How to use

CompositeRecordReader

in

org.apache.hadoop.mapreduce.lib.join

/**
 * If key provided matches that of this Composite, give JoinCollector
 * iterator over values it may emit.
 */
@SuppressWarnings("unchecked") // No values from static EMPTY class
@Override
public void accept(CompositeRecordReader.JoinCollector jc, K key)
  throws IOException, InterruptedException {
 if (hasNext() && 0 == cmp.compare(key, key())) {
  fillJoinCollector(createKey());
  jc.add(id, getDelegate());
  return;
 }
 jc.add(id, EMPTY);
}

/**
 * Create a new key common to all child RRs.
 * @throws ClassCastException if key classes differ.
 */
@SuppressWarnings("unchecked")
protected K createKey() {
 if (keyclass == null || keyclass.equals(NullWritable.class)) {
  return (K) NullWritable.get();
 }
 return (K) ReflectionUtils.newInstance(keyclass, getConf());
}

@SuppressWarnings("unchecked")
public void initialize(InputSplit split, TaskAttemptContext context) 
  throws IOException, InterruptedException {
 super.initialize(split, context);
}

/**
 * Clone the key at the top of this RR into the given object.
 */
public void key(K key) throws IOException {
 ReflectionUtils.copy(conf, key(), key);
}

@SuppressWarnings("unchecked") // child types unknowable
public ComposableRecordReader 
  createRecordReader(InputSplit split, TaskAttemptContext taskContext) 
  throws IOException, InterruptedException {
 if (!(split instanceof CompositeInputSplit)) {
  throw new IOException("Invalid split type:" +
             split.getClass().getName());
 }
 final CompositeInputSplit spl = (CompositeInputSplit)split;
 final int capacity = kids.size();
 CompositeRecordReader ret = null;
 try {
  if (!rrCstrMap.containsKey(ident)) {
   throw new IOException("No RecordReader for " + ident);
  }
  ret = (CompositeRecordReader)rrCstrMap.get(ident).
   newInstance(id, taskContext.getConfiguration(), capacity, cmpcl);
 } catch (IllegalAccessException e) {
  throw new IOException(e);
 } catch (InstantiationException e) {
  throw new IOException(e);
 } catch (InvocationTargetException e) {
  throw new IOException(e);
 }
 for (int i = 0; i < capacity; ++i) {
  ret.add(kids.get(i).createRecordReader(spl.get(i), taskContext));
 }
 return (ComposableRecordReader)ret;
}

/**
 * Clone the key at the top of this RR into the given object.
 */
public void key(K key) throws IOException {
 ReflectionUtils.copy(conf, key(), key);
}

@SuppressWarnings("unchecked") // child types unknowable
public ComposableRecordReader 
  createRecordReader(InputSplit split, TaskAttemptContext taskContext) 
  throws IOException, InterruptedException {
 if (!(split instanceof CompositeInputSplit)) {
  throw new IOException("Invalid split type:" +
             split.getClass().getName());
 }
 final CompositeInputSplit spl = (CompositeInputSplit)split;
 final int capacity = kids.size();
 CompositeRecordReader ret = null;
 try {
  if (!rrCstrMap.containsKey(ident)) {
   throw new IOException("No RecordReader for " + ident);
  }
  ret = (CompositeRecordReader)rrCstrMap.get(ident).
   newInstance(id, taskContext.getConfiguration(), capacity, cmpcl);
 } catch (IllegalAccessException e) {
  throw new IOException(e);
 } catch (InstantiationException e) {
  throw new IOException(e);
 } catch (InvocationTargetException e) {
  throw new IOException(e);
 }
 for (int i = 0; i < capacity; ++i) {
  ret.add(kids.get(i).createRecordReader(spl.get(i), taskContext));
 }
 return (ComposableRecordReader)ret;
}

/**
 * If key provided matches that of this Composite, give JoinCollector
 * iterator over values it may emit.
 */
@SuppressWarnings("unchecked") // No values from static EMPTY class
@Override
public void accept(CompositeRecordReader.JoinCollector jc, K key)
  throws IOException, InterruptedException {
 if (hasNext() && 0 == cmp.compare(key, key())) {
  fillJoinCollector(createKey());
  jc.add(id, getDelegate());
  return;
 }
 jc.add(id, EMPTY);
}

/**
 * Clone the key at the top of this RR into the given object.
 */
public void key(K key) throws IOException {
 ReflectionUtils.copy(conf, key(), key);
}

@SuppressWarnings("unchecked")
public void initialize(InputSplit split, TaskAttemptContext context) 
  throws IOException, InterruptedException {
 super.initialize(split, context);
}

