/*
 * Copyright (c) 2001, 2009, 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.
 *
 */

// The Concurrent ZF Thread.  Performs concurrent zero-filling.

class ConcurrentZFThread: public ConcurrentGCThread {
  friend class VMStructs;
  friend class ZeroFillRegionClosure;

 private:

  // Zero fill the heap region.
  void processHeapRegion(HeapRegion* r);

  // Stats
  //   Allocation (protected by heap lock).
  static int _region_allocs;  // Number of regions allocated
  static int _sync_zfs;       //   Synchronous zero-fills +
  static int _zf_waits;      //   Wait for conc zero-fill completion.

  // Number of regions CFZ thread fills.
  static int _regions_filled;

  double _vtime_start;  // Initial virtual time.

  // These are static because the "print_summary_info" method is, and
  // it currently assumes there is only one ZF thread.  We'll change when
  // we need to.
  static double _vtime_accum;  // Initial virtual time.
  static double vtime_accum() { return _vtime_accum; }

  // Offer yield for GC.  Returns true if yield occurred.
  bool offer_yield();

 public:
  // Constructor
  ConcurrentZFThread();

  // Main loop.
  virtual void run();

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

  // Waits until "r" has been zero-filled.  Requires caller to hold the
  // ZF_mon.
  static void wait_for_ZF_completed(HeapRegion* r);

  // Get or clear the current unclean region.  Should be done
  // while holding the ZF_needed_mon lock.

  // shutdown
  void stop();

  // Stats
  static void note_region_alloc() {_region_allocs++; }
  static void note_sync_zfs() { _sync_zfs++; }
  static void note_zf_wait() { _zf_waits++; }
  static void note_region_filled() { _regions_filled++; }

  static void print_summary_info();
};