Merge pull request #2964 from jbesraa/prune-stale-chanmonitor
[rust-lightning] / lightning / src / util / persist.rs
index 372a094a931bed6dcca159e4bab310cdd7863a4b..249a089cd4883170be76bf8574855379ab48c643 100644 (file)
@@ -7,26 +7,28 @@
 //! This module contains a simple key-value store trait [`KVStore`] that
 //! allows one to implement the persistence for [`ChannelManager`], [`NetworkGraph`],
 //! and [`ChannelMonitor`] all in one place.
+//!
+//! [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 
+use core::cmp;
 use core::ops::Deref;
-use bitcoin::hashes::hex::{FromHex, ToHex};
+use core::str::FromStr;
 use bitcoin::{BlockHash, Txid};
 
-use crate::io;
-use crate::prelude::{Vec, String};
-use crate::routing::scoring::WriteableScore;
+use crate::{io, log_error};
+use crate::prelude::*;
 
 use crate::chain;
 use crate::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use crate::chain::chainmonitor::{Persist, MonitorUpdateId};
-use crate::sign::{EntropySource, NodeSigner, WriteableEcdsaChannelSigner, SignerProvider};
+use crate::sign::{EntropySource, ecdsa::WriteableEcdsaChannelSigner, SignerProvider};
 use crate::chain::transaction::OutPoint;
-use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate};
-use crate::ln::channelmanager::ChannelManager;
-use crate::routing::router::Router;
+use crate::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, CLOSED_CHANNEL_UPDATE_ID};
+use crate::ln::channelmanager::AChannelManager;
 use crate::routing::gossip::NetworkGraph;
+use crate::routing::scoring::WriteableScore;
 use crate::util::logger::Logger;
-use crate::util::ser::{ReadableArgs, Writeable};
+use crate::util::ser::{Readable, ReadableArgs, Writeable};
 
 /// The alphabet of characters allowed for namespaces and keys.
 pub const KVSTORE_NAMESPACE_KEY_ALPHABET: &str = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-";
@@ -34,64 +36,100 @@ pub const KVSTORE_NAMESPACE_KEY_ALPHABET: &str = "abcdefghijklmnopqrstuvwxyzABCD
 /// The maximum number of characters namespaces and keys may have.
 pub const KVSTORE_NAMESPACE_KEY_MAX_LEN: usize = 120;
 
-/// The namespace under which the [`ChannelManager`] will be persisted.
-pub const CHANNEL_MANAGER_PERSISTENCE_NAMESPACE: &str = "";
-/// The sub-namespace under which the [`ChannelManager`] will be persisted.
-pub const CHANNEL_MANAGER_PERSISTENCE_SUB_NAMESPACE: &str = "";
+/// The primary namespace under which the [`ChannelManager`] will be persisted.
+///
+/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
+pub const CHANNEL_MANAGER_PERSISTENCE_PRIMARY_NAMESPACE: &str = "";
+/// The secondary namespace under which the [`ChannelManager`] will be persisted.
+///
+/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
+pub const CHANNEL_MANAGER_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
 /// The key under which the [`ChannelManager`] will be persisted.
+///
+/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
 pub const CHANNEL_MANAGER_PERSISTENCE_KEY: &str = "manager";
 
-/// The namespace under which [`ChannelMonitor`]s will be persisted.
-pub const CHANNEL_MONITOR_PERSISTENCE_NAMESPACE: &str = "monitors";
-/// The sub-namespace under which [`ChannelMonitor`]s will be persisted.
-pub const CHANNEL_MONITOR_PERSISTENCE_SUB_NAMESPACE: &str = "";
+/// The primary namespace under which [`ChannelMonitor`]s will be persisted.
+pub const CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE: &str = "monitors";
+/// The secondary namespace under which [`ChannelMonitor`]s will be persisted.
+pub const CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
+/// The primary namespace under which [`ChannelMonitorUpdate`]s will be persisted.
+pub const CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE: &str = "monitor_updates";
+
+/// The primary namespace under which archived [`ChannelMonitor`]s will be persisted.
+pub const ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE: &str = "archived_monitors";
+/// The secondary namespace under which archived [`ChannelMonitor`]s will be persisted.
+pub const ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
 
-/// The namespace under which the [`NetworkGraph`] will be persisted.
-pub const NETWORK_GRAPH_PERSISTENCE_NAMESPACE: &str = "";
-/// The sub-namespace under which the [`NetworkGraph`] will be persisted.
-pub const NETWORK_GRAPH_PERSISTENCE_SUB_NAMESPACE: &str = "";
+/// The primary namespace under which the [`NetworkGraph`] will be persisted.
+pub const NETWORK_GRAPH_PERSISTENCE_PRIMARY_NAMESPACE: &str = "";
+/// The secondary namespace under which the [`NetworkGraph`] will be persisted.
+pub const NETWORK_GRAPH_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
 /// The key under which the [`NetworkGraph`] will be persisted.
 pub const NETWORK_GRAPH_PERSISTENCE_KEY: &str = "network_graph";
 
