1 /*

     2  * Copyright (c) 2018, 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.internal.event;

    27 

    28 /**

    29  * Base class for events, to be subclassed in order to define events and their

    30  * fields.

    31  */

    32 public abstract class Event {

    33     /**

    34      * Sole constructor, for invocation by subclass constructors, typically

    35      * implicit.

    36      */

    37     protected Event() {

    38     }

    39 

    40     /**

    41      * Starts the timing of this event.

    42      */

    43     public void begin() {

    44     }

    45 

    46     /**

    47      * Ends the timing of this event.

    48      *

    49      * The {@code end} method must be invoked after the {@code begin} method.

    50      */

    51     public void end() {

    52     }

    53 

    54     /**

    55      * Writes the field values, time stamp, and event duration.

    56      * <p>

    57      * If the event starts with an invocation of the {@code begin} method, but does

    58      * not end with an explicit invocation of the {@code end} method, then the event

    59      * ends when the {@code commit} method is invoked.

    60      */

    61     public void commit() {

    62     }

    63 

    64     /**

    65      * Returns {@code true} if the event is enabled, {@code false} otherwise

    66      *

    67      * @return {@code true} if event is enabled, {@code false} otherwise

    68      */

    69     public boolean isEnabled() {

    70         return false;

    71     }

    72 

    73     /**

    74      * Returns {@code true} if the event is enabled and if the duration is within

    75      * the threshold for the event, {@code false} otherwise.

    76      *

    77      * @return {@code true} if the event can be written, {@code false} otherwise

    78      */

    79     public boolean shouldCommit() {

    80         return false;

    81     }

    82 

    83     /**

    84      * Sets a field value.

    85      *

    86      * @param index the index of the field to set

    87      * @param value value to set, can be {@code null}

    88      * @throws UnsupportedOperationException if functionality is not supported

    89      * @throws IndexOutOfBoundsException if {@code index} is less than {@code 0} or

    90      *         greater than or equal to the number of fields specified for the event

    91      */

    92     public void set(int index, Object value) {

    93     }

    94 }