Struct ChainMonitor

pub struct ChainMonitor<ChannelSigner, C, T, F, L, P>
where
    ChannelSigner: EcdsaChannelSigner,
    C: Deref,
    T: Deref,
    F: Deref,
    L: Deref,
    P: Deref,
    <C as Deref>::Target: Filter,
    <T as Deref>::Target: BroadcasterInterface,
    <F as Deref>::Target: FeeEstimator,
    <L as Deref>::Target: Logger,
    <P as Deref>::Target: Persist<ChannelSigner>,
{ /* private fields */ }

An implementation of chain::Watch for monitoring channels.

Connected and disconnected blocks must be provided to ChainMonitor as documented by chain::Watch. May be used in conjunction with ChannelManager to monitor channels locally or used independently to monitor channels remotely. See the module-level documentation for details.

Note that ChainMonitor should regularly trigger rebroadcasts/fee bumps of pending claims from a force-closed channel. This is crucial in preventing certain classes of pinning attacks, detecting substantial mempool feerate changes between blocks, and ensuring reliability if broadcasting fails. We recommend invoking this every 30 seconds, or lower if running in an environment with spotty connections, like on mobile.

Implementations

impl<ChannelSigner, C, T, F, L, P> ChainMonitor<ChannelSigner, C, T, F, L, P>

where ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref, <C as Deref>::Target: Filter, <T as Deref>::Target: BroadcasterInterface, <F as Deref>::Target: FeeEstimator, <L as Deref>::Target: Logger, <P as Deref>::Target: Persist<ChannelSigner>,

pub fn new( chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P, ) -> ChainMonitor<ChannelSigner, C, T, F, L, P>

Creates a new ChainMonitor used to watch on-chain activity pertaining to channels.

When an optional chain source implementing chain::Filter is provided, the chain monitor will call back to it indicating transactions and outputs of interest. This allows clients to pre-filter blocks or only fetch blocks matching a compact filter. Otherwise, clients may always need to fetch full blocks absent another means for determining which blocks contain transactions relevant to the watched channels.

pub fn get_claimable_balances( &self, ignored_channels: &[&ChannelDetails], ) -> Vec<Balance>

Gets the balances in the contained ChannelMonitors which are claimable on-chain or claims which are awaiting confirmation.

Includes the balances from each ChannelMonitor except those included in ignored_channels.

See ChannelMonitor::get_claimable_balances for more details on the exact criteria for inclusion in the return value.

pub fn get_monitor( &self, funding_txo: OutPoint, ) -> Result<LockedChannelMonitor<'_, ChannelSigner>, ()>

Gets the LockedChannelMonitor for a given funding outpoint, returning an Err if no such ChannelMonitor is currently being monitored for.

Note that the result holds a mutex over our monitor set, and should not be held indefinitely.

pub fn list_monitors(&self) -> Vec<(OutPoint, ChannelId)>

Lists the funding outpoint and channel ID of each ChannelMonitor being monitored.

Note that ChannelMonitors are not removed when a channel is closed as they are always monitoring for on-chain state resolutions.

pub fn list_pending_monitor_updates(&self) -> HashMap<OutPoint, Vec<u64>>

Lists the pending updates for each ChannelMonitor (by OutPoint being monitored). Each Vec<u64> contains update_ids from ChannelMonitor::get_latest_update_id for updates that have not yet been fully persisted. Note that if a full monitor is persisted all the pending monitor updates must be individually marked completed by calling ChainMonitor::channel_monitor_updated.

pub fn channel_monitor_updated( &self, funding_txo: OutPoint, completed_update_id: u64, ) -> Result<(), APIError>

Indicates the persistence of a ChannelMonitor has completed after ChannelMonitorUpdateStatus::InProgress was returned from an update operation.

Thus, the anticipated use is, at a high level:

1. This ChainMonitor calls Persist::update_persisted_channel which stores the update to disk and begins updating any remote (e.g. watchtower/backup) copies, returning ChannelMonitorUpdateStatus::InProgress,
2. once all remote copies are updated, you call this function with ChannelMonitor::get_latest_update_id or ChannelMonitorUpdate::update_id as the completed_update_id, and once all pending updates have completed the channel will be re-enabled.

It is only necessary to call ChainMonitor::channel_monitor_updated when you return ChannelMonitorUpdateStatus::InProgress from Persist and either:

1. A new ChannelMonitor was added in Persist::persist_new_channel, or
2. A ChannelMonitorUpdate was provided as part of Persist::update_persisted_channel. Note that we don’t care about calls to Persist::update_persisted_channel where no ChannelMonitorUpdate was provided.

Returns an APIError::APIMisuseError if funding_txo does not match any currently registered ChannelMonitors.

pub async fn process_pending_events_async<Future, H>(&self, handler: H)

where Future: Future<Output = Result<(), ReplayEvent>>, H: Fn(Event) -> Future,

Processes any events asynchronously in the order they were generated since the last call using the given event handler.

