/*

 * Copyright (c) 2016, 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

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc/shared/preservedMarks.inline.hpp"

#include "gc/shared/workgroup.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/resourceArea.hpp"

void PreservedMarks::restore() {

  while (!_stack.is_empty()) {

    const OopAndMarkOop elem = _stack.pop();

    elem.set_mark();

  }

  assert_empty();

}

#ifndef PRODUCT

void PreservedMarks::assert_empty() {

  assert(_stack.is_empty(), "stack expected to be empty, size = "SIZE_FORMAT,

         _stack.size());

  assert(_stack.cache_size() == 0,

         "stack expected to have no cached segments, cache size = "SIZE_FORMAT,

         _stack.cache_size());

}

#endif // ndef PRODUCT

void RemoveForwardedPointerClosure::do_object(oop obj) {

  if (obj->is_forwarded()) {

    PreservedMarks::init_forwarded_mark(obj);

  }

}

void PreservedMarksSet::init(uint num) {

  assert(_stacks == NULL && _num == 0, "do not re-initialize");

  assert(num > 0, "pre-condition");

  if (_in_c_heap) {

    _stacks = NEW_C_HEAP_ARRAY(Padded<PreservedMarks>, num, mtGC);

  } else {

    _stacks = NEW_RESOURCE_ARRAY(Padded<PreservedMarks>, num);

  }

  for (uint i = 0; i < num; i += 1) {

    ::new (_stacks + i) PreservedMarks();

  }

  _num = num;

  assert_empty();

}

class ParRestoreTask : public AbstractGangTask {

private:

  PreservedMarksSet* const _preserved_marks_set;

  SequentialSubTasksDone _sub_tasks;

  volatile size_t* const _total_size_addr;

public:

  virtual void work(uint worker_id) {

    uint task_id = 0;

    while (!_sub_tasks.is_task_claimed(/* reference */ task_id)) {

      PreservedMarks* const preserved_marks = _preserved_marks_set->get(task_id);

      const size_t size = preserved_marks->size();

      preserved_marks->restore();

      // Only do the atomic add if the size is > 0.

      if (size > 0) {

        Atomic::add(size, _total_size_addr);

      }

    }

    _sub_tasks.all_tasks_completed();

  }

  ParRestoreTask(uint worker_num,

                 PreservedMarksSet* preserved_marks_set,

                 volatile size_t* total_size_addr)

      : AbstractGangTask("Parallel Preserved Mark Restoration"),

        _preserved_marks_set(preserved_marks_set),

        _total_size_addr(total_size_addr) {

    _sub_tasks.set_n_threads(worker_num);

    _sub_tasks.set_n_tasks(preserved_marks_set->num());

  }

};

void PreservedMarksSet::restore_internal(WorkGang* workers,

                                         volatile size_t* total_size_addr) {

  assert(workers != NULL, "pre-condition");

  ParRestoreTask task(workers->active_workers(), this, total_size_addr);

  workers->run_task(&task);

}

class ParRestoreGCTask : public GCTask {

private:

  const uint _id;

  PreservedMarksSet* const _preserved_marks_set;

  volatile size_t* const _total_size_addr;

public:

  virtual char* name() { return (char*) "preserved mark restoration task"; }

  virtual void do_it(GCTaskManager* manager, uint which) {

    PreservedMarks* const preserved_marks = _preserved_marks_set->get(_id);

    const size_t size = preserved_marks->size();

    preserved_marks->restore();

    // Only do the atomic add if the size is > 0.

    if (size > 0) {

      Atomic::add(size, _total_size_addr);

    }

  }

  ParRestoreGCTask(uint id,

                   PreservedMarksSet* preserved_marks_set,

                   volatile size_t* total_size_addr)

    : _id(id),

      _preserved_marks_set(preserved_marks_set),

      _total_size_addr(total_size_addr) { }

};

void PreservedMarksSet::restore_internal(GCTaskManager* gc_task_manager,

                                         volatile size_t* total_size_addr) {

  // GCTask / GCTaskQueue are ResourceObjs

  ResourceMark rm;

  GCTaskQueue* q = GCTaskQueue::create();

  for (uint i = 0; i < num(); i += 1) {

    q->enqueue(new ParRestoreGCTask(i, this, total_size_addr));

  }

  gc_task_manager->execute_and_wait(q);

}

void PreservedMarksSet::reclaim() {

  assert_empty();

  for (uint i = 0; i < _num; i += 1) {

    _stacks[i].~Padded<PreservedMarks>();

  }

  if (_in_c_heap) {

    FREE_C_HEAP_ARRAY(Padded<PreservedMarks>, _stacks);

  } else {

    // the array was resource-allocated, so nothing to do

  }

  _stacks = NULL;

  _num = 0;

}

#ifndef PRODUCT

void PreservedMarksSet::assert_empty() {

  assert(_stacks != NULL && _num > 0, "should have been initialized");

  for (uint i = 0; i < _num; i += 1) {

    get(i)->assert_empty();

  }

}

#endif // ndef PRODUCT