Process monitor update events in block_[dis]connected asynchronously
[rust-lightning] / lightning / src / ln / channelmanager.rs
index c39eef3ea477a9d7558b69629601c4be14d6dbfc..51920a4f2ebc969d213b531502f7471f09785ff0 100644 (file)
@@ -18,7 +18,7 @@
 //! imply it needs to fail HTLCs/payments/channels it manages).
 //!
 
-use bitcoin::blockdata::block::BlockHeader;
+use bitcoin::blockdata::block::{Block, BlockHeader};
 use bitcoin::blockdata::constants::genesis_block;
 use bitcoin::network::constants::Network;
 
@@ -46,7 +46,7 @@ use ln::msgs;
 use ln::msgs::NetAddress;
 use ln::onion_utils;
 use ln::msgs::{ChannelMessageHandler, DecodeError, LightningError, OptionalField};
-use chain::keysinterface::{ChannelKeys, KeysInterface, KeysManager, InMemoryChannelKeys};
+use chain::keysinterface::{Sign, KeysInterface, KeysManager, InMemorySigner};
 use util::config::UserConfig;
 use util::events::{Event, EventsProvider, MessageSendEvent, MessageSendEventsProvider};
 use util::{byte_utils, events};
@@ -58,9 +58,11 @@ use util::errors::APIError;
 use std::{cmp, mem};
 use std::collections::{HashMap, hash_map, HashSet};
 use std::io::{Cursor, Read};
-use std::sync::{Arc, Mutex, MutexGuard, RwLock};
+use std::sync::{Arc, Condvar, Mutex, MutexGuard, RwLock, RwLockReadGuard};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::time::Duration;
+#[cfg(any(test, feature = "allow_wallclock_use"))]
+use std::time::Instant;
 use std::marker::{Sync, Send};
 use std::ops::Deref;
 use bitcoin::hashes::hex::ToHex;
@@ -204,7 +206,7 @@ pub struct PaymentPreimage(pub [u8;32]);
 #[derive(Hash, Copy, Clone, PartialEq, Eq, Debug)]
 pub struct PaymentSecret(pub [u8;32]);
 
-type ShutdownResult = (Option<OutPoint>, ChannelMonitorUpdate, Vec<(HTLCSource, PaymentHash)>);
+type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash)>);
 
 /// Error type returned across the channel_state mutex boundary. When an Err is generated for a
 /// Channel, we generally end up with a ChannelError::Close for which we have to close the channel
@@ -312,8 +314,8 @@ pub(super) enum RAACommitmentOrder {
 }
 
 // Note this is only exposed in cfg(test):
-pub(super) struct ChannelHolder<ChanSigner: ChannelKeys> {
-       pub(super) by_id: HashMap<[u8; 32], Channel<ChanSigner>>,
+pub(super) struct ChannelHolder<Signer: Sign> {
+       pub(super) by_id: HashMap<[u8; 32], Channel<Signer>>,
        pub(super) short_to_id: HashMap<u64, [u8; 32]>,
        /// 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
@@ -331,6 +333,15 @@ pub(super) struct ChannelHolder<ChanSigner: ChannelKeys> {
        pub(super) pending_msg_events: Vec<MessageSendEvent>,
 }
 
+/// Events which we process internally but cannot be procsesed immediately at the generation site
+/// for some reason. They are handled in timer_chan_freshness_every_min, so may be processed with
+/// quite some time lag.
+enum BackgroundEvent {
+       /// Handle a ChannelMonitorUpdate that closes a channel, broadcasting its current latest holder
+       /// commitment transaction.
+       ClosingMonitorUpdate((OutPoint, ChannelMonitorUpdate)),
+}
+
 /// State we hold per-peer. In the future we should put channels in here, but for now we only hold
 /// the latest Init features we heard from the peer.
 struct PeerState {
@@ -347,7 +358,7 @@ const ERR: () = "You need at least 32 bit pointers (well, usize, but we'll assum
 /// issues such as overly long function definitions. Note that the ChannelManager can take any
 /// type that implements KeysInterface for its keys manager, but this type alias chooses the
 /// concrete type of the KeysManager.
-pub type SimpleArcChannelManager<M, T, F, L> = Arc<ChannelManager<InMemoryChannelKeys, Arc<M>, Arc<T>, Arc<KeysManager>, Arc<F>, Arc<L>>>;
+pub type SimpleArcChannelManager<M, T, F, L> = ChannelManager<InMemorySigner, Arc<M>, Arc<T>, Arc<KeysManager>, Arc<F>, Arc<L>>;
 
 /// SimpleRefChannelManager is a type alias for a ChannelManager reference, and is the reference
 /// counterpart to the SimpleArcChannelManager type alias. Use this type by default when you don't
@@ -357,7 +368,7 @@ pub type SimpleArcChannelManager<M, T, F, L> = Arc<ChannelManager<InMemoryChanne
 /// helps with issues such as long function definitions. Note that the ChannelManager can take any
 /// type that implements KeysInterface for its keys manager, but this type alias chooses the
 /// concrete type of the KeysManager.
-pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManager<InMemoryChannelKeys, &'a M, &'b T, &'c KeysManager, &'d F, &'e L>;
+pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManager<InMemorySigner, &'a M, &'b T, &'c KeysManager, &'d F, &'e L>;
 
 /// Manager which keeps track of a number of channels and sends messages to the appropriate
 /// channel, also tracking HTLC preimages and forwarding onion packets appropriately.
@@ -378,7 +389,7 @@ pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManage
 /// ChannelMonitors passed by reference to read(), those channels will be force-closed based on the
 /// ChannelMonitor state and no funds will be lost (mod on-chain transaction fees).
 ///
-/// Note that the deserializer is only implemented for (Sha256dHash, ChannelManager), which
+/// Note that the deserializer is only implemented for (Option<BlockHash>, ChannelManager), which
 /// tells you the last block hash which was block_connect()ed. You MUST rescan any blocks along
 /// the "reorg path" (ie call block_disconnected() until you get to a common block and then call
 /// block_connected() to step towards your best block) upon deserialization before using the
@@ -395,10 +406,10 @@ pub type SimpleRefChannelManager<'a, 'b, 'c, 'd, 'e, M, T, F, L> = ChannelManage
 /// essentially you should default to using a SimpleRefChannelManager, and use a
 /// SimpleArcChannelManager when you require a ChannelManager with a static lifetime, such as when
 /// you're using lightning-net-tokio.
-pub struct ChannelManager<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+pub struct ChannelManager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
                                L::Target: Logger,
 {
@@ -416,9 +427,9 @@ pub struct ChannelManager<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref,
        secp_ctx: Secp256k1<secp256k1::All>,
 
