Trait lightning::chain::Watch

pub trait Watch<ChannelSigner: WriteableEcdsaChannelSigner> {
    // Required methods
    fn watch_channel(
        &self,
        funding_txo: OutPoint,
        monitor: ChannelMonitor<ChannelSigner>
    ) -> ChannelMonitorUpdateStatus;
    fn update_channel(
        &self,
        funding_txo: OutPoint,
        update: &ChannelMonitorUpdate
    ) -> ChannelMonitorUpdateStatus;
    fn release_pending_monitor_events(
        &self
    ) -> Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)>;
}

The Watch trait defines behavior for watching on-chain activity pertaining to channels as blocks are connected and disconnected.

Each channel is associated with a ChannelMonitor. Implementations of this trait are responsible for maintaining a set of monitors such that they can be updated accordingly as channel state changes and HTLCs are resolved. See method documentation for specific requirements.

Implementations must ensure that updates are successfully applied and persisted upon method completion. If an update fails with a PermanentFailure, then it must immediately shut down without taking any further action such as persisting the current state.

If an implementation maintains multiple instances of a channel’s monitor (e.g., by storing backup copies), then it must ensure that updates are applied across all instances. Otherwise, it could result in a revoked transaction being broadcast, allowing the counterparty to claim all funds in the channel. See ChannelMonitorUpdateStatus for more details about how to handle multiple instances.

Required Methods

fn watch_channel( &self, funding_txo: OutPoint, monitor: ChannelMonitor<ChannelSigner> ) -> ChannelMonitorUpdateStatus

Watches a channel identified by funding_txo using monitor.

Implementations are responsible for watching the chain for the funding transaction along with any spends of outputs returned by get_outputs_to_watch. In practice, this means calling block_connected and block_disconnected on the monitor.

Note: this interface MUST error with ChannelMonitorUpdateStatus::PermanentFailure if the given funding_txo has previously been registered via watch_channel.

fn update_channel( &self, funding_txo: OutPoint, update: &ChannelMonitorUpdate ) -> ChannelMonitorUpdateStatus

Updates a channel identified by funding_txo by applying update to its monitor.

Implementations must call update_monitor with the given update. See ChannelMonitorUpdateStatus for invariants around returning an error.

fn release_pending_monitor_events( &self ) -> Vec<(OutPoint, Vec<MonitorEvent>, Option<PublicKey>)>

Returns any monitor events since the last call. Subsequent calls must only return new events.

Note that after any block- or transaction-connection calls to a ChannelMonitor, no further events may be returned here until the ChannelMonitor has been fully persisted to disk.

For details on asynchronous ChannelMonitor updating and returning MonitorEvent::Completed here, see ChannelMonitorUpdateStatus::InProgress.

Implementors

impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>where C::Target: Filter, T::Target: BroadcasterInterface, F::Target: FeeEstimator, L::Target: Logger, P::Target: Persist<ChannelSigner>,