Java tutorial
/** * 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.sqoop.connector.hdfs; import java.io.IOException; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.fs.BlockLocation; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.compress.CompressionCodec; import org.apache.hadoop.io.compress.CompressionCodecFactory; import org.apache.hadoop.net.NetworkTopology; import org.apache.hadoop.net.NodeBase; import org.apache.sqoop.common.PrefixContext; import org.apache.sqoop.common.SqoopException; import org.apache.sqoop.connector.hdfs.configuration.FromJobConfiguration; import org.apache.sqoop.connector.hdfs.configuration.LinkConfiguration; import org.apache.sqoop.job.etl.Partition; import org.apache.sqoop.job.etl.Partitioner; import org.apache.sqoop.job.etl.PartitionerContext; /** * This class derives mostly from CombineFileInputFormat of Hadoop, i.e. * org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat. */ public class HdfsPartitioner extends Partitioner<LinkConfiguration, FromJobConfiguration> { public static final String SPLIT_MINSIZE_PERNODE = "mapreduce.input.fileinputformat.split.minsize.per.node"; public static final String SPLIT_MINSIZE_PERRACK = "mapreduce.input.fileinputformat.split.minsize.per.rack"; // ability to limit the size of a single split private long maxSplitSize = 0; private long minSplitSizeNode = 0; private long minSplitSizeRack = 0; // mapping from a rack name to the set of Nodes in the rack private HashMap<String, Set<String>> rackToNodes = new HashMap<String, Set<String>>(); @Override public List<Partition> getPartitions(PartitionerContext context, LinkConfiguration linkConfiguration, FromJobConfiguration fromJobConfig) { Configuration conf = HdfsUtils.configureURI(((PrefixContext) context.getContext()).getConfiguration(), linkConfiguration); try { long numInputBytes = getInputSize(conf, fromJobConfig.fromJobConfig.inputDirectory); maxSplitSize = numInputBytes / context.getMaxPartitions(); if (numInputBytes % context.getMaxPartitions() != 0) { maxSplitSize += 1; } long minSizeNode = 0; long minSizeRack = 0; long maxSize = 0; // the values specified by setxxxSplitSize() takes precedence over the // values that might have been specified in the config if (minSplitSizeNode != 0) { minSizeNode = minSplitSizeNode; } else { minSizeNode = conf.getLong(SPLIT_MINSIZE_PERNODE, 0); } if (minSplitSizeRack != 0) { minSizeRack = minSplitSizeRack; } else { minSizeRack = conf.getLong(SPLIT_MINSIZE_PERRACK, 0); } if (maxSplitSize != 0) { maxSize = maxSplitSize; } else { maxSize = conf.getLong("mapreduce.input.fileinputformat.split.maxsize", 0); } if (minSizeNode != 0 && maxSize != 0 && minSizeNode > maxSize) { throw new IOException("Minimum split size pernode " + minSizeNode + " cannot be larger than maximum split size " + maxSize); } if (minSizeRack != 0 && maxSize != 0 && minSizeRack > maxSize) { throw new IOException("Minimum split size per rack" + minSizeRack + " cannot be larger than maximum split size " + maxSize); } if (minSizeRack != 0 && minSizeNode > minSizeRack) { throw new IOException("Minimum split size per node" + minSizeNode + " cannot be smaller than minimum split " + "size per rack " + minSizeRack); } // all the files in input set String indir = fromJobConfig.fromJobConfig.inputDirectory; FileSystem fs = FileSystem.get(conf); List<Path> paths = new LinkedList<Path>(); for (FileStatus status : fs.listStatus(new Path(indir))) { if (!status.isDir()) { paths.add(status.getPath()); } } List<Partition> partitions = new ArrayList<Partition>(); if (paths.size() == 0) { return partitions; } // create splits for all files that are not in any pool. getMoreSplits(conf, paths, maxSize, minSizeNode, minSizeRack, partitions); // free up rackToNodes map rackToNodes.clear(); return partitions; } catch (IOException e) { throw new SqoopException(HdfsConnectorError.GENERIC_HDFS_CONNECTOR_0000, e); } } //TODO: Perhaps get the FS from link configuration so we can