| /** |
| * 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.mapreduce.lib.output; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.mapreduce.*; |
| import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl; |
| import org.apache.hadoop.util.ReflectionUtils; |
| |
| import java.io.IOException; |
| import java.util.*; |
| |
| /** |
| * The MultipleOutputs class simplifies writing output data |
| * to multiple outputs |
| * |
| * <p> |
| * Case one: writing to additional outputs other than the job default output. |
| * |
| * Each additional output, or named output, may be configured with its own |
| * <code>OutputFormat</code>, with its own key class and with its own value |
| * class. |
| * |
| * <p> |
| * Case two: to write data to different files provided by user |
| * </p> |
| * |
| * <p> |
| * MultipleOutputs supports counters, by default they are disabled. The |
| * counters group is the {@link MultipleOutputs} class name. The names of the |
| * counters are the same as the output name. These count the number records |
| * written to each output name. |
| * </p> |
| * |
| * Usage pattern for job submission: |
| * <pre> |
| * |
| * Job job = new Job(); |
| * |
| * FileInputFormat.setInputPath(job, inDir); |
| * FileOutputFormat.setOutputPath(job, outDir); |
| * |
| * job.setMapperClass(MOMap.class); |
| * job.setReducerClass(MOReduce.class); |
| * ... |
| * |
| * // Defines additional single text based output 'text' for the job |
| * MultipleOutputs.addNamedOutput(job, "text", TextOutputFormat.class, |
| * LongWritable.class, Text.class); |
| * |
| * // Defines additional sequence-file based output 'sequence' for the job |
| * MultipleOutputs.addNamedOutput(job, "seq", |
| * SequenceFileOutputFormat.class, |
| * LongWritable.class, Text.class); |
| * ... |
| * |
| * job.waitForCompletion(true); |
| * ... |
| * </pre> |
| * <p> |
| * Usage in Reducer: |
| * <pre> |
| * <K, V> String generateFileName(K k, V v) { |
| * return k.toString() + "_" + v.toString(); |
| * } |
| * |
| * public class MOReduce extends |
| * Reducer<WritableComparable, Writable,WritableComparable, Writable> { |
| * private MultipleOutputs mos; |
| * public void setup(Context context) { |
| * ... |
| * mos = new MultipleOutputs(context); |
| * } |
| * |
| * public void reduce(WritableComparable key, Iterator<Writable> values, |
| * Context context) |
| * throws IOException { |
| * ... |
| * mos.write("text", , key, new Text("Hello")); |
| * mos.write("seq", LongWritable(1), new Text("Bye"), "seq_a"); |
| * mos.write("seq", LongWritable(2), key, new Text("Chau"), "seq_b"); |
| * mos.write(key, new Text("value"), generateFileName(key, new Text("value"))); |
| * ... |
| * } |
| * |
| * public void cleanup(Context) throws IOException { |
| * mos.close(); |
| * ... |
| * } |
| * |
| * } |
| * </pre> |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public class MultipleOutputs<KEYOUT, VALUEOUT> { |
| |
| private static final String MULTIPLE_OUTPUTS = "mapreduce.multipleoutputs"; |
| |
| private static final String MO_PREFIX = |
| "mapreduce.multipleoutputs.namedOutput."; |
| |
| private static final String FORMAT = ".format"; |
| private static final String KEY = ".key"; |
| private static final String VALUE = ".value"; |
| private static final String COUNTERS_ENABLED = |
| "mapreduce.multipleoutputs.counters"; |
| |
| /** |
| * Counters group used by the counters of MultipleOutputs. |
| */ |
| private static final String COUNTERS_GROUP = MultipleOutputs.class.getName(); |
| |
| /** |
| * Cache for the taskContexts |
| */ |
| private Map<String, TaskAttemptContext> taskContexts = new HashMap<String, TaskAttemptContext>(); |
| |
| /** |
| * Checks if a named output name is valid token. |
| * |
| * @param namedOutput named output Name |
| * @throws IllegalArgumentException if the output name is not valid. |
| */ |
| private static void checkTokenName(String namedOutput) { |
| if (namedOutput == null || namedOutput.length() == 0) { |
| throw new IllegalArgumentException( |
