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.
In this commit we start to break up the starting process into smaller
pieces, which is needed in the following commit to initialize blockbeat
consumers.
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.
This commit removes the hack introduced in #4851. Previously we had this
issue because the chain notifier was stopped before the sweeper, which
was changed a while back and we now always stop the chain notifier last.
In addition, since we no longer subscribe to the block epoch chan
directly, this issue can no longer happen.
This commit removes the independent block subscriptions in `UtxoSweeper`
and `TxPublisher`. These subsystems now listen to the `BlockbeatChan`
for new blocks.
In this commit, a minimal implementation of `Blockbeat` is added to
synchronize block heights, which will be used in `ChainArb`, `Sweeper`,
and `TxPublisher` so blocks are processed sequentially among them.
This commit inits the package `chainio` and defines the interface
`Blockbeat` and `Consumer`. The `Consumer` must be implemented by other
subsystems if it requires block epoch subscription.