-/// The namespace under which the [`WriteableScore`] will be persisted.
-pub const SCORER_PERSISTENCE_NAMESPACE: &str = "";
-/// The sub-namespace under which the [`WriteableScore`] will be persisted.
-pub const SCORER_PERSISTENCE_SUB_NAMESPACE: &str = "";
+/// The primary namespace under which the [`WriteableScore`] will be persisted.
+pub const SCORER_PERSISTENCE_PRIMARY_NAMESPACE: &str = "";
+/// The secondary namespace under which the [`WriteableScore`] will be persisted.
+pub const SCORER_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
 /// The key under which the [`WriteableScore`] will be persisted.
 pub const SCORER_PERSISTENCE_KEY: &str = "scorer";
 
+/// The primary namespace under which [`OutputSweeper`] state will be persisted.
+///
+/// [`OutputSweeper`]: crate::util::sweep::OutputSweeper
+pub const OUTPUT_SWEEPER_PERSISTENCE_PRIMARY_NAMESPACE: &str = "";
+/// The secondary namespace under which [`OutputSweeper`] state will be persisted.
+///
+/// [`OutputSweeper`]: crate::util::sweep::OutputSweeper
+pub const OUTPUT_SWEEPER_PERSISTENCE_SECONDARY_NAMESPACE: &str = "";
+/// The secondary namespace under which [`OutputSweeper`] state will be persisted.
+/// The key under which [`OutputSweeper`] state will be persisted.
+///
+/// [`OutputSweeper`]: crate::util::sweep::OutputSweeper
+pub const OUTPUT_SWEEPER_PERSISTENCE_KEY: &str = "output_sweeper";
+
+/// A sentinel value to be prepended to monitors persisted by the [`MonitorUpdatingPersister`].
+///
+/// This serves to prevent someone from accidentally loading such monitors (which may need
+/// updates applied to be current) with another implementation.
+pub const MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL: &[u8] = &[0xFF; 2];
+
 /// Provides an interface that allows storage and retrieval of persisted values that are associated
 /// with given keys.
 ///
-/// In order to avoid collisions the key space is segmented based on the given `namespace`s and
-/// `sub_namespace`s. Implementations of this trait are free to handle them in different ways, as
-/// long as per-namespace key uniqueness is asserted.
+/// In order to avoid collisions the key space is segmented based on the given `primary_namespace`s
+/// and `secondary_namespace`s. Implementations of this trait are free to handle them in different
+/// ways, as long as per-namespace key uniqueness is asserted.
 ///
 /// Keys and namespaces are required to be valid ASCII strings in the range of
 /// [`KVSTORE_NAMESPACE_KEY_ALPHABET`] and no longer than [`KVSTORE_NAMESPACE_KEY_MAX_LEN`]. Empty
-/// namespaces and sub-namespaces (`""`) are assumed to be a valid, however, if `namespace` is
-/// empty, `sub_namespace` is required to be empty, too. This means that concerns should always be
-/// separated by namespace first, before sub-namespaces are used. While the number of namespaces
-/// will be relatively small and is determined at compile time, there may be many sub-namespaces
-/// per namespace. Note that per-namespace uniqueness needs to also hold for keys *and*
-/// namespaces/sub-namespaces in any given namespace/sub-namespace, i.e., conflicts between keys
-/// and equally named namespaces/sub-namespaces must be avoided.
+/// primary namespaces and secondary namespaces (`""`) are assumed to be a valid, however, if
+/// `primary_namespace` is empty, `secondary_namespace` is required to be empty, too. This means
+/// that concerns should always be separated by primary namespace first, before secondary
+/// namespaces are used. While the number of primary namespaces will be relatively small and is
+/// determined at compile time, there may be many secondary namespaces per primary namespace. Note
+/// that per-namespace uniqueness needs to also hold for keys *and* namespaces in any given
+/// namespace, i.e., conflicts between keys and equally named
+/// primary namespaces/secondary namespaces must be avoided.
 ///
 /// **Note:** Users migrating custom persistence backends from the pre-v0.0.117 `KVStorePersister`
-/// interface can use a concatenation of `[{namespace}/[{sub_namespace}/]]{key}` to recover a `key` compatible with the
-/// data model previously assumed by `KVStorePersister::persist`.
+/// interface can use a concatenation of `[{primary_namespace}/[{secondary_namespace}/]]{key}` to
+/// recover a `key` compatible with the data model previously assumed by `KVStorePersister::persist`.
 pub trait KVStore {
-       /// Returns the data stored for the given `namespace`, `sub_namespace`, and `key`.
+       /// Returns the data stored for the given `primary_namespace`, `secondary_namespace`, and
+       /// `key`.
        ///
        /// Returns an [`ErrorKind::NotFound`] if the given `key` could not be found in the given
-       /// `namespace` and `sub_namespace`.
+       /// `primary_namespace` and `secondary_namespace`.
        ///
        /// [`ErrorKind::NotFound`]: io::ErrorKind::NotFound
-       fn read(&self, namespace: &str, sub_namespace: &str, key: &str) -> io::Result<Vec<u8>>;
+       fn read(&self, primary_namespace: &str, secondary_namespace: &str, key: &str) -> Result<Vec<u8>, io::Error>;
        /// Persists the given data under the given `key`.
        ///
-       /// Will create the given `namespace` and `sub_namespace` if not already present in the store.
-       fn write(&self, namespace: &str, sub_namespace: &str, key: &str, buf: &[u8]) -> io::Result<()>;
+       /// Will create the given `primary_namespace` and `secondary_namespace` if not already present
+       /// in the store.
+       fn write(&self, primary_namespace: &str, secondary_namespace: &str, key: &str, buf: &[u8]) -> Result<(), io::Error>;
        /// Removes any data that had previously been persisted under the given `key`.
        ///
        /// If the `lazy` flag is set to `true`, the backend implementation might choose to lazily
@@ -104,29 +142,30 @@ pub trait KVStore {
        /// potentially get lost on crash after the method returns. Therefore, this flag should only be
        /// set for `remove` operations that can be safely replayed at a later time.
        ///
-       /// Returns successfully if no data will be stored for the given `namespace`, `sub_namespace`, and
-       /// `key`, independently of whether it was present before its invokation or not.
-       fn remove(&self, namespace: &str, sub_namespace: &str, key: &str, lazy: bool) -> io::Result<()>;
-       /// Returns a list of keys that are stored under the given `sub_namespace` in `namespace`.
+       /// Returns successfully if no data will be stored for the given `primary_namespace`,
+       /// `secondary_namespace`, and `key`, independently of whether it was present before its
+       /// invokation or not.
+       fn remove(&self, primary_namespace: &str, secondary_namespace: &str, key: &str, lazy: bool) -> Result<(), io::Error>;
+       /// Returns a list of keys that are stored under the given `secondary_namespace` in
+       /// `primary_namespace`.
        ///
        /// Returns the keys in arbitrary order, so users requiring a particular order need to sort the
-       /// returned keys. Returns an empty list if `namespace` or `sub_namespace` is unknown.
-       fn list(&self, namespace: &str, sub_namespace: &str) -> io::Result<Vec<String>>;
+       /// returned keys. Returns an empty list if `primary_namespace` or `secondary_namespace` is unknown.
+       fn list(&self, primary_namespace: &str, secondary_namespace: &str) -> Result<Vec<String>, io::Error>;
 }
 
