It doesn't store id->hash mappings for native contracts. We need blockchain's
GetContractScriptHash to serve both anyway, so it was changed a bit. The only
other direct user of native.GetContractScriptHash is the VM CLI, but I doubt
anyone will use it for native contracts (they have ~zero VM code anyway).
It's more generic and convenient than MillisecondsPerBlock. This setting is
made in backwards-compatible fashion, but it'll override SecondsPerBlock if
both are used. Configurations are specifically not changed here, it's
important to check compatibility.
Fixes#2675.
Follow neo-project/neo#2807. Notice that this data is not cached, our previous
implementation wasn't too and it shouldn't be a problem (not on the hot path).
Do not block subscribers until the unsubscription request to RPC server
is completed. Otherwise, another notification may be received from the
RPC server which will block the unsubscription process.
At the same time, fix event-based waiter. We must not block the receiver
channel during unsubscription because there's a chance that subsequent
event will be sent by the server. We need to read this event in order not
to block the WSClient's readloop.
