When a connection that's subscribe to a channel emits PUBLISH inside MULTI-EXEC,
the push notification messes up the EXEC response.
e.g. MULTI, PING, PUSH foo bar, PING, EXEC
the EXEC's response will contain: PONG, {message foo bar}, 1. and the second PONG
will be delivered outside the EXEC's response.
Additionally, this PR changes the order of responses in case of a plain PUBLISH (when
the current client also subscribed to it), by delivering the push after the command's
response instead of before it.
This also affects modules calling RM_PublishMessage in a similar way, so that we don't
run the risk of getting that push mixed together with the module command's response.
To easily distinguish between sharded channel message and a global
channel message, introducing `smessage` (instead of `message`) as
message bulk for sharded channel publish message.
This is gonna be a breaking change in 7.0.1!
Background:
Sharded pubsub introduced in redis 7.0, but after the release we quickly
realized that the fact that it's problematic that the client can't distinguish
between normal (global) pubsub messages and sharded ones.
This is important because the same connection can subscribe to both,
but messages sent to one pubsub system are not propagated to the
other (they're completely separate), so if one connection is used to
subscribe to both, we need to assist the client library to know which
message it got so it can forward it to the correct callback.
since PUBLISH and SPUBLISH use different dictionaries for channels and clients,
and we already have an API for PUBLISH, it only makes sense to have one for SPUBLISH
Add test coverage and unifying some test infrastructure.