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.limiter;
  
  
  import com.google.common.base.Stopwatch;
  import com.google.common.collect.ImmutableList;
  import java.util.concurrent.TimeUnit;
  import org.apache.bookkeeper.stats.NullStatsLogger;
  import org.apache.bookkeeper.stats.OpStatsLogger;
  import org.apache.bookkeeper.stats.StatsLogger;
  import org.apache.distributedlog.exceptions.OverCapacityException;
  
  
  
  
  /**
   * Chain request limiters for easier management of multi limiter policy.
   */
  public class ChainedRequestLimiter<Request> implements RequestLimiter<Request> {
      private final ImmutableList<RequestLimiter<Request>> limiters;
      private final OpStatsLogger applyTime;
  
      /**
       * Builder to build ChainedRequestLimiter.
       */
      public static class Builder<Request> {
          private final ImmutableList.Builder<RequestLimiter<Request>> limitersBuilder;
          private StatsLogger statsLogger = NullStatsLogger.INSTANCE;
  
          public Builder() {
              this.limitersBuilder = new ImmutableList.Builder<RequestLimiter<Request>>();
          }
  
          public Builder<Request> addLimiter(RequestLimiter<Request> limiter) {
              this.limitersBuilder.add(limiter);
              return this;
          }
  
          public Builder<Request> statsLogger(StatsLogger statsLogger) {
              this.statsLogger = statsLogger;
              return this;
          }
  
          public ChainedRequestLimiter<Request> build() {
              return new ChainedRequestLimiter<Request>(limitersBuilder.build(), statsLogger);
          }
      }
  
      private ChainedRequestLimiter(ImmutableList<RequestLimiter<Request>> limiters,
                                    StatsLogger statsLogger) {
          this.limiters = limiters;
          this.applyTime = statsLogger.getOpStatsLogger("apply");
      }
  
      public void apply(Request request) throws OverCapacityException {
          Stopwatch stopwatch = Stopwatch.createStarted();
          try {
              for (RequestLimiter<Request> limiter : limiters) {
                  limiter.apply(request);
              }
          } finally {
              applyTime.registerSuccessfulEvent(stopwatch.elapsed(TimeUnit.MICROSECONDS), TimeUnit.MICROSECONDS);
          }
      }
  }
  