Github user tdas commented on a diff in the pull request:
https://github.com/apache/spark/pull/7185#discussion_r34103210
--- Diff: python/pyspark/streaming/kafka.py ---
@@ -244,3 +263,87 @@ def __init__(self, host, port):
def _jBroker(self, helper):
return helper.createBroker(self._host, self._port)
+
+
+class KafkaRDD(RDD):
+ """
+ A Python wrapper of KafkaRDD, to provide additional information on
normal RDD.
+ """
+
+ def __init__(self, jrdd, ctx, jrdd_deserializer):
+ RDD.__init__(self, jrdd, ctx, jrdd_deserializer)
+
+ def offsetRanges(self):
+ """
+ Get the OffsetRange of specific KafkaRDD.
+ :return: A list of OffsetRange
+ """
+ try:
+ helperClass =
self.ctx._jvm.java.lang.Thread.currentThread().getContextClassLoader() \
+
.loadClass("org.apache.spark.streaming.kafka.KafkaUtilsPythonHelper")
+ helper = helperClass.newInstance()
+ joffsetRanges = helper.offsetRangesOfKafkaRDD(self._jrdd.rdd())
+ except Py4JJavaError as e:
+ if 'ClassNotFoundException' in str(e.java_exception):
+ KafkaUtils._printErrorMsg(self.ctx)
+ raise e
+
+ ranges = [OffsetRange(o.topic(), o.partition(), o.fromOffset(),
o.untilOffset())
+ for o in joffsetRanges]
+ return ranges
+
+
+class KafkaDStream(DStream):
+ """
+ A Python wrapper of KafkaDStream
+ """
+
+ def __init__(self, jdstream, ssc, jrdd_deserializer):
+ DStream.__init__(self, jdstream, ssc, jrdd_deserializer)
+
+ def foreachRDD(self, func):
+ """
+ Apply a function to each RDD in this DStream.
+ """
+ if func.__code__.co_argcount == 1:
+ old_func = func
+ func = lambda r, rdd: old_func(rdd)
+ jfunc = TransformFunction(self._sc, func, self._jrdd_deserializer)
\
+ .rdd_wrapper(lambda jrdd, ctx, ser: KafkaRDD(jrdd, ctx, ser))
+ api = self._ssc._jvm.PythonDStream
+ api.callForeachRDD(self._jdstream, jfunc)
+
+ def transform(self, func):
+ """
+ Return a new DStream in which each RDD is generated by applying a
function
+ on each RDD of this DStream.
+
+ `func` can have one argument of `rdd`, or have two arguments of
+ (`time`, `rdd`)
+ """
+ if func.__code__.co_argcount == 1:
+ oldfunc = func
+ func = lambda t, rdd: oldfunc(rdd)
+ assert func.__code__.co_argcount == 2, "func should take one or
two arguments"
+
+ return KafkaTransformedDStream(self, func)
+
+
+class KafkaTransformedDStream(TransformedDStream):
--- End diff --
LGTM, but I dnt understand the problem well enough to comment with full
conviction. I will let @davies check it out.
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