/**
 * Create a new key common to all child RRs.
 * @throws ClassCastException if key classes differ.
 */
@SuppressWarnings("unchecked")
protected K createKey() {
 if (keyclass == null || keyclass.equals(NullWritable.class)) {
  return (K) NullWritable.get();
 }
 return (K) ReflectionUtils.newInstance(keyclass, getConf());
}

@SuppressWarnings("unchecked") // child types unknowable
public ComposableRecordReader 
  createRecordReader(InputSplit split, TaskAttemptContext taskContext) 
  throws IOException, InterruptedException {
 if (!(split instanceof CompositeInputSplit)) {
  throw new IOException("Invalid split type:" +
             split.getClass().getName());
 }
 final CompositeInputSplit spl = (CompositeInputSplit)split;
 final int capacity = kids.size();
 CompositeRecordReader ret = null;
 try {
  if (!rrCstrMap.containsKey(ident)) {
   throw new IOException("No RecordReader for " + ident);
  }
  ret = (CompositeRecordReader)rrCstrMap.get(ident).
   newInstance(id, taskContext.getConfiguration(), capacity, cmpcl);
 } catch (IllegalAccessException e) {
  throw new IOException(e);
 } catch (InstantiationException e) {
  throw new IOException(e);
 } catch (InvocationTargetException e) {
  throw new IOException(e);
 }
 for (int i = 0; i < capacity; ++i) {
  ret.add(kids.get(i).createRecordReader(spl.get(i), taskContext));
 }
 return (ComposableRecordReader)ret;
}

/**
 * If key provided matches that of this Composite, give JoinCollector
 * iterator over values it may emit.
 */
@SuppressWarnings("unchecked") // No values from static EMPTY class
@Override
public void accept(CompositeRecordReader.JoinCollector jc, K key)
  throws IOException, InterruptedException {
 if (hasNext() && 0 == cmp.compare(key, key())) {
  fillJoinCollector(createKey());
  jc.add(id, getDelegate());
  return;
 }
 jc.add(id, EMPTY);
}

/**
 * Clone the key at the top of this RR into the given object.
 */
public void key(K key) throws IOException {
 ReflectionUtils.copy(conf, key(), key);
}

@SuppressWarnings("unchecked")
public void initialize(InputSplit split, TaskAttemptContext context) 
  throws IOException, InterruptedException {
 super.initialize(split, context);
}

/**
 * Create a new key common to all child RRs.
 * @throws ClassCastException if key classes differ.
 */
@SuppressWarnings("unchecked")
protected K createKey() {
 if (keyclass == null || keyclass.equals(NullWritable.class)) {
  return (K) NullWritable.get();
 }
 return (K) ReflectionUtils.newInstance(keyclass, getConf());
}

@SuppressWarnings("unchecked") // child types unknowable
public ComposableRecordReader 
  createRecordReader(InputSplit split, TaskAttemptContext taskContext) 
  throws IOException, InterruptedException {
 if (!(split instanceof CompositeInputSplit)) {
  throw new IOException("Invalid split type:" +
             split.getClass().getName());
 }
 final CompositeInputSplit spl = (CompositeInputSplit)split;
 final int capacity = kids.size();
 CompositeRecordReader ret = null;
 try {
  if (!rrCstrMap.containsKey(ident)) {
   throw new IOException("No RecordReader for " + ident);
  }
  ret = (CompositeRecordReader)rrCstrMap.get(ident).
   newInstance(id, taskContext.getConfiguration(), capacity, cmpcl);
 } catch (IllegalAccessException e) {
  throw new IOException(e);
 } catch (InstantiationException e) {
  throw new IOException(e);
 } catch (InvocationTargetException e) {
  throw new IOException(e);
 }
 for (int i = 0; i < capacity; ++i) {
  ret.add(kids.get(i).createRecordReader(spl.get(i), taskContext));
 }
 return (ComposableRecordReader)ret;
}

/**
 * If key provided matches that of this Composite, give JoinCollector
 * iterator over values it may emit.
 */
@SuppressWarnings("unchecked") // No values from static EMPTY class
@Override
public void accept(CompositeRecordReader.JoinCollector jc, K key)
  throws IOException, InterruptedException {
 if (hasNext() && 0 == cmp.compare(key, key())) {
  fillJoinCollector(createKey());
  jc.add(id, getDelegate());
  return;
 }
 jc.add(id, EMPTY);
}

/**
 * Clone the key at the top of this RR into the given object.
 */
public void key(K key) throws IOException {
 ReflectionUtils.copy(conf, key(), key);
}

@SuppressWarnings("unchecked")
public void initialize(InputSplit split, TaskAttemptContext context) 
  throws IOException, InterruptedException {
 super.initialize(split, context);
}