/*

 * 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"

#include "utilities/macros.hpp"

void PreservedMarks::restore() {

  while (!_stack.is_empty()) {

    const OopAndMarkOop elem = _stack.pop();

    elem.set_mark();

  }

  assert_empty();

}

void PreservedMarks::restore_and_increment(volatile size_t* const total_size_addr) {

  const size_t stack_size = size();

  restore();

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

  if (stack_size > 0) {

    Atomic::add(stack_size, total_size_addr);

  }

}

#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)) {

      _preserved_marks_set->get(task_id)->restore_and_increment(_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::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

void SharedRestorePreservedMarksTaskExecutor::restore(PreservedMarksSet* preserved_marks_set,

                                                      volatile size_t* total_size_addr) {

  if (_workers == NULL) {

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

      *total_size_addr += preserved_marks_set->get(i)->size();

      preserved_marks_set->get(i)->restore();

    }

  } else {

    ParRestoreTask task(_workers->active_workers(), preserved_marks_set, total_size_addr);

    _workers->run_task(&task);

  }

}