network/shuffle/BlockStoreClient.java

0001 /*
0002  * Licensed to the Apache Software Foundation (ASF) under one or more
0003  * contributor license agreements.  See the NOTICE file distributed with
0004  * this work for additional information regarding copyright ownership.
0005  * The ASF licenses this file to You under the Apache License, Version 2.0
0006  * (the "License"); you may not use this file except in compliance with
0007  * the License.  You may obtain a copy of the License at
0008  *
0009  *    http://www.apache.org/licenses/LICENSE-2.0
0010  *
0011  * Unless required by applicable law or agreed to in writing, software
0012  * distributed under the License is distributed on an "AS IS" BASIS,
0013  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0014  * See the License for the specific language governing permissions and
0015  * limitations under the License.
0016  */
0017
0018 package org.apache.spark.network.shuffle;
0019
0020 import java.io.Closeable;
0021 import java.util.Collections;
0022
0023 import com.codahale.metrics.MetricSet;
0024
0025 /**
0026  * Provides an interface for reading both shuffle files and RDD blocks, either from an Executor
0027  * or external service.
0028  */
0029 public abstract class BlockStoreClient implements Closeable {
0030
0031   /**
0032    * Fetch a sequence of blocks from a remote node asynchronously,
0033    *
0034    * Note that this API takes a sequence so the implementation can batch requests, and does not
0035    * return a future so the underlying implementation can invoke onBlockFetchSuccess as soon as
0036    * the data of a block is fetched, rather than waiting for all blocks to be fetched.
0037    *
0038    * @param host the host of the remote node.
0039    * @param port the port of the remote node.
0040    * @param execId the executor id.
0041    * @param blockIds block ids to fetch.
0042    * @param listener the listener to receive block fetching status.
0043    * @param downloadFileManager DownloadFileManager to create and clean temp files.
0044    *                        If it's not <code>null</code>, the remote blocks will be streamed
0045    *                        into temp shuffle files to reduce the memory usage, otherwise,
0046    *                        they will be kept in memory.
0047    */
0048   public abstract void fetchBlocks(
0049       String host,
0050       int port,
0051       String execId,
0052       String[] blockIds,
0053       BlockFetchingListener listener,
0054       DownloadFileManager downloadFileManager);
0055
0056   /**
0057    * Get the shuffle MetricsSet from BlockStoreClient, this will be used in MetricsSystem to
0058    * get the Shuffle related metrics.
0059    */
0060   public MetricSet shuffleMetrics() {
0061     // Return an empty MetricSet by default.
0062     return () -> Collections.emptyMap();
0063   }
0064 }