+ // Before proposing a feerate update, check that we can actually afford the new fee.
+ let inbound_stats = self.get_inbound_pending_htlc_stats(Some(feerate_per_kw));
+ let outbound_stats = self.get_outbound_pending_htlc_stats(Some(feerate_per_kw));
+ let keys = if let Ok(keys) = self.build_holder_transaction_keys(self.cur_holder_commitment_transaction_number) { keys } else { return None; };
+ let commitment_stats = self.build_commitment_transaction(self.cur_holder_commitment_transaction_number, &keys, true, true, logger);
+ let buffer_fee_msat = Channel::<Signer>::commit_tx_fee_sat(feerate_per_kw, commitment_stats.num_nondust_htlcs + outbound_stats.on_holder_tx_holding_cell_htlcs_count as usize + CONCURRENT_INBOUND_HTLC_FEE_BUFFER as usize) * 1000;
+ let holder_balance_msat = commitment_stats.local_balance_msat - outbound_stats.holding_cell_msat;
+ if holder_balance_msat < buffer_fee_msat + self.counterparty_selected_channel_reserve_satoshis.unwrap() * 1000 {
+ //TODO: auto-close after a number of failures?
+ log_debug!(logger, "Cannot afford to send new feerate at {}", feerate_per_kw);
+ return None;
+ }
+
+ // Note, we evaluate pending htlc "preemptive" trimmed-to-dust threshold at the proposed `feerate_per_kw`.
+ let holder_tx_dust_exposure = inbound_stats.on_holder_tx_dust_exposure_msat + outbound_stats.on_holder_tx_dust_exposure_msat;
+ let counterparty_tx_dust_exposure = inbound_stats.on_counterparty_tx_dust_exposure_msat + outbound_stats.on_counterparty_tx_dust_exposure_msat;
+ if holder_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() {
+ log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw);
+ return None;
+ }
+ if counterparty_tx_dust_exposure > self.get_max_dust_htlc_exposure_msat() {
+ log_debug!(logger, "Cannot afford to send new feerate at {} without infringing max dust htlc exposure", feerate_per_kw);
+ return None;
+ }
+