1 /*
   2  * Copyright (c) 2015, 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 /*
  25  * @test
  26  * @bug 8140450
  27  * @library /lib/testlibrary
  28  * @build jdk.testlibrary.*
  29  * @summary Test if the getCallerClass method returns empty optional
  30  * @run main CallerFromMain exec
  31  */
  32 
  33 import jdk.testlibrary.ProcessTools;
  34 import jdk.testlibrary.OutputAnalyzer;
  35 
  36 public class CallerFromMain {
  37 
  38     private static final StackWalker sw = StackWalker.getInstance(StackWalker.Option.RETAIN_CLASS_REFERENCE);
  39     public static void main(String[] args) throws Exception {
  40         if (args.length > 0) {
  41             ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(true, "CallerFromMain");
  42             OutputAnalyzer output = ProcessTools.executeProcess(pb);
  43             System.out.println(output.getOutput());
  44             output.shouldHaveExitValue(0);
  45             return;
  46         }
  47 
  48         // StackWalker::getCallerClass
  49         // CallerFromMain::main
  50         // no caller
  51         try {
  52             Class<?> c = sw.getCallerClass();
  53             throw new RuntimeException("UOE not thrown. Caller: " + c);
  54         } catch (IllegalStateException e) {}
  55 
  56         // StackWalker::getCallerClass
  57         // Runnable::run
  58         // Thread::run
  59         Thread t1 = new Thread(new Runnable() {
  60             @Override
  61             public void run() {
  62                 Class<?> c = sw.getCallerClass();
  63                 System.out.println("Call from Thread.run: " + c);
  64                 assertThreadClassAsCaller(c);
  65             }
  66         });
  67         t1.setDaemon(true);
  68         t1.start();
  69 
  70         // StackWalker::getCallerClass
  71         // CallerFromMain::doit
  72         // Thread::run
  73         Thread t2 = new Thread(CallerFromMain::doit);
  74         t2.setDaemon(true);
  75         t2.start();
  76 
  77         // StackWalker::getCallerClass
  78         // MyRunnable::run
  79         // Thread::run
  80         Thread t3 = new Thread(new MyRunnable());
  81         t3.setDaemon(true);
  82         t3.start();
  83 
  84         // StackWalker::getCallerClass
  85         // Runnable::run
  86         // MyThread::run
  87         Thread t4 = new MyThread(new Runnable() {
  88             @Override
  89             public void run() {
  90                 Class<?> c = sw.getCallerClass();
  91                 System.out.println("Call from MyThread.run: " + c);
  92                 if (c != MyThread.class) {
  93                     throw new RuntimeException("Expected MyThread.class but got " + c);
  94                 }
  95             }
  96         });
  97         t4.setDaemon(true);
  98         t4.start();
  99 
 100         t1.join();
 101         t2.join();
 102         t3.join();
 103         t4.join();
 104     }
 105 
 106     static class MyThread extends Thread {
 107         final Runnable runnable;
 108         MyThread(Runnable runnable) {
 109             super("MyThread");
 110             this.runnable = runnable;
 111         }
 112         public void run() {
 113             runnable.run();
 114         }
 115     }
 116 
 117     static class MyRunnable implements Runnable {
 118         @Override
 119         public void run() {
 120             Class<?> c = sw.getCallerClass();
 121             System.out.println("Call from Thread::run: " + c);
 122             assertThreadClassAsCaller(c);
 123         }
 124      }
 125 
 126     static void doit() {
 127         Class<?> c = sw.getCallerClass();
 128         System.out.println("Call from CallerFromMain.doit: " + c);
 129         assertThreadClassAsCaller(c);
 130     }
 131 
 132     static void assertThreadClassAsCaller(Class<?> caller) {
 133         if (caller != Thread.class) {
 134             throw new RuntimeException("Expected Thread.class but got " + caller);
 135         }
 136     }
 137 }
 138