/*
*
* 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.subscription;
import org.apache.qpid.server.queue.QueueEntryVisitor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.qpid.server.message.AMQMessageHeader;
import org.apache.qpid.server.message.ServerMessage;
import org.apache.qpid.server.queue.QueueEntry;
import java.util.HashMap;
import java.util.Map;
public class DefinedGroupMessageGroupManager implements MessageGroupManager
{
private static final Logger _logger = LoggerFactory.getLogger(DefinedGroupMessageGroupManager.class);
private final String _groupId;
private final String _defaultGroup;
private final Map<Object, Group> _groupMap = new HashMap<Object, Group>();
private final SubscriptionResetHelper _resetHelper;
private final class Group
{
private final Object _group;
private Subscription _subscription;
private int _activeCount;
private Group(final Object key, final Subscription subscription)
{
_group = key;
_subscription = subscription;
}
public boolean add()
{
if(_subscription != null)
{
_activeCount++;
return true;
}
else
{
return false;
}
}
public void subtract()
{
if(--_activeCount == 0)
{
_resetHelper.resetSubPointersForGroups(_subscription, false);
_subscription = null;
_groupMap.remove(_group);
}
}
@Override
public boolean equals(final Object o)
{
if (this == o)
{
return true;
}
if (o == null || getClass() != o.getClass())
{
return false;
}
Group group = (Group) o;
return _group.equals(group._group);
}
@Override
public int hashCode()
{
return _group.hashCode();
}
public boolean isValid()
{
return !(_subscription == null || (_activeCount == 0 && _subscription.isClosed()));
}
public Subscription getSubscription()
{
return _subscription;
}
@Override
public String toString()
{
return "Group{" +
"_group=" + _group +
", _subscription=" + _subscription +
", _activeCount=" + _activeCount +
'}';
}
}
public DefinedGroupMessageGroupManager(final String groupId, String defaultGroup, SubscriptionResetHelper resetHelper)
{
_groupId = groupId;
_defaultGroup = defaultGroup;
_resetHelper = resetHelper;
}
public synchronized Subscription getAssignedSubscription(final QueueEntry entry)
{
Object groupId = getKey(entry);
Group group = _groupMap.get(groupId);
return group == null || !group.isValid() ? null : group.getSubscription();
}
public synchronized boolean acceptMessage(final Subscription sub, final QueueEntry entry)
{
if(assignMessage(sub, entry))
{
return entry.acquire(sub);
}
else
{
return false;
}
}
private boolean assignMessage(final Subscription sub, final QueueEntry entry)
{
Object groupId = getKey(entry);
Group group = _groupMap.get(groupId);
if(group == null || !group.isValid())
{
group = new Group(groupId, sub);
_groupMap.put(groupId, group);
// there's a small change that the group became empty between the point at which getNextAvailable() was
// called on the subscription, and when accept message is called... in that case we want to avoid delivering
// out of order
if(_resetHelper.isEntryAheadOfSubscription(entry, sub))
{
return false;
}
}
Subscription assignedSub = group.getSubscription();
if(assignedSub == sub)
{
entry.addStateChangeListener(new GroupStateChangeListener(group, entry));
return true;
}
else
{
return false;
}
}
public synchronized QueueEntry findEarliestAssignedAvailableEntry(final Subscription sub)
{
EntryFinder visitor = new EntryFinder(sub);
sub.getQueue().visit(visitor);
return visitor.getEntry();
}
private class EntryFinder implements QueueEntryVisitor
{
private QueueEntry _entry;
private Subscription _sub;
public EntryFinder(final Subscription sub)
{
_sub = sub;
}
public boolean visit(final QueueEntry entry)
{
if(!entry.isAvailable())
{
return false;
}
Object groupId = getKey(entry);
Group group = _groupMap.get(groupId);
if(group != null && group.getSubscription() == _sub)
{
_entry = entry;
return true;
}
else
{
return false;
}
}
public QueueEntry getEntry()
{
return _entry;
}
}
public void clearAssignments(final Subscription sub)
{
}
private Object getKey(QueueEntry entry)
{
ServerMessage message = entry.getMessage();
AMQMessageHeader messageHeader = message == null ? null : message.getMessageHeader();
Object groupVal = messageHeader == null ? _defaultGroup : messageHeader.getHeader(_groupId);
if(groupVal == null)
{
groupVal = _defaultGroup;
}
return groupVal;
}
private class GroupStateChangeListener implements QueueEntry.StateChangeListener
{
private final Group _group;
public GroupStateChangeListener(final Group group,
final QueueEntry entry)
{
_group = group;
}
public void stateChanged(final QueueEntry entry,
final QueueEntry.State oldState,
final QueueEntry.State newState)
{
synchronized (DefinedGroupMessageGroupManager.this)
{
if(_group.isValid())
{
if(oldState != newState)
{
if(newState == QueueEntry.State.ACQUIRED)
{
_group.add();
}
else if(oldState == QueueEntry.State.ACQUIRED)
{
_group.subtract();
}
}
}
else
{
entry.removeStateChangeListener(this);
}
}
}
}
}