 /// Trait that handles persisting a [`ChannelManager`], [`NetworkGraph`], and [`WriteableScore`] to disk.
-pub trait Persister<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref, S: WriteableScore<'a>>
-       where M::Target: 'static + chain::Watch<<SP::Target as SignerProvider>::Signer>,
-               T::Target: 'static + BroadcasterInterface,
-               ES::Target: 'static + EntropySource,
-               NS::Target: 'static + NodeSigner,
-               SP::Target: 'static + SignerProvider,
-               F::Target: 'static + FeeEstimator,
-               R::Target: 'static + Router,
-               L::Target: 'static + Logger,
+///
+/// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
+pub trait Persister<'a, CM: Deref, L: Deref, S: WriteableScore<'a>>
+where
+       CM::Target: 'static + AChannelManager,
+       L::Target: 'static + Logger,
 {
        /// Persist the given ['ChannelManager'] to disk, returning an error if persistence failed.
-       fn persist_manager(&self, channel_manager: &ChannelManager<M, T, ES, NS, SP, F, R, L>) -> Result<(), io::Error>;
+       ///
+       /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
+       fn persist_manager(&self, channel_manager: &CM) -> Result<(), io::Error>;
 
        /// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
        fn persist_graph(&self, network_graph: &NetworkGraph<L>) -> Result<(), io::Error>;
@@ -136,76 +175,95 @@ pub trait Persister<'a, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F:
 }
 
