/**
    * 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.hadoop.hbase.client;
  
  import org.apache.hadoop.hbase.HRegionLocation;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  
  import java.io.IOException;
  
  /**
   * An {@link RpcRetryingCaller} that will update the per-region stats for the call on return,
   * if stats are available
   */
  @InterfaceAudience.Private
  public class StatsTrackingRpcRetryingCaller<T> extends RpcRetryingCaller<T> {
    private final ServerStatisticTracker stats;
  
    public StatsTrackingRpcRetryingCaller(long pause, int retries, int startLogErrorsCnt,
        ServerStatisticTracker stats) {
      super(pause, retries, startLogErrorsCnt);
      this.stats = stats;
    }
  
    public StatsTrackingRpcRetryingCaller(long pause, int retries,
        RetryingCallerInterceptor interceptor, int startLogErrorsCnt,
        ServerStatisticTracker stats) {
      super(pause, retries, interceptor, startLogErrorsCnt, 0);
      this.stats = stats;
    }
  
    @Override
    public T callWithRetries(RetryingCallable<T> callable, int callTimeout)
        throws IOException, RuntimeException {
      T result = super.callWithRetries(callable, callTimeout);
      return updateStatsAndUnwrap(result, callable);
    }
  
    @Override
    public T callWithoutRetries(RetryingCallable<T> callable, int callTimeout)
        throws IOException, RuntimeException {
      T result = super.callWithRetries(callable, callTimeout);
      return updateStatsAndUnwrap(result, callable);
    }
  
    private T updateStatsAndUnwrap(T result, RetryingCallable<T> callable) {
      // don't track stats about requests that aren't to regionservers
      if (!(callable instanceof RegionServerCallable)) {
        return result;
      }
  
      // mutli-server callables span multiple regions, so they don't have a location,
      // but they are region server callables, so we have to handle them when we process the
      // result in AsyncProcess#receiveMultiAction, not in here
      if (callable instanceof MultiServerCallable) {
        return result;
      }
  
      // update the stats for the single server callable
      RegionServerCallable<T> regionCallable = (RegionServerCallable) callable;
      HRegionLocation location = regionCallable.getLocation();
      return ResultStatsUtil.updateStats(result, stats, location);
    }
  }