support remote HDFS private long getInputSize(Configuration conf, String indir) throws IOException { FileSystem fs = FileSystem.get(conf); FileStatus[] files = fs.listStatus(new Path(indir)); long count = 0; for (FileStatus file : files) { count += file.getLen(); } return count; } /** * Return all the splits in the specified set of paths */ private void getMoreSplits(Configuration conf, List<Path> paths, long maxSize, long minSizeNode, long minSizeRack, List<Partition> partitions) throws IOException { // all blocks for all the files in input set OneFileInfo[] files; // mapping from a rack name to the list of blocks it has HashMap<String, List<OneBlockInfo>> rackToBlocks = new HashMap<String, List<OneBlockInfo>>(); // mapping from a block to the nodes on which it has replicas HashMap<OneBlockInfo, String[]> blockToNodes = new HashMap<OneBlockInfo, String[]>(); // mapping from a node to the list of blocks that it contains HashMap<String, List<OneBlockInfo>> nodeToBlocks = new HashMap<String, List<OneBlockInfo>>(); files = new OneFileInfo[paths.size()]; if (paths.size() == 0) { return; } // populate all the blocks for all files for (int i = 0; i < paths.size(); i++) { files[i] = new OneFileInfo(paths.get(i), conf, isSplitable(conf, paths.get(i)), rackToBlocks, blockToNodes, nodeToBlocks, rackToNodes, maxSize); } ArrayList<OneBlockInfo> validBlocks = new ArrayList<OneBlockInfo>(); Set<String> nodes = new HashSet<String>(); long curSplitSize = 0; // process all nodes and create splits that are local // to a node. for (Iterator<Map.Entry<String, List<OneBlockInfo>>> iter = nodeToBlocks.entrySet().iterator(); iter .hasNext();) { Map.Entry<String, List<OneBlockInfo>> one = iter.next(); nodes.add(one.getKey()); List<OneBlockInfo> blocksInNode = one.getValue(); // for each block, copy it into validBlocks. Delete it from // blockToNodes so that the same block does not appear in // two different splits. for (OneBlockInfo oneblock : blocksInNode) { if (blockToNodes.containsKey(oneblock)) { validBlocks.add(oneblock); blockToNodes.remove(oneblock); curSplitSize += oneblock.length; // if the accumulated split size exceeds the maximum, then // create this split. if (maxSize != 0 && curSplitSize >= maxSize) { // create an input split and add it to the splits array addCreatedSplit(partitions, nodes, validBlocks); curSplitSize = 0; validBlocks.clear(); } } } // if there were any blocks left over and their combined size is // larger than minSplitNode, then combine them into one split. // Otherwise add them back to the unprocessed pool. It is likely // that they will be combined with other blocks from the // same rack later on. if (minSizeNode != 0 && curSplitSize >= minSizeNode) { // create an input split and add it to the splits array addCreatedSplit(partitions, nodes, validBlocks); } else { for (OneBlockInfo oneblock : validBlocks) { blockToNodes.put(oneblock, oneblock.hosts); } } validBlocks.clear(); nodes.clear(); curSplitSize = 0; } // if blocks in a rack are below the specified minimum size, then keep them // in 'overflow'. After the processing of all racks is complete, these // overflow blocks will be combined into splits. ArrayList<OneBlockInfo> overflowBlocks = new ArrayList<OneBlockInfo>(); Set<String> racks = new HashSet<String>(); // Process all racks over and over again until there is no more work to do. while (blockToNodes.size() > 0) { // Create one split for this rack before moving over to the next rack. // Come back to this rack after creating a single split for each of the // remaining racks. // Process one rack location at a time, Combine all possible blocks that // reside on this rack as one split. (constrained by minimum and maximum // split size). // iterate over all racks for (Iterator<Map.Entry<String, List<OneBlockInfo>>> iter = rackToBlocks.entrySet().iterator(); iter .hasNext();) { Map.Entry<String, List<OneBlockInfo>> one = iter.next(); racks.add(one.getKey()); List<OneBlockInfo> blocks = one.getValue(); // for each block, copy it into validBlocks. Delete it from // blockToNodes so that the same block does not appear in // two different splits. boolean createdSplit = false; for (OneBlockInfo oneblock : blocks) { if (blockToNodes.containsKey(oneblock)) { validBlocks.add(oneblock); blockToNodes.remove(oneblock); curSplitSize += oneblock.length; // if the accumulated split size exceeds the maximum, then // create this split. if (maxSize != 0 && curSplitSize >= maxSize) { // create an input split and add it to the splits array addCreatedSplit(partitions, getHosts(racks), validBlocks); createdSplit = true; break; } } } // if we created a split, then just go to the next rack if (createdSplit) { curSplitSize = 0; validBlocks.clear(); racks.clear(); continue; } if (!validBlocks.isEmpty()) { if (minSizeRack != 0 && curSplitSize >= minSizeRack) { // if there is a minimum size specified, then create a single split // otherwise, store these blocks into overflow data structure addCreatedSplit(partitions, getHosts(racks), validBlocks); } else { // There were a few blocks in this rack that // remained to be processed. Keep them in 'overflow' block list. // These will be combined later. overflowBlocks.addAll(validBlocks); } } curSplitSize = 0; validBlocks.clear(); racks.clear(); } } assert blockToNodes.isEmpty(); assert curSplitSize == 0; assert validBlocks.isEmpty(); assert racks.isEmpty(); // Process all overflow blocks for (OneBlockInfo oneblock : overflowBlocks) { validBlocks.add(oneblock); curSplitSize += oneblock.length; // This might cause an exiting rack location to be re-added, // but it should be ok. for (int i = 0; i < oneblock.racks.length; i++) { racks.add(oneblock.racks[i]); } // if the accumulated split size exceeds the maximum, then // create this split. if (maxSize != 0 && curSplitSize >= maxSize) { // create an input split and add it to the splits array addCreatedSplit(partitions, getHosts(racks), validBlocks); curSplitSize = 0; validBlocks.clear(); racks.clear(); } } // Process any remaining blocks, if any. if (!validBlocks.isEmpty()) { addCreatedSplit(partitions, getHosts(racks), validBlocks); } } private boolean isSplitable(Configuration conf, Path file) { final CompressionCodec codec = new CompressionCodecFactory(conf).getCodec(file); // This method might be improved for SplittableCompression codec when we // drop support for Hadoop 1.0 return null == codec; } /** * Create a single split from the list of blocks specified in validBlocks * Add this new split into list. */ private void addCreatedSplit(List<Partition> partitions, Collection<String> locations, ArrayList<OneBlockInfo> validBlocks) { // create an input split Path[] files = new Path[validBlocks.size()]; long[] offsets = new long[validBlocks.size()]; long[] lengths = new long[validBlocks.size()]; for (int i = 0; i < validBlocks.size(); i++) { files[i] = validBlocks.get(i).onepath; offsets[i] = validBlocks.get(i).offset; lengths[i] = validBlocks.get(i).length; } // add this split to the list that is returned HdfsPartition partition = new HdfsPartition(files, offsets, lengths, locations.toArray(new String[0])); partitions.add(partition); } private Set<String> getHosts(Set<String> racks) { Set<String> hosts = new HashSet<String>(); for (String rack : racks) { if (rackToNodes.containsKey(rack)) { hosts.addAll(rackToNodes.get(rack)); } } return hosts; } private static void addHostToRack(HashMap<String, Set<String>> rackToNodes, String rack, String host) { Set<String> hosts = rackToNodes.get(rack); if (hosts == null) { hosts = new HashSet<String>(); rackToNodes.put(rack, hosts); } hosts.add(host); } /** * information about one file from the File System */ private static class OneFileInfo { private long fileSize; // size of the file private OneBlockInfo[] blocks; // all blocks in this file OneFileInfo(Path path, Configuration conf, boolean