/*

 * Copyright (c) 2011, 2015, 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.

 *

 */

#ifndef SHARE_VM_GC_G1_HEAPREGIONSET_HPP

#define SHARE_VM_GC_G1_HEAPREGIONSET_HPP

#include "gc/g1/heapRegion.hpp"

// Set verification will be forced either if someone defines

// HEAP_REGION_SET_FORCE_VERIFY to be 1, or in builds in which

// asserts are compiled in.

#ifndef HEAP_REGION_SET_FORCE_VERIFY

#define HEAP_REGION_SET_FORCE_VERIFY defined(ASSERT)

#endif // HEAP_REGION_SET_FORCE_VERIFY

class HRSMtSafeChecker : public CHeapObj<mtGC> {

public:

  virtual void check() = 0;

};

class MasterFreeRegionListMtSafeChecker    : public HRSMtSafeChecker { public: void check(); };

class SecondaryFreeRegionListMtSafeChecker : public HRSMtSafeChecker { public: void check(); };

class HumongousRegionSetMtSafeChecker      : public HRSMtSafeChecker { public: void check(); };

class OldRegionSetMtSafeChecker            : public HRSMtSafeChecker { public: void check(); };

class HeapRegionSetCount VALUE_OBJ_CLASS_SPEC {

  friend class VMStructs;

  uint   _length;

  size_t _capacity;

public:

  HeapRegionSetCount() : _length(0), _capacity(0) { }

  const uint   length()   const { return _length;   }

  const size_t capacity() const { return _capacity; }

  void increment(uint length_to_add, size_t capacity_to_add) {

    _length += length_to_add;

    _capacity += capacity_to_add;

  }

  void decrement(const uint length_to_remove, const size_t capacity_to_remove) {

    _length -= length_to_remove;

    _capacity -= capacity_to_remove;

  }

};

// 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 VALUE_OBJ_CLASS_SPEC {

  friend class VMStructs;

private:

  bool _is_humongous;

  bool _is_free;

  HRSMtSafeChecker* _mt_safety_checker;

protected:

  // The number of regions added to the set. If the set contains

  // only humongous regions, this reflects only 'starts humongous'

  // regions and does not include 'continues humongous' ones.

  HeapRegionSetCount _count;

  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;

  // Indicates whether all regions in the set should be humongous or

  // not. Only used during verification.

  bool regions_humongous() { return _is_humongous; }

  // Indicates whether all regions in the set should be free or

  // not. Only used during verification.

  bool regions_free() { return _is_free; }

  void check_mt_safety() {

    if (_mt_safety_checker != NULL) {

      _mt_safety_checker->check();

    }

  }

  HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker);

public:

  const char* name() { return _name; }

  uint length() const { return _count.length(); }

  bool is_empty() { return _count.length() == 0; }

  size_t total_capacity_bytes() {

    return _count.capacity();

  }

  // 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();

#if HEAP_REGION_SET_FORCE_VERIFY

  void verify_optional() {

    verify();

  }

#else // HEAP_REGION_SET_FORCE_VERIFY

  void verify_optional() { }

#endif // HEAP_REGION_SET_FORCE_VERIFY

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

};

  } while (0)

// 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, bool humongous, HRSMtSafeChecker* mt_safety_checker):

    HeapRegionSetBase(name, humongous, false /* free */, mt_safety_checker) { }

  void bulk_remove(const HeapRegionSetCount& removed) {

    _count.decrement(removed.length(), removed.capacity());

  }

};

// 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, HRSMtSafeChecker* mt_safety_checker = NULL):

    HeapRegionSetBase(name, false /* humongous */, true /* empty */, mt_safety_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();

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

};

// 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) : _curr(NULL), _list(list) {

    _curr = list->_head;

  }

};

#endif // SHARE_VM_GC_G1_HEAPREGIONSET_HPP