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 
  24 import java.util.Objects;
  25 import java.util.function.BiConsumer;
  26 import java.util.function.Function;
  27 import jdk.testlib.WhiteBox;
  28 import sun.management.*;
  29 import com.sun.management.*;
  30 import com.oracle.java.testlibrary.*;
  31 
  32 public final class VmFlagTest<T> {
  33     public static final WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();
  34 
  35     private static final String NONEXISTENT_FLAG = "NonexistentFlag";
  36     private final String flagName;
  37     private final BiConsumer<T, T> test;
  38     private final BiConsumer<String, T> set;
  39     private final Function<String, T> get;
  40     private final boolean isPositive;
  41 
  42     protected VmFlagTest(String flagName, BiConsumer<String, T> set,
  43             Function<String, T> get, boolean isPositive) {
  44         this.flagName = flagName;
  45         this.set = set;
  46         this.get = get;
  47         this.isPositive = isPositive;
  48         if (isPositive) {
  49             test = this::testWritePositive;
  50         } else {
  51             test = this::testWriteNegative;
  52         }
  53     }
  54 
  55     private void setNewValue(T value) {
  56         set.accept(flagName, value);
  57     }
  58 
  59     private T getValue() {
  60         return get.apply(flagName);
  61     }
  62 
  63     protected static <T> void runTest(String existentFlag, T[] tests,
  64             BiConsumer<String, T> set, Function<String, T> get) {
  65         runTest(existentFlag, tests, tests, set, get);
  66     }
  67 
  68     protected static <T> void runTest(String existentFlag, Function<String, T> get) {
  69         runTest(existentFlag, null, null, null, get);
  70     }
  71 
  72     protected static <T> void runTest(String existentFlag, T[] tests,
  73             T[] results, BiConsumer<String, T> set, Function<String, T> get) {
  74         if (existentFlag != null) {
  75             new VmFlagTest(existentFlag, set, get, true).test(tests, results);
  76         }
  77         new VmFlagTest(NONEXISTENT_FLAG, set, get, false).test(tests, results);
  78     }
  79 
  80     public final void test(T[] tests, T[] results) {
  81         if (isPositive) {
  82             testRead();
  83         }
  84         if (tests != null) {
  85             Asserts.assertEQ(tests.length, results.length, "[TESTBUG] tests.length != results.length");
  86             for (int i = 0, n = tests.length ; i < n; ++i) {
  87                 test.accept(tests[i], results[i]);
  88             }
  89         }
  90     }
  91 
  92     protected String getVMOptionAsString() {
  93         if (WHITE_BOX.isConstantVMFlag(flagName) || WHITE_BOX.isLockedVMFlag(flagName)) {
  94           // JMM cannot access debug flags in product builds or locked flags,
  95           // use whitebox methods to get such flags value.
  96           return asString(getValue());
  97         }
  98         HotSpotDiagnosticMXBean diagnostic
  99                 = ManagementFactoryHelper.getDiagnosticMXBean();
 100         VMOption tmp;
 101         try {
 102             tmp = diagnostic.getVMOption(flagName);
 103         } catch (IllegalArgumentException e) {
 104             tmp = null;
 105         }
 106         return tmp == null ? null : tmp.getValue();
 107     }
 108 
 109     private String testRead() {
 110         String value = getVMOptionAsString();
 111         Asserts.assertNotNull(value);
 112         Asserts.assertEQ(value, asString(getValue()));
 113         Asserts.assertEQ(value, asString(WHITE_BOX.getVMFlag(flagName)));
 114         return value;
 115     }
 116 
 117     private void testWritePositive(T value, T expected) {
 118         setNewValue(value);
 119         String newValue = testRead();
 120         Asserts.assertEQ(newValue, asString(expected));
 121     }
 122 
 123     private void testWriteNegative(T value, T expected) {
 124         // Should always return false for non-existing flags
 125         Asserts.assertFalse(WHITE_BOX.isConstantVMFlag(flagName));
 126         Asserts.assertFalse(WHITE_BOX.isLockedVMFlag(flagName));
 127         String oldValue = getVMOptionAsString();
 128         Asserts.assertEQ(oldValue, asString(getValue()));
 129         Asserts.assertEQ(oldValue, asString(WHITE_BOX.getVMFlag(flagName)));
 130         setNewValue(value);
 131         String newValue = getVMOptionAsString();
 132         Asserts.assertEQ(oldValue, newValue);
 133     }
 134 
 135     private String asString(Object value) {
 136         return value == null ? null : "" + value;
 137     }
 138 }