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.JBizz; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.DataInputStream; import java.io.InputStream; import java.io.ByteArrayInputStream; import java.util.Arrays; import java.util.Set; import java.util.Stack; import java.util.TreeSet; 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.FSDataInputStream; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.MapFile; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.BytesWritable; import org.apache.hadoop.io.WritableUtils; import org.apache.hadoop.util.Tool; import org.apache.hadoop.util.ToolRunner; import tl.lin.data.array.ArrayListWritable; import tl.lin.data.pair.PairOfInts; import tl.lin.data.pair.PairOfWritables; public class BooleanRetrievalCompressed extends Configured implements Tool { private MapFile.Reader index; private FSDataInputStream collection; private Stack<Set<Integer>> stack; private BooleanRetrievalCompressed() { } private void initialize(String indexPath, String collectionPath, FileSystem fs) throws IOException { index = new MapFile.Reader(new Path(indexPath + "/part-r-00000"), fs.getConf()); collection = fs.open(new Path(collectionPath)); stack = new Stack<Set<Integer>>(); } private void runQuery(String q) throws IOException { String[] terms = q.split("\\s+"); for (String t : terms) { if (t.equals("AND")) { performAND(); } else if (t.equals("OR")) { performOR(); } else { pushTerm(t); } } Set<Integer> set = stack.pop(); for (Integer i : set) { String line = fetchLine(i); line = line.substring(0, Math.min(line.length(), 80)); System.out.println(i + "\t" + line); } } private void pushTerm(String term) throws IOException { stack.push(fetchDocumentSet(term)); } private void performAND() { Set<Integer> s1 = stack.pop(); Set<Integer> s2 = stack.pop(); Set<Integer> sn = new TreeSet<Integer>(); for (int n : s1) { if (s2.contains(n)) { sn.add(n); } } stack.push(sn); } private void performOR() { Set<Integer> s1 = stack.pop(); Set<Integer> s2 = stack.pop(); Set<Integer> sn = new TreeSet<Integer>(); for (int n : s1) { sn.add(n); } for (int n : s2) { sn.add(n); } stack.push(sn); } private Set<Integer> fetchDocumentSet(String term) throws IOException { Set<Integer> set = new TreeSet<Integer>(); for (PairOfInts pair : fetchPostings(term)) { set.add(pair.getLeftElement()); } return set; } private ArrayListWritable<PairOfInts> fetchPostings(String term) throws IOException { Text key = new Text(); //PairOfWritables<IntWritable, ArrayListWritable<PairOfInts>> value = //new PairOfWritables<IntWritable, ArrayListWritable<PairOfInts>>(); ArrayListWritable<PairOfInts> poi = new ArrayListWritable<PairOfInts>(); BytesWritable value = new BytesWritable(); PairOfInts pair = new PairOfInts(); key.set(term); index.get(key, value); byte[] vals = value.getBytes(); DataInputStream dis = new DataInputStream(new ByteArrayInputStream(vals)); int j = 0; int i = 0; int sentinel = 0; while (sentinel == 0) { j = WritableUtils.readVInt(dis); i = WritableUtils.readVInt(dis); if (i == 0 || j == 0) { sentinel = 1; } else { pair.set(j, i); poi.add(new PairOfInts(j, i)); } } return poi; } private String fetchLine(long offset) throws IOException { collection.seek(offset); BufferedReader reader = new BufferedReader(new InputStreamReader(collection)); return reader.readLine(); } private static final String INDEX = "index"; private static final String COLLECTION = "collection"; /** * 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(INDEX)); options.addOption( OptionBuilder.withArgName("path").hasArg().withDescription("output path").create(COLLECTION)); CommandLine cmdline = null; CommandLineParser parser = new GnuParser(); try { cmdline = parser.parse(options, args); } catch (ParseException exp) { System.err.println("Error parsing command line: " + exp.getMessage()); System.exit(-1); } if (!cmdline.hasOption(INDEX) || !cmdline.hasOption(COLLECTION)) { System.out.println("args: " + Arrays.toString(args)); HelpFormatter formatter = new HelpFormatter(); formatter.setWidth(120); formatter.printHelp(LookupPostings.class.getName(), options); ToolRunner.printGenericCommandUsage(System.out); System.exit(-1); } String indexPath = cmdline.getOptionValue(INDEX); String collectionPath = cmdline.getOptionValue(COLLECTION); if (collectionPath.endsWith(".gz")) { System.out.println("gzipped collection is not seekable: use compressed version!"); System.exit(-1); } FileSystem fs = FileSystem.get(new Configuration()); initialize(indexPath, collectionPath, fs); String[] queries = { "outrageous fortune AND", "white rose AND", "means deceit AND", "white red OR rose AND pluck AND", "unhappy outrageous OR good your AND OR fortune AND" }; for (String q : queries) { System.out.println("Query: " + q); runQuery(q); System.out.println(""); } return 1; } /** * Dispatches command-line arguments to the tool via the {@code ToolRunner}. */ public static void main(String[] args) throws Exception { ToolRunner.run(new BooleanRetrievalCompressed(), args); } }