Add MempoolInterface to add mempool scan

lightning/src/chain/mempoolinterface.rs

@@ -0,0 +1,31 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! Traits and utility impls which allow other parts of rust-lightning to
+//! interact with the mempool.
+//!
+//! Includes traits for monitoring and receiving notification for in-mempool
+//! descendants of a channel output.
+
+use crate::chain::transaction::OutPoint;
+
+use bitcoin::blockdata::transaction::Transaction;
+
+pub enum MempoolWatchStatus {
+	/// The in-mempool descendant of the watched outpoint.
+	DescendantTx(Transaction)
+	/// The watch outpoint has been reorged out of the chain.
+	Reorg,
+}
+
+/// An interface to monitor a local cacche of Bitcoin transacations waiting
+/// confirmations.
+pub trait MempoolInterface {
+	fn watch_outpoint(&self, funding_txo: OutPoint) -> MempoolWatchStatus;
+}