Utility for syncing a set of chain listeners

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

diff --git a/lightning/src/chain/mod.rs b/lightning/src/chain/mod.rs
index 1d51f262216d3620fb068908864db0c545f0f734..c1fceec8c47171969397558db0ce62d11faf93ed 100644 (file)
--- a/lightning/src/chain/mod.rs
+++ b/lightning/src/chain/mod.rs
@@ -9,6 +9,7 @@
 
 //! Structs and traits which allow other parts of rust-lightning to interact with the blockchain.
 
+use bitcoin::blockdata::block::{Block, BlockHeader};
 use bitcoin::blockdata::script::Script;
 use bitcoin::blockdata::transaction::TxOut;
 use bitcoin::hash_types::{BlockHash, Txid};
@@ -46,6 +47,18 @@ pub trait Access: Send + Sync {
        fn get_utxo(&self, genesis_hash: &BlockHash, short_channel_id: u64) -> Result<TxOut, AccessError>;
 }
 
+/// The `Listen` trait is used to be notified of when blocks have been connected or disconnected
+/// from the chain.
+///
+/// Useful when needing to replay chain data upon startup or as new chain events occur.
+pub trait Listen {
+       /// Notifies the listener that a block was added at the given height.
+       fn block_connected(&self, block: &Block, height: u32);
+
+       /// Notifies the listener that a block was removed at the given height.
+       fn block_disconnected(&self, header: &BlockHeader, height: u32);
+}
+
 /// The `Watch` trait defines behavior for watching on-chain activity pertaining to channels as
 /// blocks are connected and disconnected.
 ///
@@ -123,3 +136,29 @@ pub trait Filter: Send + Sync {
        /// `script_pubkey` as the spending condition.
        fn register_output(&self, outpoint: &OutPoint, script_pubkey: &Script);
 }
+
+impl<T: Listen> Listen for std::ops::Deref<Target = T> {
+       fn block_connected(&self, block: &Block, height: u32) {
+               (**self).block_connected(block, height);
+       }
+
+       fn block_disconnected(&self, header: &BlockHeader, height: u32) {
+               (**self).block_disconnected(header, height);
+       }
+}
+
+impl<T: std::ops::Deref, U: std::ops::Deref> Listen for (T, U)
+where
+       T::Target: Listen,
+       U::Target: Listen,
+{
+       fn block_connected(&self, block: &Block, height: u32) {
+               self.0.block_connected(block, height);
+               self.1.block_connected(block, height);
+       }
+
+       fn block_disconnected(&self, header: &BlockHeader, height: u32) {
+               self.0.block_disconnected(header, height);
+               self.1.block_disconnected(header, height);
+       }
+}