package com.rho.file;

import java.io.IOException;

/**
 * Interface of file.
 * Programmer can provide its own impleentation of this interface, adding such features
 * as support of flash cards, encrypted files,...
 * Implentation of this interface should throw StorageError exception in case of failure
 */
public interface IFile 
{ 
    /**
     * Write data to the file
     * @param pos offset in the file
     * @param buf array with data to be writter (size is always equal to database page size)
     */
    void write(long pos, byte[] buf)throws IOException;

    /**
     * Read data from the file
     * @param pos offset in the file
     * @param buf array to receive readen data (size is always equal to database page size)
     * @return number of bytes actually readen
     */
    int read(long pos, byte[] buf)throws IOException;

    /**
     * Flush all fiels changes to the disk
     */
    void sync()throws IOException;

    /**
     * Close file
     */
    void close()throws IOException;

    /**
     * Length of the file
     */
    long length();
    
}