netwerk/cache/src/nsDiskCacheBlockFile.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is nsDiskCacheBlockFile.h, released
  17  * April 12, 2001.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 2001
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *   Gordon Sheridan  <gordon@netscape.com>
  26  *
  27  * Alternatively, the contents of this file may be used under the terms of
  28  * either the GNU General Public License Version 2 or later (the "GPL"), or
  29  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  30  * in which case the provisions of the GPL or the LGPL are applicable instead
  31  * of those above. If you wish to allow use of your version of this file only
  32  * under the terms of either the GPL or the LGPL, and not to allow others to
  33  * use your version of this file under the terms of the MPL, indicate your
  34  * decision by deleting the provisions above and replace them with the notice
  35  * and other provisions required by the GPL or the LGPL. If you do not delete
  36  * the provisions above, a recipient may use your version of this file under
  37  * the terms of any one of the MPL, the GPL or the LGPL.
  38  *
  39  * ***** END LICENSE BLOCK ***** */
  40
  41 #ifndef _nsDiskCacheBlockFile_h_
  42 #define _nsDiskCacheBlockFile_h_
  43
  44 #include "nsILocalFile.h"
  45
  46 /******************************************************************************
  47  *  nsDiskCacheBlockFile
  48  *
  49  *  The structure of a cache block file is a 4096 bytes bit map, followed by
  50  *  some number of blocks of mBlockSize.  The creator of a
  51  *  nsDiskCacheBlockFile object must provide the block size for a given file.
  52  *
  53  *****************************************************************************/
  54 class nsDiskCacheBlockFile {
  55 public:
  56     nsDiskCacheBlockFile()
  57            : mFD(nsnull)
  58            , mBlockSize(0)
  59            , mBitMap(nsnull)
  60            , mBitMapDirty(PR_FALSE)
  61             {}
  62     ~nsDiskCacheBlockFile() { (void) Close(PR_TRUE); }
  63
  64     nsresult  Open( nsILocalFile *  blockFile, PRUint32  blockSize);
  65     nsresult  Close(PRBool flush);
  66
  67     /*
  68      * Trim
  69      * Truncates the block file to the end of the last allocated block.
  70      */
  71     nsresult  Trim() { return nsDiskCache::Truncate(mFD, CalcBlockFileSize()); }
  72     nsresult  DeallocateBlocks( PRInt32  startBlock, PRInt32  numBlocks);
  73     nsresult  WriteBlocks( void * buffer, PRUint32 size, PRInt32  numBlocks,
  74                            PRInt32 * startBlock);
  75     nsresult  ReadBlocks( void * buffer, PRInt32  startBlock, PRInt32  numBlocks,
  76                           PRInt32 * bytesRead);
  77
  78 private:
  79     nsresult  FlushBitMap();
  80     PRInt32   AllocateBlocks( PRInt32  numBlocks);
  81     nsresult  VerifyAllocation( PRInt32 startBlock, PRInt32 numBLocks);
  82     PRUint32  CalcBlockFileSize();
  83
  84 /**
  85  *  Data members
  86  */
  87     PRFileDesc *                mFD;
  88     PRUint32                    mBlockSize;
  89     PRUint32 *                  mBitMap;      // XXX future: array of bit map blocks
  90     PRBool                      mBitMapDirty;
  91 };
  92
  93 #endif // _nsDiskCacheBlockFile_h_