Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/1195#discussion_r14306024
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/receiver/BlockGenerator.scala
---
@@ -48,6 +49,13 @@ private[streaming] class BlockGenerator(
private case class Block(id: StreamBlockId, buffer: ArrayBuffer[Any])
+ /**
+ * Internal representation of a callback function and its argument.
+ * @param function - The callback function
+ * @param arg - Argument to pass to pass to the function
+ */
+ private class Callback(val function: Any => Unit, val arg: Any)
--- End diff --
I don't know, this type feels weird to me. It feels like the the closure
itself should encapsulate any local data it needs, and any arguments here
should only be the ones that the caller of the callback is passing.
e.g.:
* if BlockGenerator does not pass any arguments to the callback, the
callback signature should be "() => Unit"
* if it passes a String, the signature should be "String => Unit"
In the call site, if the closure needs other data, that data can exist
locally and doesn't need to be known by this code, something along the lines of:
val somethingLocal = "foo"
bm.store(i, () => { println(somethingLocal) })
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