| "Name cannot be NULL or emtpy"); |
| } |
| for (char ch : namedOutput.toCharArray()) { |
| if ((ch >= 'A') && (ch <= 'Z')) { |
| continue; |
| } |
| if ((ch >= 'a') && (ch <= 'z')) { |
| continue; |
| } |
| if ((ch >= '0') && (ch <= '9')) { |
| continue; |
| } |
| throw new IllegalArgumentException( |
| "Name cannot be have a '" + ch + "' char"); |
| } |
| } |
| |
| /** |
| * Checks if output name is valid. |
| * |
| * name cannot be the name used for the default output |
| * @param outputPath base output Name |
| * @throws IllegalArgumentException if the output name is not valid. |
| */ |
| private static void checkBaseOutputPath(String outputPath) { |
| if (outputPath.equals(FileOutputFormat.PART)) { |
| throw new IllegalArgumentException("output name cannot be 'part'"); |
| } |
| } |
| |
| /** |
| * Checks if a named output name is valid. |
| * |
| * @param namedOutput named output Name |
| * @throws IllegalArgumentException if the output name is not valid. |
| */ |
| private static void checkNamedOutputName(JobContext job, |
| String namedOutput, boolean alreadyDefined) { |
| checkTokenName(namedOutput); |
| checkBaseOutputPath(namedOutput); |
| List<String> definedChannels = getNamedOutputsList(job); |
| if (alreadyDefined && definedChannels.contains(namedOutput)) { |
| throw new IllegalArgumentException("Named output '" + namedOutput + |
| "' already alreadyDefined"); |
| } else if (!alreadyDefined && !definedChannels.contains(namedOutput)) { |
| throw new IllegalArgumentException("Named output '" + namedOutput + |
| "' not defined"); |
| } |
| } |
| |
| // Returns list of channel names. |
| private static List<String> getNamedOutputsList(JobContext job) { |
| List<String> names = new ArrayList<String>(); |
| StringTokenizer st = new StringTokenizer( |
| job.getConfiguration().get(MULTIPLE_OUTPUTS, ""), " "); |
| while (st.hasMoreTokens()) { |
| names.add(st.nextToken()); |
| } |
| return names; |
| } |
| |
| // Returns the named output OutputFormat. |
| @SuppressWarnings("unchecked") |
| private static Class<? extends OutputFormat<?, ?>> getNamedOutputFormatClass( |
| JobContext job, String namedOutput) { |
| return (Class<? extends OutputFormat<?, ?>>) |
| job.getConfiguration().getClass(MO_PREFIX + namedOutput + FORMAT, null, |
| OutputFormat.class); |
| } |
| |
| // Returns the key class for a named output. |
| private static Class<?> getNamedOutputKeyClass(JobContext job, |
| String namedOutput) { |
| return job.getConfiguration().getClass(MO_PREFIX + namedOutput + KEY, null, |
| Object.class); |
| } |
| |
| // Returns the value class for a named output. |
| private static Class<?> getNamedOutputValueClass( |
| JobContext job, String namedOutput) { |
| return job.getConfiguration().getClass(MO_PREFIX + namedOutput + VALUE, |
| null, Object.class); |
| } |
| |
| /** |
| * Adds a named output for the job. |
| * <p/> |
| * |
| * @param job job to add the named output |
| * @param namedOutput named output name, it has to be a word, letters |
| * and numbers only, cannot be the word 'part' as |
| * that is reserved for the default output. |
| * @param outputFormatClass OutputFormat class. |
| * @param keyClass key class |
| * @param valueClass value class |
| */ |
| @SuppressWarnings("unchecked") |
| public static void addNamedOutput(Job job, String namedOutput, |
| Class<? extends OutputFormat> outputFormatClass, |
| Class<?> keyClass, Class<?> valueClass) { |
| checkNamedOutputName(job, namedOutput, true); |
| Configuration conf = job.getConfiguration(); |
| conf.set(MULTIPLE_OUTPUTS, |
| conf.get(MULTIPLE_OUTPUTS, "") + " " + namedOutput); |
| conf.setClass(MO_PREFIX + namedOutput + FORMAT, outputFormatClass, |
| OutputFormat.class); |
| conf.setClass(MO_PREFIX + namedOutput + KEY, keyClass, Object.class); |
| conf.setClass(MO_PREFIX + namedOutput + VALUE, valueClass, Object.class); |
| } |
| |
| /** |
| * Enables or disables counters for the named outputs. |
| * |
| * The counters group is the {@link MultipleOutputs} class name. |
