src/jdk.jfr/share/classes/jdk/jfr/SettingDescriptor.java
changeset 50113 caf115bb98ad
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/jdk.jfr/share/classes/jdk/jfr/SettingDescriptor.java	Tue May 15 20:24:34 2018 +0200
@@ -0,0 +1,215 @@
+/*
+ * 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.Collections;
+import java.util.List;
+import java.util.Objects;
+
+import jdk.jfr.internal.AnnotationConstruct;
+import jdk.jfr.internal.Type;
+
+/**
+ * Describes an event setting.
+ *
+ * @since 9
+ */
+public final class SettingDescriptor {
+
+    private final AnnotationConstruct annotationConstruct;
+    private final Type type;
+    private final String name;
+    private final String defaultValue;
+
+    // package private, invoked by jdk.internal.
+    SettingDescriptor(Type type, String name, String defaultValue, List<AnnotationElement> annotations) {
+        Objects.requireNonNull(annotations);
+        this.name = Objects.requireNonNull(name, "Name of value descriptor can't be null");
+        this.type = Objects.requireNonNull(type);
+        this.annotationConstruct = new AnnotationConstruct(annotations);
+        this.defaultValue = Objects.requireNonNull(defaultValue);
+    }
+
+    // package private
+    void setAnnotations(List<AnnotationElement> as) {
+        annotationConstruct.setAnnotationElements(as);
+    }
+
+    /**
+     * Returns the name of the setting (for example, {@code "threshold"}).
+     *
+     * @return the name, not {@code null}
+     */
+    public String getName() {
+        return name;
+    }
+
+    /**
+     * Returns a human-readable name that describes the setting (for example,
+     * {@code "Threshold"}).
+     * <p>
+     * If the setting lacks a label, the label for the type that is associated with this
+     * setting is returned, or {@code null} if doesn't exist
+     *
+     * @return a human-readable name, or {@code null} if doesn't exist
+     */
+    public String getLabel() {
+        String label = annotationConstruct.getLabel();
+        if (label == null) {
+            label = type.getLabel();
+        }
+        return label;
+    }
+
+    /**
+     * Returns a sentence that describes the setting (for example
+     * {@code "Record event with duration
+     * above or equal to threshold"}).
+     * <p>
+     * If the setting lacks a description, the description for the type that is
+     * associated with this setting is returned, or {@code null} if doesn't exist.
+     *
+     * @return the description, or {@code null} if doesn't exist
+     */
+    public String getDescription() {
+        String description = annotationConstruct.getDescription();
+        if (description == null) {
+            description = type.getDescription();
+        }
+        return description;
+    }
+
+    /**
+     * Returns a textual identifier that specifies how a value that is represented by
+     * this {@code SettingDescriptor} object is interpreted or formatted.
+     * <p>
+     * For example, if the setting descriptor represents a percentage, then
+     * {@code "jdk.jfr.Percentage"} hints to a client that a value of "0.5"
+     * is formatted as "50%".
+     * <p>
+     * The JDK provides the following predefined content types:
+     * <ul>
+     * <li>jdk.jfr.Percentage</li>
+     * <li>jdk.jfr.Timespan</li>
+     * <li>jdk.jfr.Timestamp</li>
+     * <li>jdk.jfr.Frequency</li>
+     * <li>jdk.jfr.Flag</li>
+     * <li>jdk.jfr.MemoryAddress</li>
+     * <li>jdk.jfr.DataAmount</li>
+     * <li>jdk.jfr.NetworkAddress</li>
+     * </ul>
+     * <p>
+     * User-defined content types can be created by using {@link ContentType}.
+     * <p>
+     * If the setting lacks a content type, the content type for the type
+     * that is associated with this setting is returned, or {@code null} if not
+     * available.
+     *
+     * @return the content type, or {@code null} if doesn't exist
+     *
+     * @see ContentType
+     */
+    public String getContentType() {
+        for (AnnotationElement anno : getAnnotationElements()) {
+            for (AnnotationElement meta : anno.getAnnotationElements()) {
+                if (meta.getTypeName().equals(ContentType.class.getName())) {
+                    return anno.getTypeName();
+                }
+            }
+        }
+        for (AnnotationElement anno : type.getAnnotationElements()) {
+            for (AnnotationElement meta : anno.getAnnotationElements()) {
+                if (meta.getTypeName().equals(ContentType.class.getName())) {
+                    return anno.getTypeName();
+                }
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Returns the fully qualified class name of the type that is associated with this
+     * setting descriptor.
+     *
+     * @return the type name, not {@code null}
+     *
+     * @see SettingDescriptor#getTypeId()
+     */
+    public String getTypeName() {
+        return type.getName();
+    }
+
+    /**
+     * Returns a unique ID for the type in the Java Virtual Machine (JVM).
+     * <p>
+     * The ID might not be the same between JVM instances.
+     *
+     * @return the type ID, not negative
+     */
+    public long getTypeId() {
+        return type.getId();
+    }
+
+    /**
+     * Returns the first annotation for the specified type if an annotation
+     * element with the same name is available, {@code null} otherwise.
+     *
+     * @param <A> the type of the annotation to query for and return if available
+     * @param annotationType the Class object that corresponds to the annotation
+     *        type, not {@code null}
+     * @return this element's annotation for the specified annotation type if
+     *         available, {@code null} otherwise
+     */
+    public <A extends Annotation> A getAnnotation(Class<A> annotationType) {
+        Objects.requireNonNull(annotationType);
+        return annotationConstruct.getAnnotation(annotationType);
+    }
+
+    /**
+     * Returns an immutable list of annotation elements for this value
+     * descriptor.
+     *
+     * @return a list of annotations, not {@code null}
+     */
+    public List<AnnotationElement> getAnnotationElements() {
+        return Collections.unmodifiableList(annotationConstruct.getUnmodifiableAnnotationElements());
+    }
+
+    /**
+     * Returns the default value for this setting descriptor.
+     *
+     * @return the default value, not {@code null}
+     */
+    public String getDefaultValue() {
+        return defaultValue;
+    }
+
+    // package private
+    Type getType() {
+        return type;
+    }
+}