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.Retention;
  30 import java.lang.annotation.RetentionPolicy;
  31 import java.lang.annotation.Target;
  32 
  33 /**
  34  * Event field annotation, signifies that the value is a point in time.
  35  *
  36  * @since 9
  37  */
  38 @MetadataDefinition
  39 @ContentType
  40 @Label("Timestamp")
  41 @Description("A point in time")
  42 @Retention(RetentionPolicy.RUNTIME)
  43 @Target({ ElementType.FIELD, ElementType.TYPE, ElementType.METHOD})
  44 public @interface Timestamp {
  45     /**
  46      * The unit for the difference, measured in milliseconds, between the current
  47      * time and midnight, January 1, 1970 UTC.
  48      */
  49     public final static String MILLISECONDS_SINCE_EPOCH = "MILLISECONDS_SINCE_EPOCH";
  50 
  51     /**
  52      * The unit for the number of ticks that have transpired since some arbitrary
  53      * starting date.
  54      */
  55     public final static String TICKS = "TICKS";
  56 
  57     /**
  58      * Unit for the time stamp.
  59      *
  60      * @return time-stamp unit, not {@code null}
  61      */
  62     String value() default Timestamp.MILLISECONDS_SINCE_EPOCH;
  63 }