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/*
 * 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 com.alibaba.metrics;

import java.util.Map;

/**
 * An object which maintains mean and exponentially-weighted rate.
 */
public interface Metered extends Metric, Counting {

    /**
     * Returns the number of events which have been marked.
     *
     * @return the number of events which have been marked
     */
    long getCount();

    /**
     * Get the accurate number per collecting interval
     * @return an long array, each contains the number of events, keyed by timestamp in milliseconds
     */
    Map getInstantCount();

    /**
     * Get the accurate number per collecting interval since (including) the start time
     * @param startTime the start time of the query
     * @return an long array, each contains the number of events, keyed by timestamp in milliseconds
     */
    Map getInstantCount(long startTime);

    /**
     * Get the collecting interval
     * @return the collecting interval
     */
    int getInstantCountInterval();

    /**
     * Returns the fifteen-minute exponentially-weighted moving average rate at which events have
     * occurred since the meter was created.
     * 
     * This rate has the same exponential decay factor as the fifteen-minute load average in the
     * {@code top} Unix command.
     *
     * @return the fifteen-minute exponentially-weighted moving average rate at which events have
     *         occurred since the meter was created
     */
    double getFifteenMinuteRate();

    /**
     * Returns the five-minute exponentially-weighted moving average rate at which events have
     * occurred since the meter was created.
     * 

     * This rate has the same exponential decay factor as the five-minute load average in the {@code
     * top} Unix command.
     *
     * @return the five-minute exponentially-weighted moving average rate at which events have
     *         occurred since the meter was created
     */
    double getFiveMinuteRate();

    /**
     * Returns the mean rate at which events have occurred since the meter was created.
     *
     * @return the mean rate at which events have occurred since the meter was created
     */
    double getMeanRate();

    /**
     * Returns the one-minute exponentially-weighted moving average rate at which events have
     * occurred since the meter was created.
     * 
     * This rate has the same exponential decay factor as the one-minute load average in the {@code
     * top} Unix command.
     *
     * @return the one-minute exponentially-weighted moving average rate at which events have
     *         occurred since the meter was created
     */
    double getOneMinuteRate();
}