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.
   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 package com.oracle.java.testlibrary;
  24 
  25 import com.sun.management.HotSpotDiagnosticMXBean;
  26 import com.sun.management.VMOption;
  27 import java.lang.management.ManagementFactory;
  28 
  29 /**
  30  * Simple class to check writeability, invalid and valid values for VMOption
  31  */
  32 public class DynamicVMOptionChecker {
  33 
  34     /**
  35      * Reads VM option from PlatformMXBean and parse it to integer value
  36      *
  37      * @param name of option
  38      * @return parsed value
  39      */
  40     public static int getIntValue(String name) {
  41 
  42         VMOption option = ManagementFactory.
  43                 getPlatformMXBean(HotSpotDiagnosticMXBean.class).
  44                 getVMOption(name);
  45 
  46         return Integer.parseInt(option.getValue());
  47     }
  48 
  49     /**
  50      * Checks that VM option is dynamically writable
  51      *
  52      * @param name
  53      * @throws RuntimeException if option if not writable
  54      * @return always true
  55      */
  56     public static boolean checkIsWritable(String name) {
  57         VMOption option = ManagementFactory.
  58                 getPlatformMXBean(HotSpotDiagnosticMXBean.class).
  59                 getVMOption(name);
  60 
  61         if (!option.isWriteable()) {
  62             throw new RuntimeException(name + " is not writable");
  63         }
  64 
  65         return true;
  66     }
  67 
  68     /**
  69      * Checks that value cannot be set
  70      *
  71      * @param name of flag
  72      * @param value string representation of value to set
  73      * @throws RuntimeException on error - when expected exception hasn't been thrown
  74      */
  75     public static void checkInvalidValue(String name, String value) {
  76         // should throw
  77         try {
  78             ManagementFactory.
  79                     getPlatformMXBean(HotSpotDiagnosticMXBean.class).
  80                     setVMOption(name, value);
  81 
  82         } catch (IllegalArgumentException e) {
  83             return;
  84         }
  85 
  86         throw new RuntimeException("Expected IllegalArgumentException was not thrown, " + name + "= " + value);
  87     }
  88 
  89     /**
  90      * Checks that value can be set
  91      *
  92      * @param name of flag to set
  93      * @param value string representation of value to set
  94      * @throws RuntimeException on error - when value in VM is not equal to origin
  95      */
  96     public static void checkValidValue(String name, String value) {
  97         ManagementFactory.
  98                 getPlatformMXBean(HotSpotDiagnosticMXBean.class).
  99                 setVMOption(name, value);
 100 
 101         VMOption option = ManagementFactory.
 102                 getPlatformMXBean(HotSpotDiagnosticMXBean.class).
 103                 getVMOption(name);
 104 
 105         if (!option.getValue().equals(value)) {
 106             throw new RuntimeException("Actual value of " + name + " \"" + option.getValue()
 107                     + "\" not equal origin \"" + value + "\"");
 108         }
 109     }
 110 
 111 }