        #[cfg(any(test, feature = "_test_utils"))]
-       pub(super) channel_state: Mutex<ChannelHolder<ChanSigner>>,
+       pub(super) channel_state: Mutex<ChannelHolder<Signer>>,
        #[cfg(not(any(test, feature = "_test_utils")))]
-       channel_state: Mutex<ChannelHolder<ChanSigner>>,
+       channel_state: Mutex<ChannelHolder<Signer>>,
        our_network_key: SecretKey,
 
        /// Used to track the last value sent in a node_announcement "timestamp" field. We ensure this
@@ -434,16 +445,50 @@ pub struct ChannelManager<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref,
        per_peer_state: RwLock<HashMap<PublicKey, Mutex<PeerState>>>,
 
        pending_events: Mutex<Vec<events::Event>>,
+       pending_background_events: Mutex<Vec<BackgroundEvent>>,
        /// Used when we have to take a BIG lock to make sure everything is self-consistent.
        /// Essentially just when we're serializing ourselves out.
        /// Taken first everywhere where we are making changes before any other locks.
+       /// When acquiring this lock in read mode, rather than acquiring it directly, call
+       /// `PersistenceNotifierGuard::new(..)` and pass the lock to it, to ensure the PersistenceNotifier
+       /// the lock contains sends out a notification when the lock is released.
        total_consistency_lock: RwLock<()>,
 
+       persistence_notifier: PersistenceNotifier,
+
        keys_manager: K,
 
        logger: L,
 }
 
+/// Whenever we release the `ChannelManager`'s `total_consistency_lock`, from read mode, it is
+/// desirable to notify any listeners on `wait_timeout`/`wait` that new updates are available for
+/// persistence. Therefore, this struct is responsible for locking the total consistency lock and,
+/// upon going out of scope, sending the aforementioned notification (since the lock being released
+/// indicates that the updates are ready for persistence).
+struct PersistenceNotifierGuard<'a> {
+       persistence_notifier: &'a PersistenceNotifier,
+       // We hold onto this result so the lock doesn't get released immediately.
+       _read_guard: RwLockReadGuard<'a, ()>,
+}
+
+impl<'a> PersistenceNotifierGuard<'a> {
+       fn new(lock: &'a RwLock<()>, notifier: &'a PersistenceNotifier) -> Self {
+               let read_guard = lock.read().unwrap();
+
+               Self {
+                       persistence_notifier: notifier,
+                       _read_guard: read_guard,
+               }
+       }
+}
+
+impl<'a> Drop for PersistenceNotifierGuard<'a> {
+       fn drop(&mut self) {
+               self.persistence_notifier.notify();
+       }
+}
+
 /// The amount of time we require our counterparty wait to claim their money (ie time between when
 /// we, or our watchtower, must check for them having broadcast a theft transaction).
 pub(crate) const BREAKDOWN_TIMEOUT: u16 = 6 * 24;
@@ -514,7 +559,7 @@ pub struct ChannelDetails {
 /// If a payment fails to send, it can be in one of several states. This enum is returned as the
 /// Err() type describing which state the payment is in, see the description of individual enum
 /// states for more.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub enum PaymentSendFailure {
        /// A parameter which was passed to send_payment was invalid, preventing us from attempting to
        /// send the payment at all. No channel state has been changed or messages sent to peers, and
@@ -709,10 +754,10 @@ macro_rules! maybe_break_monitor_err {
        }
 }
 
-impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
@@ -731,7 +776,8 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// Users need to notify the new ChannelManager when a new block is connected or
        /// disconnected using its `block_connected` and `block_disconnected` methods.
        pub fn new(network: Network, fee_est: F, chain_monitor: M, tx_broadcaster: T, logger: L, keys_manager: K, config: UserConfig, current_blockchain_height: usize) -> Self {
-               let secp_ctx = Secp256k1::new();
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&keys_manager.get_secure_random_bytes());
 
                ChannelManager {
                        default_configuration: config.clone(),
@@ -758,7 +804,9 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                        per_peer_state: RwLock::new(HashMap::new()),
 
                        pending_events: Mutex::new(Vec::new()),
+                       pending_background_events: Mutex::new(Vec::new()),
                        total_consistency_lock: RwLock::new(()),
+                       persistence_notifier: PersistenceNotifier::new(),
 
                        keys_manager,
 
@@ -787,7 +835,10 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                let channel = Channel::new_outbound(&self.fee_estimator, &self.keys_manager, their_network_key, channel_value_satoshis, push_msat, user_id, config)?;
                let res = channel.get_open_channel(self.genesis_hash.clone());
 
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
+               // We want to make sure the lock is actually acquired by PersistenceNotifierGuard.
+               debug_assert!(&self.total_consistency_lock.try_write().is_err());
+
                let mut channel_state = self.channel_state.lock().unwrap();
                match channel_state.by_id.entry(channel.channel_id()) {
                        hash_map::Entry::Occupied(_) => {
@@ -806,7 +857,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                Ok(())
        }
 
-       fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<ChanSigner>)) -> bool>(&self, f: Fn) -> Vec<ChannelDetails> {
+       fn list_channels_with_filter<Fn: FnMut(&(&[u8; 32], &Channel<Signer>)) -> bool>(&self, f: Fn) -> Vec<ChannelDetails> {
                let mut res = Vec::new();
                {
                        let channel_state = self.channel_state.lock().unwrap();
@@ -859,7 +910,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        ///
        /// May generate a SendShutdown message event on success, which should be relayed.
        pub fn close_channel(&self, channel_id: &[u8; 32]) -> Result<(), APIError> {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let (mut failed_htlcs, chan_option) = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
@@ -902,12 +953,12 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 
        #[inline]
        fn finish_force_close_channel(&self, shutdown_res: ShutdownResult) {
-               let (funding_txo_option, monitor_update, mut failed_htlcs) = shutdown_res;
+               let (monitor_update_option, mut failed_htlcs) = shutdown_res;
                log_trace!(self.logger, "Finishing force-closure of channel {} HTLCs to fail", failed_htlcs.len());
                for htlc_source in failed_htlcs.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), htlc_source.0, &htlc_source.1, HTLCFailReason::Reason { failure_code: 0x4000 | 8, data: Vec::new() });
                }
-               if let Some(funding_txo) = funding_txo_option {
+               if let Some((funding_txo, monitor_update)) = monitor_update_option {
                        // There isn't anything we can do if we get an update failure - we're already
                        // force-closing. The monitor update on the required in-memory copy should broadcast
                        // the latest local state, which is the best we can do anyway. Thus, it is safe to
@@ -916,21 +967,24 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                }
        }
 
