Java tutorial
/** * Bespin: reference implementations of "big data" algorithms * * Licensed 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 ca.uwaterloo.cs.bigdata2017w.assignment4; import org.apache.commons.cli.*; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.conf.Configured; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.TextInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.SequenceFileOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; import tl.lin.data.array.ArrayListOfFloatsWritable; import tl.lin.data.array.ArrayListOfIntsWritable; import java.io.IOException; import java.util.Arrays; public class BuildPersonalizedPageRankRecords extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(BuildPersonalizedPageRankRecords.class); private static final String NODE_CNT_FIELD = "node.cnt"; private static final String SOURCES = "sources"; private static class MyMapper extends Mapper<LongWritable, Text, IntWritable, PageRankNode> { private static final IntWritable nid = new IntWritable(); private static final PageRankNode node = new PageRankNode(); private static String[] sources; @Override public void setup(Context context) { int n = context.getConfiguration().getInt(NODE_CNT_FIELD, 0); if (n == 0) { throw new RuntimeException(NODE_CNT_FIELD + " cannot be 0!"); } node.setType(PageRankNode.Type.Complete); sources = context.getConfiguration().getStrings(SOURCES); } @Override public void map(LongWritable key, Text t, Context context) throws IOException, InterruptedException { String[] arr = t.toString().trim().split("\\s+"); nid.set(Integer.parseInt(arr[0])); if (arr.length == 1) { node.setNodeId(Integer.parseInt(arr[0])); node.setAdjacencyList(new ArrayListOfIntsWritable()); } else { node.setNodeId(Integer.parseInt(arr[0])); int[] neighbors = new int[arr.length - 1]; for (int i = 1; i < arr.length; i++) { neighbors[i - 1] = Integer.parseInt(arr[i]); } node.setAdjacencyList(new ArrayListOfIntsWritable(neighbors)); } ArrayListOfFloatsWritable pageRanks = new ArrayListOfFloatsWritable(); for (int i = 0; i < sources.length; i++) { int source = Integer.parseInt(sources[i]); pageRanks.add(source == nid.get() ? 0f : Float.NEGATIVE_INFINITY); } node.setPageRanks(pageRanks); context.getCounter("graph", "numNodes").increment(1); context.getCounter("graph", "numEdges").increment(arr.length - 1); if (arr.length > 1) { context.getCounter("graph", "numActiveNodes").increment(1); } context.write(nid, node); } } public BuildPersonalizedPageRankRecords() { } private static final String INPUT = "input"; private static final String OUTPUT = "output"; private static final String NUM_NODES = "numNodes"; /** * Runs this tool. */ @SuppressWarnings({ "static-access" }) public int run(String[] args) throws Exception { Options options = new Options(); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("input path").create(INPUT)); options.addOption(OptionBuilder.withArgName("path").hasArg().withDescription("output path").create(OUTPUT)); options.addOption( OptionBuilder.withArgName("num").hasArg().withDescription("number of nodes").create(NUM_NODES)); options.addOption( OptionBuilder.withArgName("sources").hasArg().withDescription("source nodes").create(SOURCES)); CommandLine cmdline; CommandLineParser parser = new GnuParser(); try { cmdline = parser.parse(options, args); } catch (ParseException exp) { System.err.println("Error parsing command line: " + exp.getMessage()); return -1; } if (!cmdline.hasOption(INPUT) || !cmdline.hasOption(OUTPUT) || !cmdline.hasOption(NUM_NODES)) { System.out.println("args: " + Arrays.toString(args)); HelpFormatter formatter = new HelpFormatter(); formatter.setWidth(120); formatter.printHelp(this.getClass().getName(), options); ToolRunner.printGenericCommandUsage(System.out); return -1; } String inputPath = cmdline.getOptionValue(INPUT); String outputPath = cmdline.getOptionValue(OUTPUT); int n = Integer.parseInt(cmdline.getOptionValue(NUM_NODES)); String sourcesString = cmdline.getOptionValue(SOURCES); String[] sources = sourcesString.split(","); for (int i = 0; i < sources.length; i++) { sources[i] = sources[i].trim(); } LOG.info("Tool name: " + BuildPersonalizedPageRankRecords.class.getSimpleName()); LOG.info(" - inputDir: " + inputPath); LOG.info(" - outputDir: " + outputPath); LOG.info(" - numNodes: " + n); LOG.info(" - use sources: " + sourcesString); Configuration conf = getConf(); conf.setInt(NODE_CNT_FIELD, n); conf.setInt("mapred.min.split.size", 1024 * 1024 * 1024); conf.setStrings(SOURCES, sources); Job job = Job.getInstance(conf); job.setJobName(BuildPersonalizedPageRankRecords.class.getSimpleName() + ":" + inputPath); job.setJarByClass(BuildPersonalizedPageRankRecords.class); job.setNumReduceTasks(0); FileInputFormat.addInputPath(job, new Path(inputPath)); FileOutputFormat.setOutputPath(job, new Path(outputPath)); job.setInputFormatClass(TextInputFormat.class); job.setOutputFormatClass(SequenceFileOutputFormat.class); job.setMapOutputKeyClass(IntWritable.class); job.setMapOutputValueClass(PageRankNode.class); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(PageRankNode.class); job.setMapperClass(MyMapper.class); // Delete the output directory if it exists already. FileSystem.get(conf).delete(new Path(outputPath), true); job.waitForCompletion(true); return 0; } /** * Dispatches command-line arguments to the tool via the {@code ToolRunner}. */ public static void main(String[] args) throws Exception { ToolRunner.run(new BuildPersonalizedPageRankRecords(), args); } }