Added old abandoned KDE3 version of the RoseGarden MIDI tool

git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/applications/rosegarden@1097595 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 211 insertions, 0 deletions

diff --git a/src/sound/Scavenger.h b/src/sound/Scavenger.h
new file mode 100644
index 0000000..b27e848
--- /dev/null
+++ b/src/sound/Scavenger.h
@@ -0,0 +1,211 @@
+// -*- c-basic-offset: 4 -*-
+
+/*
+    Rosegarden
+    A sequencer and musical notation editor.
+
+    This program is Copyright 2000-2008
+        Guillaume Laurent   <[email protected]>,
+        Chris Cannam        <[email protected]>,
+        Richard Bown        <[email protected]>
+
+    The moral right of the authors to claim authorship of this work
+    has been asserted.
+
+    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 _SCAVENGER_H_
+#define _SCAVENGER_H_
+
+#include <vector>
+#include <list>
+#include <sys/time.h>
+#include <pthread.h>
+#include <iostream>
+
+namespace Rosegarden
+{
+
+/**
+ * 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 for
+     * later disposal.  Only one thread should be calling this on any
+     * given scavenger.
+     * 
+     * This is only lock-free so long as a slot is available in the
+     * object list; otherwise it takes a lock and allocates memory.
+     * Scavengers should always be used with an object list size
+     * sufficient to ensure that enough slots are always available in
+     * normal use.
+     */
+    void claim(T *t);
+
+    /**
+     * Call from a non-RT thread.
+     * Only one thread should be calling this on any given scavenger.
+     */
+    void scavenge();
+
+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;
+    pthread_mutex_t 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)
+{
+    pthread_mutex_init(&m_excessMutex, NULL);
+}
+
+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);
+
+    pthread_mutex_destroy(&m_excessMutex);
+}
+
+template <typename T>
+void
+Scavenger<T>::claim(T *t)
+{
+    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()
+{
+    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 (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)
+{
+    pthread_mutex_lock(&m_excessMutex);
+    m_excess.push_back(t);
+    struct timeval tv;
+    (void)gettimeofday(&tv, 0);
+    m_lastExcess = tv.tv_sec;
+    pthread_mutex_unlock(&m_excessMutex);
+}
+
+template <typename T>
+void
+Scavenger<T>::clearExcess(int sec)
+{
+    pthread_mutex_lock(&m_excessMutex);
+    for (typename ObjectList::iterator i = m_excess.begin();
+         i != m_excess.end(); ++i) {
+        delete *i;
+    }
+    m_excess.clear();
+    m_lastExcess = sec;
+    pthread_mutex_unlock(&m_excessMutex);
+}
+
+}
+
+#endif