-       /// Force closes a channel, immediately broadcasting the latest local commitment transaction to
-       /// the chain and rejecting new HTLCs on the given channel.
-       pub fn force_close_channel(&self, channel_id: &[u8; 32]) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
-
+       fn force_close_channel_with_peer(&self, channel_id: &[u8; 32], peer_node_id: Option<&PublicKey>) -> Result<(), APIError> {
                let mut chan = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
-                       if let Some(chan) = channel_state.by_id.remove(channel_id) {
-                               if let Some(short_id) = chan.get_short_channel_id() {
+                       if let hash_map::Entry::Occupied(chan) = channel_state.by_id.entry(channel_id.clone()) {
+                               if let Some(node_id) = peer_node_id {
+                                       if chan.get().get_counterparty_node_id() != *node_id {
+                                               // Error or Ok here doesn't matter - the result is only exposed publicly
+                                               // when peer_node_id is None anyway.
+                                               return Ok(());
+                                       }
+                               }
+                               if let Some(short_id) = chan.get().get_short_channel_id() {
                                        channel_state.short_to_id.remove(&short_id);
                                }
-                               chan
+                               chan.remove_entry().1
                        } else {
-                               return;
+                               return Err(APIError::ChannelUnavailable{err: "No such channel".to_owned()});
                        }
                };
                log_trace!(self.logger, "Force-closing channel {}", log_bytes!(channel_id[..]));
@@ -941,17 +995,26 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                msg: update
                        });
                }
+
+               Ok(())
+       }
+
+       /// Force closes a channel, immediately broadcasting the latest local commitment transaction to
+       /// the chain and rejecting new HTLCs on the given channel. Fails if channel_id is unknown to the manager.
+       pub fn force_close_channel(&self, channel_id: &[u8; 32]) -> Result<(), APIError> {
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
+               self.force_close_channel_with_peer(channel_id, None)
        }
 
        /// Force close all channels, immediately broadcasting the latest local commitment transaction
        /// for each to the chain and rejecting new HTLCs on each.
        pub fn force_close_all_channels(&self) {
                for chan in self.list_channels() {
-                       self.force_close_channel(&chan.channel_id);
+                       let _ = self.force_close_channel(&chan.channel_id);
                }
        }
 
-       fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> (PendingHTLCStatus, MutexGuard<ChannelHolder<ChanSigner>>) {
+       fn decode_update_add_htlc_onion(&self, msg: &msgs::UpdateAddHTLC) -> (PendingHTLCStatus, MutexGuard<ChannelHolder<Signer>>) {
                macro_rules! return_malformed_err {
                        ($msg: expr, $err_code: expr) => {
                                {
@@ -1223,7 +1286,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
 
        /// only fails if the channel does not yet have an assigned short_id
        /// May be called with channel_state already locked!
-       fn get_channel_update(&self, chan: &Channel<ChanSigner>) -> Result<msgs::ChannelUpdate, LightningError> {
+       fn get_channel_update(&self, chan: &Channel<Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
                let short_channel_id = match chan.get_short_channel_id() {
                        None => return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError}),
                        Some(id) => id,
@@ -1267,7 +1330,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                }
                let onion_packet = onion_utils::construct_onion_packet(onion_payloads, onion_keys, prng_seed, payment_hash);
 
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let err: Result<(), _> = loop {
                        let mut channel_lock = self.channel_state.lock().unwrap();
@@ -1435,7 +1498,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// May panic if the funding_txo is duplicative with some other channel (note that this should
        /// be trivially prevented by using unique funding transaction keys per-channel).
        pub fn funding_transaction_generated(&self, temporary_channel_id: &[u8; 32], funding_txo: OutPoint) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let (chan, msg) = {
                        let (res, chan) = match self.channel_state.lock().unwrap().by_id.remove(temporary_channel_id) {
@@ -1471,7 +1534,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                }
        }
 
-       fn get_announcement_sigs(&self, chan: &Channel<ChanSigner>) -> Option<msgs::AnnouncementSignatures> {
+       fn get_announcement_sigs(&self, chan: &Channel<Signer>) -> Option<msgs::AnnouncementSignatures> {
                if !chan.should_announce() {
                        log_trace!(self.logger, "Can't send announcement_signatures for private channel {}", log_bytes!(chan.channel_id()));
                        return None
@@ -1518,7 +1581,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        ///
        /// Panics if addresses is absurdly large (more than 500).
        pub fn broadcast_node_announcement(&self, rgb: [u8; 3], alias: [u8; 32], addresses: Vec<NetAddress>) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                if addresses.len() > 500 {
                        panic!("More than half the message size was taken up by public addresses!");
@@ -1548,7 +1611,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// Should only really ever be called in response to a PendingHTLCsForwardable event.
        /// Will likely generate further events.
        pub fn process_pending_htlc_forwards(&self) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let mut new_events = Vec::new();
                let mut failed_forwards = Vec::new();
@@ -1802,13 +1865,42 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                events.append(&mut new_events);
        }
 
