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.client;
019
020import java.io.IOException;
021import java.net.URI;
022import java.util.ServiceLoader;
023import org.apache.commons.lang3.StringUtils;
024import org.apache.hadoop.conf.Configuration;
025import org.apache.hadoop.hbase.HConstants;
026import org.apache.hadoop.hbase.security.User;
027import org.apache.hadoop.hbase.util.ReflectionUtils;
028import org.apache.yetus.audience.InterfaceAudience;
029import org.slf4j.Logger;
030import org.slf4j.LoggerFactory;
031
032import org.apache.hbase.thirdparty.com.google.common.collect.ImmutableMap;
033
034/**
035 * The entry point for creating a {@link ConnectionRegistry}.
036 */
037@InterfaceAudience.Private
038final class ConnectionRegistryFactory {
039
040  private static final Logger LOG = LoggerFactory.getLogger(ConnectionRegistryFactory.class);
041
042  private static final ImmutableMap<String, ConnectionRegistryURIFactory> CREATORS;
043  static {
044    ImmutableMap.Builder<String, ConnectionRegistryURIFactory> builder = ImmutableMap.builder();
045    for (ConnectionRegistryURIFactory factory : ServiceLoader
046      .load(ConnectionRegistryURIFactory.class)) {
047      builder.put(factory.getScheme().toLowerCase(), factory);
048    }
049    // throw IllegalArgumentException if there are duplicated keys
050    CREATORS = builder.buildOrThrow();
051  }
052
053  private ConnectionRegistryFactory() {
054  }
055
056  /**
057   * Returns the connection registry implementation to use, for the given connection url
058   * {@code uri}.
059   * <p/>
060   * We use {@link ServiceLoader} to load different implementations, and use the scheme of the given
061   * {@code uri} to select. And if there is no protocol specified, or we can not find a
062   * {@link ConnectionRegistryURIFactory} implementation for the given scheme, we will fallback to
063   * use the old way to create the {@link ConnectionRegistry}. Notice that, if fallback happens, the
064   * specified connection url {@code uri} will not take effect, we will load all the related
065   * configurations from the given Configuration instance {@code conf}
066   */
067  static ConnectionRegistry create(URI uri, Configuration conf, User user) throws IOException {
068    if (StringUtils.isBlank(uri.getScheme())) {
069      LOG.warn("No scheme specified for {}, fallback to use old way", uri);
070      return create(conf, user);
071    }
072    ConnectionRegistryURIFactory creator = CREATORS.get(uri.getScheme().toLowerCase());
073    if (creator == null) {
074      LOG.warn("No creator registered for {}, fallback to use old way", uri);
075      return create(conf, user);
076    }
077    return creator.create(uri, conf, user);
078  }
079
080  /**
081   * Returns the connection registry implementation to use.
082   * <p/>
083   * This is used when we do not have a connection url, we will use the old way to load the
084   * connection registry, by checking the
085   * {@literal HConstants#CLIENT_CONNECTION_REGISTRY_IMPL_CONF_KEY} configuration.
086   */
087  static ConnectionRegistry create(Configuration conf, User user) {
088    Class<? extends ConnectionRegistry> clazz =
089      conf.getClass(HConstants.CLIENT_CONNECTION_REGISTRY_IMPL_CONF_KEY,
090        RpcConnectionRegistry.class, ConnectionRegistry.class);
091    return ReflectionUtils.newInstance(clazz, conf, user);
092  }
093}