/*

 * Copyright (c) 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/g1FullGCCompactionPoint.hpp"

#include "gc/g1/heapRegion.hpp"

#include "oops/oop.inline.hpp"

#include "utilities/debug.hpp"

G1FullGCCompactionPoint::G1FullGCCompactionPoint() :

    _current_region(NULL),

    _threshold(NULL),

    _compaction_top(NULL) {

  _compaction_regions = new (ResourceObj::C_HEAP, mtGC) GrowableArray<HeapRegion*>(32, true, mtGC);

  _compaction_region_iterator = _compaction_regions->begin();

}

G1FullGCCompactionPoint::~G1FullGCCompactionPoint() {

  delete _compaction_regions;

}

void G1FullGCCompactionPoint::update() {

  if (is_initialized()) {

    _current_region->set_compaction_top(_compaction_top);

  }

}

void G1FullGCCompactionPoint::initialize_values(bool init_threshold) {

  _compaction_top = _current_region->compaction_top();

  if (init_threshold) {

    _threshold = _current_region->initialize_threshold();

  }

}

bool G1FullGCCompactionPoint::has_regions() {

  return !_compaction_regions->is_empty();

}

bool G1FullGCCompactionPoint::is_initialized() {

  return _current_region != NULL;

}

void G1FullGCCompactionPoint::initialize(HeapRegion* hr, bool init_threshold) {

  _current_region = hr;

  initialize_values(init_threshold);

}

HeapRegion* G1FullGCCompactionPoint::current_region() {

  return *_compaction_region_iterator;

}

HeapRegion* G1FullGCCompactionPoint::next_region() {

  HeapRegion* next = *(++_compaction_region_iterator);

  assert(next != NULL, "Must return valid region");

  return next;

}

GrowableArray<HeapRegion*>* G1FullGCCompactionPoint::regions() {

  return _compaction_regions;

}

bool G1FullGCCompactionPoint::object_will_fit(size_t size) {

  size_t space_left = pointer_delta(_current_region->end(), _compaction_top);

  return size <= space_left;

}

void G1FullGCCompactionPoint::switch_region() {

  // Save compaction top in the region.

  _current_region->set_compaction_top(_compaction_top);

  // Get the next region and re-initialize the values.

  _current_region = next_region();

  initialize_values(true);

}

void G1FullGCCompactionPoint::forward(oop object, size_t size) {

  assert(_current_region != NULL, "Must have been initialized");

  // Ensure the object fit in the current region.

  while (!object_will_fit(size)) {

    switch_region();

  }

  // Store a forwarding pointer if the object should be moved.

  if ((HeapWord*)object != _compaction_top) {

    object->forward_to(oop(_compaction_top));

  } else {

    if (object->forwardee() != NULL) {

      // Object should not move but mark-word is used so it looks like the

      // object is forwarded. Need to clear the mark and it's no problem

      // since it will be restored by preserved marks. There is an exception

      // with BiasedLocking, in this case forwardee() will return NULL

      // even if the mark-word is used. This is no problem since

      // forwardee() will return NULL in the compaction phase as well.

      object->init_mark();

    } else {

      // Make sure object has the correct mark-word set or that it will be

      // fixed when restoring the preserved marks.

      assert(object->mark() == markOopDesc::prototype_for_object(object) || // Correct mark

             object->mark()->must_be_preserved(object) || // Will be restored by PreservedMarksSet

             (UseBiasedLocking && object->has_bias_pattern()), // Will be restored by BiasedLocking

             "should have correct prototype obj: " PTR_FORMAT " mark: " PTR_FORMAT " prototype: " PTR_FORMAT,

             p2i(object), p2i(object->mark()), p2i(markOopDesc::prototype_for_object(object)));

    }

    assert(object->forwardee() == NULL, "should be forwarded to NULL");

  }

  // Update compaction values.

  _compaction_top += size;

  if (_compaction_top > _threshold) {

    _threshold = _current_region->cross_threshold(_compaction_top - size, _compaction_top);

  }

}

void G1FullGCCompactionPoint::add(HeapRegion* hr) {

  _compaction_regions->append(hr);

}

void G1FullGCCompactionPoint::merge(G1FullGCCompactionPoint* other) {

   _compaction_regions->appendAll(other->regions());

}

HeapRegion* G1FullGCCompactionPoint::remove_last() {

  return _compaction_regions->pop();

}