1 /*
   2  * Copyright (c) 2016, 2018, 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 package sun.hotspot.gc;
  25 
  26 import sun.hotspot.WhiteBox;
  27 
  28 /**
  29  * API to obtain information about selected and supported Garbage Collectors
  30  * retrieved from the VM with the WhiteBox API.
  31  */
  32 public enum GC {
  33     /*
  34      * Enum values much match CollectedHeap::Name
  35      */
  36     Serial(1),
  37     Parallel(2),
  38     ConcMarkSweep(3),
  39     G1(4),
  40     Epsilon(5),
  41     ;
  42 
  43     private static final WhiteBox WB = WhiteBox.getWhiteBox();
  44 
  45     private final int name;
  46 
  47     private GC(int name) {
  48         this.name = name;
  49     }
  50 
  51     /**
  52      * @return true if this GC is supported by the VM
  53      */
  54     public boolean isSupported() {
  55         return WB.isGCSupported(name);
  56     }
  57 
  58     /**
  59      * @return true if this GC is currently selected/used
  60      */
  61     public boolean isSelected() {
  62         return WB.isGCSelected(name);
  63     }
  64 
  65     /**
  66      * @return true if GC was selected ergonomically, as opposed
  67      *         to being explicitly specified on the command line
  68      */
  69     public static boolean isSelectedErgonomically() {
  70         return WB.isGCSelectedErgonomically();
  71     }
  72 }