/*

 * Copyright (c) 2001, 2017, 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/g1/heapRegion.hpp"

#include "gc/g1/heapRegionBounds.inline.hpp"

#include "gc/g1/heapRegionRemSet.hpp"

#include "gc/g1/sparsePRT.hpp"

#include "gc/shared/cardTableModRefBS.hpp"

#include "gc/shared/space.inline.hpp"

#include "memory/allocation.inline.hpp"

#include "runtime/atomic.hpp"

#include "runtime/mutexLocker.hpp"

// Check that the size of the SparsePRTEntry is evenly divisible by the maximum

// member type to avoid SIGBUS when accessing them.

STATIC_ASSERT(sizeof(SparsePRTEntry) % sizeof(int) == 0);

void SparsePRTEntry::init(RegionIdx_t region_ind) {

  // Check that the card array element type can represent all cards in the region.

  // Choose a large SparsePRTEntry::card_elem_t (e.g. CardIdx_t) if required.

  assert(((size_t)1 << (sizeof(SparsePRTEntry::card_elem_t) * BitsPerByte)) *

         G1SATBCardTableModRefBS::card_size >= HeapRegionBounds::max_size(), "precondition");

  assert(G1RSetSparseRegionEntries > 0, "precondition");

  _region_ind = region_ind;

  _next_index = RSHashTable::NullEntry;

  _next_null = 0;

}

bool SparsePRTEntry::contains_card(CardIdx_t card_index) const {

  for (int i = 0; i < num_valid_cards(); i++) {

    if (card(i) == card_index) {

      return true;

    }

  }

  return false;

}

SparsePRTEntry::AddCardResult SparsePRTEntry::add_card(CardIdx_t card_index) {

  for (int i = 0; i < num_valid_cards(); i++) {

    if (card(i) == card_index) {

      return found;

    }

  }

  if (num_valid_cards() < cards_num() - 1) {

    _cards[_next_null] = (card_elem_t)card_index;

    _next_null++;

    return added;

   }

  // Otherwise, we're full.

  return overflow;

}

void SparsePRTEntry::copy_cards(card_elem_t* cards) const {

  memcpy(cards, _cards, cards_num() * sizeof(card_elem_t));

}

void SparsePRTEntry::copy_cards(SparsePRTEntry* e) const {

  copy_cards(e->_cards);

  assert(_next_null >= 0, "invariant");

  assert(_next_null <= cards_num(), "invariant");

  e->_next_null = _next_null;

}

// ----------------------------------------------------------------------

float RSHashTable::TableOccupancyFactor = 0.5f;

RSHashTable::RSHashTable(size_t capacity) :

  _capacity(capacity), _capacity_mask(capacity-1),

  _occupied_entries(0), _occupied_cards(0),

  _entries(NULL),

  _buckets(NEW_C_HEAP_ARRAY(int, capacity, mtGC)),

  _free_list(NullEntry), _free_region(0)

{

  _num_entries = (capacity * TableOccupancyFactor) + 1;

  _entries = (SparsePRTEntry*)NEW_C_HEAP_ARRAY(char, _num_entries * SparsePRTEntry::size(), mtGC);

  clear();

}

RSHashTable::~RSHashTable() {

  if (_entries != NULL) {

    FREE_C_HEAP_ARRAY(SparsePRTEntry, _entries);

    _entries = NULL;

  }

  if (_buckets != NULL) {

    FREE_C_HEAP_ARRAY(int, _buckets);

    _buckets = NULL;

  }

}

void RSHashTable::clear() {

  _occupied_entries = 0;

  _occupied_cards = 0;

  guarantee(_entries != NULL, "INV");

  guarantee(_buckets != NULL, "INV");

  guarantee(_capacity <= ((size_t)1 << (sizeof(int)*BitsPerByte-1)) - 1,

                "_capacity too large");

  // This will put -1 == NullEntry in the key field of all entries.

  memset((void*)_entries, NullEntry, _num_entries * SparsePRTEntry::size());

  memset((void*)_buckets, NullEntry, _capacity * sizeof(int));

  _free_list = NullEntry;

  _free_region = 0;

}

bool RSHashTable::add_card(RegionIdx_t region_ind, CardIdx_t card_index) {

  SparsePRTEntry* e = entry_for_region_ind_create(region_ind);

  assert(e != NULL && e->r_ind() == region_ind,

         "Postcondition of call above.");

  SparsePRTEntry::AddCardResult res = e->add_card(card_index);

  if (res == SparsePRTEntry::added) _occupied_cards++;

  assert(e->num_valid_cards() > 0, "Postcondition");

  return res != SparsePRTEntry::overflow;

}

SparsePRTEntry* RSHashTable::get_entry(RegionIdx_t region_ind) const {

  int ind = (int) (region_ind & capacity_mask());

  int cur_ind = _buckets[ind];

