/*

 * 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.ElementType;

import java.lang.annotation.Inherited;

import java.lang.annotation.Retention;

import java.lang.annotation.RetentionPolicy;

import java.lang.annotation.Target;

/**

 * Event annotation, specifies the default setting value for a periodic event.

 *

 * @since 9

 */

@MetadataDefinition

@Retention(RetentionPolicy.RUNTIME)

@Inherited

@Target(ElementType.TYPE)

public @interface Period {

    /**

     * Settings name {@code "period"} for configuring periodic events

     */

    public final static String NAME = "period";

    /**

     * Returns the default setting value for a periodic setting.

     * <p>

     * String representation of a positive {@code Long} value followed by an empty

     * space and one of the following units:<br>

     * <br>

     * {@code "ns"} (nanoseconds)<br>

     * {@code "us"} (microseconds)<br>

     * {@code "ms"} (milliseconds)<br>

     * {@code "s"} (seconds)<br>

     * {@code "m"} (minutes)<br>

     * {@code "h"} (hours)<br>

     * {@code "d"} (days)<br>

     * <p>

     * Example values: {@code "0 ns"}, {@code "10 ms"}, and {@code "1 s"}.

     * <p>

     * A period may also be <code>"everyChunk"</code> to specify that it occurs at

     * least once for every recording file. The number of events that are emitted

     * depends on how many times the file rotations occur when data is recorded.

     *

     * @return the default setting value, not {@code null}

     */

    String value() default "everyChunk";

}