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#ifndef QPID_BROKER_MESSAGES_H
#define QPID_BROKER_MESSAGES_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 "qpid/framing/SequenceNumber.h"
#include <boost/function.hpp>
namespace qpid {
namespace framing {
class SequenceNumber;
}
namespace broker {
class Message;
class QueueCursor;
/**
* This interface abstracts out the access to the messages held for
* delivery by a Queue instance. Note the the assumption at present is
* that all locking is done in the Queue itself.
*/
class Messages
{
public:
typedef boost::function1<void, Message&> Functor;
virtual ~Messages() {}
/**
* @return the number of messages available for delivery.
*/
virtual size_t size() = 0;
/**
* Called when a message is deleted from the queue.
*/
virtual bool deleted(const QueueCursor&) = 0;
/**
* Makes a message available.
*/
virtual void publish(const Message& added) = 0;
/**
* Retrieve the next message for the given cursor. A reference to
* the message is passed back via the second parameter.
*
* @return a pointer to the message if there is one, in which case
* the cursor that points to it is assigned to cursor; null
* otherwise.
*/
virtual Message* next(QueueCursor& cursor) = 0;
/**
* Release the message i.e. return it to the available state
* unless it has already been deleted.
*
* @return a pointer to the Message if it is still in acquired state and
* hence can be released; null if it has already been deleted
*/
virtual Message* release(const QueueCursor& cursor) = 0;
/**
* Find the message with the specified sequence number, returning
* a pointer if found, null otherwise. A cursor to the matched
* message can be passed back via the second parameter, regardless
* of whether the message is found, using this cursor to call
* next() will give the next message greater than position if one
* exists.
*/
virtual Message* find(const framing::SequenceNumber&, QueueCursor*) = 0;
/**
* Find the message at the specified position, returning a pointer if
* found, null otherwise.
*/
virtual Message* find(const QueueCursor&) = 0;
/**
* Apply, the functor to each message held
*/
virtual void foreach(Functor) = 0;
private:
};
}} // namespace qpid::broker
#endif /*!QPID_BROKER_MESSAGES_H*/
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