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 /*

  * Copyright (c) 2001, 2010, 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

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/concurrentG1Refine.hpp"

 #include "gc_implementation/g1/concurrentG1RefineThread.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1CollectorPolicy.hpp"

 #include "memory/resourceArea.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/mutexLocker.hpp"

 ConcurrentG1RefineThread::

 ConcurrentG1RefineThread(ConcurrentG1Refine* cg1r, ConcurrentG1RefineThread *next,

                          CardTableEntryClosure* refine_closure,

                          uint worker_id_offset, uint worker_id) :

   ConcurrentGCThread(),

   _refine_closure(refine_closure),

   _worker_id_offset(worker_id_offset),

   _worker_id(worker_id),

   _active(false),

   _next(next),

   _monitor(NULL),

   _cg1r(cg1r),

   _vtime_accum(0.0)

 {

   // Each thread has its own monitor. The i-th thread is responsible for signalling

   // to thread i+1 if the number of buffers in the queue exceeds a threashold for this

   // thread. Monitors are also used to wake up the threads during termination.

   // The 0th worker in notified by mutator threads and has a special monitor.

   // The last worker is used for young gen rset size sampling.

   if (worker_id > 0) {

     _monitor = new Monitor(Mutex::nonleaf, "Refinement monitor", true);

   } else {

     _monitor = DirtyCardQ_CBL_mon;

   }

   initialize();

   create_and_start();

 }

 void ConcurrentG1RefineThread::initialize() {

   if (_worker_id < cg1r()->worker_thread_num()) {

     // Current thread activation threshold

     _threshold = MIN2<int>(cg1r()->thread_threshold_step() * (_worker_id + 1) + cg1r()->green_zone(),

                            cg1r()->yellow_zone());

     // A thread deactivates once the number of buffer reached a deactivation threshold

     _deactivation_threshold = MAX2<int>(_threshold - cg1r()->thread_threshold_step(), cg1r()->green_zone());

   } else {

     set_active(true);

   }

 }

 void ConcurrentG1RefineThread::sample_young_list_rs_lengths() {

   SuspendibleThreadSetJoiner sts;

   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   G1CollectorPolicy* g1p = g1h->g1_policy();

   if (g1p->adaptive_young_list_length()) {

     int regions_visited = 0;

     g1h->young_list()->rs_length_sampling_init();

     while (g1h->young_list()->rs_length_sampling_more()) {

       g1h->young_list()->rs_length_sampling_next();

       ++regions_visited;

       // we try to yield every time we visit 10 regions

       if (regions_visited == 10) {

         if (sts.should_yield()) {

           sts.yield();

           // we just abandon the iteration

           break;

         }

         regions_visited = 0;

       }

     }

     g1p->revise_young_list_target_length_if_necessary();

   }

 }

 void ConcurrentG1RefineThread::run_young_rs_sampling() {

   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

   _vtime_start = os::elapsedVTime();

   while(!_should_terminate) {

     sample_young_list_rs_lengths();

     if (os::supports_vtime()) {

       _vtime_accum = (os::elapsedVTime() - _vtime_start);

     } else {

       _vtime_accum = 0.0;

     }

     MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);

     if (_should_terminate) {

       break;

     }

     _monitor->wait(Mutex::_no_safepoint_check_flag, G1ConcRefinementServiceIntervalMillis);

   }

 }

 void ConcurrentG1RefineThread::wait_for_completed_buffers() {

   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);

   while (!_should_terminate && !is_active()) {

     _monitor->wait(Mutex::_no_safepoint_check_flag);

   }

 }

 bool ConcurrentG1RefineThread::is_active() {

   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

   return _worker_id > 0 ? _active : dcqs.process_completed_buffers();

 }

 void ConcurrentG1RefineThread::activate() {

   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);

   if (_worker_id > 0) {

     if (G1TraceConcRefinement) {

       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

       gclog_or_tty->print_cr("G1-Refine-activated worker %d, on threshold %d, current %d",

                              _worker_id, _threshold, (int)dcqs.completed_buffers_num());

     }

     set_active(true);

   } else {

     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

     dcqs.set_process_completed(true);

   }

   _monitor->notify();

 }

 void ConcurrentG1RefineThread::deactivate() {

   MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);

   if (_worker_id > 0) {

     if (G1TraceConcRefinement) {

       DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

       gclog_or_tty->print_cr("G1-Refine-deactivated worker %d, off threshold %d, current %d",

                              _worker_id, _deactivation_threshold, (int)dcqs.completed_buffers_num());

     }

     set_active(false);

   } else {

     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

     dcqs.set_process_completed(false);

   }

 }

 void ConcurrentG1RefineThread::run() {

   initialize_in_thread();

   wait_for_universe_init();

   if (_worker_id >= cg1r()->worker_thread_num()) {

     run_young_rs_sampling();

     terminate();

     return;

   }

   _vtime_start = os::elapsedVTime();

   while (!_should_terminate) {

     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();

     // Wait for work

     wait_for_completed_buffers();

     if (_should_terminate) {

       break;

     }

     {

       SuspendibleThreadSetJoiner sts;

       do {

         int curr_buffer_num = (int)dcqs.completed_buffers_num();

         // If the number of the buffers falls down into the yellow zone,

         // that means that the transition period after the evacuation pause has ended.

         if (dcqs.completed_queue_padding() > 0 && curr_buffer_num <= cg1r()->yellow_zone()) {

           dcqs.set_completed_queue_padding(0);

         }

         if (_worker_id > 0 && curr_buffer_num <= _deactivation_threshold) {

           // If the number of the buffer has fallen below our threshold

           // we should deactivate. The predecessor will reactivate this

           // thread should the number of the buffers cross the threshold again.

           deactivate();

           break;

         }

         // Check if we need to activate the next thread.

         if (_next != NULL && !_next->is_active() && curr_buffer_num > _next->_threshold) {

           _next->activate();

         }

       } while (dcqs.apply_closure_to_completed_buffer(_refine_closure, _worker_id + _worker_id_offset, cg1r()->green_zone()));

       // We can exit the loop above while being active if there was a yield request.

       if (is_active()) {

         deactivate();

       }

     }

     if (os::supports_vtime()) {

       _vtime_accum = (os::elapsedVTime() - _vtime_start);

     } else {

       _vtime_accum = 0.0;

     }

   }

   assert(_should_terminate, "just checking");

   terminate();

 }

 void ConcurrentG1RefineThread::stop() {

   // it is ok to take late safepoints here, if needed

   {

     MutexLockerEx mu(Terminator_lock);

     _should_terminate = true;

   }

   {

     MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag);

     _monitor->notify();

   }

   {

     MutexLockerEx mu(Terminator_lock);

     while (!_has_terminated) {

       Terminator_lock->wait();

     }

   }

   if (G1TraceConcRefinement) {

     gclog_or_tty->print_cr("G1-Refine-stop");

   }

 }

 void ConcurrentG1RefineThread::print() const {

   print_on(tty);

 }

 void ConcurrentG1RefineThread::print_on(outputStream* st) const {

   st->print("\"G1 Concurrent Refinement Thread#%d\" ", _worker_id);

   Thread::print_on(st);

   st->cr();

 }