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 */
018package org.apache.hadoop.hbase.metrics;
019
020import java.util.Collection;
021import java.util.Optional;
022import java.util.Set;
023import org.apache.hadoop.hbase.HBaseInterfaceAudience;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.yetus.audience.InterfaceStability;
026
027/**
028 * MetricRegistries is collection of MetricRegistry's. MetricsRegistries implementations should do
029 * ref-counting of MetricRegistry's via create() and remove() methods.
030 */
031@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC)
032@InterfaceStability.Evolving
033public abstract class MetricRegistries {
034
035  private static final class LazyHolder {
036    private static final MetricRegistries GLOBAL = MetricRegistriesLoader.load();
037  }
038
039  /**
040   * Return the global singleton instance for the MetricRegistries.
041   * @return MetricRegistries implementation.
042   */
043  public static MetricRegistries global() {
044    return LazyHolder.GLOBAL;
045  }
046
047  /**
048   * Removes all the MetricRegisties.
049   */
050  public abstract void clear();
051
052  /**
053   * Create or return MetricRegistry with the given info. MetricRegistry will only be created if
054   * current reference count is 0. Otherwise ref counted is incremented, and an existing instance
055   * will be returned.
056   * @param info the info object for the MetricRegistrytry.
057   * @return created or existing MetricRegistry.
058   */
059  public abstract MetricRegistry create(MetricRegistryInfo info);
060
061  /**
062   * Decrements the ref count of the MetricRegistry, and removes if ref count == 0.
063   * @param key the info object for the MetricRegistrytry.
064   * @return true if metric registry is removed.
065   */
066  public abstract boolean remove(MetricRegistryInfo key);
067
068  /**
069   * Returns the MetricRegistry if found.
070   * @param info the info for the registry.
071   * @return a MetricRegistry optional.
072   */
073  public abstract Optional<MetricRegistry> get(MetricRegistryInfo info);
074
075  /**
076   * Returns MetricRegistryInfo's for the MetricRegistry's created.
077   * @return MetricRegistryInfo's for the MetricRegistry's created.
078   */
079  public abstract Set<MetricRegistryInfo> getMetricRegistryInfos();
080
081  /**
082   * Returns MetricRegistry's created.
083   * @return MetricRegistry's created.
084   */
085  public abstract Collection<MetricRegistry> getMetricRegistries();
086}