/*

 * Copyright (c) 2013, 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_implementation/g1/dirtyCardQueue.hpp"

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

#include "gc_implementation/g1/g1HotCardCache.hpp"

#include "gc_implementation/g1/g1RemSet.hpp"

#include "gc_implementation/g1/heapRegion.hpp"

#include "runtime/atomic.hpp"

G1HotCardCache::G1HotCardCache(G1CollectedHeap *g1h):

  _g1h(g1h), _hot_cache(NULL), _use_cache(false), _card_counts(g1h) {}

void G1HotCardCache::initialize() {

  if (default_use_cache()) {

    _use_cache = true;

    _hot_cache_size = (1 << G1ConcRSLogCacheSize);

    _hot_cache = NEW_C_HEAP_ARRAY(jbyte*, _hot_cache_size, mtGC);

    _n_hot = 0;

    _hot_cache_idx = 0;

    // For refining the cards in the hot cache in parallel

    int n_workers = (ParallelGCThreads > 0 ?

                        _g1h->workers()->total_workers() : 1);

    _hot_cache_par_chunk_size = MAX2(1, _hot_cache_size / n_workers);

    _hot_cache_par_claimed_idx = 0;

    _card_counts.initialize();

  }

}

G1HotCardCache::~G1HotCardCache() {

  if (default_use_cache()) {

    assert(_hot_cache != NULL, "Logic");

    FREE_C_HEAP_ARRAY(jbyte*, _hot_cache, mtGC);

  }

}

jbyte* G1HotCardCache::insert(jbyte* card_ptr) {

  uint count = _card_counts.add_card_count(card_ptr);

  if (!_card_counts.is_hot(count)) {

    // The card is not hot so do not store it in the cache;

    // return it for immediate refining.

    return card_ptr;

  }

  // Otherwise, the card is hot.

  jbyte* res = NULL;

  MutexLockerEx x(HotCardCache_lock, Mutex::_no_safepoint_check_flag);

  if (_n_hot == _hot_cache_size) {

    res = _hot_cache[_hot_cache_idx];

    _n_hot--;

  }

  // Now _n_hot < _hot_cache_size, and we can insert at _hot_cache_idx.

  _hot_cache[_hot_cache_idx] = card_ptr;

  _hot_cache_idx++;

  if (_hot_cache_idx == _hot_cache_size) {

    // Wrap around

    _hot_cache_idx = 0;

  }

  _n_hot++;

  return res;

}

void G1HotCardCache::drain(int worker_i,

                           G1RemSet* g1rs,

                           DirtyCardQueue* into_cset_dcq) {

  if (!default_use_cache()) {

    assert(_hot_cache == NULL, "Logic");

    return;

  }

  assert(_hot_cache != NULL, "Logic");

  assert(!use_cache(), "cache should be disabled");

  int start_idx;

  while ((start_idx = _hot_cache_par_claimed_idx) < _n_hot) { // read once

    int end_idx = start_idx + _hot_cache_par_chunk_size;

    if (start_idx ==

        Atomic::cmpxchg(end_idx, &_hot_cache_par_claimed_idx, start_idx)) {

      // The current worker has successfully claimed the chunk [start_idx..end_idx)

      end_idx = MIN2(end_idx, _n_hot);

      for (int i = start_idx; i < end_idx; i++) {

        jbyte* card_ptr = _hot_cache[i];

        if (card_ptr != NULL) {

          if (g1rs->refine_card(card_ptr, worker_i, true)) {

            // The part of the heap spanned by the card contains references

            // that point into the current collection set.

            // We need to record the card pointer in the DirtyCardQueueSet

            // that we use for such cards.

            //

            // The only time we care about recording cards that contain

            // references that point into the collection set is during

            // RSet updating while within an evacuation pause.

            // In this case worker_i should be the id of a GC worker thread

            assert(SafepointSynchronize::is_at_safepoint(), "Should be at a safepoint");

            assert(worker_i < (int) (ParallelGCThreads == 0 ? 1 : ParallelGCThreads),

                   err_msg("incorrect worker id: "INT32_FORMAT, worker_i));

            into_cset_dcq->enqueue(card_ptr);

          }

        }

      }

    }

  }

  // The existing entries in the hot card cache, which were just refined

  // above, are discarded prior to re-enabling the cache near the end of the GC.

}

void G1HotCardCache::resize_card_counts(size_t heap_capacity) {

  _card_counts.resize(heap_capacity);

}

void G1HotCardCache::reset_card_counts(HeapRegion* hr) {

  _card_counts.clear_region(hr);

}

void G1HotCardCache::reset_card_counts() {

  _card_counts.clear_all();

}