1 /*
   2  * Copyright (c) 2016, 2019, 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 
  26 package jdk.jfr;
  27 
  28 import java.lang.annotation.ElementType;
  29 import java.lang.annotation.Inherited;
  30 import java.lang.annotation.Retention;
  31 import java.lang.annotation.RetentionPolicy;
  32 import java.lang.annotation.Target;
  33 
  34 /**
  35  * Event annotation, specifies the default duration below which an event is not
  36  * recorded (for example, {@code "20 ms"}).
  37  *
  38  * @since 8
  39  */
  40 @MetadataDefinition
  41 @Target({ ElementType.TYPE })
  42 @Inherited
  43 @Retention(RetentionPolicy.RUNTIME)
  44 public @interface Threshold {
  45     /**
  46      * Setting name {@code "threshold"} for configuring event thresholds.
  47      */
  48     public final static String NAME = "threshold";
  49 
  50     /**
  51      * The threshold (for example, {@code "20 ms"}).
  52      * <p>
  53      * A {@code String} representation of a positive {@code Long} value followed by an
  54      * empty space and one of the following units:<br>
  55      * <br>
  56      * {@code "ns"} (nanoseconds)<br>
  57      * {@code "us"} (microseconds)<br>
  58      * {@code "ms"} (milliseconds)<br>
  59      * {@code "s"} (seconds)<br>
  60      * {@code "m"} (minutes)<br>
  61      * {@code "h"} (hours)<br>
  62      * {@code "d"} (days)<br>
  63      * <p>
  64      * Example values are {@code "0 ns"}, {@code "10 ms"}, and {@code "1 s"}.
  65      *
  66      * @return the threshold, default {@code "0 ns"}, not {@code null}
  67      */
  68     String value() default "0 ns";
  69 }