/**
* 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.mrunit;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.io.RawComparator;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapred.Counters;
import org.apache.hadoop.mapred.Mapper;
import org.apache.hadoop.mapred.Reducer;
import org.apache.hadoop.mrunit.types.Pair;
/**
* Harness that allows you to test a Mapper and a Reducer instance together
* (along with an optional combiner).
* You provide the input key and value that should be sent to the Mapper, and
* outputs you expect to be sent by the Reducer to the collector for those
* inputs. By calling runTest(), the harness will deliver the input to the
* Mapper, feed the intermediate results to the Reducer (without checking
* them), and will check the Reducer's outputs against the expected results.
* This is designed to handle the (k, v)* -> (k, v)* case from the
* Mapper/Reducer pair, representing a single unit test.
*
* If a combiner is specified, then it will be run exactly once after
* the Mapper and before the Reducer.
*/
public class MapReduceDriver<K1, V1, K2 extends Comparable, V2, K3, V3>
extends MapReduceDriverBase<K1, V1, K2, V2, K3, V3> {
public static final Log LOG = LogFactory.getLog(MapReduceDriver.class);
private Mapper<K1, V1, K2, V2> myMapper;
private Reducer<K2, V2, K3, V3> myReducer;
private Reducer<K2, V2, K2, V2> myCombiner;
private Counters counters;
public MapReduceDriver(final Mapper<K1, V1, K2, V2> m,
final Reducer<K2, V2, K3, V3> r) {
myMapper = m;
myReducer = r;
counters = new Counters();
}
public MapReduceDriver(final Mapper<K1, V1, K2, V2> m,
final Reducer<K2, V2, K3, V3> r,
final Reducer<K2, V2, K2, V2> c) {
myMapper = m;
myReducer = r;
myCombiner = c;
counters = new Counters();
}
public MapReduceDriver() {
counters = new Counters();
}
/** @return the counters used in this test */
public Counters getCounters() {
return counters;
}
/** Sets the counters object to use for this test.
* @param ctrs The counters object to use.
*/
public void setCounters(final Counters ctrs) {
this.counters = ctrs;
}
/** Sets the counters to use and returns self for fluent style */
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withCounters(final Counters ctrs) {
setCounters(ctrs);
return this;
}
/** Set the Mapper instance to use with this test driver
* @param m the Mapper instance to use */
public void setMapper(Mapper<K1, V1, K2, V2> m) {
myMapper = m;
}
/** Sets the Mapper instance to use and returns self for fluent style */
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withMapper(
Mapper<K1, V1, K2, V2> m) {
setMapper(m);
return this;
}
/**
* @return the Mapper object being used by this test
*/
public Mapper<K1, V1, K2, V2> getMapper() {
return myMapper;
}
/**
* Sets the reducer object to use for this test
* @param r The reducer object to use
*/
public void setReducer(Reducer<K2, V2, K3, V3> r) {
myReducer = r;
}
/**
* Identical to setReducer(), but with fluent programming style
* @param r The Reducer to use
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withReducer(
Reducer<K2, V2, K3, V3> r) {
setReducer(r);
return this;
}
/**
* @return the Reducer object being used for this test
*/
public Reducer<K2, V2, K3, V3> getReducer() {
return myReducer;
}
/**
* Sets the reducer object to use as a combiner for this test
* @param c The combiner object to use
*/
public void setCombiner(Reducer<K2, V2, K2, V2> c) {
myCombiner = c;
}
/**
* Identical to setCombiner(), but with fluent programming style
* @param c The Combiner to use
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withCombiner(
Reducer<K2, V2, K2, V2> c) {
setCombiner(c);
return this;
}
/**
* @return the Combiner object being used for this test
*/
public Reducer<K2, V2, K2, V2> getCombiner() {
return myCombiner;
}
/**
* Identical to addInput() but returns self for fluent programming style
* @param key
* @param val
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withInput(K1 key, V1 val) {
addInput(key, val);
return this;
}
/**
* Identical to addInput() but returns self for fluent programming style
* @param input The (k, v) pair to add
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withInput(
Pair<K1, V1> input) {
addInput(input);
return this;
}
/**
* Works like addOutput(), but returns self for fluent style
* @param outputRecord
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withOutput(
Pair<K3, V3> outputRecord) {
addOutput(outputRecord);
return this;
}
/**
* Functions like addOutput() but returns self for fluent programming style
* @param key
* @param val
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withOutput(K3 key, V3 val) {
addOutput(key, val);
return this;
}
/**
* Identical to addInputFromString, but with a fluent programming style
* @param input A string of the form "key \t val". Trims any whitespace.
