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Consolidate LSPS4 usability checks to execute time #13

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Consolidate LSPS4 usability checks to execute time #13

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92 changes: 29 additions & 63 deletions lightning-liquidity/src/lsps4/service.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -218,7 +218,6 @@ where
.get_cm()
.list_channels_with_counterparty(&counterparty_node_id);
let any_usable = channels.iter().any(|ch| ch.is_usable);
let has_channels = !channels.is_empty();

log_info!(
self.logger,
Expand All @@ -240,40 +239,23 @@ where
);
}

if has_channels && !any_usable {
// Channels exist but none usable yet (channel_reestablish in progress).
// Defer until process_pending_htlcs picks them up.
log_info!(
self.logger,
"[LSPS4] htlc_intercepted: peer {} has {} channels but none usable, \
deferring HTLC until channel_reestablish completes. payment_hash: {}",
counterparty_node_id,
channels.len(),
payment_hash
);
self.htlc_store.insert(htlc).unwrap();
} else {
// Either channels are usable, or no channels exist (need JIT open).
// calculate_htlc_actions_for_peer handles both: forward through usable
// channels, or emit OpenChannel event when no capacity exists.
let actions = self.calculate_htlc_actions_for_peer(
counterparty_node_id,
vec![htlc.clone()],
);
let actions = self.calculate_htlc_actions_for_peer(
counterparty_node_id,
vec![htlc.clone()],
);

if actions.needs_liquidity_action() {
self.htlc_store.insert(htlc).unwrap();
}
if actions.needs_liquidity_action() {
self.htlc_store.insert(htlc).unwrap();
}

log_debug!(
self.logger,
"[LSPS4] htlc_intercepted: calculated actions for peer {}: {:?}",
counterparty_node_id,
actions
);
log_debug!(
self.logger,
"[LSPS4] htlc_intercepted: calculated actions for peer {}: {:?}",
counterparty_node_id,
actions
);

self.execute_htlc_actions(actions, counterparty_node_id.clone());
}
self.execute_htlc_actions(actions, counterparty_node_id.clone());
}
} else {
log_error!(
Expand Down Expand Up @@ -414,28 +396,7 @@ where
}
}

if self.has_usable_channel(&counterparty_node_id) || channels.is_empty() {
// Either channels are usable (forward immediately) or no channels exist
// at all (process_htlcs_for_peer will trigger OpenChannel for JIT).
self.process_htlcs_for_peer(counterparty_node_id.clone(), htlcs);
} else {
// Channels exist but none usable yet (reestablish in progress).
// We still call process_htlcs_for_peer because calculate_htlc_actions
// skips non-usable channels. If existing capacity is insufficient, this
// will emit OpenChannel now rather than deferring to process_pending_htlcs
// (which would never open a channel). Forwards through existing channels
// will be empty since none are usable, so no premature forwarding occurs.
// The actual forwards happen later via channel_ready or process_pending_htlcs
// once reestablish completes.
log_info!(
self.logger,
"[LSPS4] peer_connected: {} has {} pending HTLCs, channels not yet usable \
(reestablish in progress) - checking if new channel needed",
counterparty_node_id,
htlcs.len()
);
self.process_htlcs_for_peer(counterparty_node_id.clone(), htlcs);
}
self.process_htlcs_for_peer(counterparty_node_id.clone(), htlcs);

log_info!(
self.logger,
Expand Down Expand Up @@ -589,11 +550,14 @@ where
}

if self.has_usable_channel(&node_id) {
let actions = self.calculate_htlc_actions_for_peer(node_id, htlcs);
if actions.is_empty() {
continue;
}
self.execute_htlc_actions(actions, node_id);
// Channel reestablish completed — attempt to forward the deferred HTLCs.
log_info!(
self.logger,
"[LSPS4] process_pending_htlcs: forwarding {} HTLCs for peer {} (channel now usable)",
htlcs.len(),
node_id
);
self.process_htlcs_for_peer(node_id, htlcs);
}
}
}
Expand Down Expand Up @@ -835,12 +799,14 @@ where

// Execute forwards
for forward_action in forwards {
// Re-check peer liveness right before forwarding to narrow the
// TOCTOU window between the usability check and the actual forward.
if !self.is_peer_connected(&their_node_id) {
// Re-check channel usability right before forwarding to narrow the
// TOCTOU window. Covers both peer disconnect and disconnect+reconnect
// (where the peer is connected but the channel is still reestablishing).
if !self.has_usable_channel(&their_node_id) {
log_info!(
self.logger,
"[LSPS4] execute_htlc_actions: peer {} disconnected before forward, skipping HTLC {:?} (will retry on next timer tick). payment_hash: {}",
"[LSPS4] execute_htlc_actions: no usable channel for peer {}, \
skipping HTLC {:?} (will retry on next timer tick). payment_hash: {}",
their_node_id,
forward_action.htlc.id(),
forward_action.htlc.payment_hash()
Expand Down
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