view data/fileio/MatrixFile.h @ 875:3e6ed8a8577b tonioni

Use a sparse time-value model only for outputs with fixed bin count of 1, not for those with unknown bin count.
(Precursor to using more than one model for outputs with unknown bin count)

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006-2009 Chris Cannam and QMUL.
    
    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.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef _MATRIX_FILE_CACHE_H_
#define _MATRIX_FILE_CACHE_H_

#include "base/ResizeableBitset.h"

#include "FileReadThread.h"

#include <sys/types.h>
#include <QString>
#include <QMutex>
#include <map>

class MatrixFile : public QObject
{
    Q_OBJECT

public:
    enum Mode { ReadOnly, WriteOnly };

    /**
     * Construct a MatrixFile object reading from and/or writing to
     * the matrix file with the given base name in the application's
     * temporary directory.
     *
     * If mode is ReadOnly, the file must exist and be readable.
     *
     * If mode is WriteOnly, the file must not exist.
     *
     * cellSize specifies the size in bytes of the object type stored
     * in the matrix.  For example, use cellSize = sizeof(float) for a
     * matrix of floats.  The MatrixFile object doesn't care about the
     * objects themselves, it just deals with raw data of a given size.
     *
     * width and height specify the dimensions of the file.  These
     * cannot be changed after construction.
     *
     * MatrixFiles are reference counted by name.  When the last
     * MatrixFile with a given name is destroyed, the file is removed.
     * These are temporary files; the normal usage is to have one
     * MatrixFile of WriteOnly type creating the file and then
     * persisting until all readers are complete.
     *
     * MatrixFile has no built-in cache and is not thread-safe.  Use a
     * separate MatrixFile in each thread.
     */
    MatrixFile(QString fileBase, Mode mode, size_t cellSize,
               size_t width, size_t height);
    virtual ~MatrixFile();

    Mode getMode() const { return m_mode; }

    size_t getWidth() const { return m_width; }
    size_t getHeight() const { return m_height; }
    size_t getCellSize() const { return m_cellSize; }

    /**
     * If this is set true on a write-mode MatrixFile, then the file
     * will close() itself when all columns have been written.
     */
    void setAutoClose(bool a) { m_autoClose = a; }

    void close(); // does not decrement ref count; that happens in dtor

    bool haveSetColumnAt(size_t x) const;
    void getColumnAt(size_t x, void *data); // may throw FileReadFailed
    void setColumnAt(size_t x, const void *data);

protected:
    int     m_fd;
    Mode    m_mode;
    int     m_flags;
    mode_t  m_fmode;
    size_t  m_cellSize;
    size_t  m_width;
    size_t  m_height;
    size_t  m_headerSize;
    QString m_fileName;

    ResizeableBitset *m_setColumns; // only in writer
    bool m_autoClose;

    // In reader: if this is >= 0, we can read that column directly
    // without seeking (and we know that the column exists)
    mutable int m_readyToReadColumn;

    static std::map<QString, int> m_refcount;
    static QMutex m_createMutex;

    void initialise();
    bool seekTo(size_t x) const;
};

#endif