isSplitable, HashMap<String, List<OneBlockInfo>> rackToBlocks, HashMap<OneBlockInfo, String[]> blockToNodes, HashMap<String, List<OneBlockInfo>> nodeToBlocks, HashMap<String, Set<String>> rackToNodes, long maxSize) throws IOException { this.fileSize = 0; // get block locations from file system FileSystem fs = path.getFileSystem(conf); FileStatus stat = fs.getFileStatus(path); BlockLocation[] locations = fs.getFileBlockLocations(stat, 0, stat.getLen()); // create a list of all block and their locations if (locations == null) { blocks = new OneBlockInfo[0]; } else { if (!isSplitable) { // if the file is not splitable, just create the one block with // full file length blocks = new OneBlockInfo[1]; fileSize = stat.getLen(); blocks[0] = new OneBlockInfo(path, 0, fileSize, locations[0].getHosts(), locations[0].getTopologyPaths()); } else { ArrayList<OneBlockInfo> blocksList = new ArrayList<OneBlockInfo>(locations.length); for (int i = 0; i < locations.length; i++) { fileSize += locations[i].getLength(); // each split can be a maximum of maxSize long left = locations[i].getLength(); long myOffset = locations[i].getOffset(); long myLength = 0; do { if (maxSize == 0) { myLength = left; } else { if (left > maxSize && left < 2 * maxSize) { // if remainder is between max and 2*max - then // instead of creating splits of size max, left-max we // create splits of size left/2 and left/2. This is // a heuristic to avoid creating really really small // splits. myLength = left / 2; } else { myLength = Math.min(maxSize, left); } } OneBlockInfo oneblock = new OneBlockInfo(path, myOffset, myLength, locations[i].getHosts(), locations[i].getTopologyPaths()); left -= myLength; myOffset += myLength; blocksList.add(oneblock); } while (left > 0); } blocks = blocksList.toArray(new OneBlockInfo[blocksList.size()]); } for (OneBlockInfo oneblock : blocks) { // add this block to the block --> node locations map blockToNodes.put(oneblock, oneblock.hosts); // For blocks that do not have host/rack information, // assign to default rack. String[] racks = null; if (oneblock.hosts.length == 0) { racks = new String[] { NetworkTopology.DEFAULT_RACK }; } else { racks = oneblock.racks; } // add this block to the rack --> block map for (int j = 0; j < racks.length; j++) { String rack = racks[j]; List<OneBlockInfo> blklist = rackToBlocks.get(rack); if (blklist == null) { blklist = new ArrayList<OneBlockInfo>(); rackToBlocks.put(rack, blklist); } blklist.add(oneblock); if (!racks[j].equals(NetworkTopology.DEFAULT_RACK)) { // Add this host to rackToNodes map addHostToRack(rackToNodes, racks[j], oneblock.hosts[j]); } } // add this block to the node --> block map for (int j = 0; j < oneblock.hosts.length; j++) { String node = oneblock.hosts[j]; List<OneBlockInfo> blklist = nodeToBlocks.get(node); if (blklist == null) { blklist = new ArrayList<OneBlockInfo>(); nodeToBlocks.put(node, blklist); } blklist.add(oneblock); } } } } } /** * information about one block from the File System */ private static class OneBlockInfo { Path onepath; // name of this file long offset; // offset in file long length; // length of this block String[] hosts; // nodes on which this block resides String[] racks; // network topology of hosts OneBlockInfo(Path path, long offset, long len, String[] hosts, String[] topologyPaths) { this.onepath = path; this.offset = offset; this.hosts = hosts; this.length = len; assert (hosts.length == topologyPaths.length || topologyPaths.length == 0); // if the file system does not have any rack information, then // use dummy rack location. if (topologyPaths.length == 0) { topologyPaths = new String[hosts.length]; for (int i = 0; i < topologyPaths.length; i++) { topologyPaths[i] = (new NodeBase(hosts[i], NetworkTopology.DEFAULT_RACK)).toString(); } } // The topology paths have the host name included as the last // component. Strip it. this.racks = new String[topologyPaths.length]; for (int i = 0; i < topologyPaths.length; i++) { this.racks[i] = (new NodeBase(topologyPaths[i])).getNetworkLocation(); } } } }