view data/fileio/FileReadThread.h @ 492:23945cdd7161

* Update RDF query stuff again so as to set up a temporary datastore
  each time we want to query over an rdf file, instead of using rasqal
  against the file.  Seems the only way to avoid threading and storage
  management issues when trying to load from a single-source file and
  perform queries against our main datastore at the same time.  Maybe.

/* -*- 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 _FILE_READ_THREAD_H_
#define _FILE_READ_THREAD_H_

#include "base/Thread.h"

#include <QMutex>
#include <QWaitCondition>

#include <map>
#include <set>

#include <stdint.h>

class FileReadThread : public Thread
{
    Q_OBJECT

public:
    FileReadThread();

    virtual void run();
    virtual void finish();

    struct Request {
        int fd;
        QMutex *mutex; // used to synchronise access to fd; may be null
        off_t start;
        size_t size;
        char *data; // caller is responsible for allocating and deallocating
        bool successful; // set by FileReadThread after processing request
    };
    
    virtual int request(const Request &request);
    virtual void cancel(int token);

    virtual bool isReady(int token);
    virtual bool isCancelled(int token); // and safe to delete
    virtual bool haveRequest(int token);
    virtual bool getRequest(int token, Request &request);
    virtual void done(int token);
    
protected:
    int m_nextToken;
    bool m_exiting;
    
    typedef std::map<int, Request> RequestQueue;
    RequestQueue m_queue;
    RequestQueue m_cancelledRequests;
    RequestQueue m_readyRequests;
    std::set<int> m_newlyCancelled;

    QMutex m_mutex;
    QWaitCondition m_condition;

    void process();
    void notifyCancelled();
};

#endif