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/*
*
* 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.qpid.server.consumer;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.log4j.Logger;
import org.apache.qpid.server.message.MessageInstance;
import org.apache.qpid.server.util.StateChangeListener;
public abstract class AbstractConsumerTarget implements ConsumerTarget
{
private static final Logger LOGGER = Logger.getLogger(AbstractConsumerTarget.class);
private final AtomicReference<State> _state;
private final Set<StateChangeListener<ConsumerTarget, State>> _stateChangeListeners = new
CopyOnWriteArraySet<>();
private final Lock _stateChangeLock = new ReentrantLock();
private final AtomicInteger _stateActivates = new AtomicInteger();
private ConcurrentLinkedQueue<ConsumerMessageInstancePair> _queue = new ConcurrentLinkedQueue();
protected AbstractConsumerTarget(final State initialState)
{
_state = new AtomicReference<State>(initialState);
}
@Override
public void processPending()
{
while(hasMessagesToSend())
{
sendNextMessage();
}
processClosed();
}
protected abstract void processClosed();
@Override
public final boolean isSuspended()
{
return getSessionModel().getConnectionModel().isMessageAssignmentSuspended() || doIsSuspended();
}
protected abstract boolean doIsSuspended();
public final State getState()
{
return _state.get();
}
protected final boolean updateState(State from, State to)
{
if(_state.compareAndSet(from, to))
{
if (to == State.ACTIVE && _stateChangeListeners.size() > 1)
{
int offset = _stateActivates.incrementAndGet();
if (offset >= _stateChangeListeners.size())
{
_stateActivates.set(0);
offset = 0;
}
List<StateChangeListener<ConsumerTarget, State>> holdovers = new ArrayList<>();
int pos = 0;
for (StateChangeListener<ConsumerTarget, State> listener : _stateChangeListeners)
{
if (pos++ < offset)
{
holdovers.add(listener);
}
else
{
listener.stateChanged(this, from, to);
}
}
for (StateChangeListener<ConsumerTarget, State> listener : holdovers)
{
listener.stateChanged(this, from, to);
}
}
else
{
for (StateChangeListener<ConsumerTarget, State> listener : _stateChangeListeners)
{
listener.stateChanged(this, from, to);
}
}
return true;
}
else
{
return false;
}
}
@Override
public final void notifyCurrentState()
{
for (StateChangeListener<ConsumerTarget, State> listener : _stateChangeListeners)
{
State state = getState();
listener.stateChanged(this, state, state);
}
}
public final void addStateListener(StateChangeListener<ConsumerTarget, State> listener)
{
_stateChangeListeners.add(listener);
}
@Override
public void removeStateChangeListener(final StateChangeListener<ConsumerTarget, State> listener)
{
_stateChangeListeners.remove(listener);
}
public final boolean trySendLock()
{
return _stateChangeLock.tryLock();
}
public final void getSendLock()
{
_stateChangeLock.lock();
}
public final void releaseSendLock()
{
_stateChangeLock.unlock();
}
@Override
public final long send(final ConsumerImpl consumer, MessageInstance entry, boolean batch)
{
_queue.add(new ConsumerMessageInstancePair(consumer, entry, batch));
getSessionModel().getConnectionModel().notifyWork();
return entry.getMessage().getSize();
}
protected abstract void doSend(final ConsumerImpl consumer, MessageInstance entry, boolean batch);
@Override
public boolean hasMessagesToSend()
{
return !_queue.isEmpty();
}
@Override
public void sendNextMessage()
{
ConsumerMessageInstancePair consumerMessage = _queue.peek();
if (consumerMessage != null)
{
_queue.poll();
ConsumerImpl consumer = consumerMessage.getConsumer();
MessageInstance entry = consumerMessage.getEntry();
boolean batch = consumerMessage.isBatch();
doSend(consumer, entry, batch);
if (consumer.acquires())
{
entry.unlockAcquisition();
}
}
}
}
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