+       /// Free the background events, generally called from timer_chan_freshness_every_min.
+       ///
+       /// Exposed for testing to allow us to process events quickly without generating accidental
+       /// BroadcastChannelUpdate events in timer_chan_freshness_every_min.
+       ///
+       /// Expects the caller to have a total_consistency_lock read lock.
+       fn process_background_events(&self) {
+               let mut background_events = Vec::new();
+               mem::swap(&mut *self.pending_background_events.lock().unwrap(), &mut background_events);
+               for event in background_events.drain(..) {
+                       match event {
+                               BackgroundEvent::ClosingMonitorUpdate((funding_txo, update)) => {
+                                       // The channel has already been closed, so no use bothering to care about the
+                                       // monitor updating completing.
+                                       let _ = self.chain_monitor.update_channel(funding_txo, update);
+                               },
+                       }
+               }
+       }
+
+       #[cfg(any(test, feature = "_test_utils"))]
+       pub(crate) fn test_process_background_events(&self) {
+               self.process_background_events();
+       }
+
        /// If a peer is disconnected we mark any channels with that peer as 'disabled'.
        /// After some time, if channels are still disabled we need to broadcast a ChannelUpdate
        /// to inform the network about the uselessness of these channels.
        ///
        /// This method handles all the details, and must be called roughly once per minute.
+       ///
+       /// Note that in some rare cases this may generate a `chain::Watch::update_channel` call.
        pub fn timer_chan_freshness_every_min(&self) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
+               self.process_background_events();
+
                let mut channel_state_lock = self.channel_state.lock().unwrap();
                let channel_state = &mut *channel_state_lock;
                for (_, chan) in channel_state.by_id.iter_mut() {
@@ -1833,7 +1925,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// Returns false if no payment was found to fail backwards, true if the process of failing the
        /// HTLC backwards has been started.
        pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash, payment_secret: &Option<PaymentSecret>) -> bool {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&(*payment_hash, *payment_secret));
@@ -1896,11 +1988,15 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// to fail and take the channel_state lock for each iteration (as we take ownership and may
        /// drop it). In other words, no assumptions are made that entries in claimable_htlcs point to
        /// still-available channels.
-       fn fail_htlc_backwards_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<ChanSigner>>, source: HTLCSource, payment_hash: &PaymentHash, onion_error: HTLCFailReason) {
+       fn fail_htlc_backwards_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<Signer>>, source: HTLCSource, payment_hash: &PaymentHash, onion_error: HTLCFailReason) {
                //TODO: There is a timing attack here where if a node fails an HTLC back to us they can
                //identify whether we sent it or not based on the (I presume) very different runtime
                //between the branches here. We should make this async and move it into the forward HTLCs
                //timer handling.
+
+               // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
+               // from block_connected which may run during initialization prior to the chain_monitor
+               // being fully configured. See the docs for `ChannelManagerReadArgs` for more.
                match source {
                        HTLCSource::OutboundRoute { ref path, .. } => {
                                log_trace!(self.logger, "Failing outbound payment HTLC with payment_hash {}", log_bytes!(payment_hash.0));
@@ -2012,7 +2108,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        pub fn claim_funds(&self, payment_preimage: PaymentPreimage, payment_secret: &Option<PaymentSecret>, expected_amount: u64) -> bool {
                let payment_hash = PaymentHash(Sha256::hash(&payment_preimage.0).into_inner());
 
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let mut channel_state = Some(self.channel_state.lock().unwrap());
                let removed_source = channel_state.as_mut().unwrap().claimable_htlcs.remove(&(payment_hash, *payment_secret));
@@ -2090,7 +2186,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                } else { false }
        }
 
-       fn claim_funds_from_hop(&self, channel_state_lock: &mut MutexGuard<ChannelHolder<ChanSigner>>, prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage) -> Result<(), Option<(PublicKey, MsgHandleErrInternal)>> {
+       fn claim_funds_from_hop(&self, channel_state_lock: &mut MutexGuard<ChannelHolder<Signer>>, prev_hop: HTLCPreviousHopData, payment_preimage: PaymentPreimage) -> Result<(), Option<(PublicKey, MsgHandleErrInternal)>> {
                //TODO: Delay the claimed_funds relaying just like we do outbound relay!
                let channel_state = &mut **channel_state_lock;
                let chan_id = match channel_state.short_to_id.get(&prev_hop.short_channel_id) {
@@ -2143,7 +2239,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                } else { unreachable!(); }
        }
 
-       fn claim_funds_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<ChanSigner>>, source: HTLCSource, payment_preimage: PaymentPreimage) {
+       fn claim_funds_internal(&self, mut channel_state_lock: MutexGuard<ChannelHolder<Signer>>, source: HTLCSource, payment_preimage: PaymentPreimage) {
                match source {
                        HTLCSource::OutboundRoute { .. } => {
                                mem::drop(channel_state_lock);
@@ -2208,7 +2304,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        ///  4) once all remote copies are updated, you call this function with the update_id that
        ///     completed, and once it is the latest the Channel will be re-enabled.
        pub fn channel_monitor_updated(&self, funding_txo: &OutPoint, highest_applied_update_id: u64) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                let mut close_results = Vec::new();
                let mut htlc_forwards = Vec::new();
@@ -2366,7 +2462,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                        // We do not do a force-close here as that would generate a monitor update for
                                        // a monitor that we didn't manage to store (and that we don't care about - we
                                        // don't respond with the funding_signed so the channel can never go on chain).
-                                       let (_funding_txo_option, _monitor_update, failed_htlcs) = chan.force_shutdown(true);
+                                       let (_monitor_update, failed_htlcs) = chan.force_shutdown(true);
                                        assert!(failed_htlcs.is_empty());
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("ChannelMonitor storage failure".to_owned(), funding_msg.channel_id));
                                },
@@ -2456,7 +2552,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                }
        }
 
-       fn internal_shutdown(&self, counterparty_node_id: &PublicKey, msg: &msgs::Shutdown) -> Result<(), MsgHandleErrInternal> {
+       fn internal_shutdown(&self, counterparty_node_id: &PublicKey, their_features: &InitFeatures, msg: &msgs::Shutdown) -> Result<(), MsgHandleErrInternal> {
                let (mut dropped_htlcs, chan_option) = {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_state_lock;
@@ -2466,7 +2562,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                        if chan_entry.get().get_counterparty_node_id() != *counterparty_node_id {
                                                return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                        }
-                                       let (shutdown, closing_signed, dropped_htlcs) = try_chan_entry!(self, chan_entry.get_mut().shutdown(&self.fee_estimator, &msg), channel_state, chan_entry);
+                                       let (shutdown, closing_signed, dropped_htlcs) = try_chan_entry!(self, chan_entry.get_mut().shutdown(&self.fee_estimator, &their_features, &msg), channel_state, chan_entry);
                                        if let Some(msg) = shutdown {
                                                channel_state.pending_msg_events.push(events::MessageSendEvent::SendShutdown {
                                                        node_id: counterparty_node_id.clone(),
@@ -2568,7 +2664,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                        return Err(MsgHandleErrInternal::send_err_msg_no_close("Got a message for a channel from the wrong node!".to_owned(), msg.channel_id));
                                }
 
