multi: remove listeners field and method from ChainWatchInterface

This includes the purpose of this PR, which is to remove the circular reference created by ChainListeners self-adding themselves to their ChainWatchInterface's `listeners` field.

Author: valentinewallace

lightning/fuzz/fuzz_targets/chanmon_fail_consistency.rs

@@ -193,7 +193,7 @@ pub fn do_test(data: &[u8]) {
 			config.channel_options.fee_proportional_millionths = 0;
 			config.channel_options.announced_channel = true;
 			config.peer_channel_config_limits.min_dust_limit_satoshis = 0;
-			(ChannelManager::new(Network::Bitcoin, fee_est.clone(), monitor.clone(), watch.clone(), broadcast.clone(), Arc::clone(&logger), keys_manager.clone(), config, 0).unwrap(),
+			(ChannelManager::new(Network::Bitcoin, fee_est.clone(), monitor.clone(), broadcast.clone(), Arc::clone(&logger), keys_manager.clone(), config, 0).unwrap(),
 			monitor)
 		} }
 	}

lightning/fuzz/fuzz_targets/full_stack_target.rs

@@ -331,7 +331,7 @@ pub fn do_test(data: &[u8], logger: &Arc<Logger>) {
 	config.channel_options.fee_proportional_millionths =  slice_to_be32(get_slice!(4));
 	config.channel_options.announced_channel = get_slice!(1)[0] != 0;
 	config.peer_channel_config_limits.min_dust_limit_satoshis = 0;
-	let channelmanager = ChannelManager::new(Network::Bitcoin, fee_est.clone(), monitor.clone(), watch.clone(), broadcast.clone(), Arc::clone(&logger), keys_manager.clone(), config, 0).unwrap();
+	let channelmanager = ChannelManager::new(Network::Bitcoin, fee_est.clone(), monitor.clone(), broadcast.clone(), Arc::clone(&logger), keys_manager.clone(), config, 0).unwrap();
 	let router = Arc::new(Router::new(PublicKey::from_secret_key(&Secp256k1::signing_only(), &keys_manager.get_node_secret()), watch.clone(), Arc::clone(&logger)));
 
 	let peers = RefCell::new([false; 256]);

lightning/src/chain/chaininterface.rs

@@ -45,11 +45,6 @@ pub trait ChainWatchInterface: Sync + Send {
 	/// Indicates that a listener needs to see all transactions.
 	fn watch_all_txn(&self);
 
-	/// Register the given listener to receive events. Only a weak pointer is provided and the
-	/// registration should be freed once that pointer expires.
-	fn register_listener(&self, listener: Weak<ChainListener>);
-	//TODO: unregister
-
 	/// Gets the script and value in satoshis for a given unspent transaction output given a
 	/// short_channel_id (aka unspent_tx_output_identier). For BTC/tBTC channels the top three
 	/// bytes are the block height, the next 3 the transaction index within the block, and the
@@ -204,7 +199,6 @@ impl ChainWatchedUtil {
 pub struct ChainWatchInterfaceUtil {
 	network: Network,
 	watched: Mutex<ChainWatchedUtil>,
-	listeners: Mutex<Vec<Weak<ChainListener>>>,
 	reentered: AtomicUsize,
 	logger: Arc<Logger>,
 }
@@ -232,11 +226,6 @@ impl ChainWatchInterface for ChainWatchInterfaceUtil {
 		}
 	}
 
-	fn register_listener(&self, listener: Weak<ChainListener>) {
-		let mut vec = self.listeners.lock().unwrap();
-		vec.push(listener);
-	}
-
 	fn get_chain_utxo(&self, genesis_hash: Sha256dHash, _unspent_tx_output_identifier: u64) -> Result<(Script, u64), ChainError> {
 		if genesis_hash != genesis_block(self.network).header.bitcoin_hash() {
 			return Err(ChainError::NotWatched);

lightning/src/ln/channelmanager.rs

@@ -25,7 +25,7 @@ use secp256k1::Secp256k1;
 use secp256k1::ecdh::SharedSecret;
 use secp256k1;
 
-use chain::chaininterface::{BroadcasterInterface,ChainListener,ChainWatchInterface,FeeEstimator};
+use chain::chaininterface::{BroadcasterInterface,ChainListener,FeeEstimator};
 use chain::transaction::OutPoint;
 use ln::channel::{Channel, ChannelError};
 use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY};
@@ -323,7 +323,6 @@ pub struct ChannelManager {
 	genesis_hash: Sha256dHash,
 	fee_estimator: Arc<FeeEstimator>,
 	monitor: Arc<ManyChannelMonitor>,
-	chain_monitor: Arc<ChainWatchInterface>,
 	tx_broadcaster: Arc<BroadcasterInterface>,
 
