1 /*
   2  * Copyright (c) 2001, 2007, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 class ReferenceProcessor;
  26 
  27 // G1MarkSweep takes care of global mark-compact garbage collection for a
  28 // G1CollectedHeap using a four-phase pointer forwarding algorithm.  All
  29 // generations are assumed to support marking; those that can also support
  30 // compaction.
  31 //
  32 // Class unloading will only occur when a full gc is invoked.
  33 
  34 
  35 class G1MarkSweep : AllStatic {
  36   friend class VM_G1MarkSweep;
  37   friend class Scavenge;
  38 
  39  public:
  40 
  41   static void invoke_at_safepoint(ReferenceProcessor* rp,
  42                                   bool clear_all_softrefs);
  43 
  44  private:
  45 
  46   // Mark live objects
  47   static void mark_sweep_phase1(bool& marked_for_deopt,
  48                                 bool clear_all_softrefs);
  49   // Calculate new addresses
  50   static void mark_sweep_phase2();
  51   // Update pointers
  52   static void mark_sweep_phase3();
  53   // Move objects to new positions
  54   static void mark_sweep_phase4();
  55 
  56   static void allocate_stacks();
  57 };