content: /*
   * 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.spark.streaming.examples;
  
  import com.google.common.collect.Lists;
  import scala.Tuple2;
  import org.apache.spark.api.java.JavaRDD;
  import org.apache.spark.api.java.function.Function2;
  import org.apache.spark.api.java.function.PairFunction;
  import org.apache.spark.streaming.Duration;
  import org.apache.spark.streaming.api.java.JavaDStream;
  import org.apache.spark.streaming.api.java.JavaPairDStream;
  import org.apache.spark.streaming.api.java.JavaStreamingContext;
  
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Queue;
  
  public final class JavaQueueStream {
    private JavaQueueStream() {
    }
  
    public static void main(String[] args) throws Exception {
      if (args.length < 1) {
        System.err.println("Usage: JavaQueueStream <master>");
        System.exit(1);
      }
  
      StreamingExamples.setStreamingLogLevels();
  
      // Create the context
      JavaStreamingContext ssc = new JavaStreamingContext(args[0], "QueueStream", new Duration(1000),
              System.getenv("SPARK_HOME"), JavaStreamingContext.jarOfClass(JavaQueueStream.class));
  
      // Create the queue through which RDDs can be pushed to
      // a QueueInputDStream
      Queue<JavaRDD<Integer>> rddQueue = new LinkedList<JavaRDD<Integer>>();
  
      // Create and push some RDDs into the queue
      List<Integer> list = Lists.newArrayList();
      for (int i = 0; i < 1000; i++) {
        list.add(i);
      }
  
      for (int i = 0; i < 30; i++) {
        rddQueue.add(ssc.sparkContext().parallelize(list));
      }
  
      // Create the QueueInputDStream and use it do some processing
      JavaDStream<Integer> inputStream = ssc.queueStream(rddQueue);
      JavaPairDStream<Integer, Integer> mappedStream = inputStream.mapToPair(
          new PairFunction<Integer, Integer, Integer>() {
            @Override
            public Tuple2<Integer, Integer> call(Integer i) {
              return new Tuple2<Integer, Integer>(i % 10, 1);
            }
          });
      JavaPairDStream<Integer, Integer> reducedStream = mappedStream.reduceByKey(
        new Function2<Integer, Integer, Integer>() {
          @Override
          public Integer call(Integer i1, Integer i2) {
            return i1 + i2;
          }
      });
  
      reducedStream.print();
      ssc.start();
      ssc.awaitTermination();
    }
  }
  