filecache.h

著名的 helix realplayer 基于手机 symbian 系统的 播放器全套源代码

/* ***** BEGIN LICENSE BLOCK ***** 
 * Version: RCSL 1.0/RPSL 1.0 
 *  
 * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. 
 *      
 * The contents of this file, and the files included with this file, are 
 * subject to the current version of the RealNetworks Public Source License 
 * Version 1.0 (the "RPSL") available at 
 * http://www.helixcommunity.org/content/rpsl unless you have licensed 
 * the file under the RealNetworks Community Source License Version 1.0 
 * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, 
 * in which case the RCSL will apply. You may also obtain the license terms 
 * directly from RealNetworks.  You may not use this file except in 
 * compliance with the RPSL or, if you have a valid RCSL with RealNetworks 
 * applicable to this file, the RCSL.  Please see the applicable RPSL or 
 * RCSL for the rights, obligations and limitations governing use of the 
 * contents of the file.  
 *  
 * This file is part of the Helix DNA Technology. RealNetworks is the 
 * developer of the Original Code and owns the copyrights in the portions 
 * it created. 
 *  
 * This file, and the files included with this file, is distributed and made 
 * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 
 * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, 
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS 
 * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 
 * 
 * Technology Compatibility Kit Test Suite(s) Location: 
 *    http://www.helixcommunity.org/content/tck 
 * 
 * Contributor(s): 
 *  
 * ***** END LICENSE BLOCK ***** */ 

#include "hxslist.h"    // CHXSimpleList
#include "hxthread.h"   // HXMutex

// In case we want to read data from the cache file and add to the 
// list, this ratio determines the size of the blocks to create.
#define CAPACITY_BLOCKSIZE_RATIO 8

class CHXFileCacheObject : public IHXCacheObject
{

public:

    /****************************************************************************
     *  CHXFileCacheObject::CHXFileCacheObject
     *
     *  Constructor
     */

    CHXFileCacheObject(IHXCommonClassFactory*   /*IN*/      pClassFactory,
                       UINT32                   /*IN*/      ulFileLength,
                       char*                    /*IN*/      pFileName);

    /****************************************************************************
     *  CHXFileCacheObject::~CHXFileCacheObject
     *
     *  Destructor
     */

    ~CHXFileCacheObject();

    // IUnknown COM Interface Methods

    /****************************************************************************
     *  IUnknown::AddRef
     *
     *  This routine increases the object reference count in a thread safe
     *  manner. The reference count is used to manage the lifetime of an object.
     *  This method must be explicitly called by the user whenever a new
     *  reference to an object is used.
     */
    
    STDMETHOD_(ULONG32,AddRef)	(THIS);
    

    /****************************************************************************
     *  IUnknown::Release
     *
     *  This routine decreases the object reference count in a thread safe
     *  manner, and deletes the object if no more references to it exist. It must
     *  be called explicitly by the user whenever an object is no longer needed.
     */

    STDMETHOD_(ULONG32,Release)	(THIS);

    /****************************************************************************
     *  IUnknown::QueryInterface
     *
     *  This routine indicates which interfaces this object supports. If a given
     *  interface is supported, the object's reference count is incremented, and
     *  a reference to that interface is returned. Otherwise a NULL object and
     *  error code are returned. This method is called by other objects to
     *  discover the functionality of this object.
     */
    
    STDMETHOD(QueryInterface)	(THIS_
				REFIID riid,
				void** ppvObj);     
    
    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::Init
     *
     *	Purpose:
     *
     *	    Associates a cache object with the response object
     *	    it should notify of operation completeness.
     */
    
    STDMETHOD(Init)	(THIS_
			IHXCacheObjectResponse*     /*IN*/  pCacheObjectResponse,
                        UINT32   /*IN*/      ulCapacity,
                        UINT32   /*IN*/      lThreshold);


    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::GetThreshold
     *
     *	Purpose:
     *
     *	    Obtain the threshold of the cache object.
     */

    STDMETHOD_(UINT32, GetThreshold)	(THIS);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::ChangeThreshold
     *
     *	Purpose:
     *
     *	    The object keeps caching data until it is full (exhausts its 
     *      capacity). Once it is full, it will overwite existing cached data
     *      with new data ONLY if the percentage of cached data which has been
     *      read from the cache using the ReadBlock() method is greater than a
     *      given percentage of Capacity.. This percentage is set using the SetThreshold()
     *      method. In case the threshold is exceeded, the oldest added data
     *      (the data with the the least offset) will be discarded and the 
     *      amount of data discarded is so that the remaining cached data just
     *      satisfies the threshold condidtion (approximately).
     *
     *      This cache object is used in the HTTP/1.0 file system plugin for
     *      mobile devices and in this case, the threshold is set to 70%
     *      i.e., utilizedDataPercentage = 0.7
     *
     */

