Github user brkyvz commented on a diff in the pull request: https://github.com/apache/spark/pull/17539#discussion_r109959911 --- Diff: examples/src/main/java/org/apache/spark/examples/sql/streaming/JavaStructuredSessionization.java --- @@ -0,0 +1,258 @@ +/* + * 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.examples.sql.streaming; + +import org.apache.spark.api.java.function.FlatMapFunction; +import org.apache.spark.api.java.function.MapFunction; +import org.apache.spark.api.java.function.MapGroupsWithStateFunction; +import org.apache.spark.sql.*; +import org.apache.spark.sql.streaming.GroupState; +import org.apache.spark.sql.streaming.GroupStateTimeout; +import org.apache.spark.sql.streaming.StreamingQuery; + +import java.io.Serializable; +import java.sql.Timestamp; +import java.util.*; + +import scala.Tuple2; + +/** + * Counts words in UTF8 encoded, '\n' delimited text received from the network. + * <p> + * Usage: JavaStructuredNetworkWordCount <hostname> <port> + * <hostname> and <port> describe the TCP server that Structured Streaming + * would connect to receive data. + * <p> + * 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.JavaStructuredSessionization + * localhost 9999` + */ +public final class JavaStructuredSessionization { + + public static void main(String[] args) throws Exception { + if (args.length < 2) { + System.err.println("Usage: JavaStructuredSessionization <hostname> <port>"); + System.exit(1); + } + + String host = args[0]; + int port = Integer.parseInt(args[1]); + + SparkSession spark = SparkSession + .builder() + .appName("JavaStructuredSessionization") + .getOrCreate(); + + // Create DataFrame representing the stream of input lines from connection to host:port + Dataset<Row> lines = spark + .readStream() + .format("socket") + .option("host", host) + .option("port", port) + .option("includeTimestamp", true) + .load(); + + FlatMapFunction<LineWithTimestamp, Event> linesToEvents = + new FlatMapFunction<LineWithTimestamp, Event>() { + @Override + public Iterator<Event> call(LineWithTimestamp lineWithTimestamp) throws Exception { + ArrayList<Event> eventList = new ArrayList<Event>(); + for (String word : lineWithTimestamp.getLine().split(" ")) { + eventList.add(new Event(word, lineWithTimestamp.getTimestamp())); + } + System.out.println( + "Number of events from " + lineWithTimestamp.getLine() + " = " + eventList.size()); + return eventList.iterator(); + } + }; + + // Split the lines into words, treat words as sessionId of events + Dataset<Event> events = lines + .withColumnRenamed("value", "line") + .as(Encoders.bean(LineWithTimestamp.class)) + .flatMap(linesToEvents, Encoders.bean(Event.class)); + + // Sessionize the events. Track number of events, start and end timestamps of session, and + // and report session updates. + // + // Step 1: Define the state update function + MapGroupsWithStateFunction<String, Event, SessionInfo, SessionUpdate> stateUpdateFunc = + new MapGroupsWithStateFunction<String, Event, SessionInfo, SessionUpdate>() { + @Override public SessionUpdate call( + String sessionId, Iterator<Event> events, GroupState<SessionInfo> state) + throws Exception { + // If timed out, then remove session and send final update + if (state.hasTimedOut()) { + SessionUpdate finalUpdate = new SessionUpdate( + sessionId, state.get().getDurationMs(), state.get().getNumEvents(), true); + state.remove(); + return finalUpdate; + + } else { + // Find max and min timestamps in events + long maxTimestampMs = Long.MIN_VALUE; + long minTimestampMs = Long.MAX_VALUE; + int numNewEvents = 0; + while (events.hasNext()) { + Event e = events.next(); + long timestampMs = e.getTimestamp().getTime(); + maxTimestampMs = Math.max(timestampMs, maxTimestampMs); + minTimestampMs = Math.min(timestampMs, minTimestampMs); + numNewEvents += 1; + } + SessionInfo updatedSession = new SessionInfo(); + + // Update start and end timestamps in session + if (state.exists()) { + SessionInfo oldSession = state.get(); + updatedSession.setNumEvents(oldSession.numEvents + numNewEvents); + updatedSession.setStartTimestampMs(oldSession.startTimestampMs); + updatedSession.setEndTimestampMs(Math.max(oldSession.endTimestampMs, maxTimestampMs)); + } else { + updatedSession.setNumEvents(numNewEvents); + updatedSession.setStartTimestampMs(minTimestampMs); + updatedSession.setEndTimestampMs(maxTimestampMs); + } + state.update(updatedSession); + // Set timeout such that the session will be expired if no data received for 10 seconds + state.setTimeoutDuration("10 seconds"); + return new SessionUpdate( + sessionId, state.get().getDurationMs(), state.get().getNumEvents(), false); + } + } + }; + + // Step 2: Apply the state update function to the events streaming Dataset grouped by sessionId + Dataset<SessionUpdate> sessionUpdates = events + .groupByKey( + new MapFunction<Event, String>() { + @Override public String call(Event event) throws Exception { + return event.getSessionId(); + } + }, Encoders.STRING()) + .mapGroupsWithState( + stateUpdateFunc, + Encoders.bean(SessionInfo.class), + Encoders.bean(SessionUpdate.class), + GroupStateTimeout.ProcessingTimeTimeout()); + + // Start running the query that prints the session updates to the console + StreamingQuery query = sessionUpdates + .writeStream() + .outputMode("update") + .format("console") + .start(); + + query.awaitTermination(); + } + + /** + * User-defined data type representing the raw lines with timestamps. + */ + public static class LineWithTimestamp implements Serializable { + private String line; + private Timestamp timestamp; + + public Timestamp getTimestamp() { return timestamp; } + public void setTimestamp(Timestamp timestamp) { this.timestamp = timestamp; } + + public String getLine() { return line; } + public void setLine(String sessionId) { this.line = sessionId; } + } + + /** + * User-defined data type representing the input events + */ + public static class Event implements Serializable { + private String sessionId; + private Timestamp timestamp; + + public Event() { } + public Event(String sessionId, Timestamp timestamp) { + this.sessionId = sessionId; + this.timestamp = timestamp; + } + + public Timestamp getTimestamp() { return timestamp; } + public void setTimestamp(Timestamp timestamp) { this.timestamp = timestamp; } + + public String getSessionId() { return sessionId; } + public void setSessionId(String sessionId) { this.sessionId = sessionId; } + } + + /** + * User-defined data type for storing a session information as state in mapGroupsWithState. + */ + public static class SessionInfo implements Serializable { + private int numEvents = 0; + private long startTimestampMs = -1; + private long endTimestampMs = -1; + + public int getNumEvents() { return numEvents; } + public void setNumEvents(int numEvents) { this.numEvents = numEvents; } + + public long getStartTimestampMs() { return startTimestampMs; } + public void setStartTimestampMs(long startTimestampMs) { + this.startTimestampMs = startTimestampMs; + } + + public long getEndTimestampMs() { return endTimestampMs; } + public void setEndTimestampMs(long endTimestampMs) { this.endTimestampMs = endTimestampMs; } + + public long getDurationMs() { return endTimestampMs - startTimestampMs; } + @Override public String toString() { + return "SessionInfo(numEvents = " + numEvents + + ", timestamps = " + startTimestampMs + " to " + endTimestampMs + ")"; + } + } + + /** + * User-defined data type representing the update information returned by mapGroupsWithState. + */ + public static class SessionUpdate implements Serializable { + private String id; + private long durationMs; + private int numEvents; + private boolean expired; + + public SessionUpdate() { } + + public SessionUpdate(String id, long durationMs, int numEvents, boolean expired) { + this.id = id; + this.durationMs = durationMs; + this.numEvents = numEvents; + this.expired = expired; + } + + public String getId() { return id; } + public void setId(String id) { this.id = id; } + + public long getDurationMs() { return durationMs; } + public void setDurationMs(long durationMs) { this.durationMs = durationMs; } + + public int getNumEvents() { return numEvents; } + public void setNumEvents(int numEvents) { this.numEvents = numEvents; } + + public boolean isExpired() { return expired; } + public void setExpired(boolean expired) { this.expired = expired; } + } +} + --- End diff -- nit: extra lines
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