/**
* 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.activemq.broker.region.cursors;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map.Entry;
import org.apache.activemq.broker.region.Destination;
import org.apache.activemq.broker.region.MessageReference;
import org.apache.activemq.command.Message;
import org.apache.activemq.command.MessageId;
import org.apache.activemq.store.MessageRecoveryListener;
import org.apache.activemq.usage.Usage;
import org.apache.activemq.usage.UsageListener;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* Store based cursor
*
*/
public abstract class AbstractStoreCursor extends AbstractPendingMessageCursor implements MessageRecoveryListener, UsageListener {
private static final Log LOG = LogFactory.getLog(AbstractStoreCursor.class);
protected final Destination regionDestination;
private final LinkedHashMap<MessageId,Message> batchList = new LinkedHashMap<MessageId,Message> ();
private Iterator<Entry<MessageId, Message>> iterator = null;
protected boolean cacheEnabled=false;
protected boolean batchResetNeeded = true;
protected boolean storeHasMessages = false;
protected int size;
protected AbstractStoreCursor(Destination destination) {
this.regionDestination=destination;
}
public final synchronized void start() throws Exception{
if (!isStarted()) {
super.start();
clear();
resetBatch();
this.size = getStoreSize();
this.storeHasMessages=this.size > 0;
if (!this.storeHasMessages&&useCache) {
cacheEnabled=true;
}
}
getSystemUsage().getMemoryUsage().addUsageListener(this);
}
public final synchronized void stop() throws Exception {
getSystemUsage().getMemoryUsage().removeUsageListener(this);
resetBatch();
super.stop();
gc();
}
public final boolean recoverMessage(Message message) throws Exception {
return recoverMessage(message,false);
}
public synchronized boolean recoverMessage(Message message, boolean cached)throws Exception {
if (!isDuplicate(message.getMessageId())) {
if (!cached) {
message.setRegionDestination(regionDestination);
if( message.getMemoryUsage()==null ) {
message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
}
}
message.incrementReferenceCount();
batchList.put(message.getMessageId(), message);
clearIterator(true);
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Ignoring batched duplicated from store: " + message);
}
storeHasMessages = true;
}
return true;
}
public final void reset() {
if (batchList.isEmpty()) {
try {
fillBatch();
} catch (Exception e) {
LOG.error("Failed to fill batch", e);
throw new RuntimeException(e);
}
}
clearIterator(true);
size();
}
public synchronized void release() {
clearIterator(false);
}
private synchronized void clearIterator(boolean ensureIterator) {
boolean haveIterator = this.iterator != null;
this.iterator=null;
if(haveIterator&&ensureIterator) {
ensureIterator();
}
}
private synchronized void ensureIterator() {
if(this.iterator==null) {
this.iterator=this.batchList.entrySet().iterator();
}
}
public final void finished() {
}
public final synchronized boolean hasNext() {
if (batchList.isEmpty()) {
try {
fillBatch();
} catch (Exception e) {
LOG.error("Failed to fill batch", e);
throw new RuntimeException(e);
}
}
ensureIterator();
return this.iterator.hasNext();
}
public final synchronized MessageReference next() {
Message result = null;
if (!this.batchList.isEmpty()&&this.iterator.hasNext()) {
result = this.iterator.next().getValue();
result.decrementReferenceCount();
}
return result;
}
public final synchronized void addMessageLast(MessageReference node) throws Exception {
if (cacheEnabled && hasSpace()) {
recoverMessage(node.getMessage(),true);
}else {
cacheEnabled=false;
}
size++;
}
public final synchronized void addMessageFirst(MessageReference node) throws Exception {
cacheEnabled=false;
size++;
}
public final synchronized void remove() {
size--;
if (size==0 && isStarted() && useCache) {
cacheEnabled=true;
}
if (iterator!=null) {
iterator.remove();
}
}
public final synchronized void remove(MessageReference node) {
size--;
cacheEnabled=false;
batchList.remove(node.getMessageId());
}
public final synchronized void onUsageChanged(Usage usage, int oldPercentUsage,
int newPercentUsage) {
if (oldPercentUsage > newPercentUsage && oldPercentUsage >= memoryUsageHighWaterMark) {
storeHasMessages = true;
try {
fillBatch();
} catch (Exception e) {
LOG.error("Failed to fill batch ", e);
}
}
}
public final synchronized void clear() {
gc();
}
public final synchronized void gc() {
for (Message msg : batchList.values()) {
rollback(msg.getMessageId());
msg.decrementReferenceCount();
}
batchList.clear();
clearIterator(false);
batchResetNeeded = true;
this.cacheEnabled=false;
if (isStarted()) {
size = getStoreSize();
} else {
size = 0;
}
}
protected final synchronized void fillBatch() {
if (batchResetNeeded) {
resetBatch();
this.batchResetNeeded = false;
}
if( this.batchList.isEmpty() && (this.storeHasMessages ||this.size >0)) {
this.storeHasMessages = false;
try {
doFillBatch();
} catch (Exception e) {
LOG.error("Failed to fill batch", e);
throw new RuntimeException(e);
}
if (!this.batchList.isEmpty()) {
this.storeHasMessages=true;
}
}
}
public final synchronized boolean isEmpty() {
// negative means more messages added to store through queue.send since last reset
return size == 0;
}
public final synchronized boolean hasMessagesBufferedToDeliver() {
return !batchList.isEmpty();
}
public final synchronized int size() {
if (size < 0) {
this.size = getStoreSize();
}
return size;
}
protected abstract void doFillBatch() throws Exception;
protected abstract void resetBatch();
protected abstract int getStoreSize();
}