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#ifndef QPID_HA_QUEUEGUARD_H
#define QPID_HA_QUEUEGUARD_H
/*
*
* 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.
*
*/
#include "types.h"
#include "QueueRange.h"
#include "qpid/framing/SequenceNumber.h"
#include "qpid/framing/SequenceSet.h"
#include "qpid/types/Uuid.h"
#include "qpid/sys/Mutex.h"
#include <boost/shared_ptr.hpp>
#include <deque>
#include <set>
namespace qpid {
namespace broker {
class Queue;
struct QueuedMessage;
class Message;
}
namespace ha {
class BrokerInfo;
class ReplicatingSubscription;
/**
* A queue guard is a QueueObserver that delays completion of new messages
* arriving on a queue. It works as part of a ReplicatingSubscription to ensure
* messages are not acknowledged till they have been replicated.
*
* The guard can be created before the ReplicatingSubscription to protect
* messages arriving before the creation of the subscription.
*
* THREAD SAFE: Concurrent calls:
* - enqueued() via QueueObserver in arbitrary connection threads.
* - attach(), cancel(), complete() from ReplicatingSubscription in subscription thread.
*
* Lock Hierarchy: ReplicatingSubscription MUS NOT call QueueGuard with it's lock held
* QueueGuard MAY call ReplicatingSubscription with it's lock held.
*/
class QueueGuard {
public:
QueueGuard(broker::Queue& q, const BrokerInfo&);
~QueueGuard();
/** QueueObserver override. Delay completion of the message.
* NOTE: Called under the queues message lock.
*/
void enqueued(const broker::Message&);
/** QueueObserver override: Complete a delayed message.
* NOTE: Called under the queues message lock.
*/
void dequeued(const broker::Message&);
/** Complete a delayed message. */
void complete(framing::SequenceNumber);
/** Complete all delayed messages. */
void cancel();
void attach(ReplicatingSubscription&);
/**
* Return the un-guarded queue range at the time the QueueGuard was created.
*
* The first position guaranteed to be protected by the guard is
* getRange().getBack()+1. It is possible that the guard has protected some
* messages before that point. Any such messages are dealt with in subscriptionStart
*
* The QueueGuard is created in 3 situations
* - when a backup is promoted, guards are created for expected backups.
* - when a new queue is created on the primary
* - when a new backup joins.
*
* In the last situation the queue is active while the guard is being
* created.
*
*/
const QueueRange& getRange() const { return range; } // range is immutable, no lock needed.
/** Inform the guard of the stating position for the attached subscription.
* Complete messages that will not be seen by the subscription.
*@return true if the subscription has already advanced to a guarded position.
*/
bool subscriptionStart(framing::SequenceNumber position);
private:
class QueueObserver;
typedef std::map<framing::SequenceNumber,
boost::intrusive_ptr<broker::AsyncCompletion> > Delayed;
void complete(framing::SequenceNumber, sys::Mutex::ScopedLock &);
void complete(Delayed::iterator, sys::Mutex::ScopedLock &);
sys::Mutex lock;
bool cancelled;
std::string logPrefix;
broker::Queue& queue;
Delayed delayed;
ReplicatingSubscription* subscription;
boost::shared_ptr<QueueObserver> observer;
QueueRange range;
};
}} // namespace qpid::ha
#endif /*!QPID_HA_QUEUEGUARD_H*/
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