/
StructuredSessionization.scala
151 lines (129 loc) · 5.21 KB
/
StructuredSessionization.scala
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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
* 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.
*/
// scalastyle:off println
package org.apache.spark.examples.sql.streaming
import java.sql.Timestamp
import org.apache.spark.sql.SparkSession
import org.apache.spark.sql.streaming._
/**
* Counts words in UTF8 encoded, '\n' delimited text received from the network.
*
* Usage: MapGroupsWithState <hostname> <port>
* <hostname> and <port> describe the TCP server that Structured 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 sql.streaming.StructuredSessionization
* localhost 9999`
*/
object StructuredSessionization {
def main(args: Array[String]): Unit = {
if (args.length < 2) {
System.err.println("Usage: StructuredSessionization <hostname> <port>")
System.exit(1)
}
val host = args(0)
val port = args(1).toInt
val spark = SparkSession
.builder
.appName("StructuredSessionization")
.getOrCreate()
import spark.implicits._
// Create DataFrame representing the stream of input lines from connection to host:port
val lines = spark.readStream
.format("socket")
.option("host", host)
.option("port", port)
.option("includeTimestamp", true)
.load()
// Split the lines into words, treat words as sessionId of events
val events = lines
.as[(String, Timestamp)]
.flatMap { case (line, timestamp) =>
line.split(" ").map(word => Event(sessionId = word, timestamp))
}
// Sessionize the events. Track number of events, start and end timestamps of session,
// and report session updates.
val sessionUpdates = events
.groupByKey(event => event.sessionId)
.mapGroupsWithState[SessionInfo, SessionUpdate](GroupStateTimeout.ProcessingTimeTimeout) {
case (sessionId: String, events: Iterator[Event], state: GroupState[SessionInfo]) =>
// If timed out, then remove session and send final update
if (state.hasTimedOut) {
val finalUpdate =
SessionUpdate(sessionId, state.get.durationMs, state.get.numEvents, expired = true)
state.remove()
finalUpdate
} else {
// Update start and end timestamps in session
val timestamps = events.map(_.timestamp.getTime).toSeq
val updatedSession = if (state.exists) {
val oldSession = state.get
SessionInfo(
oldSession.numEvents + timestamps.size,
oldSession.startTimestampMs,
math.max(oldSession.endTimestampMs, timestamps.max))
} else {
SessionInfo(timestamps.size, timestamps.min, timestamps.max)
}
state.update(updatedSession)
// Set timeout such that the session will be expired if no data received for 10 seconds
state.setTimeoutDuration("10 seconds")
SessionUpdate(sessionId, state.get.durationMs, state.get.numEvents, expired = false)
}
}
// Start running the query that prints the session updates to the console
val query = sessionUpdates
.writeStream
.outputMode("update")
.format("console")
.start()
query.awaitTermination()
}
}
/** User-defined data type representing the input events */
case class Event(sessionId: String, timestamp: Timestamp)
/**
* User-defined data type for storing a session information as state in mapGroupsWithState.
*
* @param numEvents total number of events received in the session
* @param startTimestampMs timestamp of first event received in the session when it started
* @param endTimestampMs timestamp of last event received in the session before it expired
*/
case class SessionInfo(
numEvents: Int,
startTimestampMs: Long,
endTimestampMs: Long) {
/** Duration of the session, between the first and last events */
def durationMs: Long = endTimestampMs - startTimestampMs
}
/**
* User-defined data type representing the update information returned by mapGroupsWithState.
*
* @param id Id of the session
* @param durationMs Duration the session was active, that is, from first event to its expiry
* @param numEvents Number of events received by the session while it was active
* @param expired Is the session active or expired
*/
case class SessionUpdate(
id: String,
durationMs: Long,
numEvents: Int,
expired: Boolean)
// scalastyle:on println