/*

 * Copyright (c) 2011, 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_HEAPREGIONSET_HPP

#define SHARE_GC_G1_HEAPREGIONSET_HPP

#include "gc/g1/heapRegion.hpp"

#include "utilities/macros.hpp"

#define assert_heap_region_set(p, message) \

  do {                                     \

    assert((p), "[%s] %s ln: %u",          \

           name(), message, length());     \

  } while (0)

#define guarantee_heap_region_set(p, message) \

  do {                                        \

    guarantee((p), "[%s] %s ln: %u",          \

              name(), message, length());     \

  } while (0)

#define assert_free_region_list(p, message)                          \

  do {                                                               \

    assert((p), "[%s] %s ln: %u hd: " PTR_FORMAT " tl: " PTR_FORMAT, \

           name(), message, length(), p2i(_head), p2i(_tail));       \

  } while (0)

// Interface collecting various instance specific verification methods of

// HeapRegionSets.

class HeapRegionSetChecker : public CHeapObj<mtGC> {

public:

  // Verify MT safety for this HeapRegionSet.

  virtual void check_mt_safety() = 0;

  // Returns true if the given HeapRegion is of the correct type for this HeapRegionSet.

  virtual bool is_correct_type(HeapRegion* hr) = 0;

  // Return a description of the type of regions this HeapRegionSet contains.

  virtual const char* get_description() = 0;

};

// Base class for all the classes that represent heap region sets. It

// contains the basic attributes that each set needs to maintain

// (e.g., length, region num, used bytes sum) plus any shared

// functionality (e.g., verification).

class HeapRegionSetBase {

  friend class VMStructs;

  HeapRegionSetChecker* _checker;

protected:

  // The number of regions in to the set.

  uint _length;

  const char* _name;

  bool _verify_in_progress;

  // verify_region() is used to ensure that the contents of a region

  // added to / removed from a set are consistent.

  void verify_region(HeapRegion* hr) PRODUCT_RETURN;

  void check_mt_safety() {

    if (_checker != NULL) {

      _checker->check_mt_safety();

    }

  }

  HeapRegionSetBase(const char* name, HeapRegionSetChecker* verifier);

public:

  const char* name() { return _name; }

  uint length() const { return _length; }

  bool is_empty() { return _length == 0; }

  // It updates the fields of the set to reflect hr being added to

  // the set and tags the region appropriately.

  inline void add(HeapRegion* hr);

  // It updates the fields of the set to reflect hr being removed

  // from the set and tags the region appropriately.

  inline void remove(HeapRegion* hr);

  virtual void verify();

  void verify_start();

  void verify_next_region(HeapRegion* hr);

  void verify_end();

  void verify_optional() { DEBUG_ONLY(verify();) }

  virtual void print_on(outputStream* out, bool print_contents = false);

};

// This class represents heap region sets whose members are not

// explicitly tracked. It's helpful to group regions using such sets

// so that we can reason about all the region groups in the heap using

// the same interface (namely, the HeapRegionSetBase API).

class HeapRegionSet : public HeapRegionSetBase {

public:

  HeapRegionSet(const char* name, HeapRegionSetChecker* checker):

    HeapRegionSetBase(name, checker) {

  }

  void bulk_remove(const uint removed) {

    _length -= removed;

  }

};

// A set that links all the regions added to it in a doubly-linked

// sorted list. We should try to avoid doing operations that iterate over

// such lists in performance critical paths. Typically we should

// add / remove one region at a time or concatenate two lists.

class FreeRegionListIterator;

class FreeRegionList : public HeapRegionSetBase {

  friend class FreeRegionListIterator;

private:

  HeapRegion* _head;

  HeapRegion* _tail;

  // _last is used to keep track of where we added an element the last

  // time. It helps to improve performance when adding several ordered items in a row.

  HeapRegion* _last;

  static uint _unrealistically_long_length;

  inline HeapRegion* remove_from_head_impl();

  inline HeapRegion* remove_from_tail_impl();

protected:

  // See the comment for HeapRegionSetBase::clear()

  virtual void clear();

public:

  FreeRegionList(const char* name, HeapRegionSetChecker* checker = NULL):

    HeapRegionSetBase(name, checker) {

    clear();

  }

  void verify_list();

#ifdef ASSERT

  bool contains(HeapRegion* hr) const {

    return hr->containing_set() == this;

  }

#endif

  static void set_unrealistically_long_length(uint len);

  // Add hr to the list. The region should not be a member of another set.

  // Assumes that the list is ordered and will preserve that order. The order

  // is determined by hrm_index.

  inline void add_ordered(HeapRegion* hr);

  // Removes from head or tail based on the given argument.

  HeapRegion* remove_region(bool from_head);

  // Merge two ordered lists. The result is also ordered. The order is

  // determined by hrm_index.

  void add_ordered(FreeRegionList* from_list);

  // It empties the list by removing all regions from it.

  void remove_all();

  // Remove all (contiguous) regions from first to first + num_regions -1 from

  // this list.

  // Num_regions must be > 1.

  void remove_starting_at(HeapRegion* first, uint num_regions);

  virtual void verify();

  uint num_of_regions_in_range(uint start, uint end) const;

};

// Iterator class that provides a convenient way to iterate over the

// regions of a FreeRegionList.

class FreeRegionListIterator : public StackObj {

private:

  FreeRegionList* _list;

  HeapRegion*     _curr;

public:

  bool more_available() {

    return _curr != NULL;

  }

  HeapRegion* get_next() {

    assert(more_available(),

           "get_next() should be called when more regions are available");

    // If we are going to introduce a count in the iterator we should

    // do the "cycle" check.

    HeapRegion* hr = _curr;

    _list->verify_region(hr);

    _curr = hr->next();

    return hr;

  }

  FreeRegionListIterator(FreeRegionList* list)

  : _list(list),

    _curr(list->_head) {

  }

};

#endif // SHARE_GC_G1_HEAPREGIONSET_HPP