1 /*
2  * Copyright (c) 2016, 2018, 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.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 package jdk.jfr;
26 
27 import java.lang.annotation.ElementType;
28 import java.lang.annotation.Retention;
29 import java.lang.annotation.RetentionPolicy;
30 import java.lang.annotation.Target;
31 
32 /**
33  * Annotation that specifies that a method in an event class should be used to
34  * filter out events.
35  * <p>
36  * For the method to be valid it must return a {@code SettingControl} and only have one
37  * parameter, which should be a non-abstract subclass of {@link SettingControl}
38  * <p>
39  * The return value of the method specifies whether the event is to be
40  * written to the Flight Recorder system or not.
41  * <p>
42  * The following example shows how to annotate a method in an event class.
43  *
44  * <pre>
45  * <code>
46  * class HelloWorld extend Event {
47  *
48  *   {@literal @}Label("Message");
49  *   String message;
50  *
51  *   {@literal @}SettingDefinition;
52  *   {@literal @}Label("Message Filter");
53  *   public boolean filter(RegExpControl regExp) {
54  *     return regExp.matches(message);
55  *   }
56  * }
57  * </code>
58  * </pre>
59  *
60  * For an example of how the setting controls are defined, see
61  * {@link SettingControl}.
62  *
63  * @see SettingControl
64  *
65  * @since 9
66  */
67 @Retention(RetentionPolicy.RUNTIME)
68 @Target({ ElementType.METHOD })
69 public @interface SettingDefinition {
70 }
71