text: /*
   * 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.tez.mapreduce.processor;
  
  import java.io.IOException;
  import java.util.List;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.apache.hadoop.classification.InterfaceAudience.Public;
  import org.apache.hadoop.classification.InterfaceStability.Evolving;
  import org.apache.tez.mapreduce.output.MROutput;
  import org.apache.tez.runtime.api.LogicalOutput;
  import org.apache.tez.runtime.api.Processor;
  import org.apache.tez.runtime.api.ProcessorContext;
  import org.apache.tez.runtime.library.processor.SimpleProcessor;
  
  import com.google.common.collect.Lists;
  
  /**
   * A {@link SimpleProcessor} that provides Map Reduce specific post
   * processing by calling commit (if needed) on all {@link MROutput}s 
   * connected to this {@link Processor}. 
   */
  @Public
  @Evolving
  public abstract class SimpleMRProcessor extends SimpleProcessor {
    private static final Logger LOG = LoggerFactory.getLogger(SimpleMRProcessor.class);
  
    public SimpleMRProcessor(ProcessorContext context) {
      super(context);
    }
  
    @Override
    protected void postOp() throws Exception {
      if (getOutputs() == null) {
        return; // No post op
      }
      List<MROutput> mrOuts = Lists.newLinkedList();
      for (LogicalOutput output : getOutputs().values()) {
        if (output instanceof MROutput) {
          MROutput mrOutput = (MROutput) output;
          mrOutput.flush();
          if (mrOutput.isCommitRequired()) {
            mrOuts.add((MROutput) output);
          }
        }
      }
      if (mrOuts.size() > 0) {
        // This will loop till the AM asks for the task to be killed. As
        // against, the AM sending a signal to the task to kill itself
        // gracefully. The AM waits for the current committer to successfully
        // complete and then kills us. Until then we wait in case the
        // current committer fails and we get chosen to commit.
        while (!getContext().canCommit()) {
          Thread.sleep(100);
        }
        boolean willAbort = false;
        Exception savedEx = null;
        for (MROutput output : mrOuts) {
          try {
            output.commit();
          } catch (IOException ioe) {
            LOG.warn("Error in committing output", ioe);
            willAbort = true;
            savedEx = ioe;
            break;
          }
        }
        if (willAbort == true) {
          for (MROutput output : mrOuts) {
            try {
              output.abort();
            } catch (IOException ioe) {
              LOG.warn("Error in aborting output", ioe);
            }
          }
          throw savedEx;
        }
      }
    }
  }
  