This commit adds a new method to enable us resending the blockbeat in
`ChainArbitrator`, which is needed for the channel restore as the chain
watcher and channel arbitrator are added after the start of the chain
arbitrator.
This commit moves the creation of the spending notification from `Start`
to `newChainWatcher` so we subscribe the spending event before handling
the block, which is needed to properly handle the blockbeat.
We need to offer the outgoing htlc one block earlier to make sure when
the expiry height hits, the sweeper will not miss sweeping it in the
same block. This also means the outgoing contest resolver now only does
one thing - watch for preimage spend till height expiry-1, which can
easily be moved into the timeout resolver instead in the future.
In this commit, we break the old `launchResolvers` into two steps - step
one is to launch the resolvers synchronously, and step two is to
actually waiting for the resolvers to be resolved. This is critical as
in the following commit we will require the resolvers to be launched at
the same blockbeat when a force close event is sent by the chain watcher.
When calling `NotifyExitHopHtlc` it is allowed to pass a chan to
subscribe to the HTLC's resolution when it's settled. However, this
method will also return immediately if there's already a resolution,
which means it behaves like a notifier and a getter. If the caller
decides to only use the getter to do a non-blocking lookup, it can pass
a nil subscriber chan to bypass the notification.
This commit breaks the `Resolve` into two parts - the first part is
moved into a `Launch` method that handles sending sweep requests, and
the second part remains in `Resolve` which handles waiting for the
spend. Since we are using both utxo nursery and sweeper at the same
time, to make sure this change doesn't break the existing behavior, we
implement the `Launch` as following,
- zero-fee htlc - handled by the sweeper
- direct output from the remote commit - handled by the sweeper
- legacy htlc - handled by the utxo nursery
This commit breaks the `Resolve` into two parts - the first part is
moved into a `Launch` method that handles sending sweep requests, and
the second part remains in `Resolve` which handles waiting for the
spend. Since we are using both utxo nursery and sweeper at the same
time, to make sure this change doesn't break the existing behavior, we
implement the `Launch` as following,
- zero-fee htlc - handled by the sweeper
- direct output from the remote commit - handled by the sweeper
- legacy htlc - handled by the utxo nursery
We will use this and its following commits to break the original
`Resolve` methods into two parts - the first part is moved to a new
method `Launch`, which handles sending a sweep request to the sweeper.
The second part remains in `Resolve`, which is mainly waiting for a
spending tx.
Breach resolver currently doesn't do anything in its `Launch` since the
sweeping of justice outputs are not handled by the sweeper yet.
This `immediate` flag was added as a hack so during a restart, the
pending resolvers would offer the inputs to the sweeper and ask it to
sweep them immediately. This is no longer need due to `blockbeat`, as
now during restart, a block is always sent to all subsystems via the
flow `ChainArb` -> `ChannelArb` -> resolvers -> sweeper. Thus, when
there are pending inputs offered, they will be processed by the sweeper
immediately.
The sweeper can handle the waiting so there's no need to wait for blocks
inside the resolvers. By offering the inputs prior to their mature
heights also guarantees the inputs with the same deadline are
aggregated.
When notifying the invoice registry for an exit hop htlc we also want to
include its custom records. The channelLink, the other caller of this
method, already populates this field. So we make sure the contest
resolver does so too.
In this commit, we add a rapid derived fuzz test for the HtlcAuxBlob
test. This uses the rapid (randomized property testing) into Go's built
in fuzzer. This wrapper will use the fuzz stream, and pass that into
rapid where the stream is used to make structured test inputs which are
tested against the existing properties.
This can be done more widely in the codebase, we pick a simple example
to port first before tackling others.
