Opportunistically skip log in `update_claims_view_from_matched_txn`

On each block, for each `ChannelMonitor`, we log two status
statements in `OnChainTx::update_claims_view_from_matched_txn`.
This can add up to quite a bit, and is generally not very
interesting when we don't actually do anything if there's no claims
to bump.

Here we drop both logs if we have no claims to work with, but
retain it if we process any claims.

diff --git a/lightning/src/chain/onchaintx.rs b/lightning/src/chain/onchaintx.rs
index a95cf77487d78ea48a22c79e0bca73b51e5c8ed0..94d6aa35746caa3a6bbc10e991a7161d54aaef2c 100644 (file)
--- a/lightning/src/chain/onchaintx.rs
+++ b/lightning/src/chain/onchaintx.rs
@@ -861,8 +861,15 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
                B::Target: BroadcasterInterface,
                F::Target: FeeEstimator,
        {
-               log_debug!(logger, "Updating claims view at height {} with {} matched transactions in block {}", cur_height, txn_matched.len(), conf_height);
+               let mut have_logged_intro = false;
+               let mut maybe_log_intro = || {
+                       if !have_logged_intro {
+                               log_debug!(logger, "Updating claims view at height {} with {} matched transactions in block {}", cur_height, txn_matched.len(), conf_height);
+                               have_logged_intro = true;
+                       }
+               };
                let mut bump_candidates = new_hash_map();
+               if !txn_matched.is_empty() { maybe_log_intro(); }
                for tx in txn_matched {
                        // Scan all input to verify is one of the outpoint spent is of interest for us
                        let mut claimed_outputs_material = Vec::new();
@@ -955,6 +962,7 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
                        self.onchain_events_awaiting_threshold_conf.drain(..).collect::<Vec<_>>();
                for entry in onchain_events_awaiting_threshold_conf {
                        if entry.has_reached_confirmation_threshold(cur_height) {
+                               maybe_log_intro();
                                match entry.event {
                                        OnchainEvent::Claim { claim_id } => {
                                                // We may remove a whole set of claim outpoints here, as these one may have
@@ -992,7 +1000,11 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
                }
 
                // Build, bump and rebroadcast tx accordingly
-               log_trace!(logger, "Bumping {} candidates", bump_candidates.len());
+               if !bump_candidates.is_empty() {
+                       maybe_log_intro();
+                       log_trace!(logger, "Bumping {} candidates", bump_candidates.len());
+               }
+
                for (claim_id, request) in bump_candidates.iter() {
                        if let Some((new_timer, new_feerate, bump_claim)) = self.generate_claim(
                                cur_height, &request, &FeerateStrategy::ForceBump, &*fee_estimator, &*logger,