Fixes#481.
Prior to this commit, payments stored in the channel DB only kept a
record of the payment hash. This is a problem as the preimage is what
serves as proof of payment and a user should be able to look up this
value in the future (not just immediately after payment).
Instead of storing both the payment hash and the preimage, we store the
preimage only since the hash can be derrived from this using a SHA256.
In the RPC listpayments command, we now give the preimage in addition to
the payment hash.
This commit implements an easy optimization by using bolt db’s Batch
method when writing payment details to disk. The AddPaymnent method can
be concurrently called by thousands of grouting due to the way the
payment dispatch pipeline is architected. With this commit, we shave of
a significant amount of running time when users are sending thousands
of payments a second as what would’ve been thousands of writes can now
be coalesced into one or two writes!
This commit modifies the new payment module within the database to
match the coding style of the rest of the package and the project as a
hole. Additionally, a few fields have been renamed, and the extra
timestamp added to the OutgoingPayment struct has been removed as
there’s already a CreationTime field within the Invoice struct that’s
embedded within the OutgoingPayment struct.
Go-fmt files. Refactored code according to the guidelines.
Enhanced payment test: add error checking
and individual context for each API call.
Add Timestamp field to payment struct.
