Timer.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.sling.commons.metrics;

import java.io.Closeable;
import java.util.concurrent.TimeUnit;

import org.osgi.annotation.versioning.ProviderType;


/**
 * A timer metric which aggregates timing durations and provides duration statistics.
 */
@ProviderType
public interface Timer extends Counting, Metric{
    /**
     * A timing context.
     *
     * @see Timer#time()
     */
    interface Context extends Closeable {
        /**
         * Updates the timer with the difference between current and start time. Call to this method will
         * not reset the start time. Multiple calls result in multiple updates.
         * @return the elapsed time in nanoseconds
         */
        long stop();
    }

    /**
     * Adds a recorded duration.
     *
     * @param duration the length of the duration
     * @param unit     the scale unit of {@code duration}
     */
    void update(long duration, TimeUnit unit);

    /**
     * Returns a new {@link Context}.
     *
     * @return a new {@link Context}
     * @see Context
     */
    Context time();
}