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
24package java.util;
25
26import static java.lang.StackWalker.Option.*;
27import java.lang.StackWalker.StackFrame;
28import java.util.stream.Collectors;
29
30import jdk.internal.reflect.CallerSensitive;
31import jdk.internal.reflect.Reflection;
32
33public 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}
78