Event Garbage Collector

src/simulator/event-garbage-collector.cc

@@ -0,0 +1,152 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2007 INESC Porto
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Gustavo J. A. M. Carneiro  <gjc@inescporto.pt>
+ */
+#include "event-garbage-collector.h"
+
+#define CLEANUP_CHUNK_MIN_SIZE 8
+#define CLEANUP_CHUNK_MAX_SIZE 128
+
+
+namespace ns3 {
+
+
+EventGarbageCollector::EventGarbageCollector () :
+  m_nextCleanupSize (CLEANUP_CHUNK_MIN_SIZE)
+{}
+
+void
+EventGarbageCollector::Track (EventId event)
+{
+  m_events.push_back (event);
+  if (m_events.size () >= m_nextCleanupSize)
+    Cleanup ();
+}
+
+inline bool
+EventExpiredPredicate (const EventId &event)
+{
+  return event.IsExpired ();
+}
+
+void
+EventGarbageCollector::Grow ()
+{
+  m_nextCleanupSize += (m_nextCleanupSize < CLEANUP_CHUNK_MAX_SIZE?
+                        m_nextCleanupSize : CLEANUP_CHUNK_MAX_SIZE);
+}
+
+void
+EventGarbageCollector::Shrink ()
+{
+  while (m_nextCleanupSize > m_events.size ())
+    m_nextCleanupSize >>= 1;
+  Grow ();
+}
+
+// Called when a new event was added and the cleanup limit was exceeded in consequence.
+void
+EventGarbageCollector::Cleanup ()
+{
+  m_events.remove_if (EventExpiredPredicate);
+
+  // If after cleanup we are still over the limit, increase the limit.
+  if (m_events.size () >= m_nextCleanupSize)
+    Grow ();
+  else
+    Shrink ();
+}
+
+
+EventGarbageCollector::~EventGarbageCollector ()
+{
+  for (std::list<EventId>::iterator event = m_events.begin ();
+       event != m_events.end (); event++)
+    {
+      Simulator::Cancel (*event);
+    }
+}
+
+}; // namespace ns3
+
+
+
+#ifdef RUN_SELF_TESTS
+
+#include "ns3/test.h"
+
+namespace ns3 {
+
+class EventGarbageCollectorTests : public Test
+{
+  int m_counter;
+  EventGarbageCollector *m_events;
+
+  void EventGarbageCollectorCallback ();
+
+public:
+
+  EventGarbageCollectorTests ();
+  virtual ~EventGarbageCollectorTests ();
+  virtual bool RunTests (void);
+};
+
+EventGarbageCollectorTests::EventGarbageCollectorTests ()
+  : Test ("EventGarbageCollector"), m_counter (0), m_events (0)
+{}
+
+EventGarbageCollectorTests::~EventGarbageCollectorTests ()
+{}
+
+void
+EventGarbageCollectorTests::EventGarbageCollectorCallback ()
+{
+  m_counter++;
+  if (m_counter == 50)
+    {
+      // this should cause the remaining (50) events to be cancelled
+      delete m_events;
+      m_events = 0;
+    }
+}
+
+bool EventGarbageCollectorTests::RunTests (void)
+{
+  bool result = true;
+
+  m_events = new EventGarbageCollector ();
+
+  for (int n = 0; n < 100; n++)
+    {
+      m_events->Track (Simulator::Schedule
+                       (Simulator::Now (),
+                        &EventGarbageCollectorTests::EventGarbageCollectorCallback,
+                        this));
+    }
+  Simulator::Run ();
+  NS_TEST_ASSERT_EQUAL (m_events, 0);
+  NS_TEST_ASSERT_EQUAL (m_counter, 50);
+  return result;
+}
+
+static EventGarbageCollectorTests g_eventCollectorTests;
+    
+};
+
+#endif /* RUN_SELF_TESTS */

src/simulator/event-garbage-collector.h

@@ -0,0 +1,62 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2007 INESC Porto
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Author: Gustavo J. A. M. Carneiro  <gjc@inescporto.pt>
+ */
+#ifndef EVENT_GARBAGE_COLLECTOR_H
+#define EVENT_GARBAGE_COLLECTOR_H
+
+#include <list>
+#include "event-id.h"
+#include "simulator.h"
+
+namespace ns3 {
+
+/**
+ * \brief An object that tracks scheduled events and automatically
+ * cancels them when it is destroyed.  It is useful in situations
+ * where multiple instances of the same type of event can
+ * simultaneously be scheduled, and when the events should be limited
+ * to the lifetime of a container object.
+ */
+class EventGarbageCollector
+{
+public:
+
+  EventGarbageCollector ();
+
+  /**
+   * \brief Tracks a new event
+   */
+  void Track (EventId event);
+
+  ~EventGarbageCollector ();
+
+private:
+
+  std::list<EventId>::size_type m_nextCleanupSize;
+  std::list<EventId> m_events;
+
+  void Cleanup ();
+  void Grow ();
+  void Shrink ();
+};
+
+}; // namespace ns3
+
+#endif /* EVENT_GARBAGE_COLLECTOR_H */