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/***************************************************************************
* Copyright (C) 2005 by Joris Guisson *
* joris.guisson@gmail.com *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
* This program is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with this program; if not, write to the *
* Free Software Foundation, Inc., *
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. *
***************************************************************************/
#ifndef BTCACHEFILE_H
#define BTCACHEFILE_H
#include <qmap.h>
#include <qmutex.h>
#include <qstring.h>
#include <util/constants.h>
namespace bt
{
class PreallocationThread;
/**
* Interface which classes must implement to be able to map something from a CacheFile
* It will also be used to notify when things get unmapped or remapped
*/
class MMappeable
{
public:
virtual ~MMappeable() {}
/**
* When a CacheFile is closed, this will be called on all existing mappings.
*/
virtual void unmapped() = 0;
};
/**
@author Joris Guisson <joris.guisson@gmail.com>
Used by Single and MultiFileCache to write to disk.
*/
class CacheFile
{
public:
CacheFile();
virtual ~CacheFile();
enum Mode
{
READ,WRITE,RW
};
/**
* Open the file.
* @param path Path of the file
* @param size Max size of the file
* @throw Error when something goes wrong
*/
void open(const QString & path,Uint64 size);
/// Change the path of the file
void changePath(const QString & npath);
/**
* Map a part of the file into memory, will expand the file
* if it is to small, but will not go past the limit set in open.
* @param thing The thing that wishes to map the mmapping
* @param off Offset into the file
* @param size Size of the region to map
* @param mode How the region will be mapped
* @return A ptr to the mmaped region, or 0 if something goes wrong
*/
void* map(MMappeable* thing,Uint64 off,Uint32 size,Mode mode);
/**
* Unmap a previously mapped region.
* @param ptr Ptr to the region
* @param size Size of the region
*/
void unmap(void* ptr,Uint32 size);
/**
* Close the file, everything will be unmapped.
* @param to_be_reopened Indicates if the close is temporarely (i.e. it will be reopened)
*/
void close();
/**
* Read from the file.
* @param buf Buffer to store data
* @param size Size to read
* @param off Offset to read from in file
*/
void read(Uint8* buf,Uint32 size,Uint64 off);
/**
* Write to the file.
* @param buf Buffer to write
* @param size Size to read
* @param off Offset to read from in file
*/
void write(const Uint8* buf,Uint32 size,Uint64 off);
/**
* Preallocate disk space
*/
void preallocate(PreallocationThread* prealloc);
/// Get the number of bytes this cache file is taking up
Uint64 diskUsage();
private:
void growFile(Uint64 to_write);
void closeTemporary();
void openFile(Mode mode);
private:
int fd;
bool read_only;
Uint64 max_size,file_size;
QString path;
struct Entry
{
MMappeable* thing;
void* ptr;
Uint32 size;
Uint64 offset;
Uint32 diff;
Mode mode;
};
QMap<void*,Entry> mappings; // mappings where offset wasn't a multiple of 4K
mutable QMutex mutex;
};
}
#endif
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