Do not lock while looping htlcs_to_fail

Currently we loop over `htlcs_to_fail` locking `channel_state` for each
element only to call `get_htlc_inbound_temp_fail_err_and_data` with the
same inputs on each iteration. This is unnecessary, we can refactor and
call `get_htlc_inbound_temp_fail_err_and_data` outside of the loop.

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 687d45c49a5620beac8daa1c376657a4669a31a7..97dbb4175c5e41bc282d571c4b843c992d851849 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -3974,16 +3974,16 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
                &self, mut htlcs_to_fail: Vec<(HTLCSource, PaymentHash)>, channel_id: [u8; 32],
                counterparty_node_id: &PublicKey
        ) {
-               for (htlc_src, payment_hash) in htlcs_to_fail.drain(..) {
-                       let (failure_code, onion_failure_data) =
-                               match self.channel_state.lock().unwrap().by_id.entry(channel_id) {
-                                       hash_map::Entry::Occupied(chan_entry) => {
-                                               self.get_htlc_inbound_temp_fail_err_and_data(0x1000|7, &chan_entry.get())
-                                       },
-                                       hash_map::Entry::Vacant(_) => (0x4000|10, Vec::new())
-                               };
+               let (failure_code, onion_failure_data) =
+                       match self.channel_state.lock().unwrap().by_id.entry(channel_id) {
+                               hash_map::Entry::Occupied(chan_entry) => {
+                                       self.get_htlc_inbound_temp_fail_err_and_data(0x1000|7, &chan_entry.get())
+                               },
+                               hash_map::Entry::Vacant(_) => (0x4000|10, Vec::new())
+                       };
 
-                       let reason = HTLCFailReason::reason(failure_code, onion_failure_data);
+               for (htlc_src, payment_hash) in htlcs_to_fail.drain(..) {
+                       let reason = HTLCFailReason::reason(failure_code, onion_failure_data.clone());
                        let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id };
                        self.fail_htlc_backwards_internal(&htlc_src, &payment_hash, &reason, receiver);
                }