mirror of https://github.com/apache/activemq.git
103 lines
3.5 KiB
C++
103 lines
3.5 KiB
C++
/*
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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*/
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#ifndef ACTIVEMQ_BLOCKINGMSGCONSUMER_REF_H
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#define ACTIVEMQ_BLOCKINGMSGCONSUMER_REF_H
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#include <semaphore.h>
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#include <pthread.h>
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#include <memory>
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#include <deque>
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#include "MessageConsumerRef.h"
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#include "BlockingMessageConsumer.h"
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namespace ActiveMQ {
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class CoreLib;
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/// handle on message vendor with blocking semantics.
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/**
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This class is a handle on a BlockingMessageConsumer, which is
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an object that holds messages that have been received by a
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BrokerSession object but not yet received by the application. It
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contains an internal queue and a semaphore (this class is
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thread safe).
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When a Message is enqueued, it is stored internally and the
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semaphore is posted.
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The receive() call will block until a message is ready, then
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return that message.
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BlockingMessageConsumers are owned by the library, so this weak
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reference class is provided to allow flexible sharing of the
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handle (like a pointer) while at the same time providing
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protection from pointer invalidation. When the owning library
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is destructed, it will nullify existing weak reference objects
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so that calls will throw instead of crashing.
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@version $Id$
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*/
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class BlockingMessageConsumerRef : public MessageConsumerRef {
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public:
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BlockingMessageConsumerRef() : MessageConsumerRef(), cons_(NULL) {}
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BlockingMessageConsumerRef(const BlockingMessageConsumerRef &);
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BlockingMessageConsumerRef& operator=(const BlockingMessageConsumerRef& oth);
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virtual ~BlockingMessageConsumerRef();
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/// gets the number of messages that are ready
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/**
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@returns the number of waiting messages
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*/
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int getNumReadyMessages() const;
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/// blocking receive
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/**
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Receives a Message. If none are ready, this will block
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until one is. It is returned as a std::auto_ptr to make
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the ownership policy clear.
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Note that a variant of receive() that returns a regular
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pointer is defined on ActiveMQ::MessageConsumerRef.
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@returns the new Message
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*/
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std::auto_ptr<Message> receive();
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/// checks validity
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/**
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Since this class is a weak reference, it could be
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invalidated. If it's invalid, calling these functions will
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throw.
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@returns true if the reference is invalid
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*/
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virtual bool isValid() const;
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private:
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friend class CoreLibImpl;
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BlockingMessageConsumerRef(CoreLib *a, BlockingMessageConsumer *q);
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BlockingMessageConsumer *cons_;
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MessageConsumer *getConsumer() const { return cons_; }
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};
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};
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#endif // ACTIVEMQ_BLOCKINGMSGCONSUMER_REF_H
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