 
-impl<'a, A: KVStore, M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, L: Deref, S: WriteableScore<'a>> Persister<'a, M, T, ES, NS, SP, F, R, L, S> for A
-       where M::Target: 'static + chain::Watch<<SP::Target as SignerProvider>::Signer>,
-               T::Target: 'static + BroadcasterInterface,
-               ES::Target: 'static + EntropySource,
-               NS::Target: 'static + NodeSigner,
-               SP::Target: 'static + SignerProvider,
-               F::Target: 'static + FeeEstimator,
-               R::Target: 'static + Router,
-               L::Target: 'static + Logger,
+impl<'a, A: KVStore + ?Sized, CM: Deref, L: Deref, S: WriteableScore<'a>> Persister<'a, CM, L, S> for A
+where
+       CM::Target: 'static + AChannelManager,
+       L::Target: 'static + Logger,
 {
-       /// Persist the given [`ChannelManager`] to disk, returning an error if persistence failed.
-       fn persist_manager(&self, channel_manager: &ChannelManager<M, T, ES, NS, SP, F, R, L>) -> Result<(), io::Error> {
-               self.write(CHANNEL_MANAGER_PERSISTENCE_NAMESPACE,
-                                  CHANNEL_MANAGER_PERSISTENCE_SUB_NAMESPACE,
-                                  CHANNEL_MANAGER_PERSISTENCE_KEY,
-                                  &channel_manager.encode())
+       fn persist_manager(&self, channel_manager: &CM) -> Result<(), io::Error> {
+               self.write(CHANNEL_MANAGER_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MANAGER_PERSISTENCE_SECONDARY_NAMESPACE,
+                       CHANNEL_MANAGER_PERSISTENCE_KEY,
+                       &channel_manager.get_cm().encode())
        }
 
-       /// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
        fn persist_graph(&self, network_graph: &NetworkGraph<L>) -> Result<(), io::Error> {
-               self.write(NETWORK_GRAPH_PERSISTENCE_NAMESPACE,
-                                  NETWORK_GRAPH_PERSISTENCE_SUB_NAMESPACE,
-                                  NETWORK_GRAPH_PERSISTENCE_KEY,
-                                  &network_graph.encode())
+               self.write(NETWORK_GRAPH_PERSISTENCE_PRIMARY_NAMESPACE,
+                       NETWORK_GRAPH_PERSISTENCE_SECONDARY_NAMESPACE,
+                       NETWORK_GRAPH_PERSISTENCE_KEY,
+                       &network_graph.encode())
        }
 
-       /// Persist the given [`WriteableScore`] to disk, returning an error if persistence failed.
        fn persist_scorer(&self, scorer: &S) -> Result<(), io::Error> {
-               self.write(SCORER_PERSISTENCE_NAMESPACE,
-                                  SCORER_PERSISTENCE_SUB_NAMESPACE,
-                                  SCORER_PERSISTENCE_KEY,
-                                  &scorer.encode())
+               self.write(SCORER_PERSISTENCE_PRIMARY_NAMESPACE,
+                       SCORER_PERSISTENCE_SECONDARY_NAMESPACE,
+                       SCORER_PERSISTENCE_KEY,
+                       &scorer.encode())
        }
 }
 
-impl<ChannelSigner: WriteableEcdsaChannelSigner, K: KVStore> Persist<ChannelSigner> for K {
+impl<ChannelSigner: WriteableEcdsaChannelSigner, K: KVStore + ?Sized> Persist<ChannelSigner> for K {
        // TODO: We really need a way for the persister to inform the user that its time to crash/shut
        // down once these start returning failure.
-       // A PermanentFailure implies we should probably just shut down the node since we're
-       // force-closing channels without even broadcasting!
+       // Then we should return InProgress rather than UnrecoverableError, implying we should probably
+       // just shut down the node since we're not retrying persistence!
 
        fn persist_new_channel(&self, funding_txo: OutPoint, monitor: &ChannelMonitor<ChannelSigner>, _update_id: MonitorUpdateId) -> chain::ChannelMonitorUpdateStatus {
-               let key = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
+               let key = format!("{}_{}", funding_txo.txid.to_string(), funding_txo.index);
                match self.write(
-                       CHANNEL_MONITOR_PERSISTENCE_NAMESPACE,
-                       CHANNEL_MONITOR_PERSISTENCE_SUB_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
                        &key, &monitor.encode())
                {
                        Ok(()) => chain::ChannelMonitorUpdateStatus::Completed,
-                       Err(_) => chain::ChannelMonitorUpdateStatus::PermanentFailure,
+                       Err(_) => chain::ChannelMonitorUpdateStatus::UnrecoverableError
                }
        }
 
