In this commit, we fix a lingering bug related to the way that we
deliver block epoch notifications to end users. Before this commit, we
would launch a new goroutine for *each block*. This was done in order
to ensure that the notification dispatch wouldn’t block the main
goroutine that was dispatching the notifications. This method archived
the goal, but had a nasty side effect that the goroutines could be
re-ordered during scheduling, meaning that in the case of fast
successive blocks, then notifications would be delivered out of order.
Receiving out of order notifications is either disallowed, or can cause
sub-systems that rely on these notifications to get into weird states.
In order to fix this issue, we’ll no longer launch a new goroutine to
deliver each notification to an awaiting client. Instead, each client
will now gain a concurrent in-order queue for notification delivery.
Due to the internal design of chainntnfs.ConcurrentQueue, the caller
should never block, yet the receivers will receive notifications in
order. This change solves the re-ordering issue and also minimizes the
number of goroutines that we’ll create in order to deliver block epoch
notifications.
In this commit, we fix an issue that was recently introduced to the way
we handle historical dispatches for the neutrino notifier. In a recent
change, we no return an error if we’re unable to actually find the
transaction that spends an outpoint. If this is the case, then the
outpoint is actually unspent, and we should proceed as normal.
In this commit, we fix an existing bug within the logic of the neutrino
notifier. Rather than properly dispatching only once a transaction had
reached the expected number of confirmations, the historical dispatch
logic would trigger as soon as the transaction reached a single
confirmation.
This was due to the fact that we were using the scanHeight variable
which would be set to zero to calculate the number of confirmations.
The value would end up being the current height, which is generally
always greater than the number of expected confirmations. To remedy
this, we’ll now properly use the block height the transaction was
originally confirmed in to know when to dispatch.
This also applies a fix that was discovered in
93981a85c0b47622a3a5e7089b8bca9b80b834c5.
This commit adds an initial rough implementation father ChainNotifier
interface for neutrino, our new light client implementation. This
implementation largely borrows from the existing BtcdNotifier
implementation. As a result, a follow up commit will perform two
refactoring in order to further consolidate code.
