src/jdk.jfr/share/classes/jdk/jfr/EventType.java
changeset 50113 caf115bb98ad
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jfr/share/classes/jdk/jfr/EventType.java	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,237 @@
+/*
+ * Copyright (c) 2016, 2018, 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.Annotation;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+
+import jdk.jfr.internal.JVMSupport;
+import jdk.jfr.internal.MetadataRepository;
+import jdk.jfr.internal.PlatformEventType;
+import jdk.jfr.internal.Type;
+import jdk.jfr.internal.Utils;
+
+/**
+ * Describes an event, its fields, settings and annotations.
+ *
+ * @since 9
+ */
+public final class EventType {
+    private final PlatformEventType platformEventType;
+    private final List<String> UNCATEGORIZED = Collections.singletonList("Uncategorized");
+    private Map<String, ValueDescriptor> cache; // create lazy to avoid memory overhead
+    // helper constructor
+    EventType(PlatformEventType platformEventType) {
+        this.platformEventType = platformEventType;
+    }
+
+    /**
+     * Returns an immutable list of descriptors that describe the event fields of
+     * this event type.
+     *
+     * @return the list of field descriptors, not {@code null}
+     */
+    public List<ValueDescriptor> getFields() {
+        return platformEventType.getFields();
+    }
+
+    /**
+     * Returns the field with the specified name, or {@code null} if it doesn't
+     * exist.
+     *
+     * @return a value descriptor that describes the field, or <code>null</code> if
+     *         the field with the specified name doesn't exist
+     *
+     * @return a value descriptor, or <code>null</code> if it doesn't exist
+     */
+    public ValueDescriptor getField(String name) {
+        Objects.requireNonNull(name);
+        if (cache == null) {
+            List<ValueDescriptor> fields = getFields();
+            Map<String, ValueDescriptor> newCache = new LinkedHashMap<String, ValueDescriptor>(fields.size());
+            for (ValueDescriptor v :fields) {
+                newCache.put(v.getName(), v);
+            }
+            cache = newCache;
+        }
+        return cache.get(name);
+    }
+
+    /**
+     * Returns an identifier for the event (for example,
+     * {@code "jdk.CPULoad"}).
+     * <p>
+     * The identifier is the fully qualified name of the event class, if not set using
+     * the {@link Name} annotation.
+     *
+     * @return the name, not {@code null}
+     *
+     * @see Name
+     */
+    public String getName() {
+        return platformEventType.getName();
+    }
+
+    /**
+     * Returns a human-readable name (for example, {@code "CPU Load"}).
+     * <p>
+     * The label of an event class can be set with {@link Label}.
+     *
+     * @return the label, or {@code null} if a label is not set
+     *
+     * @see Label
+     */
+    public String getLabel() {
+        return platformEventType.getLabel();
+    }
+
+    /**
+     * Returns a unique ID for this event type in the Java Virtual Machine (JVM).
+     *
+     * @return the ID that is used in the JVM
+     */
+    public long getId() {
+        return platformEventType.getId();
+    }
+
+    /**
+     * Returns an immutable list of annotation elements for this event type.
+     *
+     * @return an immutable list of annotations or an empty list if no
+     *         annotations exists, not {@code null}
+     */
+    public List<AnnotationElement> getAnnotationElements() {
+        return platformEventType.getAnnotationElements();
+    }
+
+    /**
+     * Returns {@code true} if the event is enabled and at least one recording is
+     * running, {@code false} otherwise.
+     * <p>
+     * By default, the event is enabled. The event can be enabled or disabled by
+     * setting the enabled setting to {@code true} or {@code false}, programmatically or by using a
+     * configuration file. The event can also be disabled by annotating event with
+     * the {@code @Enabled(false)} annotation.
+     *
+     * @return true if event is enabled, false otherwise
+     *
+     * @see Enabled
+     * @see Recording#enable(Class)
+     */
+    public boolean isEnabled() {
+        return platformEventType.isEnabled();
+    }
+
+    /**
+     * Returns a short sentence that describes the event class.
+     * <p>
+     * The description of an event class can be set with {@link Description}.
+     *
+     * @return the description, or {@code null} if no description exists
+     *
+     * @see Description
+     */
+    public String getDescription() {
+        return platformEventType.getDescription();
+    }
+
+    /**
+     * Returns the first annotation for the specified type if an annotation
+     * element with the same name is directly present, otherwise {@code null}.
+     *
+     * @param <A> the type of the annotation to query for and return if present
+     * @param annotationClass the {@code Class} object that corresponds to the
+     *        annotation type, not {@code null}
+     * @return this element's annotation for the specified annotation type if
+     *         directly present, else {@code null}
+     */
+    public <A extends Annotation> A getAnnotation(Class<A> annotationClass) {
+        Objects.requireNonNull(annotationClass);
+        return platformEventType.getAnnotation(annotationClass);
+    }
+
+    /**
+     * Returns the event type for an event class, or {@code null} if it doesn't
+     * exist.
+     *
+     * @param eventClass the event class, not {@code null}
+     * @return the event class, or null if class doesn't exist
+     *
+     * @throws IllegalArgumentException if {@code eventClass} is an abstract class
+     *
+     * @throws IllegalStateException if the class is annotated with
+     *         {@code Registered(false)}, but not manually registered
+     */
+    public static EventType getEventType(Class<? extends Event> eventClass) {
+        Objects.requireNonNull(eventClass);
+        Utils.ensureValidEventSubclass(eventClass);
+        JVMSupport.ensureWithInternalError();
+        return MetadataRepository.getInstance().getEventType(eventClass);
+    }
+
+    /**
+     * Returns an immutable list of the setting descriptors that describe the available
+     * event settings for this event type.
+     *
+     * @return the list of setting descriptors for this event type, not
+     *         {@code null}
+     */
+    public List<SettingDescriptor> getSettingDescriptors() {
+        return Collections.unmodifiableList(platformEventType.getSettings());
+    }
+
+    /**
+     * Returns the list of human-readable names that makes up the categories for
+     * this event type (for example, {@code "Java Application"}, {@code "Statistics"}).
+     *
+     * @return an immutable list of category names, or a list with the name
+     *         {@code "Uncategorized"} if no category is set
+     *
+     * @see Category
+     */
+    public List<String> getCategoryNames() {
+        Category c = platformEventType.getAnnotation(Category.class);
+        if (c == null) {
+            return UNCATEGORIZED;
+        }
+        return Collections.unmodifiableList(Arrays.asList(c.value()));
+    }
+
+    // package private
+    Type getType() {
+        return platformEventType;
+    }
+
+    // package private
+    PlatformEventType getPlatformEventType() {
+        return platformEventType;
+    }
+}