Circuit Breakers and per event destinations

[Licenser]

Describe the problem you are trying to solve

We have circuit breakers that handle when destinations are down and reconnect when they're back up. This is great! We also have sinks that allow customizing the destination on a per event level. This is great too!

Together those two aren't great. When a sink chan have a different destination on a per-event level we can't know if the destination is up or down before we get the event so they can't send circuit breaker events :(

Describe the solution you'd like

• Identify affected sinks
  • udp
  • rest
  • ...
• see if this can be handled configurable (i.e. a flag "single destination + CB" vs. "multi destination - CB")

Notes

[mfelsche]

This will be fixed when we implement Stream Handling throughout the runtime and scope CB events either to the whole sink or to a single stream only. See also the Connectors and Streams RFC: tremor-rs/tremor-rfcs#32