1 /*
   2  * Copyright (c) 2016, 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 package java.util;
  25 
  26 import static java.lang.StackWalker.Option.*;
  27 import java.lang.StackWalker.StackFrame;
  28 import java.util.stream.Collectors;
  29 
  30 import jdk.internal.reflect.CallerSensitive;
  31 import jdk.internal.reflect.Reflection;
  32 
  33 public class CSM {
  34     private static StackWalker walker =
  35         StackWalker.getInstance(EnumSet.of(RETAIN_CLASS_REFERENCE,
  36                                            SHOW_HIDDEN_FRAMES,
  37                                            SHOW_REFLECT_FRAMES));
  38 
  39     public static class Result {
  40         public final List<Class<?>> callers;
  41         public final List<StackWalker.StackFrame> frames;
  42         Result(List<Class<?>> callers,
  43                List<StackFrame> frames) {
  44             this.callers = callers;
  45             this.frames = frames;
  46         }
  47     }
  48 
  49     /**
  50      * Returns the caller of this caller-sensitive method returned by
  51      * by Reflection::getCallerClass.
  52      *
  53      * StackWalker::getCallerClass is expected to throw UOE
  54      */
  55     @CallerSensitive
  56     public static Class<?> caller() {
  57         Class<?> c1 = Reflection.getCallerClass();
  58 
  59         try {
  60             Class<?> c2 = walker.getCallerClass();
  61             throw new RuntimeException("Exception not thrown by StackWalker::getCallerClass");
  62         } catch (UnsupportedOperationException e) {}
  63         return c1;
  64     }
  65 
  66     /**
  67      * Returns the caller of this non-caller-sensitive method.
  68      */
  69     public static Result getCallerClass() {
  70         Class<?> caller = walker.getCallerClass();
  71         return new Result(List.of(caller), dump());
  72     }
  73 
  74     static List<StackFrame> dump() {
  75         return walker.walk(s -> s.collect(Collectors.toList()));
  76     }
  77 }