        fn update_persisted_channel(&self, funding_txo: OutPoint, _update: Option<&ChannelMonitorUpdate>, monitor: &ChannelMonitor<ChannelSigner>, _update_id: MonitorUpdateId) -> chain::ChannelMonitorUpdateStatus {
-               let key = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
+               let key = format!("{}_{}", funding_txo.txid.to_string(), funding_txo.index);
                match self.write(
-                       CHANNEL_MONITOR_PERSISTENCE_NAMESPACE,
-                       CHANNEL_MONITOR_PERSISTENCE_SUB_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
                        &key, &monitor.encode())
                {
                        Ok(()) => chain::ChannelMonitorUpdateStatus::Completed,
-                       Err(_) => chain::ChannelMonitorUpdateStatus::PermanentFailure,
+                       Err(_) => chain::ChannelMonitorUpdateStatus::UnrecoverableError
                }
        }
+
+       fn archive_persisted_channel(&self, funding_txo: OutPoint) {
+               let monitor_name = MonitorName::from(funding_txo);
+               let monitor = match self.read(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+               ) {
+                       Ok(monitor) => monitor,
+                       Err(_) => return
+               };
+               match self.write(
+                       ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       &monitor,
+               ) {
+                       Ok(()) => {}
+                       Err(_e) => return
+               };
+               let _ = self.remove(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       true,
+               );
+       }
 }
 
 /// Read previously persisted [`ChannelMonitor`]s from the store.
 pub fn read_channel_monitors<K: Deref, ES: Deref, SP: Deref>(
        kv_store: K, entropy_source: ES, signer_provider: SP,
-) -> io::Result<Vec<(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::Signer>)>>
+) -> Result<Vec<(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>)>, io::Error>
 where
        K::Target: KVStore,
        ES::Target: EntropySource + Sized,
@@ -214,7 +272,7 @@ where
        let mut res = Vec::new();
 
        for stored_key in kv_store.list(
-               CHANNEL_MONITOR_PERSISTENCE_NAMESPACE, CHANNEL_MONITOR_PERSISTENCE_SUB_NAMESPACE)?
+               CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE, CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE)?
        {
                if stored_key.len() < 66 {
                        return Err(io::Error::new(
@@ -222,7 +280,7 @@ where
                                "Stored key has invalid length"));
                }
 
-               let txid = Txid::from_hex(stored_key.split_at(64).0).map_err(|_| {
+               let txid = Txid::from_str(stored_key.split_at(64).0).map_err(|_| {
                        io::Error::new(io::ErrorKind::InvalidData, "Invalid tx ID in stored key")
                })?;
 
@@ -230,9 +288,9 @@ where
                        io::Error::new(io::ErrorKind::InvalidData, "Invalid tx index in stored key")
                })?;
 
