1 /*
   2  * Copyright (c) 2014, 2015, Red Hat, Inc. and/or its affiliates.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
  25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP
  26 
  27 #include "gc/serial/genMarkSweep.hpp"
  28 #include "gc/shared/taskqueue.hpp"
  29 #include "gc/shared/workgroup.hpp"
  30 #include "gc/shenandoah/shenandoahHeap.hpp"
  31 
  32 class HeapWord;
  33 class ShenandoahMarkCompactBarrierSet;
  34 
  35 /**
  36  * This implements full-GC (e.g. when invoking System.gc() ) using a
  37  * mark-compact algorithm. It's implemented in four phases:
  38  *
  39  * 1. Mark all live objects of the heap by traversing objects starting at GC roots.
  40  * 2. Calculate the new location of each live object. This is done by sequentially scanning
  41  *    the heap, keeping track of a next-location-pointer, which is then written to each
  42  *    object's brooks ptr field.
  43  * 3. Update all references. This is implemented by another scan of the heap, and updates
  44  *    all references in live objects by what's stored in the target object's brooks ptr.
  45  * 3. Compact the heap by copying all live objects to their new location.
  46  */
  47 
  48 class ShenandoahMarkCompact: AllStatic {
  49 
  50 public:
  51 
  52   static void do_mark_compact();
  53 
  54 private:
  55 
  56   static void phase1_mark_heap();
  57   static void phase2_calculate_target_addresses();
  58   static void phase3_update_references();
  59   static void phase4_compact_objects();
  60   static void finish_compaction(HeapWord* last_addr);
  61 
  62   static void allocate_stacks();
  63 };
  64 
  65 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHMARKCOMPACT_HPP