWriter;
+
+ /**
+ * {@inheritDoc}
+ */
+ protected boolean allowReader() {
+ Object currentId = getCurrentThreadId();
+ return (activeWriter == null && waitingWriters_ == 0) || isSameThreadId(activeWriter, currentId);
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ protected synchronized boolean startWrite() {
+ Object currentId = getCurrentThreadId();
+ if (activeWriter != null && isSameThreadId(activeWriter, currentId)) { // already held; re-acquire
+ ++writeHolds_;
+ return true;
+ } else if (writeHolds_ == 0) {
+ if (activeReaders_ == 0 || (readers_.size() == 1 && readers_.get(currentId) != null)) {
+ activeWriter = currentId;
+ writeHolds_ = 1;
+ return true;
+ } else {
+ return false;
+ }
+ } else {
+ return false;
+ }
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ protected synchronized Signaller endWrite() {
+ --writeHolds_;
+ if (writeHolds_ > 0) { // still being held
+ return null;
+ } else {
+ activeWriter = null;
+ if (waitingReaders_ > 0 && allowReader()) {
+ return readerLock_;
+ } else if (waitingWriters_ > 0) {
+ return writerLock_;
+ } else {
+ return null;
+ }
+ }
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ @SuppressWarnings("unchecked")
+ protected synchronized boolean startRead() {
+ Object currentId = getCurrentThreadId();
+ Object c = readers_.get(currentId);
+ if (c != null) { // already held -- just increment hold count
+ readers_.put(currentId, new Integer(((Integer)(c)).intValue()+1));
+ ++activeReaders_;
+ return true;
+ } else if (allowReader()) {
+ readers_.put(currentId, IONE);
+ ++activeReaders_;
+ return true;
+ } else {
+ return false;
+ }
+ }
+
+ /**
+ * {@inheritDoc}
+ */
+ @SuppressWarnings("unchecked")
+ protected synchronized Signaller endRead() {
+ Object currentId = getCurrentThreadId();
+ Object c = readers_.get(currentId);
+ if (c == null) {
+ throw new IllegalStateException();
+ }
+ --activeReaders_;
+ if (c != IONE) { // more than one hold; decrement count
+ int h = ((Integer)(c)).intValue()-1;
+ Integer ih = (h == 1)? IONE : new Integer(h);
+ readers_.put(currentId, ih);
+ return null;
+ } else {
+ readers_.remove(currentId);
+
+ if (writeHolds_ > 0) { // a write lock is still held
+ return null;
+ } else if (activeReaders_ == 0 && waitingWriters_ > 0) {
+ return writerLock_;
+ } else {
+ return null;
+ }
+ }
+ }
+
+}
\ No newline at end of file
Propchange: jackrabbit/trunk/jackrabbit-core/src/main/java/org/apache/jackrabbit/core/journal/JournalLock.java
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