Both NextLink and NextNoBlock had the same logic, with slightly
different return values. By adding a bool return value (similar to map
lookups) we can remove the duplicate method.
The head of the topic buffer was being ignored when creating a snapshot. This commit fixes
the bug by ensuring that the head of the topic buffer is included in the snapshot
before handing it off to the subscription.
Makes Payload a type with FilterByKey so that Payloads can implement
filtering by key. With this approach we don't need to expose a Namespace
field on Event, and we don't need to invest micro formats or require a
bunch of code to be aware of exactly how the key field is encoded.
Move the subscription context to Next. context.Context should generally
never be stored in a struct because it makes that struct only valid
while the context is valid. This is rarely obvious from the caller.
Adds a forceClosed channel in place of the old context, and uses the new
context as a way for the caller to stop the Subscription blocking.
Remove some recursion out of bufferImte.Next. The caller is already looping so we can continue
in that loop instead of recursing. This ensures currentItem is updated immediately (which probably
does not matter in practice), and also removes the chance that we overflow the stack.
NextNoBlock and FollowAfter do not need to handle bufferItem.Err, the caller already
handles it.
Moves filter to a method to simplify Next, and more explicitly separate filtering from looping.
Also improve some godoc
Only unwrap itemBuffer.Err when necessary
Many of the fields are only needed in one place, and by using a closure
they can be removed from the struct. This reduces the scope of the variables
making it esier to see how they are used.
