diff -r e45861098f5a -r fec48bf5a827 hotspot/src/share/vm/gc/shared/gcTimer.hpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/shared/gcTimer.hpp	Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,193 @@
+/*
+ * Copyright (c) 2012, 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_VM_GC_SHARED_GCTIMER_HPP
+#define SHARE_VM_GC_SHARED_GCTIMER_HPP
+
+#include "memory/allocation.hpp"
+#include "prims/jni_md.h"
+#include "utilities/macros.hpp"
+#include "utilities/ticks.hpp"
+
+class ConcurrentPhase;
+class GCPhase;
+class PausePhase;
+
+template <class E> class GrowableArray;
+
+class PhaseVisitor {
+ public:
+  virtual void visit(GCPhase* phase) = 0;
+  virtual void visit(PausePhase* phase) { visit((GCPhase*)phase); }
+  virtual void visit(ConcurrentPhase* phase) { visit((GCPhase*)phase); }
+};
+
+class GCPhase {
+  const char* _name;
+  int _level;
+  Ticks _start;
+  Ticks _end;
+
+ public:
+  void set_name(const char* name) { _name = name; }
+  const char* name() const { return _name; }
+
+  int level() const { return _level; }
+  void set_level(int level) { _level = level; }
+
+  const Ticks start() const { return _start; }
+  void set_start(const Ticks& time) { _start = time; }
+
+  const Ticks end() const { return _end; }
+  void set_end(const Ticks& time) { _end = time; }
+
+  virtual void accept(PhaseVisitor* visitor) = 0;
+};
+
+class PausePhase : public GCPhase {
+ public:
+  void accept(PhaseVisitor* visitor) {
+    visitor->visit(this);
+  }
+};
+
+class ConcurrentPhase : public GCPhase {
+  void accept(PhaseVisitor* visitor) {
+    visitor->visit(this);
+  }
+};
+
+class PhasesStack {
+ public:
+  // FIXME: Temporary set to 5 (used to be 4), since Reference processing needs it.
+  static const int PHASE_LEVELS = 5;
+
+ private:
+  int _phase_indices[PHASE_LEVELS];
+  int _next_phase_level;
+
+ public:
+  PhasesStack() { clear(); }
+  void clear();
+
+  void push(int phase_index);
+  int pop();
+  int count() const;
+};
+
+class TimePartitions {
+  static const int INITIAL_CAPACITY = 10;
+
+  // Currently we only support pause phases.
+  GrowableArray<PausePhase>* _phases;
+  PhasesStack _active_phases;
+
+  Tickspan _sum_of_pauses;
+  Tickspan _longest_pause;
+
+ public:
+  TimePartitions();
+  ~TimePartitions();
+  void clear();
+
+  void report_gc_phase_start(const char* name, const Ticks& time);
+  void report_gc_phase_end(const Ticks& time);
+
+  int num_phases() const;
+  GCPhase* phase_at(int index) const;
+
+  const Tickspan sum_of_pauses() const { return _sum_of_pauses; }
+  const Tickspan longest_pause() const { return _longest_pause; }
+
+  bool has_active_phases();
+ private:
+  void update_statistics(GCPhase* phase);
+};
+
+class PhasesIterator {
+ public:
+  virtual bool has_next() = 0;
+  virtual GCPhase* next() = 0;
+};
+
+class GCTimer : public ResourceObj {
+  NOT_PRODUCT(friend class GCTimerTest;)
+ protected:
+  Ticks _gc_start;
+  Ticks _gc_end;
+  TimePartitions _time_partitions;
+
+ public:
+  virtual void register_gc_start(const Ticks& time = Ticks::now());
+  virtual void register_gc_end(const Ticks& time = Ticks::now());
+
+  void register_gc_phase_start(const char* name, const Ticks& time);
+  void register_gc_phase_end(const Ticks& time);
+
+  const Ticks gc_start() const { return _gc_start; }
+  const Ticks gc_end() const { return _gc_end; }
+
+  TimePartitions* time_partitions() { return &_time_partitions; }
+
+ protected:
+  void register_gc_pause_start(const char* name, const Ticks& time = Ticks::now());
+  void register_gc_pause_end(const Ticks& time = Ticks::now());
+};
+
+class STWGCTimer : public GCTimer {
+ public:
+  virtual void register_gc_start(const Ticks& time = Ticks::now());
+  virtual void register_gc_end(const Ticks& time = Ticks::now());
+};
+
+class ConcurrentGCTimer : public GCTimer {
+ public:
+  void register_gc_pause_start(const char* name);
+  void register_gc_pause_end();
+};
+
+class TimePartitionPhasesIterator {
+  TimePartitions* _time_partitions;
+  int _next;
+
+ public:
+  TimePartitionPhasesIterator(TimePartitions* time_partitions) : _time_partitions(time_partitions), _next(0) { }
+
+  virtual bool has_next();
+  virtual GCPhase* next();
+};
+
+
+/////////////// Unit tests ///////////////
+
+#ifndef PRODUCT
+
+class GCTimerAllTest {
+ public:
+  static void all();
+};
+
+#endif
+
+#endif // SHARE_VM_GC_SHARED_GCTIMER_HPP