diff base/Scavenger.h @ 0:fc9323a41f5a

start base : Sonic Visualiser sv1-1.0rc1

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/Scavenger.h	Fri May 11 09:08:14 2007 +0000
@@ -0,0 +1,203 @@
+/* -*- 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.
+*/
+
+/*
+   This is a modified version of a source file from the 
+   Rosegarden MIDI and audio sequencer and notation editor.
+   This file copyright 2000-2006 Chris Cannam.
+*/
+
+#ifndef _SCAVENGER_H_
+#define _SCAVENGER_H_
+
+#include "system/System.h"
+
+#include <vector>
+#include <list>
+//#include <sys/time.h>
+#include <QMutex>
+#include <iostream>
+
+/**
+ * A very simple class that facilitates running things like plugins
+ * without locking, by collecting unwanted objects and deleting them
+ * after a delay so as to be sure nobody's in the middle of using
+ * them.  Requires scavenge() to be called regularly from a non-RT
+ * thread.
+ *
+ * This is currently not at all suitable for large numbers of objects
+ * -- it's just a quick hack for use with things like plugins.
+ */
+
+template <typename T>
+class Scavenger
+{
+public:
+    Scavenger(int sec = 2, int defaultObjectListSize = 200);
+    ~Scavenger();
+
+    /**
+     * Call from an RT thread etc., to pass ownership of t to us.
+     * Only one thread should be calling this on any given scavenger.
+     */
+    void claim(T *t);
+
+    /**
+     * Call from a non-RT thread.
+     * Only one thread should be calling this on any given scavenger.
+     */
+    void scavenge(bool clearNow = false);
+
+protected:
+    typedef std::pair<T *, int> ObjectTimePair;
+    typedef std::vector<ObjectTimePair> ObjectTimeList;
+    ObjectTimeList m_objects;
+    int m_sec;
+
+    typedef std::list<T *> ObjectList;
+    ObjectList m_excess;
+    int m_lastExcess;
+    QMutex m_excessMutex;
+    void pushExcess(T *);
+    void clearExcess(int);
+
+    unsigned int m_claimed;
+    unsigned int m_scavenged;
+};
+
+/**
+ * A wrapper to permit arrays to be scavenged.
+ */
+
+template <typename T>
+class ScavengerArrayWrapper
+{
+public:
+    ScavengerArrayWrapper(T *array) : m_array(array) { }
+    ~ScavengerArrayWrapper() { delete[] m_array; }
+
+private:
+    T *m_array;
+};
+
+
+template <typename T>
+Scavenger<T>::Scavenger(int sec, int defaultObjectListSize) :
+    m_objects(ObjectTimeList(defaultObjectListSize)),
+    m_sec(sec),
+    m_lastExcess(0),
+    m_claimed(0),
+    m_scavenged(0)
+{
+}
+
+template <typename T>
+Scavenger<T>::~Scavenger()
+{
+    if (m_scavenged < m_claimed) {
+	for (size_t i = 0; i < m_objects.size(); ++i) {
+	    ObjectTimePair &pair = m_objects[i];
+	    if (pair.first != 0) {
+		T *ot = pair.first;
+		pair.first = 0;
+		delete ot;
+		++m_scavenged;
+	    }
+	}
+    }
+
+    clearExcess(0);
+}
+
+template <typename T>
+void
+Scavenger<T>::claim(T *t)
+{
+//    std::cerr << "Scavenger::claim(" << t << ")" << std::endl;
+
+    struct timeval tv;
+    (void)gettimeofday(&tv, 0);
+    int sec = tv.tv_sec;
+
+    for (size_t i = 0; i < m_objects.size(); ++i) {
+	ObjectTimePair &pair = m_objects[i];
+	if (pair.first == 0) {
+	    pair.second = sec;
+	    pair.first = t;
+	    ++m_claimed;
+	    return;
+	}
+    }
+
+    std::cerr << "WARNING: Scavenger::claim(" << t << "): run out of slots, "
+	      << "using non-RT-safe method" << std::endl;
+    pushExcess(t);
+}
+
+template <typename T>
+void
+Scavenger<T>::scavenge(bool clearNow)
+{
+//    std::cerr << "Scavenger::scavenge: scavenged " << m_scavenged << ", claimed " << m_claimed << std::endl;
+
+    if (m_scavenged >= m_claimed) return;
+    
+    struct timeval tv;
+    (void)gettimeofday(&tv, 0);
+    int sec = tv.tv_sec;
+
+    for (size_t i = 0; i < m_objects.size(); ++i) {
+	ObjectTimePair &pair = m_objects[i];
+	if (clearNow ||
+	    (pair.first != 0 && pair.second + m_sec < sec)) {
+	    T *ot = pair.first;
+	    pair.first = 0;
+	    delete ot;
+	    ++m_scavenged;
+	}
+    }
+
+    if (sec > m_lastExcess + m_sec) {
+        clearExcess(sec);
+    }
+}
+
+template <typename T>
+void
+Scavenger<T>::pushExcess(T *t)
+{
+    m_excessMutex.lock();
+    m_excess.push_back(t);
+    struct timeval tv;
+    (void)gettimeofday(&tv, 0);
+    m_lastExcess = tv.tv_sec;
+    m_excessMutex.unlock();
+}
+
+template <typename T>
+void
+Scavenger<T>::clearExcess(int sec)
+{
+    m_excessMutex.lock();
+    for (typename ObjectList::iterator i = m_excess.begin();
+	 i != m_excess.end(); ++i) {
+	delete *i;
+    }
+    m_excess.clear();
+    m_lastExcess = sec;
+    m_excessMutex.unlock();
+}
+
+#endif