  SparsePRTEntry* cur;

  while (cur_ind != NullEntry &&

         (cur = entry(cur_ind))->r_ind() != region_ind) {

    cur_ind = cur->next_index();

  }

  if (cur_ind == NullEntry) return NULL;

  // Otherwise...

  assert(cur->r_ind() == region_ind, "Postcondition of loop + test above.");

  assert(cur->num_valid_cards() > 0, "Inv");

  return cur;

}

bool RSHashTable::delete_entry(RegionIdx_t region_ind) {

  int ind = (int) (region_ind & capacity_mask());

  int* prev_loc = &_buckets[ind];

  int cur_ind = *prev_loc;

  SparsePRTEntry* cur;

  while (cur_ind != NullEntry &&

         (cur = entry(cur_ind))->r_ind() != region_ind) {

    prev_loc = cur->next_index_addr();

    cur_ind = *prev_loc;

  }

  if (cur_ind == NullEntry) return false;

  // Otherwise, splice out "cur".

  *prev_loc = cur->next_index();

  _occupied_cards -= cur->num_valid_cards();

  free_entry(cur_ind);

  _occupied_entries--;

  return true;

}

SparsePRTEntry*

RSHashTable::entry_for_region_ind_create(RegionIdx_t region_ind) {

  SparsePRTEntry* res = get_entry(region_ind);

  if (res == NULL) {

    int new_ind = alloc_entry();

    res = entry(new_ind);

    res->init(region_ind);

    // Insert at front.

    int ind = (int) (region_ind & capacity_mask());

    res->set_next_index(_buckets[ind]);

    _buckets[ind] = new_ind;

    _occupied_entries++;

  }

  return res;

}

int RSHashTable::alloc_entry() {

  int res;

  if (_free_list != NullEntry) {

    res = _free_list;

    _free_list = entry(res)->next_index();

    return res;

  } else if ((size_t)_free_region < _num_entries) {

    res = _free_region;

    _free_region++;

    return res;

  } else {

    return NullEntry;

  }

}

void RSHashTable::free_entry(int fi) {

  entry(fi)->set_next_index(_free_list);

  _free_list = fi;

}

void RSHashTable::add_entry(SparsePRTEntry* e) {

  assert(e->num_valid_cards() > 0, "Precondition.");

  SparsePRTEntry* e2 = entry_for_region_ind_create(e->r_ind());

  e->copy_cards(e2);

  _occupied_cards += e2->num_valid_cards();

  assert(e2->num_valid_cards() > 0, "Postcondition.");

}

CardIdx_t RSHashTableIter::find_first_card_in_list() {

  while (_bl_ind != RSHashTable::NullEntry) {

    SparsePRTEntry* sparse_entry = _rsht->entry(_bl_ind);

    if (sparse_entry->num_valid_cards() > 0) {

      return sparse_entry->card(0);

    } else {

      _bl_ind = sparse_entry->next_index();

    }

  }

  // Otherwise, none found:

  return NoCardFound;

}

size_t RSHashTableIter::compute_card_ind(CardIdx_t ci) {

  return (_rsht->entry(_bl_ind)->r_ind() * HeapRegion::CardsPerRegion) + ci;

}

bool RSHashTableIter::has_next(size_t& card_index) {

  _card_ind++;

  if (_bl_ind >= 0) {

    SparsePRTEntry* e = _rsht->entry(_bl_ind);

    if (_card_ind < e->num_valid_cards()) {

      CardIdx_t ci = e->card(_card_ind);

      card_index = compute_card_ind(ci);

      return true;

    }

  }

  // Otherwise, must find the next valid entry.

  _card_ind = 0;

  if (_bl_ind != RSHashTable::NullEntry) {

      _bl_ind = _rsht->entry(_bl_ind)->next_index();

      CardIdx_t ci = find_first_card_in_list();

      if (ci != NoCardFound) {

        card_index = compute_card_ind(ci);

        return true;

      }

  }

  // If we didn't return above, must go to the next non-null table index.

  _tbl_ind++;

  while ((size_t)_tbl_ind < _rsht->capacity()) {

    _bl_ind = _rsht->_buckets[_tbl_ind];

    CardIdx_t ci = find_first_card_in_list();

    if (ci != NoCardFound) {

      card_index = compute_card_ind(ci);

      return true;

    }

    // Otherwise, try next entry.

