src/contrib/mrunit/src/java/org/apache/hadoop/mrunit/mapreduce/mock/MockMapContext.java

/**
 * 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.mapreduce.mock;

import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.mapreduce.Counters;
import org.apache.hadoop.mapreduce.InputSplit;
import org.apache.hadoop.mapreduce.TaskAttemptID;
import org.apache.hadoop.mapreduce.TaskType;
import org.apache.hadoop.mapreduce.task.MapContextImpl;
import org.apache.hadoop.mrunit.mock.MockOutputCollector;
import org.apache.hadoop.mrunit.types.Pair;

public class MockMapContext<KEYIN, VALUEIN, KEYOUT, VALUEOUT> 
    extends MapContextImpl<KEYIN, VALUEIN, KEYOUT, VALUEOUT> {

  private Iterator<Pair<KEYIN, VALUEIN>> inputIter;
  private Pair<KEYIN, VALUEIN> curInput;
  private MockOutputCollector<KEYOUT, VALUEOUT> output;
  
  /**
   * Create a new instance with the passed configuration, map key/value input 
   * pairs and counters
   * 
   * @param configuration Configuration for the mapper
   * @param in input key/value pairs for the mapper
   * @param counters pre-initialized counter values
   */
  public MockMapContext(final Configuration configuration,
                        final List<Pair<KEYIN, VALUEIN>> in, 
                        final Counters counters) {
    super(configuration,
        new TaskAttemptID("mrunit-jt", 0, TaskType.MAP, 0, 0),
        null, null, new MockOutputCommitter(), new MockReporter(counters), null);
    this.inputIter = in.iterator();
    this.output = new MockOutputCollector<KEYOUT, VALUEOUT>();
  }
  
  /**
   * Create a new instance with the passed map key/value input pairs and
   * counters. A new {@link Configuration} object will be created and used
   * to configure the mapper
   * 
   * @param in input key/value pairs for the mapper
   * @param counters pre-initialized counter values
   */
  public MockMapContext(final List<Pair<KEYIN, VALUEIN>> in, 
          final Counters counters) {
    this(new Configuration(), in, counters);  
  }
  
  @Override
  public InputSplit getInputSplit() {
    return new MockInputSplit();
  }

  @Override
  public KEYIN getCurrentKey() {
    return curInput.getFirst();
  }

  @Override
  public VALUEIN getCurrentValue() {
    return curInput.getSecond();
  }

  @Override
  public boolean nextKeyValue() throws IOException {
    if (this.inputIter.hasNext()) {
      this.curInput = this.inputIter.next();
      return true;
    } else {
      return false;
    }
  }

  public void write(KEYOUT key, VALUEOUT value) throws IOException {
    output.collect(key, value);
  }

  @Override
  /** This method does nothing in the mock version. */
  public void progress() {
  }

  @Override
  /** This method does nothing in the mock version. */
  public void setStatus(String status) {
  }

  /**
   * @return the outputs from the MockOutputCollector back to
   * the test harness.
   */
  public List<Pair<KEYOUT, VALUEOUT>> getOutputs() {
    return output.getOutputs();
  }
}