Remove BlockNotifier

[rust-lightning] / lightning / src / chain / mod.rs

diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs
index d0b5b65014d736d27b04c08ca23408da68a8393e..c77883edddf89dcb8afc404fa0ca7675e6428288 100644 (file)
--- a/lightning/src/chain/mod.rs
+++ b/lightning/src/chain/mod.rs
@@ -13,7 +13,9 @@ use bitcoin::blockdata::script::Script;
 use bitcoin::blockdata::transaction::TxOut;
 use bitcoin::hash_types::{BlockHash, Txid};
 
+use chain::keysinterface::ChannelKeys;
 use chain::transaction::OutPoint;
+use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, MonitorEvent};
 
 pub mod chaininterface;
 pub mod transaction;
@@ -42,6 +44,57 @@ pub enum AccessError {
        UnknownTx,
 }
 
+/// 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 [`ChannelMonitorUpdateErr`] for more details about how to handle
+/// multiple instances.
+///
+/// [`ChannelMonitor`]: ../ln/channelmonitor/struct.ChannelMonitor.html
+/// [`ChannelMonitorUpdateErr`]: ../ln/channelmonitor/enum.ChannelMonitorUpdateErr.html
+/// [`PermanentFailure`]: ../ln/channelmonitor/enum.ChannelMonitorUpdateErr.html#variant.PermanentFailure
+pub trait Watch: Send + Sync {
+       /// Keys needed by monitors for creating and signing transactions.
+       type Keys: ChannelKeys;
+
+       /// Watches a channel identified by `funding_txo` using `monitor`.
+       ///
+       /// Implementations are responsible for watching the chain for the funding transaction along
+       /// with spends of its output and any outputs returned by [`get_outputs_to_watch`]. In practice,
+       /// this means calling [`block_connected`] and [`block_disconnected`] on the monitor and
+       /// including all such transactions that meet this criteria.
+       ///
+       /// [`get_outputs_to_watch`]: ../ln/channelmonitor/struct.ChannelMonitor.html#method.get_outputs_to_watch
+       /// [`block_connected`]: ../ln/channelmonitor/struct.ChannelMonitor.html#method.block_connected
+       /// [`block_disconnected`]: ../ln/channelmonitor/struct.ChannelMonitor.html#method.block_disconnected
+       fn watch_channel(&self, funding_txo: OutPoint, monitor: ChannelMonitor<Self::Keys>) -> Result<(), ChannelMonitorUpdateErr>;
+
+       /// Updates a channel identified by `funding_txo` by applying `update` to its monitor.
+       ///
+       /// Implementations must call [`update_monitor`] with the given update. See
+       /// [`ChannelMonitorUpdateErr`] for invariants around returning an error.
+       ///
+       /// [`update_monitor`]: ../ln/channelmonitor/struct.ChannelMonitor.html#method.update_monitor
+       /// [`ChannelMonitorUpdateErr`]: ../ln/channelmonitor/enum.ChannelMonitorUpdateErr.html
+       fn update_channel(&self, funding_txo: OutPoint, update: ChannelMonitorUpdate) -> Result<(), ChannelMonitorUpdateErr>;
+
+       /// Returns any monitor events since the last call. Subsequent calls must only return new
+       /// events.
+       fn release_pending_monitor_events(&self) -> Vec<MonitorEvent>;
+}
+
 /// An interface for providing [`WatchEvent`]s.
 ///
 /// [`WatchEvent`]: enum.WatchEvent.html