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 * Meta annotation for defining new types of event metadata. 35 * <p> 36 * In the following example, a transaction event is defined with two 37 * user-defined annotations, {@code @Severity} and {@code @TransactionId}. 38 * 39 * <pre> 40 * <code> 41 *{@literal @}MetadataDefinition 42 *{@literal @}Label("Severity") 43 *{@literal @}Description("Value between 0 and 100 that indicates severity. 100 is most severe.") 44 *{@literal @}Retention(RetentionPolicy.RUNTIME) 45 *{@literal @}Target({ ElementType.TYPE }) 46 * public {@literal @}interface {@literal @}Severity { 47 * int value() default 50; 48 * } 49 * 50 *{@literal @}MetadataDefinition 51 *{@literal @}Label("Transaction Id") 52 *{@literal @}Relational 53 *{@literal @}Retention(RetentionPolicy.RUNTIME) 54 *{@literal @}Target({ ElementType.FIELD }) 55 * public {@literal @}interface {@literal @}Severity { 56 * } 57 * 58 *{@literal @}Severity(80) 59 *{@literal @}Label("Transaction Blocked"); 60 * class TransactionBlocked extends Event { 61 * {@literal @}TransactionId 62 * {@literal @}Label("Transaction"); 63 * long transactionId; 64 * 65 * {@literal @}TransactionId 66 * {@literal @}Label("Transaction Blocker"); 67 * long transactionId; 68 * } 69 * 70 * </code> 71 * </pre> 72 * 73 * Adding {@code @MetadataDefinition} to the declaration of {@code @Severity} and {@code @TransactionId} 74 * ensures the information is saved by Flight Recorder. 75 * 76 * @since 9 77 */ 78 @Retention(RetentionPolicy.RUNTIME) 79 @Target({ ElementType.TYPE }) 80 public @interface MetadataDefinition { 81 }