view data/fileio/MatrixFile.h @ 316:3a6725f285d6

* Make RemoteFile far more pervasive, and use it for local files as well
  so that we can handle both transparently.  Make it shallow copy with
  reference counting, so it can be used by value without having to worry
  about the cache file lifetime.  Use RemoteFile for MainWindow file-open
  functions, etc

/* -*- 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 Chris Cannam.
    
    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, ReadWrite };

    /**
     * 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 ReadWrite and the file does not exist, it will be
     * created.  If mode is ReadWrite and the file does exist, the
     * existing file will be used and the mode will be reset to
     * ReadOnly.  Call getMode() to check whether this has occurred
     * after construction.
     *
     * 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.
     *
     * If eagerCache is true, blocks from the file will be cached for
     * read.  If eagerCache is false, only columns that have been set
     * by calling setColumnAt on this MatrixFile (i.e. columns for
     * which haveSetColumnAt returns true) will be cached.
     */
    MatrixFile(QString fileBase, Mode mode, size_t cellSize, bool eagerCache);
    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; }
    
    void resize(size_t width, size_t height);
    void reset();

    bool haveSetColumnAt(size_t x) const { return m_columnBitset->get(x); }
    void getColumnAt(size_t x, void *data);
    void setColumnAt(size_t x, const void *data);

    void suspend();

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;
    size_t  m_defaultCacheWidth;
    size_t  m_prevX;

    struct Cache {
        size_t x;
        size_t width;
        char *data;
    };

    Cache m_cache;
    bool  m_eagerCache;

    bool getFromCache(size_t x, size_t ystart, size_t ycount, void *data);
    void primeCache(size_t x, bool left);

    void resume();

    bool seekTo(size_t x, size_t y);

    static FileReadThread *m_readThread;
    int m_requestToken;

    size_t m_requestingX;
    size_t m_requestingWidth;
    char *m_spareData;

    static std::map<QString, int> m_refcount;
    static QMutex m_refcountMutex;
    QMutex m_fdMutex;
    QMutex m_cacheMutex;

    typedef std::map<QString, ResizeableBitset *> ResizeableBitsetMap;
    static ResizeableBitsetMap m_columnBitsets;
    static QMutex m_columnBitsetWriteMutex;
    ResizeableBitset *m_columnBitset;
};

#endif