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 * Copyright (c) 2001, 2019, 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

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#ifndef SHARE_GC_G1_G1CONCURRENTREFINE_HPP

#define SHARE_GC_G1_G1CONCURRENTREFINE_HPP

#include "memory/allocation.hpp"

#include "utilities/globalDefinitions.hpp"

// Forward decl

class G1ConcurrentRefine;

class G1ConcurrentRefineThread;

class outputStream;

class ThreadClosure;

// Helper class for refinement thread management. Used to start, stop and

// iterate over them.

class G1ConcurrentRefineThreadControl {

  G1ConcurrentRefine* _cr;

  G1ConcurrentRefineThread** _threads;

  uint _num_max_threads;

  // Create the refinement thread for the given worker id.

  // If initializing is true, ignore InjectGCWorkerCreationFailure.

  G1ConcurrentRefineThread* create_refinement_thread(uint worker_id, bool initializing);

public:

  G1ConcurrentRefineThreadControl();

  ~G1ConcurrentRefineThreadControl();

  jint initialize(G1ConcurrentRefine* cr, uint num_max_threads);

  // If there is a "successor" thread that can be activated given the current id,

  // activate it.

  void maybe_activate_next(uint cur_worker_id);

  void print_on(outputStream* st) const;

  void worker_threads_do(ThreadClosure* tc);

  void stop();

};

// Controls refinement threads and their activation based on the number of completed

// buffers currently available in the global dirty card queue.

// Refinement threads pick work from the queue based on these thresholds. They are activated

// gradually based on the amount of work to do.

// Refinement thread n activates thread n+1 if the instance of this class determines there

// is enough work available. Threads deactivate themselves if the current amount of

// completed buffers falls below their individual threshold.

class G1ConcurrentRefine : public CHeapObj<mtGC> {

  G1ConcurrentRefineThreadControl _thread_control;

  /*

   * The value of the completed dirty card queue length falls into one of 3 zones:

   * green, yellow, red. If the value is in [0, green) nothing is

   * done, the buffers are left unprocessed to enable the caching effect of the

   * dirtied cards. In the yellow zone [green, yellow) the concurrent refinement

   * threads are gradually activated. In [yellow, red) all threads are

   * running. If the length becomes red (max queue length) the mutators start

   * processing the buffers.

   *

   * There are some interesting cases (when G1UseAdaptiveConcRefinement

   * is turned off):

   * 1) green = yellow = red = 0. In this case the mutator will process all

   *    buffers. Except for those that are created by the deferred updates

   *    machinery during a collection.

   * 2) green = 0. Means no caching. Can be a good way to minimize the

   *    amount of time spent updating remembered sets during a collection.

   */

  size_t _green_zone;

  size_t _yellow_zone;

  size_t _red_zone;

  size_t _min_yellow_zone_size;

  G1ConcurrentRefine(size_t green_zone,

                     size_t yellow_zone,

                     size_t red_zone,

                     size_t min_yellow_zone_size);

  // Update green/yellow/red zone values based on how well goals are being met.

                    double goal_ms);

  static uint worker_id_offset();

  void maybe_activate_more_threads(uint worker_id, size_t num_cur_buffers);

  jint initialize();

public:

  ~G1ConcurrentRefine();

  // Returns a G1ConcurrentRefine instance if succeeded to create/initialize the

  // G1ConcurrentRefine instance. Otherwise, returns NULL with error code.

  static G1ConcurrentRefine* create(jint* ecode);

  void stop();

  // Adjust refinement thresholds based on work done during the pause and the goal time.

  size_t activation_threshold(uint worker_id) const;

  size_t deactivation_threshold(uint worker_id) const;

  // Perform a single refinement step. Called by the refinement threads when woken up.

  bool do_refinement_step(uint worker_id);

  // Iterate over all concurrent refinement threads applying the given closure.

  void threads_do(ThreadClosure *tc);

  // Maximum number of refinement threads.

  static uint max_num_threads();

  void print_threads_on(outputStream* st) const;

  size_t green_zone() const      { return _green_zone;  }

  size_t yellow_zone() const     { return _yellow_zone; }

  size_t red_zone() const        { return _red_zone;    }

};

#endif // SHARE_GC_G1_G1CONCURRENTREFINE_HPP