1 /*
   2  * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 // Forward Decl.
  26 class ConcurrentG1Refine;
  27 
  28 // The G1 Concurrent Refinement Thread (could be several in the future).
  29 
  30 class ConcurrentG1RefineThread: public ConcurrentGCThread {
  31   friend class VMStructs;
  32   friend class G1CollectedHeap;
  33 
  34   double _vtime_start;  // Initial virtual time.
  35   double _vtime_accum;  // Initial virtual time.
  36   int _worker_id;
  37   int _worker_id_offset;
  38 
  39   // The refinement threads collection is linked list. A predecessor can activate a successor
  40   // when the number of the rset update buffer crosses a certain threshold. A successor
  41   // would self-deactivate when the number of the buffers falls below the threshold.
  42   bool _active;
  43   ConcurrentG1RefineThread* _next;
  44   Monitor* _monitor;
  45   ConcurrentG1Refine* _cg1r;
  46 
  47   int _thread_threshold_step;
  48   // This thread activation threshold
  49   int _threshold;
  50   // This thread deactivation threshold
  51   int _deactivation_threshold;
  52 
  53   void sample_young_list_rs_lengths();
  54   void run_young_rs_sampling();
  55   void wait_for_completed_buffers();
  56 
  57   void set_active(bool x) { _active = x; }
  58   bool is_active();
  59   void activate();
  60   void deactivate();
  61 
  62   // For use by G1CollectedHeap, which is a friend.
  63   static SuspendibleThreadSet* sts() { return &_sts; }
  64 
  65 public:
  66   virtual void run();
  67   // Constructor
  68   ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread* next,
  69                            int worker_id_offset, int worker_id);
  70 
  71   void initialize();
  72 
  73   // Printing
  74   void print() const;
  75   void print_on(outputStream* st) const;
  76 
  77   // Total virtual time so far.
  78   double vtime_accum() { return _vtime_accum; }
  79 
  80   ConcurrentG1Refine* cg1r() { return _cg1r;     }
  81 
  82   // Yield for GC
  83   void yield();
  84   // shutdown
  85   void stop();
  86 };