001/*
002 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.debug;
024
025import java.util.concurrent.*;
026
027/**
028 * A timer for some activity of interest. A timer should be deployed using the try-with-resources
029 * pattern:
030 *
031 * <pre>
032 * try (TimerCloseable a = timer.start()) {
033 *     // the code to time
034 * }
035 * </pre>
036 */
037public interface DebugTimer {
038
039    /**
040     * Starts this timer if timing is {@linkplain Debug#isTimeEnabled() enabled} or this is an
041     * {@linkplain #isConditional() unconditional} timer.
042     *
043     * @return an object that must be closed once the activity has completed to add the elapsed time
044     *         since this call to the total for this timer
045     */
046    DebugCloseable start();
047
048    /**
049     * Sets a flag determining if this timer is only enabled if timing is
050     * {@link Debug#isTimeEnabled() enabled}.
051     */
052    void setConditional(boolean flag);
053
054    /**
055     * Determines if this timer is only enabled if timing is {@link Debug#isTimeEnabled() enabled}.
056     */
057    boolean isConditional();
058
059    /**
060     * Gets the current value of this timer.
061     */
062    long getCurrentValue();
063
064    /**
065     * Gets the time unit of this timer.
066     */
067    TimeUnit getTimeUnit();
068
069    /**
070     * Gets the timer recording the amount time spent within a timed scope minus the time spent in
071     * any nested timed scopes.
072     *
073     * @return null if this timer does not support flat timing
074     */
075    default DebugTimer getFlat() {
076        return null;
077    }
078}