/**
* 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 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.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Store based cursor
*
*/
public abstract class AbstractStoreCursor extends AbstractPendingMessageCursor implements MessageRecoveryListener {
private static final Logger LOG = LoggerFactory.getLogger(AbstractStoreCursor.class);
protected final Destination regionDestination;
protected final PendingList batchList;
private Iterator<MessageReference> iterator = null;
protected boolean batchResetNeeded = false;
private boolean storeHasMessages = false;
protected int size;
private MessageId lastCachedId;
private boolean hadSpace = false;
protected AbstractStoreCursor(Destination destination) {
super((destination != null ? destination.isPrioritizedMessages():false));
this.regionDestination=destination;
if (this.prioritizedMessages) {
this.batchList= new PrioritizedPendingList();
} else {
this.batchList = new OrderedPendingList();
}
}
public final synchronized void start() throws Exception{
if (!isStarted()) {
super.start();
resetBatch();
resetSize();
setCacheEnabled(!this.storeHasMessages&&useCache);
}
}
protected void resetSize() {
this.size = getStoreSize();
this.storeHasMessages=this.size > 0;
}
public final synchronized void stop() throws Exception {
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 {
boolean recovered = false;
if (recordUniqueId(message.getMessageId())) {
if (!cached) {
message.setRegionDestination(regionDestination);
if( message.getMemoryUsage()==null ) {
message.setMemoryUsage(this.getSystemUsage().getMemoryUsage());
}
}
message.incrementReferenceCount();
batchList.addMessageLast(message);
clearIterator(true);
recovered = true;
storeHasMessages = true;
} else {
/*
* we should expect to get these - as the message is recorded as it before it goes into
* the cache. If subsequently, we pull out that message from the store (before its deleted)
* it will be a duplicate - but should be ignored
*/
if (LOG.isTraceEnabled()) {
LOG.trace(this + " - cursor got duplicate: " + message.getMessageId() + ", " + message.getPriority());
}
}
return recovered;
}
public final synchronized void reset() {
if (batchList.isEmpty()) {
try {
fillBatch();
} catch (Exception e) {
LOG.error(this + " - 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.iterator();
}
}
public final void finished() {
}
public final synchronized boolean hasNext() {
if (batchList.isEmpty()) {
try {
fillBatch();
} catch (Exception e) {
LOG.error(this + " - Failed to fill batch", e);
throw new RuntimeException(e);
}
}
ensureIterator();
return this.iterator.hasNext();
}
public final synchronized MessageReference next() {
MessageReference result = null;
if (!this.batchList.isEmpty()&&this.iterator.hasNext()) {
result = this.iterator.next();
}
last = result;
if (result != null) {
result.incrementReferenceCount();
}
return result;
}
public final synchronized void addMessageLast(MessageReference node) throws Exception {
boolean disableCache = false;
if (hasSpace()) {
if (!isCacheEnabled() && size==0 && isStarted() && useCache) {
if (LOG.isTraceEnabled()) {
LOG.trace(this + " - enabling cache for empty store " + node.getMessageId());
}
setCacheEnabled(true);
}
if (isCacheEnabled()) {
if (recoverMessage(node.getMessage(),true)) {
lastCachedId = node.getMessageId();
} else {
// failed to recover, possible duplicate from concurrent dispatchPending,
// lets not recover further in case of out of order
disableCache = true;
}
}
} else {
disableCache = true;
}
if (disableCache && isCacheEnabled()) {
setCacheEnabled(false);
// sync with store on disabling the cache
if (lastCachedId != null) {
if (LOG.isTraceEnabled()) {
LOG.trace(this + " - disabling cache"
+ ", lastCachedId: " + lastCachedId
+ " current node Id: " + node.getMessageId() + " batchList size: " + batchList.size());
}
setBatch(lastCachedId);
lastCachedId = null;
}
}
this.storeHasMessages = true;
size++;
}
protected void setBatch(MessageId messageId) throws Exception {
}
public final synchronized void addMessageFirst(MessageReference node) throws Exception {
setCacheEnabled(false);
size++;
}
public final synchronized void remove() {
size--;
if (iterator!=null) {
iterator.remove();
}
if (last != null) {
last.decrementReferenceCount();
}
}
public final synchronized void remove(MessageReference node) {
if (batchList.remove(node) != null) {
size--;
setCacheEnabled(false);
}
}
public final synchronized void clear() {
gc();
}
public synchronized void gc() {
for (Iterator<MessageReference>i = batchList.iterator();i.hasNext();) {
MessageReference msg = i.next();
rollback(msg.getMessageId());
msg.decrementReferenceCount();
}
batchList.clear();
clearIterator(false);
batchResetNeeded = true;
setCacheEnabled(false);
}
@Override
public boolean hasSpace() {
hadSpace = super.hasSpace();
return hadSpace;
}
protected final synchronized void fillBatch() {
if (LOG.isTraceEnabled()) {
LOG.trace(this + " - fillBatch");
}
if (batchResetNeeded) {
resetSize();
setMaxBatchSize(Math.min(regionDestination.getMaxPageSize(), size));
resetBatch();
this.batchResetNeeded = false;
}
if (this.batchList.isEmpty() && this.storeHasMessages && this.size >0) {
try {
doFillBatch();
} catch (Exception e) {
LOG.error(this + " - Failed to fill batch", e);
throw new RuntimeException(e);
}
this.storeHasMessages = !this.batchList.isEmpty() || !hadSpace;
}
}
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;
}
@Override
public String toString() {
return super.toString() + ":" + regionDestination.getActiveMQDestination().getPhysicalName() + ",batchResetNeeded=" + batchResetNeeded
+ ",storeHasMessages=" + this.storeHasMessages + ",size=" + this.size + ",cacheEnabled=" + isCacheEnabled()
+ ",maxBatchSize:" + maxBatchSize;
}
protected abstract void doFillBatch() throws Exception;
protected abstract void resetBatch();
protected abstract int getStoreSize();
protected abstract boolean isStoreEmpty();
}