-               match <(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::Signer>)>::read(
+               match <(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>)>::read(
                        &mut io::Cursor::new(
-                               kv_store.read(CHANNEL_MONITOR_PERSISTENCE_NAMESPACE, CHANNEL_MONITOR_PERSISTENCE_SUB_NAMESPACE, &stored_key)?),
+                               kv_store.read(CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE, CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE, &stored_key)?),
                        (&*entropy_source, &*signer_provider),
                ) {
                        Ok((block_hash, channel_monitor)) => {
@@ -249,10 +307,958 @@ where
                        Err(_) => {
                                return Err(io::Error::new(
                                        io::ErrorKind::InvalidData,
-                                       "Failed to deserialize ChannelMonitor"
+                                       "Failed to read ChannelMonitor"
                                ))
                        }
                }
        }
        Ok(res)
 }
+
+/// Implements [`Persist`] in a way that writes and reads both [`ChannelMonitor`]s and
+/// [`ChannelMonitorUpdate`]s.
+///
+/// # Overview
+///
+/// The main benefit this provides over the [`KVStore`]'s [`Persist`] implementation is decreased
+/// I/O bandwidth and storage churn, at the expense of more IOPS (including listing, reading, and
+/// deleting) and complexity. This is because it writes channel monitor differential updates,
+/// whereas the other (default) implementation rewrites the entire monitor on each update. For
+/// routing nodes, updates can happen many times per second to a channel, and monitors can be tens
+/// of megabytes (or more). Updates can be as small as a few hundred bytes.
+///
+/// Note that monitors written with `MonitorUpdatingPersister` are _not_ backward-compatible with
+/// the default [`KVStore`]'s [`Persist`] implementation. They have a prepended byte sequence,
+/// [`MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL`], applied to prevent deserialization with other
+/// persisters. This is because monitors written by this struct _may_ have unapplied updates. In
+/// order to downgrade, you must ensure that all updates are applied to the monitor, and remove the
+/// sentinel bytes.
+///
+/// # Storing monitors
+///
+/// Monitors are stored by implementing the [`Persist`] trait, which has two functions:
+///
+///   - [`Persist::persist_new_channel`], which persists whole [`ChannelMonitor`]s.
+///   - [`Persist::update_persisted_channel`], which persists only a [`ChannelMonitorUpdate`]
+///
+/// Whole [`ChannelMonitor`]s are stored in the [`CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE`],
+/// using the familiar encoding of an [`OutPoint`] (for example, `[SOME-64-CHAR-HEX-STRING]_1`).
+///
+/// Each [`ChannelMonitorUpdate`] is stored in a dynamic secondary namespace, as follows:
+///
+///   - primary namespace: [`CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE`]
+///   - secondary namespace: [the monitor's encoded outpoint name]
+///
+/// Under that secondary namespace, each update is stored with a number string, like `21`, which
+/// represents its `update_id` value.
+///
+/// For example, consider this channel, named for its transaction ID and index, or [`OutPoint`]:
+///
+///   - Transaction ID: `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef`
+///   - Index: `1`
+///
+/// Full channel monitors would be stored at a single key:
+///
+/// `[CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1`
+///
+/// Updates would be stored as follows (with `/` delimiting primary_namespace/secondary_namespace/key):
+///
+/// ```text
+/// [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/1
+/// [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/2
+/// [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/3
+/// ```
+/// ... and so on.
+///
+/// # Reading channel state from storage
+///
+/// Channel state can be reconstructed by calling
+/// [`MonitorUpdatingPersister::read_all_channel_monitors_with_updates`]. Alternatively, users can
+/// list channel monitors themselves and load channels individually using
+/// [`MonitorUpdatingPersister::read_channel_monitor_with_updates`].
+///
+/// ## EXTREMELY IMPORTANT
+///
+/// It is extremely important that your [`KVStore::read`] implementation uses the
+/// [`io::ErrorKind::NotFound`] variant correctly: that is, when a file is not found, and _only_ in
+/// that circumstance (not when there is really a permissions error, for example). This is because
+/// neither channel monitor reading function lists updates. Instead, either reads the monitor, and
+/// using its stored `update_id`, synthesizes update storage keys, and tries them in sequence until
+/// one is not found. All _other_ errors will be bubbled up in the function's [`Result`].
+///
+/// # Pruning stale channel updates
+///
+/// Stale updates are pruned when the consolidation threshold is reached according to `maximum_pending_updates`.
+/// Monitor updates in the range between the latest `update_id` and `update_id - maximum_pending_updates`
+/// are deleted.
+/// The `lazy` flag is used on the [`KVStore::remove`] method, so there are no guarantees that the deletions
+/// will complete. However, stale updates are not a problem for data integrity, since updates are
+/// only read that are higher than the stored [`ChannelMonitor`]'s `update_id`.
+///
+/// If you have many stale updates stored (such as after a crash with pending lazy deletes), and
+/// would like to get rid of them, consider using the
+/// [`MonitorUpdatingPersister::cleanup_stale_updates`] function.
+pub struct MonitorUpdatingPersister<K: Deref, L: Deref, ES: Deref, SP: Deref>
+where
+       K::Target: KVStore,
+       L::Target: Logger,
+       ES::Target: EntropySource + Sized,
+       SP::Target: SignerProvider + Sized,
+{
+       kv_store: K,
+       logger: L,
+       maximum_pending_updates: u64,
+       entropy_source: ES,
+       signer_provider: SP,
+}
+
+#[allow(dead_code)]
+impl<K: Deref, L: Deref, ES: Deref, SP: Deref>
+       MonitorUpdatingPersister<K, L, ES, SP>
+where
+       K::Target: KVStore,
+       L::Target: Logger,
+       ES::Target: EntropySource + Sized,
+       SP::Target: SignerProvider + Sized,
+{
+       /// Constructs a new [`MonitorUpdatingPersister`].
+       ///
+       /// The `maximum_pending_updates` parameter controls how many updates may be stored before a
+       /// [`MonitorUpdatingPersister`] consolidates updates by writing a full monitor. Note that
+       /// consolidation will frequently occur with fewer updates than what you set here; this number
