/* * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package jdk.jfr; import java.lang.annotation.ElementType; import java.lang.annotation.Inherited; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; /** * Event annotation, to associate the event type with a category, in the format * of a human-readable path. *
* The category determines how an event is presented to the user. Events that * are in the same category are typically displayed together in graphs and * trees. To avoid that the overlap of durational events in graphical * representations, overlapping events must be in separate categories. *
* For example, to monitor image uploads to a web server with a separate thread * for each upload, an event called File Upload starts when the user uploads a * file and ends when the upload is complete. For advanced diagnostics about * image uploads, more detailed events are created (for example, Image Read, * Image Resize, and Image Write). During these detailed events. other low * level-events could occur (for example, Socket Read and File Write). *
* The following example shows a visualization that avoid overlaps: * *
* ------------------------------------------------------------------- * | File Upload | * ------------------------------------------------------------------ * | Image Read | Image Resize | Image Write | * ------------------------------------------------------------------ * | Socket Read | Socket Read | | File Write | * ------------------------------------------------------------------- ** * The example can be achieved by using the following categories: * *
Event Name | *Annotation | *
---|---|
File Upload | *@Category("Upload") |
*
Image Read | *@Category({"Upload", "Image Upload"}) |
*
Image Resize | *@Category({"Upload", "Image Upload"}) |
*
Image Write | *@Category({"Upload", "Image Upload"}) |
*
Socket Read | *@Category("Java Application") |
*
File Write | *@Category("Java Application") |
*
* The File Upload, Image Read, and Socket Read events happen concurrently (in * the same thread), but the events are in different categories so they do not * overlap in the visualization. *
* The following examples shows how the category is used to determine how events * are visualized in a tree: * *
* |- Java Application * | |- Socket Read * | |- File Write * |- Upload * |- File Upload * |- Image Upload * |- Image Read * |- Image Resize * |- File Write ** * @since 9 */ @MetadataDefinition @Target({ ElementType.TYPE }) @Inherited @Retention(RetentionPolicy.RUNTIME) public @interface Category { /** * Returns the category names for this annotation, starting with the root. * * @return the category names */ String[] value(); }