/*

 * Copyright (c) 2013, 2018, 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/g1CardCounts.hpp"

#include "gc/g1/g1CollectedHeap.inline.hpp"

#include "gc/shared/cardTableBarrierSet.hpp"

#include "services/memTracker.hpp"

#include "utilities/copy.hpp"

void G1CardCountsMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {

  if (zero_filled) {

    return;

  }

  MemRegion mr(G1CollectedHeap::heap()->bottom_addr_for_region(start_idx), num_regions * HeapRegion::GrainWords);

  _counts->clear_range(mr);

}

size_t G1CardCounts::compute_size(size_t mem_region_size_in_words) {

  // We keep card counts for every card, so the size of the card counts table must

  // be the same as the card table.

  return G1CardTable::compute_size(mem_region_size_in_words);

}

size_t G1CardCounts::heap_map_factor() {

  // See G1CardCounts::compute_size() why we reuse the card table value.

  return G1CardTable::heap_map_factor();

}

void G1CardCounts::clear_range(size_t from_card_num, size_t to_card_num) {

  if (has_count_table()) {

    assert(from_card_num < to_card_num,

           "Wrong order? from: " SIZE_FORMAT ", to: " SIZE_FORMAT,

           from_card_num, to_card_num);

    Copy::fill_to_bytes(&_card_counts[from_card_num], (to_card_num - from_card_num));

  }

}

G1CardCounts::G1CardCounts(G1CollectedHeap *g1h):

  _listener(), _g1h(g1h), _card_counts(NULL), _reserved_max_card_num(0) {

  _listener.set_cardcounts(this);

}

void G1CardCounts::initialize(G1RegionToSpaceMapper* mapper) {

  assert(_g1h->max_capacity() > 0, "initialization order");

  assert(_g1h->capacity() == 0, "initialization order");

  if (G1ConcRSHotCardLimit > 0) {

    // The max value we can store in the counts table is

    // max_jubyte. Guarantee the value of the hot

    // threshold limit is no more than this.

    guarantee(G1ConcRSHotCardLimit <= max_jubyte, "sanity");

    _ct = _g1h->card_table();

    _ct_bot = _ct->byte_for_const(_g1h->reserved_region().start());

    _card_counts = (jubyte*) mapper->reserved().start();

    _reserved_max_card_num = mapper->reserved().byte_size();

    mapper->set_mapping_changed_listener(&_listener);

  }

}

uint G1CardCounts::add_card_count(jbyte* card_ptr) {

  // Returns the number of times the card has been refined.

  // If we failed to reserve/commit the counts table, return 0.

  // If card_ptr is beyond the committed end of the counts table,

  // return 0.

  // Otherwise return the actual count.

  // Unless G1ConcRSHotCardLimit has been set appropriately,

  // returning 0 will result in the card being considered

  // cold and will be refined immediately.

  uint count = 0;

  if (has_count_table()) {

    size_t card_num = ptr_2_card_num(card_ptr);

    assert(card_num < _reserved_max_card_num,

           "Card " SIZE_FORMAT " outside of card counts table (max size " SIZE_FORMAT ")",

           card_num, _reserved_max_card_num);

    count = (uint) _card_counts[card_num];

    if (count < G1ConcRSHotCardLimit) {

      _card_counts[card_num] =

        (jubyte)(MIN2((uintx)(_card_counts[card_num] + 1), G1ConcRSHotCardLimit));

    }

  }

  return count;

}

bool G1CardCounts::is_hot(uint count) {

  return (count >= G1ConcRSHotCardLimit);

}

void G1CardCounts::clear_region(HeapRegion* hr) {

  MemRegion mr(hr->bottom(), hr->end());

  clear_range(mr);

}

void G1CardCounts::clear_range(MemRegion mr) {

  if (has_count_table()) {

    const jbyte* from_card_ptr = _ct->byte_for_const(mr.start());

    // We use the last address in the range as the range could represent the

    // last region in the heap. In which case trying to find the card will be an

    // OOB access to the card table.

    const jbyte* last_card_ptr = _ct->byte_for_const(mr.last());

#ifdef ASSERT

    HeapWord* start_addr = _ct->addr_for(from_card_ptr);

    assert(start_addr == mr.start(), "MemRegion start must be aligned to a card.");

    HeapWord* last_addr = _ct->addr_for(last_card_ptr);

    assert((last_addr + G1CardTable::card_size_in_words) == mr.end(), "MemRegion end must be aligned to a card.");

#endif // ASSERT

    // Clear the counts for the (exclusive) card range.

    size_t from_card_num = ptr_2_card_num(from_card_ptr);

    size_t to_card_num = ptr_2_card_num(last_card_ptr) + 1;

    clear_range(from_card_num, to_card_num);

  }

}

class G1CardCountsClearClosure : public HeapRegionClosure {

 private:

  G1CardCounts* _card_counts;

 public:

  G1CardCountsClearClosure(G1CardCounts* card_counts) :

    HeapRegionClosure(), _card_counts(card_counts) { }

  virtual bool do_heap_region(HeapRegion* r) {

    _card_counts->clear_region(r);

    return false;

  }

};

void G1CardCounts::clear_all() {

  assert(SafepointSynchronize::is_at_safepoint(), "don't call this otherwise");

  G1CardCountsClearClosure cl(this);

  _g1h->heap_region_iterate(&cl);

}