| * The names of the counters are the same as the named outputs. These |
| * counters count the number records written to each output name. |
| * By default these counters are disabled. |
| * |
| * @param job job to enable counters |
| * @param enabled indicates if the counters will be enabled or not. |
| */ |
| public static void setCountersEnabled(Job job, boolean enabled) { |
| job.getConfiguration().setBoolean(COUNTERS_ENABLED, enabled); |
| } |
| |
| /** |
| * Returns if the counters for the named outputs are enabled or not. |
| * By default these counters are disabled. |
| * |
| * @param job the job |
| * @return TRUE if the counters are enabled, FALSE if they are disabled. |
| */ |
| public static boolean getCountersEnabled(JobContext job) { |
| return job.getConfiguration().getBoolean(COUNTERS_ENABLED, false); |
| } |
| |
| /** |
| * Wraps RecordWriter to increment counters. |
| */ |
| @SuppressWarnings("unchecked") |
| private static class RecordWriterWithCounter extends RecordWriter { |
| private RecordWriter writer; |
| private String counterName; |
| private TaskInputOutputContext context; |
| |
| public RecordWriterWithCounter(RecordWriter writer, String counterName, |
| TaskInputOutputContext context) { |
| this.writer = writer; |
| this.counterName = counterName; |
| this.context = context; |
| } |
| |
| @SuppressWarnings({"unchecked"}) |
| public void write(Object key, Object value) |
| throws IOException, InterruptedException { |
| context.getCounter(COUNTERS_GROUP, counterName).increment(1); |
| writer.write(key, value); |
| } |
| |
| public void close(TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| writer.close(context); |
| } |
| } |
| |
| // instance code, to be used from Mapper/Reducer code |
| |
| private TaskInputOutputContext<?, ?, KEYOUT, VALUEOUT> context; |
| private Set<String> namedOutputs; |
| private Map<String, RecordWriter<?, ?>> recordWriters; |
| private boolean countersEnabled; |
| |
| /** |
| * Creates and initializes multiple outputs support, |
| * it should be instantiated in the Mapper/Reducer setup method. |
| * |
| * @param context the TaskInputOutputContext object |
| */ |
| public MultipleOutputs( |
| TaskInputOutputContext<?, ?, KEYOUT, VALUEOUT> context) { |
| this.context = context; |
| namedOutputs = Collections.unmodifiableSet( |
| new HashSet<String>(MultipleOutputs.getNamedOutputsList(context))); |
| recordWriters = new HashMap<String, RecordWriter<?, ?>>(); |
| countersEnabled = getCountersEnabled(context); |
| } |
| |
| /** |
| * Write key and value to the namedOutput. |
| * |
| * Output path is a unique file generated for the namedOutput. |
| * For example, {namedOutput}-(m|r)-{part-number} |
| * |
| * @param namedOutput the named output name |
| * @param key the key |
| * @param value the value |
| */ |
| @SuppressWarnings("unchecked") |
| public <K, V> void write(String namedOutput, K key, V value) |
| throws IOException, InterruptedException { |
| write(namedOutput, key, value, namedOutput); |
| } |
| |
| /** |
| * Write key and value to baseOutputPath using the namedOutput. |
| * |
| * @param namedOutput the named output name |
| * @param key the key |
| * @param value the value |
| * @param baseOutputPath base-output path to write the record to. |
| * Note: Framework will generate unique filename for the baseOutputPath |
| */ |
| @SuppressWarnings("unchecked") |
| public <K, V> void write(String namedOutput, K key, V value, |
| String baseOutputPath) throws IOException, InterruptedException { |
| checkNamedOutputName(context, namedOutput, false); |
| checkBaseOutputPath(baseOutputPath); |
| if (!namedOutputs.contains(namedOutput)) { |
| throw new IllegalArgumentException("Undefined named output '" + |
| namedOutput + "'"); |
| } |
| TaskAttemptContext taskContext = getContext(namedOutput); |
| getRecordWriter(taskContext, baseOutputPath).write(key, value); |
| } |
| |
| /** |
| * Write key value to an output file name. |
| * |
| * Gets the record writer from job's output format. |
