message_queue.cpp

这是DVD中伺服部分的核心代码

/******************************************************************************
*******************************************************************************
**                                                                           **
**  Copyright (c) 2006 Videon Central, Inc.                                  **
**  All rights reserved.                                                     **
**                                                                           **
**  The computer program contained herein contains proprietary information   **
**  which is the property of Videon Central, Inc.  The program may be used   **
**  and/or copied only with the written permission of Videon Central, Inc.   **
**  or in accordance with the terms and conditions stipulated in the         **
**  agreement/contract under which the programs have been supplied.          **
**                                                                           **
*******************************************************************************
******************************************************************************/
/**
 * @file message_queue.cpp
 *
 * $Revision: 1.5 $ 
 *
 * Implements a Message Queue class
 *
 */


#include "message_queue.h"






/**
 *******************************************************************************
 *  MessageQueue::MessageQueue  initializes object to valid state
 *
 *******************************************************************************/
MessageQueue::MessageQueue ( void )
{
    m_messageQueueHandle    = 0;
    m_queueSize             = 0;
    m_messageSize           = 0;
}






/**
 *******************************************************************************
 *  MessageQueue::Construct  allocates required resources, prepares object for use
 *
 *  This method is private and will be automatically called from 
 *  ReferenceCounter::AddReference method and will be inside a critical section
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Construct ( void )
{
    if  (( m_queueSize == 0) || (m_messageSize == 0))
    {
        return ( VDVD_ERROR_OBJECT_HAS_INVALID_STATE );
    }


    m_messageQueueHandle = OS_MsgQCreate(m_queueSize, m_messageSize, 0);
    VDVD_ASSERT_ERROR( (m_messageQueueHandle==0), VDVD_ERROR_PLATFORM_FAILED );


    return ( VDVD_SUCCESS );
}






/**
 *******************************************************************************
 *  MessageQueue::Destruct   frees allocated resources, prepares object for non-use
 *
 *  This method is private and will be automatically called from 
 *  ReferenceCounter::DeleteReference method when the object is no longer being
 *  referenced(used). This code will execute inside a critical section.
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Destruct ( void )
{
    OS_STATUS     osStatus;

    m_queueSize   = 0;
    m_messageSize = 0;

    VDVD_ASSERT_ERROR( (m_messageQueueHandle==0), VDVD_ERROR_OBJECT_HAS_INVALID_STATE );

    osStatus = OS_MsgQDelete( m_messageQueueHandle );
    VDVD_ASSERT_ERROR( (osStatus!=OS_OK), VDVD_ERROR_PLATFORM_FAILED );

    return ( VDVD_SUCCESS );
}






/**
 *******************************************************************************
 *  MessageQueue::Create    Creates message queue
 *
 *  Creates message queue via Construct method automatically called from method
 *  ReferenceCounter::AddReference.
 *
 *  @param      queueSize       max number of messages queue can hold
 *  @param      messageSize     size(in bytes) of message. (all messages must be same size)
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *              VDVD_ERROR_OBJECT_HAS_INVALID_STATE if the queue has already been referenced(created)
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Create( uint32 queueSize, uint32 messageSize )
{
    VDVD_ERROR   error = VDVD_SUCCESS;

    VDVD_ASSERT_ERROR( (queueSize==0), VDVD_ERROR_INVALID_PARAMETER );
    VDVD_ASSERT_ERROR( (messageSize==0), VDVD_ERROR_INVALID_PARAMETER );

    m_mutex.Lock();

    if (( m_queueSize == 0 ) && ( m_messageSize == 0 ))
    {
        m_queueSize     = queueSize;
        m_messageSize   = messageSize;
        error = AddReference();
    }
    else
    {
        error = VDVD_ERROR_OBJECT_HAS_INVALID_STATE;
    }


    m_mutex.Unlock();

    return( error );
}






/**
 *******************************************************************************
 *  MessageQueue::Destroy    Destroys message queue
 *
 *  Deletes reference. If there are no more references(no one is using the object)
 *  the Destruct method will be called automatically from the method
 *  ReferenceCounter::DeleteReference.
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *              VDVD_ERROR_OBJECT_HAS_INVALID_STATE if the queue has already been referenced(created)
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Destroy( void )
{
    return ( DeleteReference() );
}






/**
 *******************************************************************************
 *  MessageQueue::Send    Adds a message to the message queue
 *
 *  @param      message     pointer to a buffer containing the message
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Send( void* message )
{
    VDVD_ASSERT_ERROR( (IsReferenced()==FALSE),        VDVD_ERROR_OBJECT_HAS_INVALID_STATE );
    VDVD_ASSERT_ERROR( (message==NULL),                VDVD_ERROR_INVALID_PARAMETER );

    VDVD_RAISE_ERROR( (VDVD_ERROR)OS_MsgQSend( m_messageQueueHandle, (char*)message, m_messageSize, OS_WAIT_FOREVER, 0 ) );

    return ( VDVD_SUCCESS );
}






/**
 *******************************************************************************
 *  MessageQueue::Receive   Reads a message from the message queue
 *
 *  @param      message     pointer to a buffer containing the message
 *
 *  @return     VDVD_SUCCESS if the function is successful
 *******************************************************************************/
VDVD_ERROR   MessageQueue::Receive( void* message, int timeoutMilliseconds )
{
    VDVD_ASSERT_ERROR( (IsReferenced()==FALSE),  VDVD_ERROR_OBJECT_HAS_INVALID_STATE );
    VDVD_ASSERT_ERROR( (message==NULL),          VDVD_ERROR_INVALID_PARAMETER );


    VDVD_RAISE_ERROR( (VDVD_ERROR)OS_MsgQReceive( m_messageQueueHandle, (char*)message, m_messageSize, timeoutMilliseconds ));
   

    return ( VDVD_SUCCESS );
}