Github user JoshRosen commented on a diff in the pull request:
https://github.com/apache/spark/pull/2538#discussion_r18554420
--- Diff: python/pyspark/streaming/util.py ---
@@ -0,0 +1,113 @@
+#
+# 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.
+#
+
+import time
+from datetime import datetime
+import traceback
+
+from pyspark import SparkContext, RDD
+
+
+class TransformFunction(object):
+ """
+ This class is for py4j callback.
--- End diff --
This `TransformFunction` (and its Java counterpart) is one of the most
complex parts of the PySpark Streaming code, so it would help to have some
additional documentation explaining how it works.
To confirm my understanding:
> This class wraps a function `RDD[X] -> RDD[Y]` that was passed to
`DStream.transform()`, allowing it to be called from Java via Py4J's callback
server. Java calls this function with a sequence of JavaRDDs and this function
returns a single JavaRDD pointer back to Java.
Is that an accurate summary?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
