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 * This code is free software; you can redistribute it and/or modify it

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 * 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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#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 signaling

  // to thread i+1 if the number of buffers in the queue exceeds a threshold 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) {

  } else {

    _monitor = DirtyCardQ_CBL_mon;

  }

  initialize();

  create_and_start();

  // set name

  set_name("G1 Concurrent Refinement Thread#%d", worker_id);

}

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");

  }

}