+       /// is merely the maximum that may be stored. When setting this value, consider that for higher
+       /// values of `maximum_pending_updates`:
+       ///
+       ///   - [`MonitorUpdatingPersister`] will tend to write more [`ChannelMonitorUpdate`]s than
+       /// [`ChannelMonitor`]s, approaching one [`ChannelMonitor`] write for every
+       /// `maximum_pending_updates` [`ChannelMonitorUpdate`]s.
+       ///   - [`MonitorUpdatingPersister`] will issue deletes differently. Lazy deletes will come in
+       /// "waves" for each [`ChannelMonitor`] write. A larger `maximum_pending_updates` means bigger,
+       /// less frequent "waves."
+       ///   - [`MonitorUpdatingPersister`] will potentially have more listing to do if you need to run
+       /// [`MonitorUpdatingPersister::cleanup_stale_updates`].
+       pub fn new(
+               kv_store: K, logger: L, maximum_pending_updates: u64, entropy_source: ES,
+               signer_provider: SP,
+       ) -> Self {
+               MonitorUpdatingPersister {
+                       kv_store,
+                       logger,
+                       maximum_pending_updates,
+                       entropy_source,
+                       signer_provider,
+               }
+       }
+
+       /// Reads all stored channel monitors, along with any stored updates for them.
+       ///
+       /// It is extremely important that your [`KVStore::read`] implementation uses the
+       /// [`io::ErrorKind::NotFound`] variant correctly. For more information, please see the
+       /// documentation for [`MonitorUpdatingPersister`].
+       pub fn read_all_channel_monitors_with_updates<B: Deref, F: Deref>(
+               &self, broadcaster: &B, fee_estimator: &F,
+       ) -> Result<Vec<(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>)>, io::Error>
+       where
+               B::Target: BroadcasterInterface,
+               F::Target: FeeEstimator,
+       {
+               let monitor_list = self.kv_store.list(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+               )?;
+               let mut res = Vec::with_capacity(monitor_list.len());
+               for monitor_key in monitor_list {
+                       res.push(self.read_channel_monitor_with_updates(
+                               broadcaster,
+                               fee_estimator,
+                               monitor_key,
+                       )?)
+               }
+               Ok(res)
+       }
+
+       /// Read a single channel monitor, along with any stored updates for it.
+       ///
+       /// It is extremely important that your [`KVStore::read`] implementation uses the
+       /// [`io::ErrorKind::NotFound`] variant correctly. For more information, please see the
+       /// documentation for [`MonitorUpdatingPersister`].
+       ///
+       /// For `monitor_key`, channel storage keys be the channel's transaction ID and index, or
+       /// [`OutPoint`], with an underscore `_` between them. For example, given:
+       ///
+       ///   - Transaction ID: `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef`
+       ///   - Index: `1`
+       ///
+       /// The correct `monitor_key` would be:
+       /// `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1`
+       ///
+       /// Loading a large number of monitors will be faster if done in parallel. You can use this
+       /// function to accomplish this. Take care to limit the number of parallel readers.
+       pub fn read_channel_monitor_with_updates<B: Deref, F: Deref>(
+               &self, broadcaster: &B, fee_estimator: &F, monitor_key: String,
+       ) -> Result<(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>), io::Error>
+       where
+               B::Target: BroadcasterInterface,
+               F::Target: FeeEstimator,
+       {
+               let monitor_name = MonitorName::new(monitor_key)?;
+               let (block_hash, monitor) = self.read_monitor(&monitor_name)?;
+               let mut current_update_id = monitor.get_latest_update_id();
+               loop {
+                       current_update_id = match current_update_id.checked_add(1) {
+                               Some(next_update_id) => next_update_id,
+                               None => break,
+                       };
+                       let update_name = UpdateName::from(current_update_id);
+                       let update = match self.read_monitor_update(&monitor_name, &update_name) {
+                               Ok(update) => update,
+                               Err(err) if err.kind() == io::ErrorKind::NotFound => {
+                                       // We can't find any more updates, so we are done.
+                                       break;
+                               }
+                               Err(err) => return Err(err),
+                       };
+
+                       monitor.update_monitor(&update, broadcaster, fee_estimator, &self.logger)
+                               .map_err(|e| {
+                                       log_error!(
+                                               self.logger,
+                                               "Monitor update failed. monitor: {} update: {} reason: {:?}",
+                                               monitor_name.as_str(),
+                                               update_name.as_str(),
+                                               e
+                                       );
+                                       io::Error::new(io::ErrorKind::Other, "Monitor update failed")
+                               })?;
+               }
+               Ok((block_hash, monitor))
+       }
+
+       /// Read a channel monitor.
+       fn read_monitor(
+               &self, monitor_name: &MonitorName,
+       ) -> Result<(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>), io::Error> {
+               let outpoint: OutPoint = monitor_name.try_into()?;
+               let mut monitor_cursor = io::Cursor::new(self.kv_store.read(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+               )?);
+               // Discard the sentinel bytes if found.
+               if monitor_cursor.get_ref().starts_with(MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL) {
+                       monitor_cursor.set_position(MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL.len() as u64);
+               }
+               match <(BlockHash, ChannelMonitor<<SP::Target as SignerProvider>::EcdsaSigner>)>::read(
+                       &mut monitor_cursor,
+                       (&*self.entropy_source, &*self.signer_provider),
+               ) {
+                       Ok((blockhash, channel_monitor)) => {
