/*

 * copyright (c) 2011, 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_IMPLEMENTATION_G1_HEAPREGIONSET_HPP

#define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP

#include "gc_implementation/g1/heapRegion.hpp"

// Large buffer for some cases where the output might be larger than normal.

#define HRS_ERR_MSG_BUFSZ 512

typedef FormatBuffer<HRS_ERR_MSG_BUFSZ> hrs_err_msg;

// 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

//////////////////// HeapRegionSetBase ////////////////////

// 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 hrs_ext_msg;

class HeapRegionSetBase VALUE_OBJ_CLASS_SPEC {

  friend class hrs_ext_msg;

protected:

  static size_t calculate_region_num(HeapRegion* hr);

  static size_t _unrealistically_long_length;

  // 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.

  size_t _length;

  // The total number of regions represented by the set. If the set

  // does not contain humongous regions, this should be the same as

  // _length. If the set contains only humongous regions, this will

  // include the 'continues humongous' regions.

  size_t _region_num;

  // We don't keep track of the total capacity explicitly, we instead

  // recalculate it based on _region_num and the heap region size.

  // The sum of used bytes in the all the regions in the set.

  size_t _total_used_bytes;

  const char* _name;

  bool        _verify_in_progress;

  size_t      _calc_length;

  size_t      _calc_region_num;

  size_t      _calc_total_capacity_bytes;

  size_t      _calc_total_used_bytes;

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

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

  // make different assumptions about the regions added to them. So

  // each set can override verify_region_extra(), which is called

  // from verify_region(), and do any extra verification it needs to

  // perform in that.

  virtual const char* verify_region_extra(HeapRegion* hr) { return NULL; }

  bool verify_region(HeapRegion* hr,

                     HeapRegionSetBase* expected_containing_set);

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

  // not. Only used during verification.

  virtual bool regions_humongous() = 0;

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

  // not. Only used during verification.

  virtual bool regions_empty() = 0;

  // Subclasses can optionally override this to do MT safety protocol

  // checks. It is called in an assert from all methods that perform

  // updates on the set (and subclasses should also call it too).

  virtual bool check_mt_safety() { return true; }

  // fill_in_ext_msg() writes the the values of the set's attributes

  // in the custom err_msg (hrs_ext_msg). fill_in_ext_msg_extra()

  // allows subclasses to append further information.

  virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg) { }

  void fill_in_ext_msg(hrs_ext_msg* msg, const char* message);

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

  // the set.

  inline void update_for_addition(HeapRegion* hr);

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

  // the set and tags the region appropriately.

  inline void add_internal(HeapRegion* hr);

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

  // from the set.

  inline void update_for_removal(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_internal(HeapRegion* hr);

  // It clears all the fields of the sets. Note: it will not iterate

  // over the set and remove regions from it. It assumes that the

  // caller has already done so. It will literally just clear the fields.

  virtual void clear();

  HeapRegionSetBase(const char* name);

public:

  static void set_unrealistically_long_length(size_t len);

  const char* name() { return _name; }

  size_t length() { return _length; }

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

  size_t region_num() { return _region_num; }

  size_t total_capacity_bytes() {

    return region_num() << HeapRegion::LogOfHRGrainBytes;

  }

  size_t total_used_bytes() { return _total_used_bytes; }

  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);

};

// Customized err_msg for heap region sets. Apart from a

// assert/guarantee-specific message it also prints out the values of

// the fields of the associated set. This can be very helpful in

// diagnosing failures.

class hrs_ext_msg : public hrs_err_msg {

public:

  hrs_ext_msg(HeapRegionSetBase* set, const char* message) : hrs_err_msg("") {

    set->fill_in_ext_msg(this, message);

  }

};

// These two macros are provided for convenience, to keep the uses of

// these two asserts a bit more concise.

