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.spark.network.shuffle;
  
  import java.io.Closeable;
  
  /** Provides an interface for reading shuffle files, either from an Executor or external service. */
  public abstract class ShuffleClient implements Closeable {
  
    /**
     * Initializes the ShuffleClient, specifying this Executor's appId.
     * Must be called before any other method on the ShuffleClient.
     */
    public void init(String appId) { }
  
    /**
     * Fetch a sequence of blocks from a remote node asynchronously,
     *
     * Note that this API takes a sequence so the implementation can batch requests, and does not
     * return a future so the underlying implementation can invoke onBlockFetchSuccess as soon as
     * the data of a block is fetched, rather than waiting for all blocks to be fetched.
     */
    public abstract void fetchBlocks(
        String host,
        int port,
        String execId,
        String[] blockIds,
        BlockFetchingListener listener);
  }
  