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 java.util.Optional;
  34 import jdk.testlibrary.ProcessTools;
  35 import jdk.testlibrary.OutputAnalyzer;
  36 
  37 public class CallerFromMain {
  38 
  39     public static void getCaller(Class<?> caller) {
  40         // StackWalker::getCallerClass
  41         // CallerFromMain::doIt
  42         // caller
  43         Optional<Class<?>> c = sw.getCallerClass();
  44         if (caller != null && c.get() != caller) {
  45             throw new RuntimeException("Expected " + caller + " but got " + c);
  46         }
  47         if (caller == null && c.isPresent()) {
  48             throw new RuntimeException("Expected empty optional: " + c);
  49         }
  50     }
  51 
  52     private static final StackWalker sw = StackWalker.create(StackWalker.Option.RETAIN_CLASS_REFERENCE);
  53     public static void main(String[] args) throws Exception {
  54         if (args.length > 0) {
  55             ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(true, "CallerFromMain");
  56             OutputAnalyzer output = ProcessTools.executeProcess(pb);
  57             System.out.println(output.getOutput());
  58             output.shouldHaveExitValue(0);
  59             return;
  60         }
  61 
  62         // StackWalker::getCallerClass
  63         // CallerFromMain::main
  64         // no caller
  65         Optional<Class<?>> c = sw.getCallerClass();
  66         System.out.println("Call from main: " + c);
  67         if (c.isPresent()) {
  68             throw new RuntimeException("Expected empty optional: " + c);
  69         }
  70 
  71         // call from Thread::run
  72         Thread t1 = new Thread(new Runnable() {
  73             @Override
  74             public void run() {
  75                 Optional<Class<?>> c = sw.getCallerClass();
  76                 System.out.println("Call from Thread.run: " + c);
  77 
  78                 if (c.get() != Thread.class) {
  79                     throw new RuntimeException("Expected Thread.class but got " + c);
  80                 }
  81             }
  82         });
  83 
  84         t1.setDaemon(true);
  85         t1.start();
  86 
  87         // call from MyThread::run
  88         Thread t2 = new MyThread(new Runnable() {
  89             @Override
  90             public void run() {
  91                 Optional<Class<?>> c = sw.getCallerClass();
  92                 System.out.println("Call from MyThread.run: " + c);
  93 
  94                 if (c.get() != MyThread.class) {
  95                     throw new RuntimeException("Expected MyThread.class but got " + c);
  96                 }
  97             }
  98         });
  99         t2.setDaemon(true);
 100         t2.start();
 101 
 102         t1.join();
 103         t2.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