src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp

/*
 * Copyright (c) 2001, 2012, 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.
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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP

#include "gc_implementation/shared/concurrentGCThread.hpp"

// The Concurrent Mark GC Thread (could be several in the future).
// This is copied from the Concurrent Mark Sweep GC Thread
// Still under construction.

class ConcurrentMark;

class ConcurrentMarkThread: public ConcurrentGCThread {
  friend class VMStructs;

  double _vtime_start;  // Initial virtual time.
  double _vtime_accum;  // Accumulated virtual time.

  double _vtime_mark_accum;

 public:
  virtual void run();

 private:
  ConcurrentMark*                  _cm;
  volatile bool                    _started;
  volatile bool                    _in_progress;

  void sleepBeforeNextCycle();

  static SurrogateLockerThread*         _slt;

 public:
  // Constructor
  ConcurrentMarkThread(ConcurrentMark* cm);

  static void makeSurrogateLockerThread(TRAPS);
  static SurrogateLockerThread* slt() { return _slt; }

  // Printing
  void print_on(outputStream* st) const;
  void print() const;

  // Total virtual time so far.
  double vtime_accum();
  // Marking virtual time so far
  double vtime_mark_accum();

  ConcurrentMark* cm()     { return _cm; }

  void set_started()       { assert(!_in_progress, "cycle in progress"); _started = true;  }
  void clear_started()     { assert(_in_progress, "must be starting a cycle"); _started = false; }
  bool started()           { return _started;  }

  void set_in_progress()   { assert(_started, "must be starting a cycle"); _in_progress = true;  }
  void clear_in_progress() { assert(!_started, "must not be starting a new cycle"); _in_progress = false; }
  bool in_progress()       { return _in_progress;  }

  // This flag returns true from the moment a marking cycle is
  // initiated (during the initial-mark pause when started() is set)
  // to the moment when the cycle completes (just after the next
  // marking bitmap has been cleared and in_progress() is
  // cleared). While this flag is true we will not start another cycle
  // so that cycles do not overlap. We cannot use just in_progress()
  // as the CM thread might take some time to wake up before noticing
  // that started() is set and set in_progress().
  bool during_cycle()      { return started() || in_progress(); }

  // shutdown
  void stop();
};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARKTHREAD_HPP