| /** |
| * 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.join; |
| |
| import java.io.IOException; |
| import java.util.PriorityQueue; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| import org.apache.hadoop.conf.Configuration; |
| import org.apache.hadoop.io.Writable; |
| import org.apache.hadoop.io.WritableComparable; |
| import org.apache.hadoop.io.WritableComparator; |
| import org.apache.hadoop.mapreduce.InputSplit; |
| import org.apache.hadoop.mapreduce.TaskAttemptContext; |
| import org.apache.hadoop.util.ReflectionUtils; |
| |
| /** |
| * Base class for Composite join returning values derived from multiple |
| * sources, but generally not tuples. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public abstract class MultiFilterRecordReader<K extends WritableComparable<?>, |
| V extends Writable> |
| extends CompositeRecordReader<K,V,V> { |
| |
| private TupleWritable ivalue = null; |
| |
| public MultiFilterRecordReader(int id, Configuration conf, int capacity, |
| Class<? extends WritableComparator> cmpcl) throws IOException { |
| super(id, capacity, cmpcl); |
| setConf(conf); |
| } |
| |
| /** |
| * For each tuple emitted, return a value (typically one of the values |
| * in the tuple). |
| * Modifying the Writables in the tuple is permitted and unlikely to affect |
| * join behavior in most cases, but it is not recommended. It's safer to |
| * clone first. |
| */ |
| protected abstract V emit(TupleWritable dst) throws IOException; |
| |
| /** |
| * Default implementation offers {@link #emit} every Tuple from the |
| * collector (the outer join of child RRs). |
| */ |
| protected boolean combine(Object[] srcs, TupleWritable dst) { |
| return true; |
| } |
| |
| /** {@inheritDoc} */ |
| public boolean nextKeyValue() throws IOException, InterruptedException { |
| if (key == null) { |
| key = createKey(); |
| } |
| if (value == null) { |
| value = createValue(); |
| } |
| if (jc.flush(ivalue)) { |
| ReflectionUtils.copy(conf, jc.key(), key); |
| ReflectionUtils.copy(conf, emit(ivalue), value); |
| return true; |
| } |
| if (ivalue == null) { |
| ivalue = createTupleWritable(); |
| } |
| jc.clear(); |
| final PriorityQueue<ComposableRecordReader<K,?>> q = |
| getRecordReaderQueue(); |
| K iterkey = createKey(); |
| while (q != null && !q.isEmpty()) { |
| fillJoinCollector(iterkey); |
| jc.reset(iterkey); |
| if (jc.flush(ivalue)) { |
| ReflectionUtils.copy(conf, jc.key(), key); |
| ReflectionUtils.copy(conf, emit(ivalue), value); |
| return true; |
| } |
| jc.clear(); |
| } |
| return false; |
| } |
| |
| @SuppressWarnings("unchecked") |
| public void initialize(InputSplit split, TaskAttemptContext context) |
| throws IOException, InterruptedException { |
| super.initialize(split, context); |
| } |
| |
| /** |
| * Return an iterator returning a single value from the tuple. |
| * @see MultiFilterDelegationIterator |
| */ |
| protected ResetableIterator<V> getDelegate() { |
| return new MultiFilterDelegationIterator(); |
| } |
| |
| /** |
| * Proxy the JoinCollector, but include callback to emit. |
| */ |
| protected class MultiFilterDelegationIterator |
| implements ResetableIterator<V> { |
| |
| public boolean hasNext() { |
| return jc.hasNext(); |
| } |
| |
| public boolean next(V val) throws IOException { |
| boolean ret; |
| if (ret = jc.flush(ivalue)) { |
| ReflectionUtils.copy(getConf(), emit(ivalue), val); |
| } |
| return ret; |
| } |
| |
| public boolean replay(V val) throws IOException { |
| ReflectionUtils.copy(getConf(), emit(ivalue), val); |
| return true; |
| } |
| |
| public void reset() { |
| jc.reset(jc.key()); |
| } |
| |
| public void add(V item) throws IOException { |
| throw new UnsupportedOperationException(); |
| } |
| |
| public void close() throws IOException { |
| jc.close(); |
| } |
| |
| public void clear() { |
| jc.clear(); |
| } |
| } |
| |
| } |