content: /*
   * 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.distributedlog;
  
  import static com.google.common.base.Preconditions.checkArgument;
  import static com.google.common.base.Preconditions.checkNotNull;
  
  import io.netty.channel.EventLoopGroup;
  import io.netty.util.HashedWheelTimer;
  import java.util.Optional;
  import org.apache.bookkeeper.feature.FeatureProvider;
  import org.apache.bookkeeper.stats.NullStatsLogger;
  import org.apache.bookkeeper.stats.StatsLogger;
  
  /**
   * Builder to build bookkeeper client.
   */
  public class BookKeeperClientBuilder {
  
      /**
       * Create a bookkeeper client builder to build bookkeeper clients.
       *
       * @return bookkeeper client builder.
       */
      public static BookKeeperClientBuilder newBuilder() {
          return new BookKeeperClientBuilder();
      }
  
      // client name
      private String name = null;
      // dl config
      private DistributedLogConfiguration dlConfig = null;
      // bookkeeper settings
      // zookeeper client
      private ZooKeeperClient zkc = null;
      // or zookeeper servers
      private String zkServers = null;
      // ledgers path
      private String ledgersPath = null;
      // statsLogger
      private StatsLogger statsLogger = NullStatsLogger.INSTANCE;
      // client channel factory
      private EventLoopGroup eventLoopGroup = null;
      // request timer
      private HashedWheelTimer requestTimer = null;
      // feature provider
      private Optional<FeatureProvider> featureProvider = Optional.empty();
  
      // Cached BookKeeper Client
      private BookKeeperClient cachedClient = null;
  
      /**
       * Private bookkeeper builder.
       */
      private BookKeeperClientBuilder() {}
  
      /**
       * Set client name.
       *
       * @param name
       *          client name.
       * @return builder
       */
      public synchronized BookKeeperClientBuilder name(String name) {
          this.name = name;
          return this;
      }
  
      /**
       * <i>dlConfig</i> used to configure bookkeeper client.
       *
       * @param dlConfig
       *          distributedlog config.
       * @return builder.
       */
      public synchronized BookKeeperClientBuilder dlConfig(DistributedLogConfiguration dlConfig) {
          this.dlConfig = dlConfig;
          return this;
      }
  
      /**
       * Set the zkc used to build bookkeeper client. If a zookeeper client is provided in this
       * method, bookkeeper client will use it rather than creating a brand new one.
       *
       * @param zkc
       *          zookeeper client.
       * @return builder
       * @see #zkServers(String)
       */
      public synchronized BookKeeperClientBuilder zkc(ZooKeeperClient zkc) {
          this.zkc = zkc;
          return this;
      }
  
      /**
       * Set the zookeeper servers that bookkeeper client would connect to. If no zookeeper client
       * is provided by {@link #zkc(ZooKeeperClient)}, bookkeeper client will use the given string
       * to create a brand new zookeeper client.
       *
       * @param zkServers
       *          zookeeper servers that bookkeeper client would connect to.
       * @return builder
       * @see #zkc(ZooKeeperClient)
       */
      public synchronized BookKeeperClientBuilder zkServers(String zkServers) {
          this.zkServers = zkServers;
          return this;
      }
  
      /**
       * Set the ledgers path that bookkeeper client is going to access.
       *
       * @param ledgersPath
       *          ledgers path
       * @return builder
       * @see org.apache.bookkeeper.conf.ClientConfiguration#getZkLedgersRootPath()
       */
      public synchronized BookKeeperClientBuilder ledgersPath(String ledgersPath) {
          this.ledgersPath = ledgersPath;
          return this;
      }
  
      /**
       * Build BookKeeper client using existing <i>bkc</i> client.
       *
       * @param bkc
       *          bookkeeper client.
       * @return builder
       */
      public synchronized BookKeeperClientBuilder bkc(BookKeeperClient bkc) {
          this.cachedClient = bkc;
          return this;
      }
  
      /**
       * Build BookKeeper client using existing <i>channelFactory</i>.
       *
       * @param eventLoopGroup
       *          event loop group used to build bookkeeper client.
       * @return bookkeeper client builder.
       */
      public synchronized BookKeeperClientBuilder eventLoopGroup(EventLoopGroup eventLoopGroup) {
          this.eventLoopGroup = eventLoopGroup;
          return this;
      }
  
      /**
       * Build BookKeeper client using existing <i>request timer</i>.
       *
       * @param requestTimer
       *          HashedWheelTimer used to build bookkeeper client.
       * @return bookkeeper client builder.
       */
      public synchronized BookKeeperClientBuilder requestTimer(HashedWheelTimer requestTimer) {
          this.requestTimer = requestTimer;
          return this;
      }
  
      /**
       * Build BookKeeper Client using given stats logger <i>statsLogger</i>.
       *
       * @param statsLogger
       *          stats logger to report stats
       * @return builder.
       */
      public synchronized BookKeeperClientBuilder statsLogger(StatsLogger statsLogger) {
          this.statsLogger = statsLogger;
          return this;
      }
  
      public synchronized BookKeeperClientBuilder featureProvider(Optional<FeatureProvider> featureProvider) {
          this.featureProvider = featureProvider;
          return this;
      }
  
      private void validateParameters() {
          checkNotNull(name, "Missing client name.");
          checkNotNull(dlConfig, "Missing DistributedLog Configuration.");
          checkArgument(null == zkc || null == zkServers, "Missing zookeeper setting.");
          checkNotNull(ledgersPath, "Missing Ledgers Root Path.");
      }
  
      public synchronized BookKeeperClient build() {
          if (null == cachedClient) {
              cachedClient = buildClient();
          }
          return cachedClient;
      }
  
      private BookKeeperClient buildClient() {
          validateParameters();
          return new BookKeeperClient(
              dlConfig,
              name,
              zkServers,
              zkc,
              ledgersPath,
              eventLoopGroup,
              requestTimer,
              statsLogger,
              featureProvider);
      }
  }
  