This commit adds height-based invoice expiry for hodl invoices
that have active htlcs. This allows us to cancel our intentionally
held htlcs before channels are force closed. We only add this for
hodl invoices because we expect regular invoices to automatically
be resolved.
We still keep hodl invoices in the time-based expiry queue,
because we want to expire open invoices that reach their timeout
before any htlcs are added. Since htlcs are added after the
invoice is created, we add new htlcs as they arrive in the
invoice registry. In this commit, we allow adding of duplicate
entries for an invoice to be added to the expiry queue as each
htlc arrives to keep implementation simple. Our cancellation
logic can already handle the case where an entry is already
canceled, so this is ok.
This commit adds channeldb.ScanInvoices to scan through all invoices in
the database. The new call will also replace the already existing
channeldb.FetchAllInvoicesWithPaymentHash call in preparation to collect
invoices we'd like to delete and watch for expiry in one scan in later
commits.
Adds a new configuration flag to lnd that will keep keysend payments in
the accepted state. An application can then inspect the payment
parameters and decide whether to settle or cancel.
The on-the-fly inserted keysend invoices get a configurable expiry time.
This is a safeguard in case the application that should decide on the
keysend payments isn't active.
This commit intends to fix slow first startup time when there are many
invoices that need to be canceled. The slowdown is caused by a combination
of adding invoices to the expiry watcher one-by-one and slow
cancellation. Due to slow cancellation and the unbuffered channel which
we use to pass invoices to the expiry watcher blocks the registry.
With this fix we'll instead batch add invoices to the expiry watcher and
thereby won't block the registry startup.
This commit adds InvoiceExpryWatcher which is a separate class that
receives new invoices (and existing ones upon restart) from InvoiceRegistry
and actively watches their expiry. When an invoice is expired
InvoiceExpiryWatcher will call into InvoiceRegistry to cancel the
invoice and by that notify all subscribers about the state change.
