#
# 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
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# distributed under the License is distributed on an "AS IS" BASIS,
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"""
 Counts words in UTF8 encoded, '\n' delimited text received from the
 network every second.

 Usage: stateful_network_wordcount.py <hostname> <port>
   <hostname> and <port> 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/spark-submit examples/src/main/python/streaming/stateful_network_wordcount.py \
        localhost 9999`
"""

import sys

from pyspark import SparkContext
from pyspark.streaming import StreamingContext

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print >> sys.stderr, "Usage: stateful_network_wordcount.py <hostname> <port>"
        exit(-1)
    sc = SparkContext(appName="PythonStreamingStatefulNetworkWordCount")
    ssc = StreamingContext(sc, 1)
    ssc.checkpoint("checkpoint")

    def updateFunc(new_values, last_sum):
        return sum(new_values) + (last_sum or 0)

    lines = ssc.socketTextStream(sys.argv[1], int(sys.argv[2]))
    running_counts = lines.flatMap(lambda line: line.split(" "))\
                          .map(lambda word: (word, 1))\
                          .updateStateByKey(updateFunc)

    running_counts.pprint()

    ssc.start()
    ssc.awaitTermination()
