/*

 * 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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// 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();

};