1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   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.
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   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
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP
  26 #define SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP
  27 
  28 #include "gc/shared/concurrentGCThread.hpp"
  29 
  30 class G1ConcurrentMark;
  31 class G1Policy;
  32 
  33 // The concurrent mark thread triggers the various steps of the concurrent marking
  34 // cycle, including various marking cleanup.
  35 class G1ConcurrentMarkThread: public ConcurrentGCThread {
  36   friend class VMStructs;
  37 
  38   double _vtime_start;  // Initial virtual time.
  39   double _vtime_accum;  // Accumulated virtual time.
  40   double _vtime_mark_accum;
  41 
  42   G1ConcurrentMark* _cm;
  43 
  44   enum ServiceState {
  45     Idle,
  46     Started,
  47     InProgress
  48   };
  49 
  50   volatile ServiceState _state;
  51 
  52   // Wait for next cycle. Returns true if we should stop the service.
  53   bool wait_for_next_cycle();
  54   void run_cycle();
  55 
  56   void concurrent_cycle_start();
  57   void concurrent_cycle_end();
  58   // Delay marking to meet MMU.
  59   void delay_to_keep_mmu(G1Policy* g1_policy, bool remark);
  60   double mmu_delay_end(G1Policy* g1_policy, bool remark);
  61 
  62   void run_service();
  63   void stop_service();
  64 
  65  public:
  66   // Constructor
  67   G1ConcurrentMarkThread(G1ConcurrentMark* cm);
  68 
  69   // Total virtual time so far for this thread and concurrent marking tasks.
  70   double vtime_accum();
  71   // Marking virtual time so far this thread and concurrent marking tasks.
  72   double vtime_mark_accum();
  73 
  74   G1ConcurrentMark* cm()   { return _cm; }
  75 
  76   void set_idle()          { assert(_state != Started, "must not be starting a new cycle"); _state = Idle; }
  77   bool idle()              { return _state == Idle; }
  78   void set_started()       { assert(_state == Idle, "cycle in progress"); _state = Started; }
  79   bool started()           { return _state == Started; }
  80   void set_in_progress()   { assert(_state == Started, "must be starting a cycle"); _state = InProgress; }
  81   bool in_progress()       { return _state == InProgress; }
  82 
  83   // Returns true from the moment a marking cycle is
  84   // initiated (during the initial-mark pause when started() is set)
  85   // to the moment when the cycle completes (just after the next
  86   // marking bitmap has been cleared and in_progress() is
  87   // cleared). While during_cycle() is true we will not start another cycle
  88   // so that cycles do not overlap. We cannot use just in_progress()
  89   // as the CM thread might take some time to wake up before noticing
  90   // that started() is set and set in_progress().
  91   bool during_cycle()      { return !idle(); }
  92 };
  93 
  94 #endif // SHARE_GC_G1_G1CONCURRENTMARKTHREAD_HPP