-                               let create_pending_htlc_status = |chan: &Channel<ChanSigner>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
+                               let create_pending_htlc_status = |chan: &Channel<Signer>, pending_forward_info: PendingHTLCStatus, error_code: u16| {
                                        // Ensure error_code has the UPDATE flag set, since by default we send a
                                        // channel update along as part of failing the HTLC.
                                        assert!((error_code & 0x1000) != 0);
@@ -2959,7 +3055,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// (C-not exported) Cause its doc(hidden) anyway
        #[doc(hidden)]
        pub fn update_fee(&self, channel_id: [u8;32], feerate_per_kw: u32) -> Result<(), APIError> {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let counterparty_node_id;
                let err: Result<(), _> = loop {
                        let mut channel_state_lock = self.channel_state.lock().unwrap();
@@ -3048,12 +3144,35 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                        self.finish_force_close_channel(failure);
                }
        }
+
+       /// Handle a list of channel failures during a block_connected or block_disconnected call,
+       /// pushing the channel monitor update (if any) to the background events queue and removing the
+       /// Channel object.
+       fn handle_init_event_channel_failures(&self, mut failed_channels: Vec<ShutdownResult>) {
+               for mut failure in failed_channels.drain(..) {
+                       // Either a commitment transactions has been confirmed on-chain or
+                       // Channel::block_disconnected detected that the funding transaction has been
+                       // reorganized out of the main chain.
+                       // We cannot broadcast our latest local state via monitor update (as
+                       // Channel::force_shutdown tries to make us do) as we may still be in initialization,
+                       // so we track the update internally and handle it when the user next calls
+                       // timer_chan_freshness_every_min, guaranteeing we're running normally.
+                       if let Some((funding_txo, update)) = failure.0.take() {
+                               assert_eq!(update.updates.len(), 1);
+                               if let ChannelMonitorUpdateStep::ChannelForceClosed { should_broadcast } = update.updates[0] {
+                                       assert!(should_broadcast);
+                               } else { unreachable!(); }
+                               self.pending_background_events.lock().unwrap().push(BackgroundEvent::ClosingMonitorUpdate((funding_txo, update)));
+                       }
+                       self.finish_force_close_channel(failure);
+               }
+       }
 }
 
-impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> MessageSendEventsProvider for ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> MessageSendEventsProvider for ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
                                L::Target: Logger,
 {
@@ -3069,10 +3188,10 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        }
 }
 
-impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> EventsProvider for ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> EventsProvider for ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
                                L::Target: Logger,
 {
@@ -3088,18 +3207,39 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        }
 }
 
-impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> chain::Listen for ChannelManager<Signer, M, T, K, F, L>
+where
+       M::Target: chain::Watch<Signer>,
+       T::Target: BroadcasterInterface,
+       K::Target: KeysInterface<Signer = Signer>,
+       F::Target: FeeEstimator,
+       L::Target: Logger,
+{
+       fn block_connected(&self, block: &Block, height: u32) {
+               let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
+               ChannelManager::block_connected(self, &block.header, &txdata, height);
+       }
+
+       fn block_disconnected(&self, header: &BlockHeader, _height: u32) {
+               ChannelManager::block_disconnected(self, header);
+       }
+}
+
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
        /// Updates channel state based on transactions seen in a connected block.
        pub fn block_connected(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
+               // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
+               // during initialization prior to the chain_monitor being fully configured in some cases.
+               // See the docs for `ChannelManagerReadArgs` for more.
                let header_hash = header.block_hash();
                log_trace!(self.logger, "Block {} at height {} connected", header_hash, height);
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
                let mut timed_out_htlcs = Vec::new();
                {
@@ -3148,9 +3288,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                                                if let Some(short_id) = channel.get_short_channel_id() {
                                                                        short_to_id.remove(&short_id);
                                                                }
-                                                               // It looks like our counterparty went on-chain. We go ahead and
-                                                               // broadcast our latest local state as well here, just in case its
-                                                               // some kind of SPV attack, though we expect these to be dropped.
+                                                               // It looks like our counterparty went on-chain. Close the channel.
                                                                failed_channels.push(channel.force_shutdown(true));
                                                                if let Ok(update) = self.get_channel_update(&channel) {
                                                                        pending_msg_events.push(events::MessageSendEvent::BroadcastChannelUpdate {
@@ -3184,9 +3322,8 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                !htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
                        });
                }
-               for failure in failed_channels.drain(..) {
-                       self.finish_force_close_channel(failure);
-               }
+
+               self.handle_init_event_channel_failures(failed_channels);
 
                for (source, payment_hash, reason) in timed_out_htlcs.drain(..) {
                        self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), source, &payment_hash, reason);
@@ -3212,7 +3349,10 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
        /// If necessary, the channel may be force-closed without letting the counterparty participate
        /// in the shutdown.
        pub fn block_disconnected(&self, header: &BlockHeader) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               // Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
+               // during initialization prior to the chain_monitor being fully configured in some cases.
+               // See the docs for `ChannelManagerReadArgs` for more.
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
                {
                        let mut channel_lock = self.channel_state.lock().unwrap();
@@ -3236,104 +3376,125 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
                                }
                        });
                }
-               for failure in failed_channels.drain(..) {
-                       self.finish_force_close_channel(failure);
-               }
+               self.handle_init_event_channel_failures(failed_channels);
                self.latest_block_height.fetch_sub(1, Ordering::AcqRel);
                *self.last_block_hash.try_lock().expect("block_(dis)connected must not be called in parallel") = header.block_hash();
        }
+
+       /// Blocks until ChannelManager needs to be persisted or a timeout is reached. It returns a bool
+       /// indicating whether persistence is necessary. Only one listener on `wait_timeout` is
+       /// guaranteed to be woken up.
+       /// Note that the feature `allow_wallclock_use` must be enabled to use this function.
+       #[cfg(any(test, feature = "allow_wallclock_use"))]
+       pub fn wait_timeout(&self, max_wait: Duration) -> bool {
+               self.persistence_notifier.wait_timeout(max_wait)
+       }
+
+       /// Blocks until ChannelManager needs to be persisted. Only one listener on `wait` is
+       /// guaranteed to be woken up.
+       pub fn wait(&self) {
+               self.persistence_notifier.wait()
+       }
+
+       #[cfg(any(test, feature = "_test_utils"))]
+       pub fn get_persistence_condvar_value(&self) -> bool {
+               let mutcond = &self.persistence_notifier.persistence_lock;
+               let &(ref mtx, _) = mutcond;
+               let guard = mtx.lock().unwrap();
+               *guard
+       }
 }
 
