init() and cleanup() for Spark map functions

[Amit Sela <am...@gmail.com>]

I have a use case where I use Spark (streaming) as a way to distribute a
set of computations, which requires (some) of the computations to call an
external service.
Naturally, I'd like to manage my connections (per executor/worker).

I know this pattern for DStream:
https://people.apache.org/~pwendell/spark-nightly/spark-branch-2.0-docs/spark-2.0.1-SNAPSHOT-2016_07_21_04_05-f9367d6-docs/streaming-programming-guide.html#design-patterns-for-using-foreachrdd
and
I was wondering how I'd do the same for map functions ? as I would like to
"commit" the output iterator and only afterwards "return" my connection.
And generally, how's this going to work with Structured Streaming ?

Thanks,
Amit