[OPNFLWPLUG-174] Implement ingress back pressure based on netty channel-autoread

Blocks — Mon, 27 Sep 2021 09:01:12 +0000

Strategy proposal:

netty delivers message to connectionConductor (e.g.: onPacketInMessage())
put message into per-connection-queue (Queue.offer())
if queue is full then
store the message into local slot
invoke stopReading() on corresponding channel (still in netty thread)
and return Future<Void> with having value set only after 50% of queue is free
hook up a listener on this future which once the future value is set:
turns on channel reading
and enqueues the message in local slot into queue
return thread to OFJava/Netty (expect no more messages will arrive)
else return thread in order to deliver next message

QueueKeeper's push method wont be accessed by Netty's thread in ConnectionConductor.on* methods but queueKeeper will sequentially poll each per-connection-queue taking one item per turn using it's own thread. This way flooding by one device or connection is suppressed and all messages are enqueued fair.

OpenDaylight JIRA

[OPNFLWPLUG-174] Implement ingress back pressure based on netty channel-autoread