| /* |
| * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package com.oracle.java.testlibrary; |
| |
| import com.sun.management.HotSpotDiagnosticMXBean; |
| import java.lang.management.ManagementFactory; |
| |
| /** |
| * A utility class to work with VM options which could be altered during |
| * execution. |
| * |
| * This class is a wrapper around {@code com.sun.management.VMOption}. |
| * It provides more convenient interface to read/write the values. |
| * |
| */ |
| public class DynamicVMOption { |
| |
| private final HotSpotDiagnosticMXBean mxBean; |
| |
| /** |
| * VM option name, like "MinHeapFreeRatio". |
| */ |
| public final String name; |
| |
| /** |
| * Creates an instance of DynamicVMOption. |
| * |
| * @param name the VM option name |
| */ |
| public DynamicVMOption(String name) { |
| this.name = name; |
| mxBean = ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class); |
| } |
| |
| /** |
| * Sets a new value for the option. |
| * Trying to set not applicable value will cause IllegalArgumentException. |
| * Behavior with null is undefined, most likely NPE will be thrown. |
| * |
| * @param newValue the value to be set |
| * @see #getValue() |
| * @throws IllegalArgumentException if newValue is not applicable to the option |
| */ |
| public final void setValue(String newValue) { |
| mxBean.setVMOption(name, newValue); |
| } |
| |
| /** |
| * Returns the value of option. |
| * |
| * @return the current option value |
| * @see #setValue(java.lang.String) |
| */ |
| public final String getValue() { |
| return mxBean.getVMOption(name).getValue(); |
| } |
| |
| /** |
| * Returns true, if option is writable, false otherwise. |
| * |
| * @return true, if option is writable, false otherwise |
| */ |
| public final boolean isWriteable() { |
| return mxBean.getVMOption(name).isWriteable(); |
| } |
| |
| /** |
| * Checks if the given value is applicable for the option. |
| * |
| * This method tries to set the option to the new value. If no exception |
| * has been thrown the value is treated as valid. |
| * |
| * Calling this method will not change the option value. After an attempt |
| * to set a new value, the option will be restored to its previous value. |
| * |
| * @param value the value to verify |
| * @return true if option could be set to the given value |
| */ |
| public boolean isValidValue(String value) { |
| boolean isValid = true; |
| String oldValue = getValue(); |
| try { |
| setValue(value); |
| } catch (NullPointerException e) { |
| if (value == null) { |
| isValid = false; |
| } |
| } catch (IllegalArgumentException e) { |
| isValid = false; |
| } finally { |
| setValue(oldValue); |
| } |
| return isValid; |
| } |
| |
| /** |
| * Returns the value of the given VM option as String. |
| * |
| * This is a simple shortcut for {@code new DynamicVMOption(name).getValue()} |
| * |
| * @param name the name of VM option |
| * @return value as a string |
| * @see #getValue() |
| */ |
| public static String getString(String name) { |
| return new DynamicVMOption(name).getValue(); |
| } |
| |
| /** |
| * Returns the value of the given option as int. |
| * |
| * @param name the name of VM option |
| * @return value parsed as integer |
| * @see #getString(java.lang.String) |
| * |
| */ |
| public static int getInt(String name) { |
| return Integer.parseInt(getString(name)); |
| } |
| |
| /** |
| * Sets the VM option to a new value. |
| * |
| * This is a simple shortcut for {@code new DynamicVMOption(name).setValue(value)} |
| * |
| * @param name the name of VM option |
| * @param value the value to be set |
| * @see #setValue(java.lang.String) |
| */ |
| public static void setString(String name, String value) { |
| new DynamicVMOption(name).setValue(value); |
| } |
| |
| /** |
| * Sets the VM option value to a new integer value. |
| * |
| * @param name the name of VM option |
| * @param value the integer value to be set |
| * @see #setString(java.lang.String, java.lang.String) |
| */ |
| public static void setInt(String name, int value) { |
| new DynamicVMOption(name).setValue(Integer.toString(value)); |
| } |
| |
| } |