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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 <boost/function.hpp>
namespace qpid {
namespace framing {
class SequenceNumber;
}
namespace broker {
struct QueuedMessage;
/**
* This interface abstracts out the access to the messages held for
* delivery by a Queue instance.
*/
class Messages
{
public:
typedef boost::function1<void, QueuedMessage&> Functor;
typedef boost::function1<bool, QueuedMessage&> Predicate;
virtual ~Messages() {}
/**
* @return the number of messages available for delivery.
*/
virtual size_t size() = 0;
/**
* @return true if there are no messages for delivery, false otherwise
*/
virtual bool empty() = 0;
/**
* Re-inserts a message back into its original position - used
* when requeing released messages.
*/
virtual void reinsert(const QueuedMessage&) = 0;
/**
* Remove the message at the specified position, returning true if
* found, false otherwise. The removed message is passed back via
* the second parameter.
*/
virtual bool remove(const framing::SequenceNumber&, QueuedMessage&) = 0;
/**
* Find the message at the specified position, returning true if
* found, false otherwise. The matched message is passed back via
* the second parameter.
*/
virtual bool find(const framing::SequenceNumber&, QueuedMessage&) = 0;
/**
* Return the next message to be given to a browsing subscrption
* that has reached the specified poisition. The next messages is
* passed back via the second parameter.
*
* @return true if there is another message, false otherwise.
*/
virtual bool next(const framing::SequenceNumber&, QueuedMessage&) = 0;
/**
* Note: Caller is responsible for ensuring that there is a front
* (e.g. empty() returns false)
*
* @return the next message to be delivered
*/
virtual QueuedMessage& front() = 0;
/**
* Removes the front message
*/
virtual void pop() = 0;
/**
* @return true if there is a mesage to be delivered - in which
* case that message will be returned via the parameter and
* removed - otherwise false.
*/
virtual bool pop(QueuedMessage&) = 0;
/**
* Pushes a message to the back of the 'queue'. For some types of
* queue this may cause another message to be removed; if that is
* the case the method will return true and the removed message
* will be passed out via the second parameter.
*/
virtual bool push(const QueuedMessage& added, QueuedMessage& removed) = 0;
/**
* Apply the functor to each message held
*/
virtual void foreach(Functor) = 0;
/**
* Remove every message held that for which the specified
* predicate returns true
*/
virtual void removeIf(Predicate) = 0;
private:
};
}} // namespace qpid::broker
#endif /*!QPID_BROKER_MESSAGES_H*/
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