1 /*
   2  * Copyright (c) 2014, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.lang.invoke;
  26 
  27 import java.lang.reflect.Method;
  28 import java.util.Properties;
  29 import sun.hotspot.WhiteBox;
  30 
  31 public class StableConfiguration {
  32     static final WhiteBox WB = WhiteBox.getWhiteBox();
  33     static final boolean isStableEnabled;
  34     static final boolean isServerWithStable;
  35 
  36     static {
  37         Boolean value = WB.getBooleanVMFlag("FoldStableValues");
  38         isStableEnabled = (value == null ? false : value);
  39         isServerWithStable = isStableEnabled && get();
  40         System.out.println("@Stable:         " + (isStableEnabled ? "enabled" : "disabled"));
  41         System.out.println("Server Compiler: " + get());
  42     }
  43 
  44     // ::get() is among immediately compiled methods.
  45     static boolean get() {
  46         try {
  47             Method m = StableConfiguration.class.getDeclaredMethod("get");
  48             int level = WB.getMethodCompilationLevel(m);
  49             if (level > 0) {
  50               return (level == 4);
  51             } else {
  52               String javaVM = System.getProperty("java.vm.name", "");
  53               if (javaVM.contains("Server")) return true;
  54               if (javaVM.contains("Client")) return false;
  55               throw new Error("Unknown VM type: "+javaVM);
  56             }
  57         } catch (NoSuchMethodException e) {
  58             throw new Error(e);
  59         }
  60     }
  61 
  62 }