Java tutorial
/* * Cloud9: A Hadoop toolkit for working with big data * * 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 edu.umd.honghongie; import java.io.IOException; import java.util.Arrays; import java.util.Iterator; import org.apache.commons.cli.CommandLine; import org.apache.commons.cli.CommandLineParser; import org.apache.commons.cli.GnuParser; import org.apache.commons.cli.HelpFormatter; import org.apache.commons.cli.OptionBuilder; import org.apache.commons.cli.Options; import org.apache.commons.cli.ParseException; 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.FloatWritable; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.mapreduce.Job; import org.apache.hadoop.mapreduce.Mapper; import org.apache.hadoop.mapreduce.Reducer; import org.apache.hadoop.mapreduce.lib.input.FileInputFormat; import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat; import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat; import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import org.apache.log4j.Logger; import tl.lin.data.pair.PairOfObjectFloat; import tl.lin.data.queue.TopScoredObjects; import tl.lin.data.array.ArrayListOfInts; import tl.lin.data.array.ArrayListOfFloatsWritable; public class ExtractTopPersonalizedPageRankNodes extends Configured implements Tool { private static final Logger LOG = Logger.getLogger(ExtractTopPersonalizedPageRankNodes.class); private static class MyMapper extends Mapper<IntWritable, PageRankNode, IntWritable, FloatWritable> { private TopScoredObjects<Integer> queue; private int times; @Override public void setup(Context context) throws IOException { int k = context.getConfiguration().getInt("n", 100); times = context.getConfiguration().getInt("times", 0); //**** queue = new TopScoredObjects<Integer>(k); } @Override public void map(IntWritable nid, PageRankNode node, Context context) throws IOException, InterruptedException { ArrayListOfFloatsWritable pagerankvalues = node.getPageRank(); queue.add(node.getNodeId(), pagerankvalues.get(times)); } @Override public void cleanup(Context context) throws IOException, InterruptedException { IntWritable key = new IntWritable(); FloatWritable value = new FloatWritable(); for (PairOfObjectFloat<Integer> pair : queue.extractAll()) { key.set(pair.getLeftElement()); value.set(pair.getRightElement()); context.write(key, value); } } } private static class MyReducer extends Reducer<IntWritable, FloatWritable, IntWritable, FloatWritable> { private static TopScoredObjects<Integer> queue; private int sourceid; //*** @Override public void setup(Context context) throws IOException { int k = context.getConfiguration().getInt("n", 100); queue = new TopScoredObjects<Integer>(k); sourceid = context.getConfiguration().getInt("source", 0); //*** } @Override public void reduce(IntWritable nid, Iterable<FloatWritable> iterable, Context context) throws IOException { Iterator<FloatWritable> iter = iterable.iterator(); float pagerank = (float) StrictMath.exp(iter.next().get()); // transform to normal pagerank value queue.add(nid.get(), pagerank); // Shouldn't happen. Throw an exception. if (iter.hasNext()) { throw new RuntimeException(); } } @Override public void cleanup(Context context) throws IOException, InterruptedException { IntWritable key = new IntWritable(); FloatWritable value = new FloatWritable(); System.out.println("Source: " + sourceid); for (PairOfObjectFloat<Integer> pair : queue.extractAll()) { key.set(pair.getLeftElement()); value.set(pair.getRightElement()); context.write(key, value); float pagerank = pair.getRightElement(); int thenodeid = pair.getLeftElement(); String ss = String.format("%.5f %d", pagerank, thenodeid); System.out.println(ss); } } } public ExtractTopPersonalizedPageRankNodes() { } private static final String INPUT = "input"; private static final String OUTPUT = "output"; private static final String TOP = "top"; private static final String SOURCE = "sources"; /** * 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("top n").create(TOP)); //****** options.addOption( OptionBuilder.withArgName("node").hasArg().withDescription("source nodes").create(SOURCE)); 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(TOP) || !cmdline.hasOption(SOURCE)) //source node { 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 = "TestOutput"; //*********???? int n = Integer.parseInt(cmdline.getOptionValue(TOP)); //******* String nodeid = cmdline.getOptionValue(SOURCE); ArrayListOfInts sourceids = new ArrayListOfInts(); String ss[] = nodeid.split(","); for (int i = 0; i < ss.length; i++) { sourceids.add(Integer.parseInt(ss[i])); } LOG.info("Tool name: " + ExtractTopPersonalizedPageRankNodes.class.getSimpleName()); LOG.info(" - input: " + inputPath); LOG.info(" - output: " + outputPath); LOG.info(" - top: " + n); LOG.info(" - source node: " + nodeid); for (int i = 0; i < sourceids.size(); i++) { int source = sourceids.get(i); iterateSort(i, source, n, inputPath, outputPath); //times, sourcenode, top n } return 0; } //run each iteration private void iterateSort(int i, int source, int n, String input, String output) throws Exception { Configuration conf = getConf(); conf.setInt("mapred.min.split.size", 1024 * 1024 * 1024); conf.setInt("n", n); conf.setInt("times", i); conf.setInt("source", source); Job job = Job.getInstance(conf); job.setJobName(ExtractTopPersonalizedPageRankNodes.class.getName() + ":" + input); job.setJarByClass(ExtractTopPersonalizedPageRankNodes.class); job.setNumReduceTasks(1); FileInputFormat.addInputPath(job, new Path(input)); FileOutputFormat.setOutputPath(job, new Path(output + Integer.toString(i))); job.setInputFormatClass(SequenceFileInputFormat.class); job.setOutputFormatClass(TextOutputFormat.class); job.setMapOutputKeyClass(IntWritable.class); job.setMapOutputValueClass(FloatWritable.class); job.setOutputKeyClass(IntWritable.class); job.setOutputValueClass(FloatWritable.class); job.setMapperClass(MyMapper.class); job.setReducerClass(MyReducer.class); // Delete the output directory if it exists already. FileSystem.get(conf).delete(new Path(output + Integer.toString(i)), true); long startTime = System.currentTimeMillis(); job.waitForCompletion(true); System.out.println("Job Finished in " + (System.currentTimeMillis() - startTime) / 1000.0 + " seconds"); } /** * Dispatches command-line arguments to the tool via the {@code ToolRunner}. */ public static void main(String[] args) throws Exception { int res = ToolRunner.run(new ExtractTopPersonalizedPageRankNodes(), args); System.exit(res); } }