feat(sync_handlers): send partial db getter results asap

[CHr15F0x]

We don't need to "collect" all results for the requested range before sending them to the p2p loop for forwarding.

[Mirko-von-Leipzig]

Might be a dumb question: but why do we need flume for this? Would a normal channel not suffice?

[CHr15F0x]

Would a normal channel not suffice?

The "normal" channel is currently a futures::channel, for which the sender only implements a non-async try_send so we would have to implement error handling and retrying in a smart way to avoid busy looping in the thread from the tokio blocking thread pool which imo is not worth it.

[Mirko-von-Leipzig]

Would a normal channel not suffice?

The "normal" channel is currently a futures::channel, for which the sender only implements a non-async try_send so we would have to implement error handling and retrying in a smart way to avoid busy looping in the thread from the tokio blocking thread pool which imo is not worth it.

Does this mean we should grep for other blocking usage of tokio channels to replace them?

[CHr15F0x]

Flume was not required, following an offline discussion with @Mirko-von-Leipzig , I've switched to tokio::mpsc and then Sender::blocking_send.