This is part of the work described by #7156. Remove "unbuffered subscriptions" from the pubsub service. Replace them with a dedicated blocking "observer" mechanism. Use the observer mechanism for indexing. Add a SubscribeWithArgs method and deprecate the old Subscribe method. Remove SubscribeUnbuffered entirely (breaking). Rework the Subscription interface to eliminate exposed channels. Subscriptions now use a context to manage lifecycle notifications. Internalize the eventbus package.
Tendermint RPC
Pagination
Requests that return multiple items will be paginated to 30 items by default. You can specify further pages with the ?page parameter. You can also set a custom page size up to 100 with the ?per_page parameter.
Subscribing to events
The user can subscribe to events emitted by Tendermint, using /subscribe. If
the maximum number of clients is reached or the client has too many
subscriptions, an error will be returned. The subscription timeout is 5 sec.
Each subscription has a buffer to accommodate short bursts of events or some
slowness in clients. If the buffer gets full, the subscription will be canceled
("client is not pulling messages fast enough"). If Tendermint exits, all
subscriptions are canceled ("Tendermint exited"). The user can unsubscribe
using either /unsubscribe or /unsubscribe_all.