Module Rpc_effect_kernel.On_conn_failure

Persistent connections reuse a single connection. If there's a failure to connect, it will wait a bit, then attempt to re-establish the connection.

On connection failure, our RPC can either wait until some retry attempt succeeds, or treat the failure as an error.

For almost all polling RPCs, and most one-shot RPCs, Surface_error_to_rpc is preferable. However, with one-shot RPCs, you might then want to repeatedly retry the RPC until it succeeds. The Retry_until_success option can be useful here, but if the connection never succeeds, the effect will never resolve.