-impl<ChanSigner: ChannelKeys, M: Deref + Sync + Send, T: Deref + Sync + Send, K: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send>
-       ChannelMessageHandler for ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref + Sync + Send, T: Deref + Sync + Send, K: Deref + Sync + Send, F: Deref + Sync + Send, L: Deref + Sync + Send>
+       ChannelMessageHandler for ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
        fn handle_open_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::OpenChannel) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_open_channel(counterparty_node_id, their_features, msg), *counterparty_node_id);
        }
 
        fn handle_accept_channel(&self, counterparty_node_id: &PublicKey, their_features: InitFeatures, msg: &msgs::AcceptChannel) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_accept_channel(counterparty_node_id, their_features, msg), *counterparty_node_id);
        }
 
        fn handle_funding_created(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingCreated) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_funding_created(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_funding_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingSigned) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_funding_signed(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_funding_locked(&self, counterparty_node_id: &PublicKey, msg: &msgs::FundingLocked) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_funding_locked(counterparty_node_id, msg), *counterparty_node_id);
        }
 
-       fn handle_shutdown(&self, counterparty_node_id: &PublicKey, msg: &msgs::Shutdown) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
-               let _ = handle_error!(self, self.internal_shutdown(counterparty_node_id, msg), *counterparty_node_id);
+       fn handle_shutdown(&self, counterparty_node_id: &PublicKey, their_features: &InitFeatures, msg: &msgs::Shutdown) {
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
+               let _ = handle_error!(self, self.internal_shutdown(counterparty_node_id, their_features, msg), *counterparty_node_id);
        }
 
        fn handle_closing_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::ClosingSigned) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_closing_signed(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_update_add_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateAddHTLC) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_add_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_update_fulfill_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFulfillHTLC) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_fulfill_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_update_fail_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailHTLC) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_fail_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_update_fail_malformed_htlc(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFailMalformedHTLC) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_fail_malformed_htlc(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_commitment_signed(&self, counterparty_node_id: &PublicKey, msg: &msgs::CommitmentSigned) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_commitment_signed(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_revoke_and_ack(&self, counterparty_node_id: &PublicKey, msg: &msgs::RevokeAndACK) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_revoke_and_ack(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_update_fee(&self, counterparty_node_id: &PublicKey, msg: &msgs::UpdateFee) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_update_fee(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_announcement_signatures(&self, counterparty_node_id: &PublicKey, msg: &msgs::AnnouncementSignatures) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_announcement_signatures(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn handle_channel_reestablish(&self, counterparty_node_id: &PublicKey, msg: &msgs::ChannelReestablish) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let _ = handle_error!(self, self.internal_channel_reestablish(counterparty_node_id, msg), *counterparty_node_id);
        }
 
        fn peer_disconnected(&self, counterparty_node_id: &PublicKey, no_connection_possible: bool) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
                let mut failed_channels = Vec::new();
                let mut failed_payments = Vec::new();
                let mut no_channels_remain = true;
@@ -3426,7 +3587,7 @@ impl<ChanSigner: ChannelKeys, M: Deref + Sync + Send, T: Deref + Sync + Send, K:
        fn peer_connected(&self, counterparty_node_id: &PublicKey, init_msg: &msgs::Init) {
                log_debug!(self.logger, "Generating channel_reestablish events for {}", log_pubkey!(counterparty_node_id));
 
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                {
                        let mut peer_state_lock = self.per_peer_state.write().unwrap();
@@ -3466,20 +3627,85 @@ impl<ChanSigner: ChannelKeys, M: Deref + Sync + Send, T: Deref + Sync + Send, K:
        }
 
        fn handle_error(&self, counterparty_node_id: &PublicKey, msg: &msgs::ErrorMessage) {
-               let _consistency_lock = self.total_consistency_lock.read().unwrap();
+               let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
 
                if msg.channel_id == [0; 32] {
                        for chan in self.list_channels() {
                                if chan.remote_network_id == *counterparty_node_id {
-                                       self.force_close_channel(&chan.channel_id);
+                                       // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
+                                       let _ = self.force_close_channel_with_peer(&chan.channel_id, Some(counterparty_node_id));
                                }
                        }
                } else {
-                       self.force_close_channel(&msg.channel_id);
+                       // Untrusted messages from peer, we throw away the error if id points to a non-existent channel
+                       let _ = self.force_close_channel_with_peer(&msg.channel_id, Some(counterparty_node_id));
                }
        }
 }
 
+/// Used to signal to the ChannelManager persister that the manager needs to be re-persisted to
+/// disk/backups, through `wait_timeout` and `wait`.
+struct PersistenceNotifier {
+       /// Users won't access the persistence_lock directly, but rather wait on its bool using
+       /// `wait_timeout` and `wait`.
+       persistence_lock: (Mutex<bool>, Condvar),
+}
+
+impl PersistenceNotifier {
+       fn new() -> Self {
+               Self {
+                       persistence_lock: (Mutex::new(false), Condvar::new()),
+               }
+       }
+
+       fn wait(&self) {
+               loop {
+                       let &(ref mtx, ref cvar) = &self.persistence_lock;
+                       let mut guard = mtx.lock().unwrap();
+                       guard = cvar.wait(guard).unwrap();
+                       let result = *guard;
+                       if result {
+                               *guard = false;
+                               return
+                       }
+               }
+       }
+
+       #[cfg(any(test, feature = "allow_wallclock_use"))]
+       fn wait_timeout(&self, max_wait: Duration) -> bool {
+               let current_time = Instant::now();
+               loop {
+                       let &(ref mtx, ref cvar) = &self.persistence_lock;
+                       let mut guard = mtx.lock().unwrap();
+                       guard = cvar.wait_timeout(guard, max_wait).unwrap().0;
+                       // Due to spurious wakeups that can happen on `wait_timeout`, here we need to check if the
+                       // desired wait time has actually passed, and if not then restart the loop with a reduced wait
+                       // time. Note that this logic can be highly simplified through the use of
+                       // `Condvar::wait_while` and `Condvar::wait_timeout_while`, if and when our MSRV is raised to
+                       // 1.42.0.
+                       let elapsed = current_time.elapsed();
+                       let result = *guard;
+                       if result || elapsed >= max_wait {
+                               *guard = false;
+                               return result;
+                       }
+                       match max_wait.checked_sub(elapsed) {
+                               None => return result,
+                               Some(_) => continue
+                       }
+               }
+       }
+
+       // Signal to the ChannelManager persister that there are updates necessitating persisting to disk.
+       fn notify(&self) {
+               let &(ref persist_mtx, ref cnd) = &self.persistence_lock;
+               let mut persistence_lock = persist_mtx.lock().unwrap();
+               *persistence_lock = true;
+               mem::drop(persistence_lock);
+               cnd.notify_all();
+       }
+}
+
 const SERIALIZATION_VERSION: u8 = 1;
 const MIN_SERIALIZATION_VERSION: u8 = 1;
 
