From d2d37fc06d3b70470a48b099ac070dd773faf9cf Mon Sep 17 00:00:00 2001
From: Tobin Harding <me@tobin.cc>
Date: Thu, 8 Jul 2021 11:56:05 +1000
Subject: [PATCH] Return early if required UTXOs already big enough

If the required UTXO set is already bigger (including fees) than the
amount required for the transaction we can return early, no need to go
through the BNB algorithm or random selection.
---
 src/wallet/coin_selection.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/wallet/coin_selection.rs b/src/wallet/coin_selection.rs
index 978f3d16..1dcc2c9e 100644
--- a/src/wallet/coin_selection.rs
+++ b/src/wallet/coin_selection.rs
@@ -345,6 +345,14 @@ impl<D: Database> CoinSelectionAlgorithm<D> for BranchAndBoundCoinSelection {
             .try_into()
             .expect("Bitcoin amount to fit into i64");
 
+        if curr_value > actual_target {
+            return Ok(BranchAndBoundCoinSelection::calculate_cs_result(
+                vec![],
+                required_utxos,
+                fee_amount,
+            ));
+        }
+
         Ok(self
             .bnb(
                 required_utxos.clone(),