--- /dev/null 2018-06-17 23:18:20.806999507 +0800 +++ new/src/share/classes/jdk/jfr/Category.java 2019-01-29 10:58:31.246561061 +0800 @@ -0,0 +1,130 @@ +/* + * 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: + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + * + *
Recording options and their purpose.
Event NameAnnotation
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(); +}