| * Job's output format should be a FileOutputFormat. |
| * |
| * @param key the key |
| * @param value the value |
| * @param baseOutputPath base-output path to write the record to. |
| * Note: Framework will generate unique filename for the baseOutputPath |
| */ |
| @SuppressWarnings("unchecked") |
| public void write(KEYOUT key, VALUEOUT value, String baseOutputPath) |
| throws IOException, InterruptedException { |
| checkBaseOutputPath(baseOutputPath); |
| TaskAttemptContext taskContext = |
| new TaskAttemptContextImpl(context.getConfiguration(), |
| context.getTaskAttemptID(), |
| new WrappedStatusReporter(context)); |
| getRecordWriter(taskContext, baseOutputPath).write(key, value); |
| } |
| |
| // by being synchronized MultipleOutputTask can be use with a |
| // MultithreadedMapper. |
| @SuppressWarnings("unchecked") |
| private synchronized RecordWriter getRecordWriter( |
| TaskAttemptContext taskContext, String baseFileName) |
| throws IOException, InterruptedException { |
| |
| // look for record-writer in the cache |
| RecordWriter writer = recordWriters.get(baseFileName); |
| |
| // If not in cache, create a new one |
| if (writer == null) { |
| // get the record writer from context output format |
| FileOutputFormat.setOutputName(taskContext, baseFileName); |
| try { |
| writer = ((OutputFormat) ReflectionUtils.newInstance( |
| taskContext.getOutputFormatClass(), taskContext.getConfiguration())) |
| .getRecordWriter(taskContext); |
| } catch (ClassNotFoundException e) { |
| throw new IOException(e); |
| } |
| |
| // if counters are enabled, wrap the writer with context |
| // to increment counters |
| if (countersEnabled) { |
| writer = new RecordWriterWithCounter(writer, baseFileName, context); |
| } |
| |
| // add the record-writer to the cache |
| recordWriters.put(baseFileName, writer); |
| } |
| return writer; |
| } |
| |
| // Create a taskAttemptContext for the named output with |
| // output format and output key/value types put in the context |
| private TaskAttemptContext getContext(String nameOutput) throws IOException { |
| |
| TaskAttemptContext taskContext = taskContexts.get(nameOutput); |
| |
| if (taskContext != null) { |
| return taskContext; |
| } |
| |
| // The following trick leverages the instantiation of a record writer via |
| // the job thus supporting arbitrary output formats. |
| Job job = new Job(context.getConfiguration()); |
| job.setOutputFormatClass(getNamedOutputFormatClass(context, nameOutput)); |
| job.setOutputKeyClass(getNamedOutputKeyClass(context, nameOutput)); |
| job.setOutputValueClass(getNamedOutputValueClass(context, nameOutput)); |
| taskContext = new TaskAttemptContextImpl(job.getConfiguration(), context |
| .getTaskAttemptID(), new WrappedStatusReporter(context)); |
| |
| taskContexts.put(nameOutput, taskContext); |
| |
| return taskContext; |
| } |
| |
| private static class WrappedStatusReporter extends StatusReporter { |
| |
| TaskAttemptContext context; |
| |
| public WrappedStatusReporter(TaskAttemptContext context) { |
| this.context = context; |
| } |
| |
| @Override |
| public Counter getCounter(Enum<?> name) { |
| return context.getCounter(name); |
| } |
| |
| @Override |
| public Counter getCounter(String group, String name) { |
| return context.getCounter(group, name); |
| } |
| |
| @Override |
| public void progress() { |
| context.progress(); |
| } |
| |
| @Override |
| public float getProgress() { |
| return context.getProgress(); |
| } |
| |
| @Override |
| public void setStatus(String status) { |
| context.setStatus(status); |
| } |
| } |
| |
| /** |
| * Closes all the opened outputs. |
| * |
| * This should be called from cleanup method of map/reduce task. |
| * If overridden subclasses must invoke <code>super.close()</code> at the |
| * end of their <code>close()</code> |
| * |
| */ |
| @SuppressWarnings("unchecked") |
| public void close() throws IOException, InterruptedException { |
| for (RecordWriter writer : recordWriters.values()) { |
| writer.close(context); |
| } |
| } |
| } |