@@ -3693,10 +3919,10 @@ impl Readable for HTLCForwardInfo {
        }
 }
 
-impl<ChanSigner: ChannelKeys + Writeable, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> Writeable for ChannelManager<ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> Writeable for ChannelManager<Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
@@ -3756,6 +3982,18 @@ impl<ChanSigner: ChannelKeys + Writeable, M: Deref, T: Deref, K: Deref, F: Deref
                        event.write(writer)?;
                }
 
+               let background_events = self.pending_background_events.lock().unwrap();
+               (background_events.len() as u64).write(writer)?;
+               for event in background_events.iter() {
+                       match event {
+                               BackgroundEvent::ClosingMonitorUpdate((funding_txo, monitor_update)) => {
+                                       0u8.write(writer)?;
+                                       funding_txo.write(writer)?;
+                                       monitor_update.write(writer)?;
+                               },
+                       }
+               }
+
                (self.last_node_announcement_serial.load(Ordering::Acquire) as u32).write(writer)?;
 
                Ok(())
@@ -3767,24 +4005,35 @@ impl<ChanSigner: ChannelKeys + Writeable, M: Deref, T: Deref, K: Deref, F: Deref
 /// At a high-level, the process for deserializing a ChannelManager and resuming normal operation
 /// is:
 /// 1) Deserialize all stored ChannelMonitors.
-/// 2) Deserialize the ChannelManager by filling in this struct and calling <(Sha256dHash,
+/// 2) Deserialize the ChannelManager by filling in this struct and calling <(Option<BlockHash>,
 ///    ChannelManager)>::read(reader, args).
 ///    This may result in closing some Channels if the ChannelMonitor is newer than the stored
 ///    ChannelManager state to ensure no loss of funds. Thus, transactions may be broadcasted.
 /// 3) Register all relevant ChannelMonitor outpoints with your chain watch mechanism using
 ///    ChannelMonitor::get_outputs_to_watch() and ChannelMonitor::get_funding_txo().
 /// 4) Reconnect blocks on your ChannelMonitors.
-/// 5) Move the ChannelMonitors into your local chain::Watch.
-/// 6) Disconnect/connect blocks on the ChannelManager.
-pub struct ChannelManagerReadArgs<'a, ChanSigner: 'a + ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+/// 5) Disconnect/connect blocks on the ChannelManager.
+/// 6) Move the ChannelMonitors into your local chain::Watch.
+///
+/// Note that the ordering of #4-6 is not of importance, however all three must occur before you
+/// call any other methods on the newly-deserialized ChannelManager.
+///
+/// Note that because some channels may be closed during deserialization, it is critical that you
+/// always deserialize only the latest version of a ChannelManager and ChannelMonitors available to
+/// you. If you deserialize an old ChannelManager (during which force-closure transactions may be
+/// broadcast), and then later deserialize a newer version of the same ChannelManager (which will
+/// not force-close the same channels but consider them live), you may end up revoking a state for
+/// which you've already broadcasted the transaction.
+pub struct ChannelManagerReadArgs<'a, Signer: 'a + Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
        /// The keys provider which will give us relevant keys. Some keys will be loaded during
-       /// deserialization.
+       /// deserialization and KeysInterface::read_chan_signer will be used to read per-Channel
+       /// signing data.
        pub keys_manager: K,
 
        /// The fee_estimator for use in the ChannelManager in the future.
@@ -3821,14 +4070,14 @@ pub struct ChannelManagerReadArgs<'a, ChanSigner: 'a + ChannelKeys, M: Deref, T:
        /// this struct.
        ///
        /// (C-not exported) because we have no HashMap bindings
-       pub channel_monitors: HashMap<OutPoint, &'a mut ChannelMonitor<ChanSigner>>,
+       pub channel_monitors: HashMap<OutPoint, &'a mut ChannelMonitor<Signer>>,
 }
 
-impl<'a, ChanSigner: 'a + ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-               ChannelManagerReadArgs<'a, ChanSigner, M, T, K, F, L>
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<'a, Signer: 'a + Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
+               ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>
+       where M::Target: chain::Watch<Signer>,
                T::Target: BroadcasterInterface,
-               K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+               K::Target: KeysInterface<Signer = Signer>,
                F::Target: FeeEstimator,
                L::Target: Logger,
        {
@@ -3836,7 +4085,7 @@ impl<'a, ChanSigner: 'a + ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L
        /// HashMap for you. This is primarily useful for C bindings where it is not practical to
        /// populate a HashMap directly from C.
        pub fn new(keys_manager: K, fee_estimator: F, chain_monitor: M, tx_broadcaster: T, logger: L, default_config: UserConfig,
-                       mut channel_monitors: Vec<&'a mut ChannelMonitor<ChanSigner>>) -> Self {
+                       mut channel_monitors: Vec<&'a mut ChannelMonitor<Signer>>) -> Self {
                Self {
                        keys_manager, fee_estimator, chain_monitor, tx_broadcaster, logger, default_config,
                        channel_monitors: channel_monitors.drain(..).map(|monitor| { (monitor.get_funding_txo().0, monitor) }).collect()
@@ -3846,29 +4095,29 @@ impl<'a, ChanSigner: 'a + ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref, L
 
 // Implement ReadableArgs for an Arc'd ChannelManager to make it a bit easier to work with the
 // SipmleArcChannelManager type:
-impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-       ReadableArgs<ChannelManagerReadArgs<'a, ChanSigner, M, T, K, F, L>> for (BlockHash, Arc<ChannelManager<ChanSigner, M, T, K, F, L>>)
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
+       ReadableArgs<ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>> for (Option<BlockHash>, Arc<ChannelManager<Signer, M, T, K, F, L>>)
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
-       fn read<R: ::std::io::Read>(reader: &mut R, args: ChannelManagerReadArgs<'a, ChanSigner, M, T, K, F, L>) -> Result<Self, DecodeError> {
-               let (blockhash, chan_manager) = <(BlockHash, ChannelManager<ChanSigner, M, T, K, F, L>)>::read(reader, args)?;
+       fn read<R: ::std::io::Read>(reader: &mut R, args: ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>) -> Result<Self, DecodeError> {
+               let (blockhash, chan_manager) = <(Option<BlockHash>, ChannelManager<Signer, M, T, K, F, L>)>::read(reader, args)?;
                Ok((blockhash, Arc::new(chan_manager)))
        }
 }
 
-impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-       ReadableArgs<ChannelManagerReadArgs<'a, ChanSigner, M, T, K, F, L>> for (BlockHash, ChannelManager<ChanSigner, M, T, K, F, L>)
-       where M::Target: chain::Watch<Keys=ChanSigner>,
+impl<'a, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
+       ReadableArgs<ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>> for (Option<BlockHash>, ChannelManager<Signer, M, T, K, F, L>)
+       where M::Target: chain::Watch<Signer>,
         T::Target: BroadcasterInterface,
-        K::Target: KeysInterface<ChanKeySigner = ChanSigner>,
+        K::Target: KeysInterface<Signer = Signer>,
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
-       fn read<R: ::std::io::Read>(reader: &mut R, mut args: ChannelManagerReadArgs<'a, ChanSigner, M, T, K, F, L>) -> Result<Self, DecodeError> {
+       fn read<R: ::std::io::Read>(reader: &mut R, mut args: ChannelManagerReadArgs<'a, Signer, M, T, K, F, L>) -> Result<Self, DecodeError> {
                let _ver: u8 = Readable::read(reader)?;
                let min_ver: u8 = Readable::read(reader)?;
                if min_ver > SERIALIZATION_VERSION {
@@ -3886,7 +4135,7 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
                let mut by_id = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                let mut short_to_id = HashMap::with_capacity(cmp::min(channel_count as usize, 128));
                for _ in 0..channel_count {
-                       let mut channel: Channel<ChanSigner> = Readable::read(reader)?;
+                       let mut channel: Channel<Signer> = Channel::read(reader, &args.keys_manager)?;
                        if channel.last_block_connected != Default::default() && channel.last_block_connected != last_block_hash {
                                return Err(DecodeError::InvalidValue);
                        }
@@ -3905,7 +4154,7 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
                                                channel.get_cur_counterparty_commitment_transaction_number() > monitor.get_cur_counterparty_commitment_number() ||
                                                channel.get_latest_monitor_update_id() < monitor.get_latest_update_id() {
                                        // But if the channel is behind of the monitor, close the channel:
-                                       let (_, _, mut new_failed_htlcs) = channel.force_shutdown(true);
+                                       let (_, mut new_failed_htlcs) = channel.force_shutdown(true);
                                        failed_htlcs.append(&mut new_failed_htlcs);
                                        monitor.broadcast_latest_holder_commitment_txn(&args.tx_broadcaster, &args.logger);
                                } else {
@@ -3969,8 +4218,20 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
                        }
                }
 
+               let background_event_count: u64 = Readable::read(reader)?;
+               let mut pending_background_events_read: Vec<BackgroundEvent> = Vec::with_capacity(cmp::min(background_event_count as usize, MAX_ALLOC_SIZE/mem::size_of::<BackgroundEvent>()));
+               for _ in 0..background_event_count {
+                       match <u8 as Readable>::read(reader)? {
+                               0 => pending_background_events_read.push(BackgroundEvent::ClosingMonitorUpdate((Readable::read(reader)?, Readable::read(reader)?))),
+                               _ => return Err(DecodeError::InvalidValue),
+                       }
+               }
+
                let last_node_announcement_serial: u32 = Readable::read(reader)?;
 
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&args.keys_manager.get_secure_random_bytes());
+
                let channel_manager = ChannelManager {
                        genesis_hash,
                        fee_estimator: args.fee_estimator,
@@ -3979,7 +4240,7 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
 
                        latest_block_height: AtomicUsize::new(latest_block_height as usize),
                        last_block_hash: Mutex::new(last_block_hash),
-                       secp_ctx: Secp256k1::new(),
+                       secp_ctx,
 
                        channel_state: Mutex::new(ChannelHolder {
                                by_id,
@@ -3995,7 +4256,10 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
                        per_peer_state: RwLock::new(per_peer_state),
 
                        pending_events: Mutex::new(pending_events_read),
+                       pending_background_events: Mutex::new(pending_background_events_read),
                        total_consistency_lock: RwLock::new(()),
+                       persistence_notifier: PersistenceNotifier::new(),
+
                        keys_manager: args.keys_manager,
                        logger: args.logger,
                        default_configuration: args.default_config,
@@ -4008,6 +4272,62 @@ impl<'a, ChanSigner: ChannelKeys + Readable, M: Deref, T: Deref, K: Deref, F: De
                //TODO: Broadcast channel update for closed channels, but only after we've made a
                //connection or two.
 
-               Ok((last_block_hash.clone(), channel_manager))
+               let last_seen_block_hash = if last_block_hash == Default::default() {
+                       None
+               } else {
+                       Some(last_block_hash)
+               };
+               Ok((last_seen_block_hash, channel_manager))
+       }
+}
+
+#[cfg(test)]
+mod tests {
+       use ln::channelmanager::PersistenceNotifier;
+       use std::sync::Arc;
+       use std::sync::atomic::{AtomicBool, Ordering};
+       use std::thread;
+       use std::time::Duration;
+
+       #[test]
+       fn test_wait_timeout() {
+               let persistence_notifier = Arc::new(PersistenceNotifier::new());
+               let thread_notifier = Arc::clone(&persistence_notifier);
+
+               let exit_thread = Arc::new(AtomicBool::new(false));
+               let exit_thread_clone = exit_thread.clone();
+               thread::spawn(move || {
+                       loop {
+                               let &(ref persist_mtx, ref cnd) = &thread_notifier.persistence_lock;
+                               let mut persistence_lock = persist_mtx.lock().unwrap();
+                               *persistence_lock = true;
+                               cnd.notify_all();
+
+                               if exit_thread_clone.load(Ordering::SeqCst) {
+                                       break
+                               }
+                       }
+               });
+
+               // Check that we can block indefinitely until updates are available.
+               let _ = persistence_notifier.wait();
+
+               // Check that the PersistenceNotifier will return after the given duration if updates are
+               // available.
+               loop {
+                       if persistence_notifier.wait_timeout(Duration::from_millis(100)) {
+                               break
+                       }
+               }
+
+               exit_thread.store(true, Ordering::SeqCst);
+
+               // Check that the PersistenceNotifier will return after the given duration even if no updates
+               // are available.
+               loop {
+                       if !persistence_notifier.wait_timeout(Duration::from_millis(100)) {
+                               break
+                       }
+               }
        }
 }