001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.metrics2.lib;
020
021import java.lang.reflect.Method;
022import java.util.Set;
023
024import static com.google.common.base.Preconditions.*;
025import com.google.common.collect.Sets;
026
027import org.apache.commons.logging.Log;
028import org.apache.commons.logging.LogFactory;
029
030import org.apache.hadoop.classification.InterfaceAudience;
031import org.apache.hadoop.classification.InterfaceStability;
032import org.apache.hadoop.metrics2.MetricsRecordBuilder;
033
034/**
035 * Helper class to manage a group of mutable rate metrics
036 */
037@InterfaceAudience.Public
038@InterfaceStability.Evolving
039public class MutableRates extends MutableMetric {
040  static final Log LOG = LogFactory.getLog(MutableRates.class);
041  private final MetricsRegistry registry;
042  private final Set<Class<?>> protocolCache = Sets.newHashSet();
043
044  MutableRates(MetricsRegistry registry) {
045    this.registry = checkNotNull(registry, "metrics registry");
046  }
047
048  /**
049   * Initialize the registry with all the methods in a protocol
050   * so they all show up in the first snapshot.
051   * Convenient for JMX implementations.
052   * @param protocol the protocol class
053   */
054  public void init(Class<?> protocol) {
055    if (protocolCache.contains(protocol)) return;
056    protocolCache.add(protocol);
057    for (Method method : protocol.getDeclaredMethods()) {
058      String name = method.getName();
059      LOG.debug(name);
060      try { registry.newRate(name, name, false, true); }
061      catch (Exception e) {
062        LOG.error("Error creating rate metrics for "+ method.getName(), e);
063      }
064    }
065  }
066
067  /**
068   * Add a rate sample for a rate metric
069   * @param name of the rate metric
070   * @param elapsed time
071   */
072  public void add(String name, long elapsed) {
073    registry.add(name, elapsed);
074  }
075
076  @Override
077  public void snapshot(MetricsRecordBuilder rb, boolean all) {
078    registry.snapshot(rb, all);
079  }
080}