Source code for pyspark.streaming.flume
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import sys
if sys.version >= "3":
from io import BytesIO
else:
from StringIO import StringIO
from py4j.java_gateway import Py4JJavaError
from pyspark.storagelevel import StorageLevel
from pyspark.serializers import PairDeserializer, NoOpSerializer, UTF8Deserializer, read_int
from pyspark.streaming import DStream
__all__ = ['FlumeUtils', 'utf8_decoder']
[docs]def utf8_decoder(s):
""" Decode the unicode as UTF-8 """
if s is None:
return None
return s.decode('utf-8')
[docs]class FlumeUtils(object):
@staticmethod
[docs] def createStream(ssc, hostname, port,
storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
enableDecompression=False,
bodyDecoder=utf8_decoder):
"""
Create an input stream that pulls events from Flume.
:param ssc: StreamingContext object
:param hostname: Hostname of the slave machine to which the flume data will be sent
:param port: Port of the slave machine to which the flume data will be sent
:param storageLevel: Storage level to use for storing the received objects
:param enableDecompression: Should netty server decompress input stream
:param bodyDecoder: A function used to decode body (default is utf8_decoder)
:return: A DStream object
"""
jlevel = ssc._sc._getJavaStorageLevel(storageLevel)
try:
helperClass = ssc._jvm.java.lang.Thread.currentThread().getContextClassLoader()\
.loadClass("org.apache.spark.streaming.flume.FlumeUtilsPythonHelper")
helper = helperClass.newInstance()
jstream = helper.createStream(ssc._jssc, hostname, port, jlevel, enableDecompression)
except Py4JJavaError as e:
if 'ClassNotFoundException' in str(e.java_exception):
FlumeUtils._printErrorMsg(ssc.sparkContext)
raise e
return FlumeUtils._toPythonDStream(ssc, jstream, bodyDecoder)
@staticmethod
[docs] def createPollingStream(ssc, addresses,
storageLevel=StorageLevel.MEMORY_AND_DISK_SER_2,
maxBatchSize=1000,
parallelism=5,
bodyDecoder=utf8_decoder):
"""
Creates an input stream that is to be used with the Spark Sink deployed on a Flume agent.
This stream will poll the sink for data and will pull events as they are available.
:param ssc: StreamingContext object
:param addresses: List of (host, port)s on which the Spark Sink is running.
:param storageLevel: Storage level to use for storing the received objects
:param maxBatchSize: The maximum number of events to be pulled from the Spark sink
in a single RPC call
:param parallelism: Number of concurrent requests this stream should send to the sink.
Note that having a higher number of requests concurrently being pulled
will result in this stream using more threads
:param bodyDecoder: A function used to decode body (default is utf8_decoder)
:return: A DStream object
"""
jlevel = ssc._sc._getJavaStorageLevel(storageLevel)
hosts = []
ports = []
for (host, port) in addresses:
hosts.append(host)
ports.append(port)
try:
helperClass = ssc._jvm.java.lang.Thread.currentThread().getContextClassLoader() \
.loadClass("org.apache.spark.streaming.flume.FlumeUtilsPythonHelper")
helper = helperClass.newInstance()
jstream = helper.createPollingStream(
ssc._jssc, hosts, ports, jlevel, maxBatchSize, parallelism)
except Py4JJavaError as e:
if 'ClassNotFoundException' in str(e.java_exception):
FlumeUtils._printErrorMsg(ssc.sparkContext)
raise e
return FlumeUtils._toPythonDStream(ssc, jstream, bodyDecoder)
@staticmethod
def _toPythonDStream(ssc, jstream, bodyDecoder):
ser = PairDeserializer(NoOpSerializer(), NoOpSerializer())
stream = DStream(jstream, ssc, ser)
def func(event):
headersBytes = BytesIO(event[0]) if sys.version >= "3" else StringIO(event[0])
headers = {}
strSer = UTF8Deserializer()
for i in range(0, read_int(headersBytes)):
key = strSer.loads(headersBytes)
value = strSer.loads(headersBytes)
headers[key] = value
body = bodyDecoder(event[1])
return (headers, body)
return stream.map(func)
@staticmethod
def _printErrorMsg(sc):
print("""
________________________________________________________________________________________________
Spark Streaming's Flume libraries not found in class path. Try one of the following.
1. Include the Flume library and its dependencies with in the
spark-submit command as
$ bin/spark-submit --packages org.apache.spark:spark-streaming-flume:%s ...
2. Download the JAR of the artifact from Maven Central http://search.maven.org/,
Group Id = org.apache.spark, Artifact Id = spark-streaming-flume-assembly, Version = %s.
Then, include the jar in the spark-submit command as
$ bin/spark-submit --jars <spark-streaming-flume-assembly.jar> ...
________________________________________________________________________________________________
""" % (sc.version, sc.version))
