X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=blobdiff_plain;f=lightning%2Fsrc%2Fchain%2Fmod.rs;h=c77883edddf89dcb8afc404fa0ca7675e6428288;hb=367834ca9039eb64d6f85b6bd4432c735e776b81;hp=d0b5b65014d736d27b04c08ca23408da68a8393e;hpb=3ee6a27bc6cef28ba52059a405913ca5c6e1dcb7;p=rust-lightning

diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs
index d0b5b650..c77883ed 100644
--- 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