/*

 * Copyright (c) 2017, 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/g1CollectedHeap.hpp"

#include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"

#include "gc/g1/g1FullCollector.hpp"

#include "gc/g1/g1FullGCCompactionPoint.hpp"

#include "gc/g1/g1FullGCMarker.hpp"

#include "gc/g1/g1FullGCOopClosures.inline.hpp"

#include "gc/g1/g1FullGCPrepareTask.hpp"

#include "gc/g1/g1HotCardCache.hpp"

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

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

#include "gc/shared/referenceProcessor.hpp"

#include "logging/log.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/ticks.inline.hpp"

bool G1FullGCPrepareTask::G1CalculatePointersClosure::do_heap_region(HeapRegion* hr) {

  if (hr->is_humongous()) {

    oop obj = oop(hr->humongous_start_region()->bottom());

    if (_bitmap->is_marked(obj)) {

      if (hr->is_starts_humongous()) {

        obj->forward_to(obj);

      }

    } else {

      free_humongous_region(hr);

    }

  } else if (!hr->is_pinned()) {

    prepare_for_compaction(hr);

  }

  // Reset data structures not valid after Full GC.

  reset_region_metadata(hr);

  return false;

}

G1FullGCPrepareTask::G1FullGCPrepareTask(G1FullCollector* collector) :

    G1FullGCTask("G1 Prepare Compact Task", collector),

    _hrclaimer(collector->workers()),

    _freed_regions(false) {

}

void G1FullGCPrepareTask::set_freed_regions() {

  if (!_freed_regions) {

    _freed_regions = true;

  }

}

bool G1FullGCPrepareTask::has_freed_regions() {

  return _freed_regions;

}

void G1FullGCPrepareTask::work(uint worker_id) {

  Ticks start = Ticks::now();

  G1FullGCCompactionPoint* compaction_point = collector()->compaction_point(worker_id);

  G1CalculatePointersClosure closure(collector()->mark_bitmap(), compaction_point);

  G1CollectedHeap::heap()->heap_region_par_iterate_from_start(&closure, &_hrclaimer);

  // Update humongous region sets

  closure.update_sets();

  compaction_point->update();

  // Check if any regions was freed by this worker and store in task.

  if (closure.freed_regions()) {

    set_freed_regions();

  }

  log_task("Prepare compaction task", worker_id, start);

}

G1FullGCPrepareTask::G1CalculatePointersClosure::G1CalculatePointersClosure(G1CMBitMap* bitmap,

                                                                            G1FullGCCompactionPoint* cp) :

    _g1h(G1CollectedHeap::heap()),

    _bitmap(bitmap),

    _cp(cp),

    _humongous_regions_removed(0) { }

void G1FullGCPrepareTask::G1CalculatePointersClosure::free_humongous_region(HeapRegion* hr) {

  FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");

  hr->set_containing_set(NULL);

  _humongous_regions_removed++;

  _g1h->free_humongous_region(hr, &dummy_free_list);

  prepare_for_compaction(hr);

  dummy_free_list.remove_all();

}

void G1FullGCPrepareTask::G1CalculatePointersClosure::reset_region_metadata(HeapRegion* hr) {

  hr->rem_set()->clear();

  hr->clear_cardtable();

  if (_g1h->g1_hot_card_cache()->use_cache()) {

    _g1h->g1_hot_card_cache()->reset_card_counts(hr);

  }

}

G1FullGCPrepareTask::G1PrepareCompactLiveClosure::G1PrepareCompactLiveClosure(G1FullGCCompactionPoint* cp) :

    _cp(cp) { }

size_t G1FullGCPrepareTask::G1PrepareCompactLiveClosure::apply(oop object) {

  size_t size = object->size();

  _cp->forward(object, size);

  return size;

}

size_t G1FullGCPrepareTask::G1RePrepareClosure::apply(oop obj) {

  // We only re-prepare objects forwarded within the current region, so

  // skip objects that are already forwarded to another region.

  oop forwarded_to = obj->forwardee();

  if (forwarded_to != NULL && !_current->is_in(forwarded_to)) {

    return obj->size();

  }

  // Get size and forward.

  size_t size = obj->size();

  _cp->forward(obj, size);

  return size;

}

void G1FullGCPrepareTask::G1CalculatePointersClosure::prepare_for_compaction_work(G1FullGCCompactionPoint* cp,

                                                                                  HeapRegion* hr) {

  G1PrepareCompactLiveClosure prepare_compact(cp);

  hr->set_compaction_top(hr->bottom());

  hr->apply_to_marked_objects(_bitmap, &prepare_compact);

}

void G1FullGCPrepareTask::G1CalculatePointersClosure::prepare_for_compaction(HeapRegion* hr) {

  if (!_cp->is_initialized()) {

    hr->set_compaction_top(hr->bottom());

    _cp->initialize(hr, true);

  }

  // Add region to the compaction queue and prepare it.

  _cp->add(hr);

  prepare_for_compaction_work(_cp, hr);

}

void G1FullGCPrepareTask::prepare_serial_compaction() {

  GCTraceTime(Debug, gc, phases) debug("Phase 2: Prepare Serial Compaction", collector()->scope()->timer());

  // At this point we know that no regions were completely freed by

  // the parallel compaction. That means that the last region of

  // all compaction queues still have data in them. We try to compact

  // these regions in serial to avoid a premature OOM.

  for (uint i = 0; i < collector()->workers(); i++) {

    G1FullGCCompactionPoint* cp = collector()->compaction_point(i);

    if (cp->has_regions()) {

      collector()->serial_compaction_point()->add(cp->remove_last());

    }

  }

  // Update the forwarding information for the regions in the serial

  // compaction point.

  G1FullGCCompactionPoint* cp = collector()->serial_compaction_point();

  for (GrowableArrayIterator<HeapRegion*> it = cp->regions()->begin(); it != cp->regions()->end(); ++it) {

    HeapRegion* current = *it;

    if (!cp->is_initialized()) {

      // Initialize the compaction point. Nothing more is needed for the first heap region

      // since it is already prepared for compaction.

      cp->initialize(current, false);

    } else {

      assert(!current->is_humongous(), "Should be no humongous regions in compaction queue");

      G1RePrepareClosure re_prepare(cp, current);

      current->set_compaction_top(current->bottom());

      current->apply_to_marked_objects(collector()->mark_bitmap(), &re_prepare);

    }

  }

  cp->update();

}

void G1FullGCPrepareTask::G1CalculatePointersClosure::update_sets() {

  // We'll recalculate total used bytes and recreate the free list

  // at the end of the GC, so no point in updating those values here.

  _g1h->remove_from_old_sets(0, _humongous_regions_removed);

}

bool G1FullGCPrepareTask::G1CalculatePointersClosure::freed_regions() {

  if (_humongous_regions_removed > 0) {

    // Free regions from dead humongous regions.

    return true;

  }

  if (!_cp->has_regions()) {

    // No regions in queue, so no free ones either.

    return false;

  }

  if (_cp->current_region() != _cp->regions()->last()) {

    // The current region used for compaction is not the last in the

    // queue. That means there is at least one free region in the queue.

    return true;

  }

  // No free regions in the queue.

  return false;

}