org.apache.hadoop.metrics2.lib.MutableRates.java Source code

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Here is the source code for org.apache.hadoop.metrics2.lib.MutableRates.java

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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 org.apache.hadoop.metrics2.lib;

import java.lang.reflect.Method;
import java.util.Set;

import static com.google.common.base.Preconditions.*;
import com.google.common.collect.Sets;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.metrics2.MetricsRecordBuilder;

/**
 * Helper class to manage a group of mutable rate metrics
 *
 * This class synchronizes all accesses to the metrics it
 * contains, so it should not be used in situations where
 * there is high contention on the metrics.
 * {@link MutableRatesWithAggregation} is preferable in that
 * situation.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class MutableRates extends MutableMetric {
    static final Log LOG = LogFactory.getLog(MutableRates.class);
    private final MetricsRegistry registry;
    private final Set<Class<?>> protocolCache = Sets.newHashSet();

    MutableRates(MetricsRegistry registry) {
        this.registry = checkNotNull(registry, "metrics registry");
    }

    /**
     * Initialize the registry with all the methods in a protocol
     * so they all show up in the first snapshot.
     * Convenient for JMX implementations.
     * @param protocol the protocol class
     */
    public void init(Class<?> protocol) {
        if (protocolCache.contains(protocol))
            return;
        protocolCache.add(protocol);
        for (Method method : protocol.getDeclaredMethods()) {
            String name = method.getName();
            LOG.debug(name);
            try {
                registry.newRate(name, name, false, true);
            } catch (Exception e) {
                LOG.error("Error creating rate metrics for " + method.getName(), e);
            }
        }
    }

    /**
     * Add a rate sample for a rate metric
     * @param name of the rate metric
     * @param elapsed time
     */
    public void add(String name, long elapsed) {
        registry.add(name, elapsed);
    }

    @Override
    public void snapshot(MetricsRecordBuilder rb, boolean all) {
        registry.snapshot(rb, all);
    }
}