Drop system clock calls for PendingHTLCsForwardable events.

Instead, return a Duration and let the user do the work of waiting.
This is one of only a handful of steps to make us
mostly-syscall-free, at least enough to run in WASM according to
elichai.

Author: TheBlueMatt

src/ln/chanmon_update_fail_tests.rs

@@ -13,8 +13,6 @@ use util::errors::APIError;
 use bitcoin_hashes::sha256::Hash as Sha256;
 use bitcoin_hashes::Hash;
 
-use std::time::Instant;
-
 use ln::functional_test_utils::*;
 
 #[test]
@@ -1495,7 +1493,6 @@ fn test_monitor_update_on_pending_forwards() {
 		Event::PendingHTLCsForwardable { .. } => { },
 		_ => panic!("Unexpected event"),
 	};
-	nodes[0].node.channel_state.lock().unwrap().next_forward = Instant::now();
 	nodes[0].node.process_pending_htlc_forwards();
 	expect_payment_received!(nodes[0], payment_hash_2, 1000000);
 

src/ln/channelmanager.rs

@@ -46,7 +46,7 @@ use std::collections::{HashMap, hash_map, HashSet};
 use std::io::Cursor;
 use std::sync::{Arc, Mutex, MutexGuard, RwLock};
 use std::sync::atomic::{AtomicUsize, Ordering};
-use std::time::{Instant,Duration};
+use std::time::Duration;
 
 // We hold various information about HTLC relay in the HTLC objects in Channel itself:
 //
@@ -247,7 +247,6 @@ pub(super) enum RAACommitmentOrder {
 pub(super) struct ChannelHolder {
 	pub(super) by_id: HashMap<[u8; 32], Channel>,
 	pub(super) short_to_id: HashMap<u64, [u8; 32]>,
-	pub(super) next_forward: Instant,
 	/// short channel id -> forward infos. Key of 0 means payments received
 	/// Note that while this is held in the same mutex as the channels themselves, no consistency
 	/// guarantees are made about the existence of a channel with the short id here, nor the short
@@ -266,7 +265,6 @@ pub(super) struct ChannelHolder {
 pub(super) struct MutChannelHolder<'a> {
 	pub(super) by_id: &'a mut HashMap<[u8; 32], Channel>,
 	pub(super) short_to_id: &'a mut HashMap<u64, [u8; 32]>,
-	pub(super) next_forward: &'a mut Instant,
 	pub(super) forward_htlcs: &'a mut HashMap<u64, Vec<HTLCForwardInfo>>,
 	pub(super) claimable_htlcs: &'a mut HashMap<PaymentHash, Vec<(u64, HTLCPreviousHopData)>>,
 	pub(super) pending_msg_events: &'a mut Vec<events::MessageSendEvent>,
@@ -276,7 +274,6 @@ impl ChannelHolder {
 		MutChannelHolder {
 			by_id: &mut self.by_id,
 			short_to_id: &mut self.short_to_id,
-			next_forward: &mut self.next_forward,
 			forward_htlcs: &mut self.forward_htlcs,
 			claimable_htlcs: &mut self.claimable_htlcs,
 			pending_msg_events: &mut self.pending_msg_events,
@@ -549,7 +546,6 @@ impl ChannelManager {
 			channel_state: Mutex::new(ChannelHolder{
 				by_id: HashMap::new(),
 				short_to_id: HashMap::new(),
-				next_forward: Instant::now(),
 				forward_htlcs: HashMap::new(),
 				claimable_htlcs: HashMap::new(),
 				pending_msg_events: Vec::new(),
@@ -1184,10 +1180,6 @@ impl ChannelManager {
 			let mut channel_state_lock = self.channel_state.lock().unwrap();
 			let channel_state = channel_state_lock.borrow_parts();
 
-			if cfg!(not(feature = "fuzztarget")) && Instant::now() < *channel_state.next_forward {
-				return;
-			}
-
 			for (short_chan_id, mut pending_forwards) in channel_state.forward_htlcs.drain() {
 				if short_chan_id != 0 {
 					let forward_chan_id = match channel_state.short_to_id.get(&short_chan_id) {
@@ -1467,8 +1459,7 @@ impl ChannelManager {
 
