lbajardsilogic@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
lbajardsilogic@0: 
lbajardsilogic@0: /*
lbajardsilogic@0:     Sonic Visualiser
lbajardsilogic@0:     An audio file viewer and annotation editor.
lbajardsilogic@0:     Centre for Digital Music, Queen Mary, University of London.
lbajardsilogic@0:     This file copyright 2006 Chris Cannam.
lbajardsilogic@0:     
lbajardsilogic@0:     This program is free software; you can redistribute it and/or
lbajardsilogic@0:     modify it under the terms of the GNU General Public License as
lbajardsilogic@0:     published by the Free Software Foundation; either version 2 of the
lbajardsilogic@0:     License, or (at your option) any later version.  See the file
lbajardsilogic@0:     COPYING included with this distribution for more information.
lbajardsilogic@0: */
lbajardsilogic@0: 
lbajardsilogic@0: /*
lbajardsilogic@0:    This is a modified version of a source file from the 
lbajardsilogic@0:    Rosegarden MIDI and audio sequencer and notation editor.
lbajardsilogic@0:    This file copyright 2000-2006 Chris Cannam.
lbajardsilogic@0: */
lbajardsilogic@0: 
lbajardsilogic@0: #ifndef _SCAVENGER_H_
lbajardsilogic@0: #define _SCAVENGER_H_
lbajardsilogic@0: 
lbajardsilogic@0: #include "system/System.h"
lbajardsilogic@0: 
lbajardsilogic@0: #include <vector>
lbajardsilogic@0: #include <list>
lbajardsilogic@0: //#include <sys/time.h>
lbajardsilogic@0: #include <QMutex>
lbajardsilogic@0: #include <iostream>
lbajardsilogic@0: 
lbajardsilogic@0: /**
lbajardsilogic@0:  * A very simple class that facilitates running things like plugins
lbajardsilogic@0:  * without locking, by collecting unwanted objects and deleting them
lbajardsilogic@0:  * after a delay so as to be sure nobody's in the middle of using
lbajardsilogic@0:  * them.  Requires scavenge() to be called regularly from a non-RT
lbajardsilogic@0:  * thread.
lbajardsilogic@0:  *
lbajardsilogic@0:  * This is currently not at all suitable for large numbers of objects
lbajardsilogic@0:  * -- it's just a quick hack for use with things like plugins.
lbajardsilogic@0:  */
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: class Scavenger
lbajardsilogic@0: {
lbajardsilogic@0: public:
lbajardsilogic@0:     Scavenger(int sec = 2, int defaultObjectListSize = 200);
lbajardsilogic@0:     ~Scavenger();
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Call from an RT thread etc., to pass ownership of t to us.
lbajardsilogic@0:      * Only one thread should be calling this on any given scavenger.
lbajardsilogic@0:      */
lbajardsilogic@0:     void claim(T *t);
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Call from a non-RT thread.
lbajardsilogic@0:      * Only one thread should be calling this on any given scavenger.
lbajardsilogic@0:      */
lbajardsilogic@0:     void scavenge(bool clearNow = false);
lbajardsilogic@0: 
lbajardsilogic@0: protected:
lbajardsilogic@0:     typedef std::pair<T *, int> ObjectTimePair;
lbajardsilogic@0:     typedef std::vector<ObjectTimePair> ObjectTimeList;
lbajardsilogic@0:     ObjectTimeList m_objects;
lbajardsilogic@0:     int m_sec;
lbajardsilogic@0: 
lbajardsilogic@0:     typedef std::list<T *> ObjectList;
lbajardsilogic@0:     ObjectList m_excess;
lbajardsilogic@0:     int m_lastExcess;
lbajardsilogic@0:     QMutex m_excessMutex;
lbajardsilogic@0:     void pushExcess(T *);
lbajardsilogic@0:     void clearExcess(int);
lbajardsilogic@0: 
lbajardsilogic@0:     unsigned int m_claimed;
lbajardsilogic@0:     unsigned int m_scavenged;
lbajardsilogic@0: };
lbajardsilogic@0: 
lbajardsilogic@0: /**
lbajardsilogic@0:  * A wrapper to permit arrays to be scavenged.
