gecko/netwerk/cache/nsDiskCacheBlockFile.h
2012-05-21 12:12:37 +01:00

66 lines
2.4 KiB
C++

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* vim: set sw=4 ts=8 et tw=80 : */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#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(false)
{}
~nsDiskCacheBlockFile() { (void) Close(true); }
nsresult Open( nsILocalFile * blockFile, PRUint32 blockSize,
PRUint32 bitMapSize);
nsresult Close(bool 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;
bool mBitMapDirty;
};
#endif // _nsDiskCacheBlockFile_h_