fileperblock_file.h

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/***************************************************************************
 * include/stxxl/bits/io/fileperblock_file.h
 *
 * Part of the STXXL. See http://stxxl.sourceforge.net
 *
 * Copyright (C) 2008, 2009 Johannes Singler <[email protected]>
 *
 * Distributed under the Boost Software License, Version 1.0.
 * (See accompanying file LICENSE_1_0.txt or copy at
 * http://www.boost.org/LICENSE_1_0.txt)
 **************************************************************************/

#ifndef STXXL_IO_FILEPERBLOCK_FILE_HEADER
#define STXXL_IO_FILEPERBLOCK_FILE_HEADER

#include <string>
#include <stxxl/bits/io/disk_queued_file.h>

STXXL_BEGIN_NAMESPACE

//! \addtogroup fileimpl
//! \{

//! Implementation of file based on other files, dynamically allocate one file per block.
//! Allows for dynamic disk space consumption.
template <class base_file_type>
class fileperblock_file : public disk_queued_file
{
private:
 std::string filename_prefix;
 int mode;
 offset_type current_size;
 bool lock_file_created;
 base_file_type lock_file;

protected:
 //! Constructs a file name for a given block.
 std::string filename_for_block(offset_type offset);

public:
 //! Constructs file object.
 //! param filename_prefix filename prefix, numbering will be appended to it
 //! param mode open mode, see \c file::open_modes
 fileperblock_file(
 const std::string& filename_prefix,
 int mode,
 int queue_id = DEFAULT_QUEUE,
 int allocator_id = NO_ALLOCATOR,
 unsigned int device_id = DEFAULT_DEVICE_ID);

 virtual ~fileperblock_file();

 virtual void serve(void* buffer, offset_type offset, size_type bytes,
 request::request_type type);

 //! Changes the size of the file.
 //! \param new_size value of the new file size
 virtual void set_size(offset_type new_size) { current_size = new_size; }

 //! Returns size of the file.
 //! \return file size in length
 virtual offset_type size() { return current_size; }

 virtual void lock();

 //! Frees the specified region.
 //! Actually deletes the corresponding file if the whole thing is deleted.
 virtual void discard(offset_type offset, offset_type length);

 //! Rename the file corresponding to the offset such that it is out of reach for deleting.
 virtual void export_files(offset_type offset, offset_type length, std::string filename);

 const char * io_type() const;
};

//! \}

STXXL_END_NAMESPACE

#endif // !STXXL_IO_FILEPERBLOCK_FILE_HEADER