Incompatibility between handle tsdoc and implementation

[wemeetagain]

• Version:
  all

• Platform:
  all

• Subsystem:
  registrar

Severity:

medium (due to blatantly incorrect documentation)

Description:

o The tsdoc says you can override the existing handler by calling handle. but turns out it is an error to override an existing handler.

I don't see why replacing a handler should be an error.

[achingbrain]

I don't see why replacing a handler should be an error

If you have two services that register a handler for the same protocol, it'd be a last-update-wins situation which (for example) would make the functionality of your node dependent on the order of the services defined in the service map.

One day some well-wisher decides to put them into alphabetical order and then things mysteriously start to break.

Throwing an error if a handler is already registered means you have to explicitly un-register a previously registered handler first - the expectation is that an attempt to register two handlers for the same protocol is probably an error.

The docs should be updated though.

[nflaig]

Throwing an error if a handler is already registered means you have to explicitly un-register a previously registered handler first - the expectation is that an attempt to register two handlers for the same protocol is probably an error.

the use case in Lodestar is that we have to update the handlers across hard forks, I am not sure about the internals of unhandle but since handle is async I am not sure it's safe to re-register handlers on the fly.

Maybe a flag to by pass the error and allow override?

[wemeetagain]

unhandle+handle triggers self:peer:update which is not great because it will trigger identify-push which may have unintended consequences.

[achingbrain]

Maybe a flag to by pass the error and allow override?

A force flag sounds like a reasonable compromise. The user can opt-in if they know what they're doing then, and users that don't will still get the error message telling them they're doing something they might not realise they are doing.