 	#[cfg(test)]
@@ -596,7 +595,6 @@ impl ChannelManager {
 			genesis_hash: genesis_block(network).header.bitcoin_hash(),
 			fee_estimator: feeest.clone(),
 			monitor: monitor.clone(),
-			chain_monitor,
 			tx_broadcaster,
 
 			latest_block_height: AtomicUsize::new(current_blockchain_height),
@@ -619,8 +617,7 @@ impl ChannelManager {
 
 			logger,
 		});
-		let weak_res = Arc::downgrade(&res);
-		res.chain_monitor.register_listener(weak_res);
+
 		Ok(res)
 	}
 
@@ -3133,10 +3130,7 @@ pub struct ChannelManagerReadArgs<'a> {
 	/// you have deserialized ChannelMonitors separately and will add them to your
 	/// ManyChannelMonitor after deserializing this ChannelManager.
 	pub monitor: Arc<ManyChannelMonitor>,
-	/// The ChainWatchInterface for use in the ChannelManager in the future.
-	///
-	/// No calls to the ChainWatchInterface will be made during deserialization.
-	pub chain_monitor: Arc<ChainWatchInterface>,
+
 	/// The BroadcasterInterface which will be used in the ChannelManager in the future and may be
 	/// used to broadcast the latest local commitment transactions of channels which must be
 	/// force-closed during deserialization.
@@ -3239,7 +3233,6 @@ impl<'a, R : ::std::io::Read> ReadableArgs<R, ChannelManagerReadArgs<'a>> for (S
 			genesis_hash,
 			fee_estimator: args.fee_estimator,
 			monitor: args.monitor,
-			chain_monitor: args.chain_monitor,
 			tx_broadcaster: args.tx_broadcaster,
 
 			latest_block_height: AtomicUsize::new(latest_block_height as usize),

lightning/src/ln/channelmonitor.rs

@@ -223,8 +223,7 @@ impl<Key : Send + cmp::Eq + hash::Hash + 'static> SimpleManyChannelMonitor<Key>
 			logger,
 			fee_estimator: feeest,
 		});
-		let weak_res = Arc::downgrade(&res);
-		res.chain_monitor.register_listener(weak_res);
+
 		res
 	}
 

lightning/src/ln/functional_test_utils.rs

@@ -844,7 +844,7 @@ pub fn create_network(node_count: usize, node_config: &[Option<UserConfig>]) ->
 		let mut default_config = UserConfig::new();
 		default_config.channel_options.announced_channel = true;
 		default_config.peer_channel_config_limits.force_announced_channel_preference = false;
-		let node = ChannelManager::new(Network::Testnet, feeest.clone(), chan_monitor.clone(), chain_monitor.clone(), tx_broadcaster.clone(), Arc::clone(&logger), keys_manager.clone(), if node_config[i].is_some() { node_config[i].clone().unwrap() } else { default_config }, 0).unwrap();
+		let node = ChannelManager::new(Network::Testnet, feeest.clone(), chan_monitor.clone(), tx_broadcaster.clone(), Arc::clone(&logger), keys_manager.clone(), if node_config[i].is_some() { node_config[i].clone().unwrap() } else { default_config }, 0).unwrap();
 		let router = Router::new(PublicKey::from_secret_key(&secp_ctx, &keys_manager.get_node_secret()), chain_monitor.clone(), Arc::clone(&logger));
 		nodes.push(Node { chain_monitor, tx_broadcaster, chan_monitor, node, router, keys_manager, node_seed: seed,
 			network_payment_count: payment_count.clone(),

lightning/src/ln/functional_tests.rs

@@ -3367,7 +3367,6 @@ fn test_no_txn_manager_serialize_deserialize() {
 			keys_manager,
 			fee_estimator: Arc::new(test_utils::TestFeeEstimator { sat_per_kw: 253 }),
 			monitor: nodes[0].chan_monitor.clone(),
-			chain_monitor: nodes[0].chain_monitor.clone(),
 			tx_broadcaster: nodes[0].tx_broadcaster.clone(),
 			logger: Arc::new(test_utils::TestLogger::new()),
 			channel_monitors: &channel_monitors,
@@ -3493,7 +3492,6 @@ fn test_manager_serialize_deserialize_inconsistent_monitor() {
 		keys_manager,
 		fee_estimator: Arc::new(test_utils::TestFeeEstimator { sat_per_kw: 253 }),
 		monitor: nodes[0].chan_monitor.clone(),
-		chain_monitor: nodes[0].chain_monitor.clone(),
 		tx_broadcaster: nodes[0].tx_broadcaster.clone(),
 		logger: Arc::new(test_utils::TestLogger::new()),
 		channel_monitors: &node_0_monitors.iter().map(|monitor| { (monitor.get_funding_txo().unwrap(), monitor) }).collect(),
@@ -6100,7 +6098,6 @@ fn test_data_loss_protect() {
 		keys_manager: Arc::new(keysinterface::KeysManager::new(&nodes[0].node_seed, Network::Testnet, Arc::clone(&logger), 42, 21)),
 		fee_estimator: feeest.clone(),
 		monitor: monitor.clone(),
-		chain_monitor: chain_monitor.clone(),
 		logger: Arc::clone(&logger),
 		tx_broadcaster,
 		default_config: UserConfig::new(),