See the trait-level documentation of EventsProvider for requirements.

pub fn get_update_future(&self) -> Future

Gets a Future that completes when an event is available either via chain::Watch::release_pending_monitor_events or EventsProvider::process_pending_events.

Note that callbacks registered on the Future MUST NOT call back into this ChainMonitor and should instead register actions to be taken later.

pub fn rebroadcast_pending_claims(&self)

Triggers rebroadcasts/fee-bumps of pending claims from a force-closed channel. This is crucial in preventing certain classes of pinning attacks, detecting substantial mempool feerate changes between blocks, and ensuring reliability if broadcasting fails. We recommend invoking this every 30 seconds, or lower if running in an environment with spotty connections, like on mobile.

pub fn signer_unblocked(&self, monitor_opt: Option<OutPoint>)

Triggers rebroadcasts of pending claims from force-closed channels after a transaction signature generation failure.

monitor_opt can be used as a filter to only trigger them for a specific channel monitor.

pub fn archive_fully_resolved_channel_monitors(&self)

Archives fully resolved channel monitors by calling Persist::archive_persisted_channel.

This is useful for pruning fully resolved monitors from the monitor set and primary storage so they are not kept in memory and reloaded on restart.

Should be called occasionally (once every handful of blocks or on startup).

Depending on the implementation of Persist::archive_persisted_channel the monitor data could be moved to an archive location or removed entirely.

Trait Implementations

impl<ChannelSigner, C, T, F, L, P> Confirm for ChainMonitor<ChannelSigner, C, T, F, L, P>

where ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref, <C as Deref>::Target: Filter, <T as Deref>::Target: BroadcasterInterface, <F as Deref>::Target: FeeEstimator, <L as Deref>::Target: Logger, <P as Deref>::Target: Persist<ChannelSigner>,

fn transactions_confirmed( &self, header: &Header, txdata: &[(usize, &Transaction)], height: u32, )

Notifies LDK of transactions confirmed in a block with a given header and height.

fn transaction_unconfirmed(&self, txid: &Txid)

Notifies LDK of a transaction that is no longer confirmed as result of a chain reorganization.

fn best_block_updated(&self, header: &Header, height: u32)

Notifies LDK of an update to the best header connected at the given height.

fn get_relevant_txids(&self) -> Vec<(Txid, u32, Option<BlockHash>)>

Returns transactions that must be monitored for reorganization out of the chain along with the height and the hash of the block as part of which it had been previously confirmed.

impl<ChannelSigner, C, T, F, L, P> EventsProvider for ChainMonitor<ChannelSigner, C, T, F, L, P>

where ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref, <C as Deref>::Target: Filter, <T as Deref>::Target: BroadcasterInterface, <F as Deref>::Target: FeeEstimator, <L as Deref>::Target: Logger, <P as Deref>::Target: Persist<ChannelSigner>,

fn process_pending_events<H>(&self, handler: H)

where H: Deref, <H as Deref>::Target: EventHandler,

Processes SpendableOutputs events produced from each ChannelMonitor upon maturity.

For channels featuring anchor outputs, this method will also process BumpTransaction events produced from each ChannelMonitor while there is a balance to claim onchain within each channel. As the confirmation of a commitment transaction may be critical to the safety of funds, we recommend invoking this every 30 seconds, or lower if running in an environment with spotty connections, like on mobile.

An EventHandler may safely call back to the provider, though this shouldn’t be needed in order to handle these events.

impl<ChannelSigner, C, T, F, L, P> Listen for ChainMonitor<ChannelSigner, C, T, F, L, P>

where ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref, <C as Deref>::Target: Filter, <T as Deref>::Target: BroadcasterInterface, <F as Deref>::Target: FeeEstimator, <L as Deref>::Target: Logger, <P as Deref>::Target: Persist<ChannelSigner>,

fn filtered_block_connected( &self, header: &Header, txdata: &[(usize, &Transaction)], height: u32, )

Notifies the listener that a block was added at the given height, with the transaction data possibly filtered.

fn block_disconnected(&self, header: &Header, height: u32)

Notifies the listener that a block was removed at the given height.

fn block_connected(&self, block: &Block, height: u32)

Notifies the listener that a block was added at the given height.

impl<ChannelSigner, C, T, F, L, P> Watch<ChannelSigner> for ChainMonitor<ChannelSigner, C, T, F, L, P>

where ChannelSigner: EcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref, <C as Deref>::Target: Filter, <T as Deref>::Target: BroadcasterInterface, <F as Deref>::Target: FeeEstimator, <L as Deref>::Target: Logger, <P as Deref>::Target: Persist<ChannelSigner>,

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

Watches a channel identified by funding_txo using monitor.

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

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

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

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