annotate base/TempDirectory.h @ 335:02d2ad95ea52 spectrogram-cache-rejig

* Get storage advice for each cache in an FFT data server.  Allows us to be
  more confident about the actual memory situation and cut over from memory
  to disc part way through an FFT calculation if necessary.  StorageAdviser
  is now a bit too optimistic though (it's too keen to allocate large numbers
  of small blocks in memory).

/* -*- 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 _TEMP_DIRECTORY_H_
#define _TEMP_DIRECTORY_H_

#include <QString>
#include <QMutex>

#include <exception>

/**
 * A class that manages the creation and removal of a temporary
 * directory tree to store data during the program run.  There is one
 * root temporary directory for the program, created on demand and
 * deleted when the program exits.
 *
 * This class is thread safe.
 */

class TempDirectory
{
public:
    static TempDirectory *getInstance();
    
    virtual ~TempDirectory();

    /**
     * Create the root temporary directory if necessary, and return
     * its path.  Throw DirectoryCreationFailed if the directory
     * cannot be created.
     */
    QString getPath();

    /** 
     * Create an immediate subdirectory of the root temporary
     * directory of the given name, if it doesn't already exist, and
     * return its path.  Throw DirectoryCreationFailed if the
     * directory cannot be created.
     */
    QString getSubDirectoryPath(QString subdir);

    /**
     * Delete the temporary directory (before exiting).
     */
    void cleanup();

protected:
    TempDirectory();

    QString createTempDirectoryIn(QString inDir);
    void cleanupDirectory(QString tmpDir);
    void cleanupAbandonedDirectories(QString svDir);

    QString m_tmpdir;
    QMutex m_mutex;

    static TempDirectory *m_instance;
};


#endif