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.Annotation;
  29 import java.util.Arrays;
  30 import java.util.Collections;
  31 import java.util.LinkedHashMap;
  32 import java.util.List;
  33 import java.util.Map;
  34 import java.util.Objects;
  35 
  36 import jdk.jfr.internal.JVMSupport;
  37 import jdk.jfr.internal.MetadataRepository;
  38 import jdk.jfr.internal.PlatformEventType;
  39 import jdk.jfr.internal.Type;
  40 import jdk.jfr.internal.Utils;
  41 
  42 /**
  43  * Describes an event, its fields, settings and annotations.
  44  *
  45  * @since 8
  46  */
  47 public final class EventType {
  48     private final PlatformEventType platformEventType;
  49     private final List<String> UNCATEGORIZED = Collections.singletonList("Uncategorized");
  50     private Map<String, ValueDescriptor> cache; // create lazy to avoid memory overhead
  51     // helper constructor
  52     EventType(PlatformEventType platformEventType) {
  53         this.platformEventType = platformEventType;
  54     }
  55 
  56     /**
  57      * Returns an immutable list of descriptors that describe the event fields of
  58      * this event type.
  59      *
  60      * @return the list of field descriptors, not {@code null}
  61      */
  62     public List<ValueDescriptor> getFields() {
  63         return platformEventType.getFields();
  64     }
  65 
  66     /**
  67      * Returns the field with the specified name, or {@code null} if it doesn't
  68      * exist.
  69      *
  70      * @return a value descriptor that describes the field, or <code>null</code> if
  71      *         the field with the specified name doesn't exist
  72      *
  73      * @return a value descriptor, or <code>null</code> if it doesn't exist
  74      */
  75     public ValueDescriptor getField(String name) {
  76         Objects.requireNonNull(name);
  77         if (cache == null) {
  78             List<ValueDescriptor> fields = getFields();
  79             Map<String, ValueDescriptor> newCache = new LinkedHashMap<String, ValueDescriptor>(fields.size());
  80             for (ValueDescriptor v :fields) {
  81                 newCache.put(v.getName(), v);
  82             }
  83             cache = newCache;
  84         }
  85         return cache.get(name);
  86     }
  87 
  88     /**
  89      * Returns an identifier for the event (for example,
  90      * {@code "jdk.CPULoad"}).
  91      * <p>
  92      * The identifier is the fully qualified name of the event class, if not set using
  93      * the {@link Name} annotation.
  94      *
  95      * @return the name, not {@code null}
  96      *
  97      * @see Name
  98      */
  99     public String getName() {
 100         return platformEventType.getName();
 101     }
 102 
 103     /**
 104      * Returns a human-readable name (for example, {@code "CPU Load"}).
 105      * <p>
 106      * The label of an event class can be set with {@link Label}.
 107      *
 108      * @return the label, or {@code null} if a label is not set
 109      *
 110      * @see Label
 111      */
 112     public String getLabel() {
 113         return platformEventType.getLabel();
 114     }
 115 
 116     /**
 117      * Returns a unique ID for this event type in the Java Virtual Machine (JVM).
 118      *
 119      * @return the ID that is used in the JVM
 120      */
 121     public long getId() {
 122         return platformEventType.getId();
 123     }
 124 
 125     /**
 126      * Returns an immutable list of annotation elements for this event type.
 127      *
 128      * @return an immutable list of annotations or an empty list if no
 129      *         annotations exists, not {@code null}
 130      */
 131     public List<AnnotationElement> getAnnotationElements() {
 132         return platformEventType.getAnnotationElements();
 133     }
 134 
 135     /**
 136      * Returns {@code true} if the event is enabled and at least one recording is
 137      * running, {@code false} otherwise.
 138      * <p>
 139      * By default, the event is enabled. The event can be enabled or disabled by
 140      * setting the enabled setting to {@code true} or {@code false}, programmatically or by using a
 141      * configuration file. The event can also be disabled by annotating event with
 142      * the {@code @Enabled(false)} annotation.
 143      *
 144      * @return true if event is enabled, false otherwise
 145      *
 146      * @see Enabled
 147      * @see Recording#enable(Class)
 148      */
 149     public boolean isEnabled() {
 150         return platformEventType.isEnabled();
 151     }
 152 
 153     /**
 154      * Returns a short sentence that describes the event class.
 155      * <p>
 156      * The description of an event class can be set with {@link Description}.
 157      *
 158      * @return the description, or {@code null} if no description exists
 159      *
 160      * @see Description
 161      */
 162     public String getDescription() {
 163         return platformEventType.getDescription();
 164     }
 165 
 166     /**
 167      * Returns the first annotation for the specified type if an annotation
 168      * element with the same name is directly present, otherwise {@code null}.
 169      *
 170      * @param <A> the type of the annotation to query for and return if present
 171      * @param annotationClass the {@code Class} object that corresponds to the
 172      *        annotation type, not {@code null}
 173      * @return this element's annotation for the specified annotation type if
 174      *         directly present, else {@code null}
 175      */
 176     public <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
 177         Objects.requireNonNull(annotationClass);
 178         return platformEventType.getAnnotation(annotationClass);
 179     }
 180 
 181     /**
 182      * Returns the event type for an event class, or {@code null} if it doesn't
 183      * exist.
 184      *
 185      * @param eventClass the event class, not {@code null}
 186      * @return the event class, or null if class doesn't exist
 187      *
 188      * @throws IllegalArgumentException if {@code eventClass} is an abstract class
 189      *
 190      * @throws IllegalStateException if the class is annotated with
 191      *         {@code Registered(false)}, but not manually registered
 192      */
 193     public static EventType getEventType(Class<? extends Event> eventClass) {
 194         Objects.requireNonNull(eventClass);
 195         Utils.ensureValidEventSubclass(eventClass);
 196         JVMSupport.ensureWithInternalError();
 197         return MetadataRepository.getInstance().getEventType(eventClass);
 198     }
 199 
 200     /**
 201      * Returns an immutable list of the setting descriptors that describe the available
 202      * event settings for this event type.
 203      *
 204      * @return the list of setting descriptors for this event type, not
 205      *         {@code null}
 206      */
 207     public List<SettingDescriptor> getSettingDescriptors() {
 208         return Collections.unmodifiableList(platformEventType.getSettings());
 209     }
 210 
 211     /**
 212      * Returns the list of human-readable names that makes up the categories for
 213      * this event type (for example, {@code "Java Application"}, {@code "Statistics"}).
 214      *
 215      * @return an immutable list of category names, or a list with the name
 216      *         {@code "Uncategorized"} if no category is set
 217      *
 218      * @see Category
 219      */
 220     public List<String> getCategoryNames() {
 221         Category c = platformEventType.getAnnotation(Category.class);
 222         if (c == null) {
 223             return UNCATEGORIZED;
 224         }
 225         return Collections.unmodifiableList(Arrays.asList(c.value()));
 226     }
 227 
 228     // package private
 229     Type getType() {
 230         return platformEventType;
 231     }
 232 
 233     // package private
 234     PlatformEventType getPlatformEventType() {
 235         return platformEventType;
 236     }
 237 }