/*

 * Copyright (c) 2014, 2018, Red Hat, Inc. All rights reserved.

 *

 * 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.

 *

 */

#ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP

#define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP

#include "gc/shared/gcTimer.hpp"

#include "gc/shenandoah/shenandoahHeap.hpp"

#include "gc/shenandoah/shenandoahHeapRegionSet.hpp"

/**

 * This implements Full GC (e.g. when invoking System.gc()) using a mark-compact algorithm.

 *

 * Current implementation is parallel sliding Lisp-2-style algorithm, based on

 * "Parallel Garbage Collection for Shared Memory Multiprocessors", by Christine Flood et al.

 * http://people.csail.mit.edu/shanir/publications/dfsz2001.pdf

 *

 * It is implemented in four phases:

 *

 * 1. Mark all live objects of the heap by traversing objects starting at GC roots.

 * 2. Calculate the new location of each live object. This is done by sequentially scanning

 *    the heap, keeping track of a next-location-pointer, which is then written to each

 *    object's fwdptr field.

 * 3. Update all references. This is implemented by another scan of the heap, and updates

 *    all references in live objects by what's stored in the target object's fwdptr.

 * 4. Compact the heap by copying all live objects to their new location.

 *

 * Parallelization is handled by assigning each GC worker the slice of the heap (the set of regions)

 * where it does sliding compaction, without interfering with other threads.

 */

class ShenandoahMarkCompact : public CHeapObj<mtGC> {

private:

  GCTimer* _gc_timer;

public:

  void initialize(GCTimer* gc_timer);

  void do_it(GCCause::Cause gc_cause);

private:

  void phase1_mark_heap();

  void phase2_calculate_target_addresses(ShenandoahHeapRegionSet** worker_slices);

  void phase3_update_references();

  void phase4_compact_objects(ShenandoahHeapRegionSet** worker_slices);

  void calculate_target_humongous_objects();

  void compact_humongous_objects();

};

#endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP