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From: devtagare <git@git.apache.org>
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Subject: [GitHub] apex-malhar pull request #298: *For review only* [APEXMALHAR-2086] Kafka out...
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Message-Id: <20160613052530.8AA53E01E2@git1-us-west.apache.org>
Date: Mon, 13 Jun 2016 05:25:30 +0000 (UTC)
archived-at: Mon, 13 Jun 2016 05:25:37 -0000

Github user devtagare commented on a diff in the pull request:

    https://github.com/apache/apex-malhar/pull/298#discussion_r66741302
  
    --- Diff: kafka/src/main/java/org/apache/apex/malhar/kafka/AbstractExactlyOnceKafkaOutputOperator.java ---
    @@ -0,0 +1,366 @@
    +/**
    + * 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.apex.malhar.kafka;
    +
    +import java.io.IOException;
    +import java.util.ArrayList;
    +import java.util.HashMap;
    +import java.util.List;
    +import java.util.Map;
    +import java.util.Properties;
    +import java.util.concurrent.ExecutionException;
    +
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +import org.apache.apex.malhar.lib.wal.FSWindowDataManager;
    +import org.apache.apex.malhar.lib.wal.WindowDataManager;
    +
    +import org.apache.kafka.clients.consumer.ConsumerRecord;
    +import org.apache.kafka.clients.consumer.ConsumerRecords;
    +import org.apache.kafka.clients.consumer.KafkaConsumer;
    +import org.apache.kafka.clients.producer.ProducerRecord;
    +import org.apache.kafka.common.PartitionInfo;
    +import org.apache.kafka.common.TopicPartition;
    +
    +import com.datatorrent.api.Context;
    +import com.datatorrent.api.Operator;
    +
    +import static org.apache.kafka.clients.consumer.ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG;
    +import static org.apache.kafka.clients.consumer.ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG;
    +import static org.apache.kafka.clients.consumer.ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG;
    +import static org.apache.kafka.clients.producer.ProducerConfig.ACKS_CONFIG;
    +
    +/**
    + * Kafka output operator with exactly once processing semantics under certain conditions.,
    + *
    + *  Requirement for Exactly Once:
    + *   Every message within the Window is unique
    + *
    + *  This operator uses *Key* to distinguish the messages written by particular instance of the Output operator.
    + *  Operator users can only use *value* for storing the data.
    + *
    + * @displayName Abstract Exactly Once Kafka Output(0.9.0)
    + * @category Messaging
    + * @tags output operator
    + *
    + * @since 3.5
    + */
    +@org.apache.hadoop.classification.InterfaceStability.Evolving
    +public abstract class AbstractExactlyOnceKafkaOutputOperator<T> extends AbstractKafkaOutputOperator<String, T>
    +    implements Operator.CheckpointNotificationListener
    +{
    +  private transient String key;
    +  private transient String appId;
    +  private transient Integer operatorId;
    +  private transient Long windowId;
    +  private transient Map<T, Integer> partialWindowTuples = new HashMap<>();
    +  private transient KafkaConsumer consumer;
    +
    +  private WindowDataManager windowDataManager = new FSWindowDataManager();
    +  private final int KAFKA_CONNECT_ATTEMPT = 10;
    +  private final String KEY_SEPARATOR = "#";
    +  private final String KEY_SERIALIZER = "org.apache.kafka.common.serialization.StringDeserializer";
    +  private final String VALUE_SERIALIZER = "org.apache.kafka.common.serialization.StringDeserializer";
    +
    +  @Override
    +  public void setup(Context.OperatorContext context)
    +  {
    +    super.setup(context);
    +
    +    this.operatorId = context.getId();
    +    this.windowDataManager.setup(context);
    +    this.appId = context.getValue(Context.DAGContext.APPLICATION_ID);
    +    this.key = appId + KEY_SEPARATOR + (new Integer(operatorId));
    +    this.consumer = KafkaConsumerInit();
    +
    +    setProperty(ACKS_CONFIG, "all");
    +  }
    +
    +  @Override
    +  public void beginWindow(long windowId)
    +  {
    +    this.windowId = windowId;
    +
    +    if (windowId == windowDataManager.getLargestRecoveryWindow()) {
    +      rebuildPartialWindow();
    +    }
    +  }
    +
    +  @Override
    +  public void checkpointed(long windowId)
    +  {
    +  }
    +
    +  @Override
    +  public void committed(long windowId)
    +  {
    +    try {
    +      windowDataManager.deleteUpTo(operatorId, windowId);
    +    } catch (IOException e) {
    +      throw new RuntimeException(e);
    +    }
    +  }
    +
    +  @Override
    +  public void beforeCheckpoint(long windowId)
    +  {
    +  }
    +
    +  @Override
    +  public void teardown()
    +  {
    +    consumer.close();
    +    super.teardown();
    +  }
    +
    +  @Override
    +  public void endWindow()
    +  {
    +    if (!partialWindowTuples.isEmpty()) {
    +      // Throw exception
    +    }
    +
    +    try {
    +      this.windowDataManager.save(getPartitionsAndOffsets(), operatorId, windowId);
    +    } catch (IOException e) {
    +      throw new RuntimeException(e);
    +    } catch (ExecutionException e) {
    +      throw new RuntimeException(e);
    +    } catch (InterruptedException e) {
    +      throw new RuntimeException(e);
    +    }
    +  }
    +
    +  public WindowDataManager getWindowDataManager()
    +  {
    +    return windowDataManager;
    +  }
    +
    +  public void setWindowDataManager(WindowDataManager windowDataManager)
    +  {
    +    this.windowDataManager = windowDataManager;
    +  }
    +
    +  private boolean doesKeyBelongsToThisInstance(Integer operatorId, String key)
    +  {
    +    String[] split = key.split(KEY_SEPARATOR);
    +
    +    if (split.length != 2) {
    +      return false;
    +    }
    +
    +    if ((Integer.parseInt(split[1]) == operatorId) && (split[0].equals(appId))) {
    --- End diff --
    
    why not have a partitionId instead of appId.A re-launch will give a new applicationId so the second check will not work.


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