org.apache.spark.examples.streaming.StatefulNetworkWordCount.scala Maven / Gradle / Ivy
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* 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
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package org.apache.spark.examples.streaming
import org.apache.spark.SparkConf
import org.apache.spark.streaming._
import org.apache.spark.streaming.StreamingContext._
/**
* Counts words cumulatively in UTF8 encoded, '\n' delimited text received from the network every
* second.
* Usage: StatefulNetworkWordCount
* and describe the TCP server that Spark Streaming would connect to receive
* data.
*
* To run this on your local machine, you need to first run a Netcat server
* `$ nc -lk 9999`
* and then run the example
* `$ bin/run-example
* org.apache.spark.examples.streaming.StatefulNetworkWordCount localhost 9999`
*/
object StatefulNetworkWordCount {
def main(args: Array[String]) {
if (args.length < 2) {
System.err.println("Usage: StatefulNetworkWordCount ")
System.exit(1)
}
StreamingExamples.setStreamingLogLevels()
val updateFunc = (values: Seq[Int], state: Option[Int]) => {
val currentCount = values.foldLeft(0)(_ + _)
val previousCount = state.getOrElse(0)
Some(currentCount + previousCount)
}
val sparkConf = new SparkConf().setAppName("StatefulNetworkWordCount")
// Create the context with a 1 second batch size
val ssc = new StreamingContext(sparkConf, Seconds(1))
ssc.checkpoint(".")
// Create a NetworkInputDStream on target ip:port and count the
// words in input stream of \n delimited test (eg. generated by 'nc')
val lines = ssc.socketTextStream(args(0), args(1).toInt)
val words = lines.flatMap(_.split(" "))
val wordDstream = words.map(x => (x, 1))
// Update the cumulative count using updateStateByKey
// This will give a Dstream made of state (which is the cumulative count of the words)
val stateDstream = wordDstream.updateStateByKey[Int](updateFunc)
stateDstream.print()
ssc.start()
ssc.awaitTermination()
}
}