/*

 * 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

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 */

#ifndef SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP

#define SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP

#include "memory/allocation.hpp"

#include "memory/padded.hpp"

#include "oops/oop.hpp"

#include "utilities/stack.hpp"

class OopAndMarkOop {

private:

  oop _o;

  markOop _m;

public:

  OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { }

  void set_mark() const {

    _o->set_mark(_m);

  }

};

typedef Stack<OopAndMarkOop, mtGC> OopAndMarkOopStack;

class PreservedMarks VALUE_OBJ_CLASS_SPEC {

private:

  OopAndMarkOopStack _stack;

  inline bool should_preserve_mark(oop obj, markOop m) const;

  inline void push(oop obj, markOop m);

public:

  bool is_empty() const { return _stack.is_empty(); }

  inline void push_if_necessary(oop obj, markOop m);

  // Iterate over the stack, restore the preserved marks, then reclaim

  // the memory taken up by stack chunks.

  void restore();

  ~PreservedMarks() { assert(is_empty(), "should have been cleared"); }

};

class RemoveForwardedPointerClosure: public ObjectClosure {

public:

  virtual void do_object(oop obj);

};

private:

  // true -> _stacks will be allocated in the C heap

  // false -> _stacks will be allocated in the resource arena

  const bool _in_c_heap;

  // Number of stacks we have allocated (typically, one stack per GC worker).

  // This should be >= 1 if the stacks have been initialized,

  // or == 0 if they have not.

  uint _num;

  // Stack array (typically, one stack per GC worker) of length _num.

  // This should be != NULL if the stacks have been initialized,

  // or == NULL if they have not.

  Padded<PreservedMarks>* _stacks;

public:

  // Return the i'th stack.

  PreservedMarks* get(uint i = 0) const {

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

    assert(i < _num, "pre-condition");

    return (_stacks + i);

  }

  // Allocate stack array.

  void init(uint num);

  // Iterate over all stacks, restore all preserved marks, then

  // reclaim the memory taken up by stack chunks.

  void restore();

  // Reclaim stack array.

  void reclaim();

  // Assert all the stacks are empty.

  void assert_empty() PRODUCT_RETURN;

  PreservedMarksSet(bool in_c_heap)

      : _in_c_heap(in_c_heap), _num(0), _stacks(NULL) { }

  ~PreservedMarksSet() {

    assert(_stacks == NULL && _num == 0, "stacks should have been reclaimed");

  }

};

#endif // SHARE_VM_GC_SHARED_PRESERVEDMARKS_HPP