    _tbl_ind++;

  }

  // Otherwise, there were no entry.

  return false;

}

bool RSHashTable::contains_card(RegionIdx_t region_index, CardIdx_t card_index) const {

  SparsePRTEntry* e = get_entry(region_index);

  return (e != NULL && e->contains_card(card_index));

}

size_t RSHashTable::mem_size() const {

  return sizeof(RSHashTable) +

    _num_entries * (SparsePRTEntry::size() + sizeof(int));

}

// ----------------------------------------------------------------------

SparsePRT* volatile SparsePRT::_head_expanded_list = NULL;

void SparsePRT::add_to_expanded_list(SparsePRT* sprt) {

  // We could expand multiple times in a pause -- only put on list once.

  if (sprt->expanded()) return;

  sprt->set_expanded(true);

  SparsePRT* hd = _head_expanded_list;

  while (true) {

    sprt->_next_expanded = hd;

    SparsePRT* res = Atomic::cmpxchg(sprt, &_head_expanded_list, hd);

    if (res == hd) return;

    else hd = res;

  }

}

SparsePRT* SparsePRT::get_from_expanded_list() {

  SparsePRT* hd = _head_expanded_list;

  while (hd != NULL) {

    SparsePRT* next = hd->next_expanded();

    SparsePRT* res = Atomic::cmpxchg(next, &_head_expanded_list, hd);

    if (res == hd) {

      hd->set_next_expanded(NULL);

      return hd;

    } else {

      hd = res;

    }

  }

  return NULL;

}

void SparsePRT::reset_for_cleanup_tasks() {

  _head_expanded_list = NULL;

}

void SparsePRT::do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task) {

  if (should_be_on_expanded_list()) {

    sprt_cleanup_task->add(this);

  }

}

void SparsePRT::finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task) {

  assert(ParGCRareEvent_lock->owned_by_self(), "pre-condition");

  SparsePRT* head = sprt_cleanup_task->head();

  SparsePRT* tail = sprt_cleanup_task->tail();

  if (head != NULL) {

    assert(tail != NULL, "if head is not NULL, so should tail");

    tail->set_next_expanded(_head_expanded_list);

    _head_expanded_list = head;

  } else {

    assert(tail == NULL, "if head is NULL, so should tail");

  }

}

bool SparsePRT::should_be_on_expanded_list() {

  if (_expanded) {

    assert(_cur != _next, "if _expanded is true, cur should be != _next");

  } else {

    assert(_cur == _next, "if _expanded is false, cur should be == _next");

  }

  return expanded();

}

void SparsePRT::cleanup_all() {

  // First clean up all expanded tables so they agree on next and cur.

  SparsePRT* sprt = get_from_expanded_list();

  while (sprt != NULL) {

    sprt->cleanup();

    sprt = get_from_expanded_list();

  }

}

SparsePRT::SparsePRT(HeapRegion* hr) :

  _hr(hr), _expanded(false), _next_expanded(NULL)

{

  _cur = new RSHashTable(InitialCapacity);

  _next = _cur;

}

SparsePRT::~SparsePRT() {

  assert(_next != NULL && _cur != NULL, "Inv");

  if (_cur != _next) { delete _cur; }

  delete _next;

}

size_t SparsePRT::mem_size() const {

  // We ignore "_cur" here, because it either = _next, or else it is

  // on the deleted list.

  return sizeof(SparsePRT) + _next->mem_size();

}

bool SparsePRT::add_card(RegionIdx_t region_id, CardIdx_t card_index) {

  if (_next->should_expand()) {

    expand();

  }

  return _next->add_card(region_id, card_index);

}

SparsePRTEntry* SparsePRT::get_entry(RegionIdx_t region_id) {

  return _next->get_entry(region_id);

}

bool SparsePRT::delete_entry(RegionIdx_t region_id) {

  return _next->delete_entry(region_id);

}

void SparsePRT::clear() {

  // If they differ, _next is bigger then cur, so next has no chance of

  // being the initial size.

  if (_next != _cur) {

    delete _next;

  }

  if (_cur->capacity() != InitialCapacity) {

    delete _cur;

    _cur = new RSHashTable(InitialCapacity);

  } else {

    _cur->clear();

  }

  _next = _cur;

  _expanded = false;

}

void SparsePRT::cleanup() {

  // Make sure that the current and next tables agree.

  if (_cur != _next) {

    delete _cur;

  }

  _cur = _next;

  set_expanded(false);

}

void SparsePRT::expand() {

  RSHashTable* last = _next;

  _next = new RSHashTable(last->capacity() * 2);

  for (size_t i = 0; i < last->num_entries(); i++) {

    SparsePRTEntry* e = last->entry((int)i);

    if (e->valid_entry()) {

      _next->add_entry(e);

    }

  }

  if (last != _cur) {

    delete last;

  }

  add_to_expanded_list(this);

}

void SparsePRTCleanupTask::add(SparsePRT* sprt) {

  assert(sprt->should_be_on_expanded_list(), "pre-condition");

  sprt->set_next_expanded(NULL);

  if (_tail != NULL) {

    _tail->set_next_expanded(sprt);

  } else {

    _head = sprt;

  }

  _tail = sprt;

}