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 signifies 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  * Example.
  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 }