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withInputFromString(String input) {
addInputFromString(input);
return this;
}
/**
* Identical to addOutputFromString, but with a fluent programming style
* @param output A string of the form "key \t val". Trims any whitespace.
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withOutputFromString(String output) {
addOutputFromString(output);
return this;
}
/** The private class to manage starting the reduce phase is used for type
genericity reasons. This class is used in the run() method. */
private class ReducePhaseRunner<OUTKEY, OUTVAL> {
private List<Pair<OUTKEY, OUTVAL>> runReduce(
List<Pair<K2, List<V2>>> inputs, Reducer<K2, V2, OUTKEY, OUTVAL> reducer)
throws IOException {
List<Pair<OUTKEY, OUTVAL>> reduceOutputs = new ArrayList<Pair<OUTKEY, OUTVAL>>();
for (Pair<K2, List<V2>> input : inputs) {
K2 inputKey = input.getFirst();
List<V2> inputValues = input.getSecond();
StringBuilder sb = new StringBuilder();
formatValueList(inputValues, sb);
LOG.debug("Reducing input (" + inputKey.toString() + ", "
+ sb.toString() + ")");
reduceOutputs.addAll(new ReduceDriver<K2, V2, OUTKEY, OUTVAL>(reducer)
.withCounters(getCounters())
.withInputKey(inputKey)
.withInputValues(inputValues)
.run());
}
return reduceOutputs;
}
}
public List<Pair<K3, V3>> run() throws IOException {
List<Pair<K2, V2>> mapOutputs = new ArrayList<Pair<K2, V2>>();
// run map component
for (Pair<K1, V1> input : inputList) {
LOG.debug("Mapping input " + input.toString() + ")");
mapOutputs.addAll(new MapDriver<K1, V1, K2, V2>(myMapper).withInput(
input).withCounters(getCounters()).run());
}
if (myCombiner != null) {
// User has specified a combiner. Run this and replace the mapper outputs
// with the result of the combiner.
LOG.debug("Starting combine phase with combiner: " + myCombiner);
mapOutputs = new ReducePhaseRunner<K2, V2>().runReduce(shuffle(mapOutputs), myCombiner);
}
// Run the reduce phase.
LOG.debug("Starting reduce phase with reducer: " + myReducer);
return new ReducePhaseRunner<K3, V3>().runReduce(shuffle(mapOutputs), myReducer);
}
@Override
public String toString() {
return "MapReduceDriver (" + myMapper + ", " + myReducer + ")";
}
/**
* Identical to {@link #setKeyGroupingComparator(RawComparator)}, but with a
* fluent programming style
* @param groupingComparator Comparator to use in the shuffle stage for key
* grouping
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withKeyGroupingComparator(
RawComparator<K2> groupingComparator) {
setKeyGroupingComparator(groupingComparator);
return this;
}
/**
* Identical to {@link #setKeyOrderComparator(RawComparator)}, but with a
* fluent programming style
* @param orderComparator Comparator to use in the shuffle stage for key
* value ordering
* @return this
*/
public MapReduceDriver<K1, V1, K2, V2, K3, V3> withKeyOrderComparator(
RawComparator<K2> orderComparator) {
setKeyOrderComparator(orderComparator);
return this;
}
}