pjs/netwerk/cache/nsDiskCacheBlockFile.h

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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsDiskCacheBlockFile.h, released
* April 12, 2001.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Gordon Sheridan <gordon@netscape.com>
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef _nsDiskCacheBlockFile_h_
#define _nsDiskCacheBlockFile_h_
#include "nsILocalFile.h"
/******************************************************************************
* nsDiskCacheBlockFile
*
* The structure of a cache block file is a 4096 bytes bit map, followed by
* some number of blocks of mBlockSize. The creator of a
* nsDiskCacheBlockFile object must provide the block size for a given file.
*
*****************************************************************************/
class nsDiskCacheBlockFile {
public:
nsDiskCacheBlockFile()
: mFD(nsnull)
, mBitMap(nsnull)
, mBlockSize(0)
, mBitMapWords(0)
, mFileSize(0)
, mBitMapDirty(PR_FALSE)
{}
~nsDiskCacheBlockFile() { (void) Close(PR_TRUE); }
nsresult Open( nsILocalFile * blockFile, PRUint32 blockSize,
PRUint32 bitMapSize);
nsresult Close(PRBool flush);
/*
* Trim
* Truncates the block file to the end of the last allocated block.
*/
nsresult Trim() { return nsDiskCache::Truncate(mFD, CalcBlockFileSize()); }
nsresult DeallocateBlocks( PRInt32 startBlock, PRInt32 numBlocks);
nsresult WriteBlocks( void * buffer, PRUint32 size, PRInt32 numBlocks,
PRInt32 * startBlock);
nsresult ReadBlocks( void * buffer, PRInt32 startBlock, PRInt32 numBlocks,
PRInt32 * bytesRead);
private:
nsresult FlushBitMap();
PRInt32 AllocateBlocks( PRInt32 numBlocks);
nsresult VerifyAllocation( PRInt32 startBlock, PRInt32 numBLocks);
PRUint32 CalcBlockFileSize();
bool Write(PRInt32 offset, const void *buf, PRInt32 amount);
/**
* Data members
*/
PRFileDesc * mFD;
PRUint32 * mBitMap; // XXX future: array of bit map blocks
PRUint32 mBlockSize;
PRUint32 mBitMapWords;
PRInt32 mFileSize;
PRBool mBitMapDirty;
};
#endif // _nsDiskCacheBlockFile_h_