lbajardsilogic@0:  */
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: class ScavengerArrayWrapper
lbajardsilogic@0: {
lbajardsilogic@0: public:
lbajardsilogic@0:     ScavengerArrayWrapper(T *array) : m_array(array) { }
lbajardsilogic@0:     ~ScavengerArrayWrapper() { delete[] m_array; }
lbajardsilogic@0: 
lbajardsilogic@0: private:
lbajardsilogic@0:     T *m_array;
lbajardsilogic@0: };
lbajardsilogic@0: 
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: Scavenger<T>::Scavenger(int sec, int defaultObjectListSize) :
lbajardsilogic@0:     m_objects(ObjectTimeList(defaultObjectListSize)),
lbajardsilogic@0:     m_sec(sec),
lbajardsilogic@0:     m_lastExcess(0),
lbajardsilogic@0:     m_claimed(0),
lbajardsilogic@0:     m_scavenged(0)
lbajardsilogic@0: {
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: Scavenger<T>::~Scavenger()
lbajardsilogic@0: {
lbajardsilogic@0:     if (m_scavenged < m_claimed) {
lbajardsilogic@0: 	for (size_t i = 0; i < m_objects.size(); ++i) {
lbajardsilogic@0: 	    ObjectTimePair &pair = m_objects[i];
lbajardsilogic@0: 	    if (pair.first != 0) {
lbajardsilogic@0: 		T *ot = pair.first;
lbajardsilogic@0: 		pair.first = 0;
lbajardsilogic@0: 		delete ot;
lbajardsilogic@0: 		++m_scavenged;
lbajardsilogic@0: 	    }
lbajardsilogic@0: 	}
lbajardsilogic@0:     }
lbajardsilogic@0: 
lbajardsilogic@0:     clearExcess(0);
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: void
lbajardsilogic@0: Scavenger<T>::claim(T *t)
lbajardsilogic@0: {
lbajardsilogic@0: //    std::cerr << "Scavenger::claim(" << t << ")" << std::endl;
lbajardsilogic@0: 
lbajardsilogic@0:     struct timeval tv;
lbajardsilogic@0:     (void)gettimeofday(&tv, 0);
lbajardsilogic@0:     int sec = tv.tv_sec;
lbajardsilogic@0: 
lbajardsilogic@0:     for (size_t i = 0; i < m_objects.size(); ++i) {
lbajardsilogic@0: 	ObjectTimePair &pair = m_objects[i];
lbajardsilogic@0: 	if (pair.first == 0) {
lbajardsilogic@0: 	    pair.second = sec;
lbajardsilogic@0: 	    pair.first = t;
lbajardsilogic@0: 	    ++m_claimed;
lbajardsilogic@0: 	    return;
lbajardsilogic@0: 	}
lbajardsilogic@0:     }
lbajardsilogic@0: 
lbajardsilogic@0:     std::cerr << "WARNING: Scavenger::claim(" << t << "): run out of slots, "
lbajardsilogic@0: 	      << "using non-RT-safe method" << std::endl;
lbajardsilogic@0:     pushExcess(t);
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: void
lbajardsilogic@0: Scavenger<T>::scavenge(bool clearNow)
lbajardsilogic@0: {
lbajardsilogic@0: //    std::cerr << "Scavenger::scavenge: scavenged " << m_scavenged << ", claimed " << m_claimed << std::endl;
lbajardsilogic@0: 
lbajardsilogic@0:     if (m_scavenged >= m_claimed) return;
lbajardsilogic@0:     
lbajardsilogic@0:     struct timeval tv;
lbajardsilogic@0:     (void)gettimeofday(&tv, 0);
lbajardsilogic@0:     int sec = tv.tv_sec;
lbajardsilogic@0: 
lbajardsilogic@0:     for (size_t i = 0; i < m_objects.size(); ++i) {
lbajardsilogic@0: 	ObjectTimePair &pair = m_objects[i];
lbajardsilogic@0: 	if (clearNow ||
lbajardsilogic@0: 	    (pair.first != 0 && pair.second + m_sec < sec)) {
lbajardsilogic@0: 	    T *ot = pair.first;
lbajardsilogic@0: 	    pair.first = 0;
lbajardsilogic@0: 	    delete ot;
lbajardsilogic@0: 	    ++m_scavenged;
lbajardsilogic@0: 	}
lbajardsilogic@0:     }
lbajardsilogic@0: 
lbajardsilogic@0:     if (sec > m_lastExcess + m_sec) {
lbajardsilogic@0:         clearExcess(sec);
lbajardsilogic@0:     }
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: void
lbajardsilogic@0: Scavenger<T>::pushExcess(T *t)
lbajardsilogic@0: {
lbajardsilogic@0:     m_excessMutex.lock();
lbajardsilogic@0:     m_excess.push_back(t);
lbajardsilogic@0:     struct timeval tv;
lbajardsilogic@0:     (void)gettimeofday(&tv, 0);
lbajardsilogic@0:     m_lastExcess = tv.tv_sec;
lbajardsilogic@0:     m_excessMutex.unlock();
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: template <typename T>
lbajardsilogic@0: void
lbajardsilogic@0: Scavenger<T>::clearExcess(int sec)
lbajardsilogic@0: {
lbajardsilogic@0:     m_excessMutex.lock();
lbajardsilogic@0:     for (typename ObjectList::iterator i = m_excess.begin();
lbajardsilogic@0: 	 i != m_excess.end(); ++i) {
lbajardsilogic@0: 	delete *i;
lbajardsilogic@0:     }
lbajardsilogic@0:     m_excess.clear();
lbajardsilogic@0:     m_lastExcess = sec;
lbajardsilogic@0:     m_excessMutex.unlock();
lbajardsilogic@0: }
lbajardsilogic@0: 
lbajardsilogic@0: #endif