view layer/RenderTimer.h @ 1160:a429b2acb45d 3.0-integration

Make SVDEBUG always write to a log file -- formerly this was disabled in NDEBUG builds. I think there's little use to that, it just means that we keep adding more cerr debug output because we aren't getting the log we need. And SVDEBUG logging is not usually used in tight loops, I don't think the performance overhead is too serious.

Also update the About box.

/* -*- 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 RENDER_TIMER_H
#define RENDER_TIMER_H

#include <chrono>

class RenderTimer
{
public:
    enum Type {
	/// A normal rendering operation with normal responsiveness demands
	FastRender,

	/// An operation that the user might accept being slower
	SlowRender,

	/// An operation that should always complete, i.e. as if there
	/// were no RenderTimer in use, but without having to change
	/// client code structurally
	NoTimeout
    };
    
    /**
     * Create a new RenderTimer and start timing. Make one of these
     * before rendering, and then call outOfTime() regularly during
     * rendering. If outOfTime() returns true, abandon rendering!  and
     * schedule the rest for after some user responsiveness has
     * happened.
     */
    RenderTimer(Type t) :
	m_start(std::chrono::steady_clock::now()),
	m_haveLimits(true),
	m_minFraction(0.1),
	m_softLimit(0.1),
	m_hardLimit(0.2),
	m_softLimitOverridden(false) {

	if (t == NoTimeout) {
	    m_haveLimits = false;
	} else if (t == SlowRender) {
	    m_softLimit = 0.2;
	    m_hardLimit = 0.4;
	}
    }


    /**
     * Return true if we have run out of time and should suspend
     * rendering and handle user events instead. Call this regularly
     * during rendering work: fractionComplete should be an estimate
     * of how much of the work has been done as of this call, as a
     * number between 0.0 (none of it) and 1.0 (all of it).
     */
    bool outOfTime(double fractionComplete) {

	if (!m_haveLimits || fractionComplete < m_minFraction) {
	    return false;
	}
	
	auto t = std::chrono::steady_clock::now();
	double elapsed = std::chrono::duration<double>(t - m_start).count();
	
	if (elapsed > m_hardLimit) {
	    return true;
	} else if (!m_softLimitOverridden && elapsed > m_softLimit) {
	    if (fractionComplete > 0.6) {
		// If we're significantly more than half way by the
		// time we reach the soft limit, ignore it (though
		// always respect the hard limit, above). Otherwise
		// respect the soft limit and report out of time now.
		m_softLimitOverridden = true;
	    } else {
		return true;
	    }
	}

	return false;
    }

private:
    std::chrono::time_point<std::chrono::steady_clock> m_start;
    bool m_haveLimits;
    double m_minFraction;
    double m_softLimit;
    double m_hardLimit;
    bool m_softLimitOverridden;
};

#endif