/* -*- 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 "mozilla/MemoryReporting.h"

#include "nsIFile.h"

#include "nsDiskCache.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(nullptr)

           , mBitMap(nullptr)

           , mBlockSize(0)

           , mBitMapWords(0)

           , mFileSize(0)

           , mBitMapDirty(false)

            {}

    ~nsDiskCacheBlockFile() { (void) Close(true); }

    nsresult  Open( nsIFile *  blockFile, uint32_t  blockSize,

                    uint32_t  bitMapSize, nsDiskCache::CorruptCacheInfo *  corruptInfo);

    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( int32_t  startBlock, int32_t  numBlocks);

    nsresult  WriteBlocks( void * buffer, uint32_t size, int32_t  numBlocks,

                           int32_t * startBlock);

    nsresult  ReadBlocks( void * buffer, int32_t  startBlock, int32_t  numBlocks,

                          int32_t * bytesRead);

    size_t   SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf);

private:

    nsresult  FlushBitMap();

    int32_t   AllocateBlocks( int32_t  numBlocks);

    nsresult  VerifyAllocation( int32_t startBlock, int32_t numBLocks);

    uint32_t  CalcBlockFileSize();

    bool   Write(int32_t offset, const void *buf, int32_t amount);

/**

 *  Data members

 */

    PRFileDesc *                mFD;

    uint32_t *                  mBitMap;      // XXX future: array of bit map blocks

    uint32_t                    mBlockSize;

    uint32_t                    mBitMapWords;

    int32_t                     mFileSize;

    bool                        mBitMapDirty;

};

#endif // _nsDiskCacheBlockFile_h_