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.hadoop.mapred; import java.io.*; import java.util.*; import junit.framework.TestCase; import org.apache.commons.logging.*; import org.apache.hadoop.fs.*; import org.apache.hadoop.io.*; import org.apache.hadoop.io.compress.*; import org.apache.hadoop.util.LineReader; import org.apache.hadoop.util.ReflectionUtils; public class TestKeyValueTextInputFormat extends TestCase { private static final Log LOG = LogFactory.getLog(TestKeyValueTextInputFormat.class.getName()); private static int MAX_LENGTH = 10000; private static JobConf defaultConf = new JobConf(); private static FileSystem localFs = null; static { try { localFs = FileSystem.getLocal(defaultConf); } catch (IOException e) { throw new RuntimeException("init failure", e); } } private static Path workDir = new Path(new Path(System.getProperty("test.build.data", "."), "data"), "TestKeyValueTextInputFormat"); public void testFormat() throws Exception { JobConf job = new JobConf(); Path file = new Path(workDir, "test.txt"); // A reporter that does nothing Reporter reporter = Reporter.NULL; int seed = new Random().nextInt(); LOG.info("seed = " + seed); Random random = new Random(seed); localFs.delete(workDir, true); FileInputFormat.setInputPaths(job, workDir); // for a variety of lengths for (int length = 0; length < MAX_LENGTH; length += random.nextInt(MAX_LENGTH / 10) + 1) { LOG.debug("creating; entries = " + length); // create a file with length entries Writer writer = new OutputStreamWriter(localFs.create(file)); try { for (int i = 0; i < length; i++) { writer.write(Integer.toString(i * 2)); writer.write("\t"); writer.write(Integer.toString(i)); writer.write("\n"); } } finally { writer.close(); } // try splitting the file in a variety of sizes KeyValueTextInputFormat format = new KeyValueTextInputFormat(); format.configure(job); for (int i = 0; i < 3; i++) { int numSplits = random.nextInt(MAX_LENGTH / 20) + 1; LOG.debug("splitting: requesting = " + numSplits); InputSplit[] splits = format.getSplits(job, numSplits); LOG.debug("splitting: got = " + splits.length); // check each split BitSet bits = new BitSet(length); for (int j = 0; j < splits.length; j++) { LOG.debug("split[" + j + "]= " + splits[j]); RecordReader<Text, Text> reader = format.getRecordReader(splits[j], job, reporter); Class readerClass = reader.getClass(); assertEquals("reader class is KeyValueLineRecordReader.", KeyValueLineRecordReader.class, readerClass); Text key = reader.createKey(); Class keyClass = key.getClass(); Text value = reader.createValue(); Class valueClass = value.getClass(); assertEquals("Key class is Text.", Text.class, keyClass); assertEquals("Value class is Text.", Text.class, valueClass); try { int count = 0; while (reader.next(key, value)) { int v = Integer.parseInt(value.toString()); LOG.debug("read " + v); if (bits.get(v)) { LOG.warn("conflict with " + v + " in split " + j + " at position " + reader.getPos()); } assertFalse("Key in multiple partitions.", bits.get(v)); bits.set(v); count++; } LOG.debug("splits[" + j + "]=" + splits[j] + " count=" + count); } finally { reader.close(); } } assertEquals("Some keys in no partition.", length, bits.cardinality()); } } } private LineReader makeStream(String str) throws IOException { return new LineReader(new ByteArrayInputStream(str.getBytes("UTF-8")), defaultConf); } public void testUTF8() throws Exception { LineReader in = makeStream("abcd\u20acbdcd\u20ac"); Text line = new Text(); in.readLine(line); assertEquals("readLine changed utf8 characters", "abcd\u20acbdcd\u20ac", line.toString()); in = makeStream("abc\u200axyz"); in.readLine(line); assertEquals("split on fake newline", "abc\u200axyz", line.toString()); } public void testNewLines() throws Exception { LineReader in = makeStream("a\nbb\n\nccc\rdddd\r\neeeee"); Text out = new Text(); in.readLine(out); assertEquals("line1 length", 1, out.getLength()); in.readLine(out); assertEquals("line2 length", 2, out.getLength()); in.readLine(out); assertEquals("line3 length", 0, out.getLength()); in.readLine(out); assertEquals("line4 length", 3, out.getLength()); in.readLine(out); assertEquals("line5 length", 4, out.getLength()); in.readLine(out); assertEquals("line5 length", 5, out.getLength()); assertEquals("end of file", 0, in.readLine(out)); } private static void writeFile(FileSystem fs, Path name, CompressionCodec codec, String contents) throws IOException { OutputStream stm; if (codec == null) { stm = fs.create(name); } else { stm = codec.createOutputStream(fs.create(name)); } stm.write(contents.getBytes()); stm.close(); } private static final Reporter voidReporter = Reporter.NULL; private static List<Text> readSplit(KeyValueTextInputFormat format, InputSplit split, JobConf job) throws IOException { List<Text> result = new ArrayList<Text>(); RecordReader<Text, Text> reader = format.getRecordReader(split, job, voidReporter); Text key = reader.createKey(); Text value = reader.createValue(); while (reader.next(key, value)) { result.add(value); value = (Text) reader.createValue(); } return result; } /** * Test using the gzip codec for reading */ public static void testGzip() throws IOException { JobConf job = new JobConf(); CompressionCodec gzip = new GzipCodec(); ReflectionUtils.setConf(gzip, job); localFs.delete(workDir, true); writeFile(localFs, new Path(workDir, "part1.txt.gz"), gzip, "line-1\tthe quick\nline-2\tbrown\nline-3\tfox jumped\nline-4\tover\nline-5\t the lazy\nline-6\t dog\n"); writeFile(localFs, new Path(workDir, "part2.txt.gz"), gzip, "line-1\tthis is a test\nline-1\tof gzip\n"); FileInputFormat.setInputPaths(job, workDir); KeyValueTextInputFormat format = new KeyValueTextInputFormat(); format.configure(job); InputSplit[] splits = format.getSplits(job, 100); assertEquals("compressed splits == 2", 2, splits.length); FileSplit tmp = (FileSplit) splits[0]; if (tmp.getPath().getName().equals("part2.txt.gz")) { splits[0] = splits[1]; splits[1] = tmp; } List<Text> results = readSplit(format, splits[0], job); assertEquals("splits[0] length", 6, results.size()); assertEquals("splits[0][5]", " dog", results.get(5).toString()); results = readSplit(format, splits[1], job); assertEquals("splits[1] length", 2, results.size()); assertEquals("splits[1][0]", "this is a test", results.get(0).toString()); assertEquals("splits[1][1]", "of gzip", results.get(1).toString()); } public static void main(String[] args) throws Exception { new TestKeyValueTextInputFormat().testFormat(); } }