 				let mut forward_event = None;
 				if channel_state_lock.forward_htlcs.is_empty() {
-					forward_event = Some(Instant::now() + Duration::from_millis(((rng::rand_f32() * 4.0 + 1.0) * MIN_HTLC_RELAY_HOLDING_CELL_MILLIS as f32) as u64));
-					channel_state_lock.next_forward = forward_event.unwrap();
+					forward_event = Some(Duration::from_millis(((rng::rand_f32() * 4.0 + 1.0) * MIN_HTLC_RELAY_HOLDING_CELL_MILLIS as f32) as u64));
 				}
 				match channel_state_lock.forward_htlcs.entry(short_channel_id) {
 					hash_map::Entry::Occupied(mut entry) => {
@@ -2077,8 +2068,7 @@ impl ChannelManager {
 			if !pending_forwards.is_empty() {
 				let mut channel_state = self.channel_state.lock().unwrap();
 				if channel_state.forward_htlcs.is_empty() {
-					forward_event = Some(Instant::now() + Duration::from_millis(((rng::rand_f32() * 4.0 + 1.0) * MIN_HTLC_RELAY_HOLDING_CELL_MILLIS as f32) as u64));
-					channel_state.next_forward = forward_event.unwrap();
+					forward_event = Some(Duration::from_millis(((rng::rand_f32() * 4.0 + 1.0) * MIN_HTLC_RELAY_HOLDING_CELL_MILLIS as f32) as u64));
 				}
 				for (forward_info, prev_htlc_id) in pending_forwards.drain(..) {
 					match channel_state.forward_htlcs.entry(forward_info.short_channel_id) {
@@ -3087,7 +3077,6 @@ impl<'a, R : ::std::io::Read> ReadableArgs<R, ChannelManagerReadArgs<'a>> for (S
 			channel_state: Mutex::new(ChannelHolder {
 				by_id,
 				short_to_id,
-				next_forward: Instant::now(),
 				forward_htlcs,
 				claimable_htlcs,
 				pending_msg_events: Vec::new(),

src/ln/functional_test_utils.rs

@@ -32,7 +32,6 @@ use std::collections::HashMap;
 use std::default::Default;
 use std::rc::Rc;
 use std::sync::{Arc, Mutex};
-use std::time::Instant;
 use std::mem;
 
 pub const CHAN_CONFIRM_DEPTH: u32 = 100;
@@ -536,8 +535,6 @@ macro_rules! expect_pending_htlcs_forwardable {
 			Event::PendingHTLCsForwardable { .. } => { },
 			_ => panic!("Unexpected event"),
 		};
-		let node_ref: &Node = &$node;
-		node_ref.node.channel_state.lock().unwrap().next_forward = Instant::now();
 		$node.node.process_pending_htlc_forwards();
 	}}
 }

src/ln/functional_tests.rs

@@ -43,7 +43,6 @@ use std::collections::{BTreeSet, HashMap, HashSet};
 use std::default::Default;
 use std::sync::Arc;
 use std::sync::atomic::Ordering;
-use std::time::Instant;
 use std::mem;
 
 use ln::functional_test_utils::*;
@@ -2460,7 +2459,6 @@ fn do_test_commitment_revoked_fail_backward_exhaustive(deliver_bs_raa: bool, use
 			_ => panic!("Unexpected event"),
 		};
 	}
-	nodes[1].node.channel_state.lock().unwrap().next_forward = Instant::now();
 	nodes[1].node.process_pending_htlc_forwards();
 	check_added_monitors!(nodes[1], 1);
 
@@ -2813,7 +2811,6 @@ fn do_test_drop_messages_peer_disconnect(messages_delivered: u8) {
 	nodes[1].node.peer_disconnected(&nodes[0].node.get_our_node_id(), false);
 	reconnect_nodes(&nodes[0], &nodes[1], (false, false), (0, 0), (0, 0), (0, 0), (0, 0), (false, false));
 
-	nodes[1].node.channel_state.lock().unwrap().next_forward = Instant::now();
 	nodes[1].node.process_pending_htlc_forwards();
 
 	let events_2 = nodes[1].node.get_and_clear_pending_events();
@@ -4463,7 +4460,6 @@ fn run_onion_failure_test_with_fail_intercept<F1,F2,F3>(_name: &str, test_case:
 	macro_rules! expect_htlc_forward {
 		($node: expr) => {{
 			expect_event!($node, Event::PendingHTLCsForwardable);
-			$node.node.channel_state.lock().unwrap().next_forward = Instant::now();
 			$node.node.process_pending_htlc_forwards();
 		}}
 	}

src/util/events.rs

@@ -21,7 +21,7 @@ use bitcoin::blockdata::script::Script;
 
 use secp256k1::key::PublicKey;
 
-use std::time::Instant;
+use std::time::Duration;
 
 /// An Event which you should probably take some action in response to.
 pub enum Event {
@@ -92,8 +92,8 @@ pub enum Event {
 	/// Used to indicate that ChannelManager::process_pending_htlc_forwards should be called at a
 	/// time in the future.
 	PendingHTLCsForwardable {
-		/// The earliest time at which process_pending_htlc_forwards should be called.
-		time_forwardable: Instant,
+		/// The amount of time that should be waited prior to calling process_pending_htlc_forwards
+		time_forwardable: Duration,
 	},
 	/// Used to indicate that an output was generated on-chain which you should know how to spend.
 	/// Such an output will *not* ever be spent by rust-lightning, so you need to store them