fix: wait couple rounds for no pings to send an event

[Cifko]

Description

Wait couple rounds of no ping before sending the event.

How Has This Been Tested?

npm test -- --name "Full block sync with small reorg"
npm test -- --name "Pruned mode reorg simple"
npm test -- --name "Pruned mode reorg past horizon"

[sdbondi]

need to check that there are no pings (i.e. num_peers == 0)

[sdbondi]

Also suggest 3 rounds (~ 1 minute to decide on network silence) - the ping interval is currently set to 30s by default in the base node, so 10 will take too long

const NUM_ROUNDS_NETWORK_SILENCE: u16 = 3; // updated from 5

Suggested change

	if self.number_of_rounds_no_pings >= 10 {
	if self.number_of_rounds_no_pings >= NUM_ROUNDS_NETWORK_SILENCE {

[Cifko]

That's one of the questions I had prepared. If there are peers it should trigger the pings so the counter should be nullified.
Or should I nullify the counter when the num_peers are not zero? There are several ways to do this.
Should I nullify the number_of_rounds_no_pings once we call the send_chain_metadata_to_event_publisher or not.
i.e. should we send it everytime (since the limit is reached) or just from time to time?

[sdbondi]

Ah ok I see what you did, makes sense. I think that we should add a NetworkSilence event that gets emitted every time there are n rounds in a row that have no responses before the next one starts. The reason is, because if we get pings, then stop getting pings send_chain_metadata_to_event_publisher will carry on sending old metadata from previous rounds whereas NetworkSilence is more explicit. Obviously the listener will need to handle this event in the same way that it handles PeerChainMetadataReceived([]) (which will never be broadcast after this change). What do you think?

[Cifko]

Yeah, the NetworkSilence sounds really good. I've added the ChainMetadataEvent::NetworkSilence event.

[SWvheerden]

I also think we should reduce the NUM_ROUNDS_NETWORK_SILENCE to be around 3. That's basically 90 seconds of zero inbound or outbound comms. 10 rounds is around 10 minutes. That wont work for cucumber. But 90 seconds might not either. We might want to make this a config option and for cucumber make it like 10 seconds or so.

[Cifko]

It's 15 in the tests, 30 in the default_config in utils.rs (both for igor and weatherwax), Still 90 seconds is enough. I've change it to 3, and refactored it to the top as a constant.

[SWvheerden]

I like this approach so far.

My only comment is about the number of rounds and the time delay.