SpecialRowFile.hpp

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/*******************************************************************************
 *
 * Copyright (c) 2010-2015   Edans Sandes
 *
 * This file is part of MASA-Core.
 * 
 * MASA-Core 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 3 of the License, or
 * (at your option) any later version.
 * 
 * MASA-Core 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 MASA-Core.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

#ifndef SPECIALROWFILE_HPP_
#define SPECIALROWFILE_HPP_

#include "SpecialRow.hpp"

/** @brief Class that reads and stores an Special Row in the disk.
 *
 * This class is the implementation of a SpecialRow that stores the cells
 * in a file saved in the disk.
 *
 * While the special row is in write mode, a temporary file (*.tmp) store the
 * cells. As soon as the row turn to read mode, the temporary file is closed
 * and renamed to the definitive name.
 */
class SpecialRowFile : public SpecialRow {
public:
        /**
         * Creates a new Special Row associated with a given file.
         *
         * @param path the path to save this file.
         * @param filename the name of this file. The rowId is extracted from this
         *   name. If the filename is not a valid row name, rowId is set to -1.
         */
        SpecialRowFile(string* path, string filename);

        /**
         * Creates a new Special Row associated with a given rowId.
         *
         * @param path the path to save this file.
         * @param id the rowId of this file. The filename is associated to this id.
         *      The rowId must be relative to the partition, so the rowId 0 is the first
         *      row of the partition.
         */
        SpecialRowFile(string* path, int id);

        /**
         * Destroys any allocated resource previously allocated by this object.
         */
        virtual ~SpecialRowFile();

        /**
         * Closes the file.
         */
        virtual void close();

        /**
         * Truncates the file.
         *
         * @param size the number of cells to keep in the file.
         */
        virtual void truncateRow(int size);

private:
        /** Dynamic path name of the partition. */
        string* path; // this string changes when the partition changes its name.

        /** File name basic prefix*/
        string filename;

        /** Opened file descriptor */
        FILE* file;

        /**
         * Opens the file for read or write mode.
         * @param readOnly true if it must be opened for read mode, false otherwise.
         * @param length the initial size of the file.
         */
        virtual void initialize(bool readOnly, int length);

        /*
         * @see description in superclass header.
         */
        virtual int write(const cell_t* buf, int offset, int len);

        /*
         * @see description in superclass header.
         */
        virtual int read(cell_t* buf, int offset, int len);

        /**
         * Returns the complete filename (with path) of the special row.
         * @param temp indicates if the filename is temporary or definitive.
         */
        string getFullFilename(bool temp);
};

#endif /* SPECIALROWFILE_HPP_ */