#define hrs_assert_mt_safety_ok(_set_)                                        \

  do {                                                                        \

    assert((_set_)->check_mt_safety(), hrs_ext_msg((_set_), "MT safety"));    \

  } while (0)

#define hrs_assert_region_ok(_set_, _hr_, _expected_)                         \

  do {                                                                        \

    assert((_set_)->verify_region((_hr_), (_expected_)),                      \

           hrs_ext_msg((_set_), "region verification"));                      \

  } while (0)

//////////////////// HeapRegionSet ////////////////////

#define hrs_assert_sets_match(_set1_, _set2_)                                 \

  do {                                                                        \

    assert(((_set1_)->regions_humongous() ==                                  \

                                            (_set2_)->regions_humongous()) && \

           ((_set1_)->regions_empty() == (_set2_)->regions_empty()),          \

           hrs_err_msg("the contents of set %s and set %s should match",      \

                       (_set1_)->name(), (_set2_)->name()));                  \

  } 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 {

protected:

  virtual const char* verify_region_extra(HeapRegion* hr) {

    if (hr->next() != NULL) {

      return "next() should always be NULL as we do not link the regions";

    }

    return HeapRegionSetBase::verify_region_extra(hr);

  }

  HeapRegionSet(const char* name) : HeapRegionSetBase(name) {

    clear();

  }

public:

  // It adds hr to the set. The region should not be a member of

  // another set.

  inline void add(HeapRegion* hr);

  // It removes hr from the set. The region should be a member of

  // this set.

  inline void remove(HeapRegion* hr);

  // It removes a region from the set. Instead of updating the fields

  // of the set to reflect this removal, it accumulates the updates

  // in proxy_set. The idea is that proxy_set is thread-local to

  // avoid multiple threads updating the fields of the set

  // concurrently and having to synchronize. The method

  // update_from_proxy() will update the fields of the set from the

  // proxy_set.

  inline void remove_with_proxy(HeapRegion* hr, HeapRegionSet* proxy_set);

  // After multiple calls to remove_with_proxy() the updates to the

  // fields of the set are accumulated in proxy_set. This call

  // updates the fields of the set from proxy_set.

  void update_from_proxy(HeapRegionSet* proxy_set);

};

//////////////////// HeapRegionLinkedList ////////////////////

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

// 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. All

// those operations are done in constant time.

class HeapRegionLinkedListIterator;

class HeapRegionLinkedList : public HeapRegionSetBase {

  friend class HeapRegionLinkedListIterator;

private:

  HeapRegion* _head;

  HeapRegion* _tail;

  // These are provided for use by the friend classes.

  HeapRegion* head() { return _head; }

  HeapRegion* tail() { return _tail; }

protected:

  virtual void fill_in_ext_msg_extra(hrs_ext_msg* msg);

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

  virtual void clear();

  HeapRegionLinkedList(const char* name) : HeapRegionSetBase(name) {

    clear();

  }

public:

  // It adds hr to the list as the new tail. The region should not be

  // a member of another set.

  inline void add_as_tail(HeapRegion* hr);

  // It removes and returns the head of the list. It assumes that the

  // list is not empty so it will return a non-NULL value.

  inline HeapRegion* remove_head();

  // Convenience method.

  inline HeapRegion* remove_head_or_null();

  // It moves the regions from from_list to this list and empties

  // from_list. The new regions will appear in the same order as they

  // were in from_list and be linked in the end of this list.

  void add_as_tail(HeapRegionLinkedList* from_list);

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

  void remove_all();

  // It removes all regions in the list that are pending for removal

  // (i.e., they have been tagged with "pending_removal"). The list

  // must not be empty, target_count should reflect the exact number

  // of regions that are pending for removal in the list, and

  // target_count should be > 1 (currently, we never need to remove a

  // single region using this).

  void remove_all_pending(size_t target_count);

  virtual void verify();

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

};

//////////////////// HeapRegionLinkedListIterator ////////////////////

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

// regions of a HeapRegionLinkedList instance.

class HeapRegionLinkedListIterator : public StackObj {

private:

  HeapRegionLinkedList* _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;

    assert(_list->verify_region(hr, _list), "region verification");

    _curr = hr->next();

    return hr;

  }

  HeapRegionLinkedListIterator(HeapRegionLinkedList* list)

    : _curr(NULL), _list(list) {

    _curr = list->head();

  }

};

#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGIONSET_HPP