     STDMETHOD(ChangeThreshold)      (THIS_
			              UINT32  /*IN*/	lNewThreshold);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::GetCapacity
     *
     *	Purpose:
     *
     *	    Obtain the capacity in bytes of the cache object.
     */

     STDMETHOD_(UINT32, GetCapacity)	(THIS);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::ChangeCapacity
     *
     *	Purpose:
     *
     *	    Changes the capacity of the cache object (in bytes). It is used to
     *      increase or decrease the capacity after the cache object has been
     *      created and it's capacity set using SetCapacity(). This method can
     *      called any number of times. If new capacity is less than old capacity,
     *      the oldest data are discarded.
     *
     */

    STDMETHOD(ChangeCapacity)      (THIS_
			            UINT32  /*IN*/	newByteCount);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::GetUnusedCapacity
     *
     *	Purpose:
     *
     *	    Obtain the unused capacity in bytes of the cache object.
     */

    STDMETHOD_(UINT32, GetUnusedCapacity)	(THIS);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::AddBlock
     *
     *	Purpose:
     *
     *	    Adds a block of data to the cache.
     */

    STDMETHOD(AddBlock)	(THIS_
			 IHXBuffer*		/*IN*/	pBlock);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::VerifyBlock
     *
     *	Purpose:
     *
     *	    Verify that a block of data is in the cache.
     */

    STDMETHOD(VerifyBlock)	(THIS_
				 UINT32		/*IN*/	ulBlockOffset,
				 UINT32		/*IN*/	ulBlockLength);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::ReadBlock
     *
     *	Purpose:
     *
     *	    Read a block out of the cache.
     */

    STDMETHOD(ReadBlock)	(THIS_
				 UINT32		/*IN*/	ulBlockOffset,
				 UINT32		/*IN*/	ulBlockLength);

    /************************************************************************
     *	Method:
     *	    IHXCacheObject::Flush
     *
     *	Purpose:
     *
     *	    Flushes all data to the cache file AND releases all data buffers 
     *      in the memory.After flushing, the object can be used for reading/writing
     *      as before.
     */

    STDMETHOD(Flush)	(THIS);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::IsFull
     *
     *	Purpose:
     *
     *	    Can the cache object accept any more data for storage?
     */
    
    STDMETHOD_(BOOL, IsFull)	(THIS);

    /************************************************************************
     *	Method:
     *
     *	    IHXCacheObject::IsEmpty
     *
     *	Purpose:
     *
     *	    Does the cache object have any data stored?
     */
    
    STDMETHOD_(BOOL, IsEmpty)	(THIS);

private:
    INT32                       m_RefCount;
    IHXCacheObjectResponse*     m_pCacheObjectResponse;
    IHXCommonClassFactory*      m_pClassFactory;
    UINT32                      m_ulCapacity;
    UINT32                      m_lThreshold;
    UINT32                      m_ulUsedCapacity;
    CHXSimpleList*              m_pList;
    UINT32                      m_ulCurrentWriteOffset;
    IHXBuffer*                  m_pPendingAddBlock;
    BOOL                        m_bInAddBlockDone;
    BOOL                        m_bInReadBlockDone;
    HXMutex*                    m_pMutex;
    UINT32                      m_ulCurrentReadOffset;   // Offset of the first byte that has NOT been read.
    UINT32                      m_ulFileLength;
    char*                       m_pFileName;
    UINT32                      m_ulFileWriteOffset;
    FILE*                       m_pCacheFileHandle;
    UINT32                      m_ulHighestByteNotRead;
    FILE*                       m_pFileHandle;

    struct PendingReadInfo
    {
        UINT32      ulOffset;
        UINT32      ulLength;
        IHXBuffer*  pBlock;
    
    } m_pPendingReadInfo;

    struct Info
    {
        UINT32      ulOffset;         // Offset of the starting byte of the block
        UINT32      ulSize;           // Size of the block
        IHXBuffer*  pBlock;      // The actual block data
    };
    

    // Discards 'byteCount' amount of oldest data. Note that this
    // method is not thread safe. The caller has to take care of 
    // locking common data structures before calling this method.
    HX_RESULT _DiscardDataFromHead(UINT32 byteCount, BOOL bWriteToFile);
    
    HX_RESULT _DiscardDataFromTail(UINT32 byteCount, BOOL bWriteToFile);

    // Check if utilizedData has exceeded THRESHOLD. If yes, discard 
    // appropriate amount of data. Note that this
    // method is not thread safe. The caller has to take care of 
    // locking common data structures before calling this method.
    HX_RESULT _CheckForThresholdCondition();

    HX_RESULT _CopyFromFileToHead(UINT32 ulOffset, UINT32 ulSize);

    HX_RESULT _CopyFromFileToTail(UINT32 ulOffset, UINT32 ulSize);

    HX_RESULT _CopyAllDataToFile();

    
    
}; // CHXFileCacheObject