view plugin/PluginScan.h @ 1376:d9511f9e04d7 dev/refactor-piper-related

Introduce some POD structs for describing an external server application and the desired libraries to load from it, and disambiguating between empty list request and invalid list request. This allows for overriding PiperVampPluginFactory behaviour for using a PluginScan to populate the list request.

/* -*- 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 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 PLUGIN_SCAN_H
#define PLUGIN_SCAN_H

#include <QStringList>
#include <QMutex>
#include <vector>
#include <map>

class KnownPlugins;

class PluginScan
{
public:
    static PluginScan *getInstance();

    /**
     * Carry out startup scan of available plugins. Do not call
     * getCandidateLibrariesFor() unless this has been called and
     * scanSucceeded() is returning true.
     */
    void scan();

    /**
     * Return true if scan() completed successfully. If the scan
     * failed, consider using the normal plugin path to load any
     * available plugins (as if they had all been found to be
     * loadable) rather than rejecting all of them -- i.e. consider
     * falling back on the behaviour of code from before the scan
     * logic was added.
     */
    bool scanSucceeded() const;
    
    enum PluginType {
	VampPlugin,
	LADSPAPlugin,
	DSSIPlugin
    };
    struct Candidate {
        QString libraryPath;    // full path, not just soname
        QString helperTag;      // identifies the helper that found it
                                // (see HelperExecPath) 
    };

    /**
     * Return the candidate plugin libraries of the given type that
     * were found by helpers during the startup scan.
     *
     * This could return an empty list for two reasons: the scan
     * succeeded but no libraries were found; or the scan failed. Call
     * scanSucceeded() to distinguish between them.
     */
    QList<Candidate> getCandidateLibrariesFor(PluginType) const;

    QString getStartupFailureReport() const;

private:
    PluginScan();
    ~PluginScan();

    void clear();

    mutable QMutex m_mutex; // while scanning; definitely can't multi-thread this
    
    std::map<QString, KnownPlugins *> m_kp; // tag -> KnownPlugins client
    bool m_succeeded;

    class Logger;
    Logger *m_logger;
};

#endif