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#ifndef QPID_HA_QUEUERANGE_H
#define QPID_HA_QUEUERANGE_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 "ReplicatingSubscription.h"
#include "qpid/broker/Queue.h"
#include "qpid/broker/QueueCursor.h"
#include "qpid/framing/FieldTable.h"
#include "qpid/framing/SequenceNumber.h"
#include <iostream>
namespace qpid {
namespace ha {
/**
* Get the front/back range of a queue or from a ReplicatingSubscription arguments table.
*
* The *back* of the queue is the position of the latest (most recently pushed)
* message on the queue or, if the queue is empty, the back is n-1 where n is
* the position that will be assigned to the next message pushed onto the queue.
*
* The *front* of the queue is the position of the oldest (next to be consumed) message
* on the queue or, if the queue is empty, it is the position that will be occupied
* by the next message pushed onto the queue.
*
* This leads to the slightly surprising conclusion that for an empty queue
* front = back+1
*/
struct QueueRange {
public:
framing::SequenceNumber front, back;
QueueRange() : front(1), back(0) { } // Empty range.
QueueRange(broker::Queue& q) { q.getRange(front, back, broker::REPLICATOR); }
QueueRange(const framing::FieldTable& args) {
back = args.getAsInt(ReplicatingSubscription::QPID_BACK);
front = back+1;
if (args.isSet(ReplicatingSubscription::QPID_FRONT))
front = args.getAsInt(ReplicatingSubscription::QPID_FRONT);
if (back+1 < front)
throw Exception(QPID_MSG("Invalid range [" << front << "," << back <<"]"));
}
bool empty() const { return front == back+1; }
};
inline std::ostream& operator<<(std::ostream& o, const QueueRange& qr) {
if (qr.front > qr.back) return o << "[-," << qr.back << "]";
else return o << "[" << qr.front << "," << qr.back << "]";
}
}} // namespace qpid::ha
#endif /*!QPID_HA_QUEUERANGE_H*/
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