+                               if channel_monitor.get_funding_txo().0.txid != outpoint.txid
+                                       || channel_monitor.get_funding_txo().0.index != outpoint.index
+                               {
+                                       log_error!(
+                                               self.logger,
+                                               "ChannelMonitor {} was stored under the wrong key!",
+                                               monitor_name.as_str()
+                                       );
+                                       Err(io::Error::new(
+                                               io::ErrorKind::InvalidData,
+                                               "ChannelMonitor was stored under the wrong key",
+                                       ))
+                               } else {
+                                       Ok((blockhash, channel_monitor))
+                               }
+                       }
+                       Err(e) => {
+                               log_error!(
+                                       self.logger,
+                                       "Failed to read ChannelMonitor {}, reason: {}",
+                                       monitor_name.as_str(),
+                                       e,
+                               );
+                               Err(io::Error::new(io::ErrorKind::InvalidData, "Failed to read ChannelMonitor"))
+                       }
+               }
+       }
+
+       /// Read a channel monitor update.
+       fn read_monitor_update(
+               &self, monitor_name: &MonitorName, update_name: &UpdateName,
+       ) -> Result<ChannelMonitorUpdate, io::Error> {
+               let update_bytes = self.kv_store.read(
+                       CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       update_name.as_str(),
+               )?;
+               ChannelMonitorUpdate::read(&mut io::Cursor::new(update_bytes)).map_err(|e| {
+                       log_error!(
+                               self.logger,
+                               "Failed to read ChannelMonitorUpdate {}/{}/{}, reason: {}",
+                               CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                               monitor_name.as_str(),
+                               update_name.as_str(),
+                               e,
+                       );
+                       io::Error::new(io::ErrorKind::InvalidData, "Failed to read ChannelMonitorUpdate")
+               })
+       }
+
+       /// Cleans up stale updates for all monitors.
+       ///
+       /// This function works by first listing all monitors, and then for each of them, listing all
+       /// updates. The updates that have an `update_id` less than or equal to than the stored monitor
+       /// are deleted. The deletion can either be lazy or non-lazy based on the `lazy` flag; this will
+       /// be passed to [`KVStore::remove`].
+       pub fn cleanup_stale_updates(&self, lazy: bool) -> Result<(), io::Error> {
+               let monitor_keys = self.kv_store.list(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+               )?;
+               for monitor_key in monitor_keys {
+                       let monitor_name = MonitorName::new(monitor_key)?;
+                       let (_, current_monitor) = self.read_monitor(&monitor_name)?;
+                       let updates = self
+                               .kv_store
+                               .list(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str())?;
+                       for update in updates {
+                               let update_name = UpdateName::new(update)?;
+                               // if the update_id is lower than the stored monitor, delete
+                               if update_name.0 <= current_monitor.get_latest_update_id() {
+                                       self.kv_store.remove(
+                                               CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                                               monitor_name.as_str(),
+                                               update_name.as_str(),
+                                               lazy,
+                                       )?;
+                               }
+                       }
+               }
+               Ok(())
+       }
+}
+
+impl<ChannelSigner: WriteableEcdsaChannelSigner, K: Deref, L: Deref, ES: Deref, SP: Deref>
+       Persist<ChannelSigner> for MonitorUpdatingPersister<K, L, ES, SP>
+where
+       K::Target: KVStore,
+       L::Target: Logger,
+       ES::Target: EntropySource + Sized,
+       SP::Target: SignerProvider + Sized,
+{
+       /// Persists a new channel. This means writing the entire monitor to the
+       /// parametrized [`KVStore`].
+       fn persist_new_channel(
+               &self, funding_txo: OutPoint, monitor: &ChannelMonitor<ChannelSigner>,
+               _monitor_update_call_id: MonitorUpdateId,
+       ) -> chain::ChannelMonitorUpdateStatus {
+               // Determine the proper key for this monitor
+               let monitor_name = MonitorName::from(funding_txo);
+               // Serialize and write the new monitor
+               let mut monitor_bytes = Vec::with_capacity(
+                       MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL.len() + monitor.serialized_length(),
+               );
+               monitor_bytes.extend_from_slice(MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL);
+               monitor.write(&mut monitor_bytes).unwrap();
+               match self.kv_store.write(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       &monitor_bytes,
+               ) {
+                       Ok(_) => {
+                               chain::ChannelMonitorUpdateStatus::Completed
+                       }
+                       Err(e) => {
+                               log_error!(
+                                       self.logger,
+                                       "Failed to write ChannelMonitor {}/{}/{} reason: {}",
+                                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                                       monitor_name.as_str(),
+                                       e
+                               );
+                               chain::ChannelMonitorUpdateStatus::UnrecoverableError
+                       }
+               }
+       }
+
+       /// Persists a channel update, writing only the update to the parameterized [`KVStore`] if possible.
+       ///
+       /// In some cases, this will forward to [`MonitorUpdatingPersister::persist_new_channel`]:
+       ///
+       ///   - No full monitor is found in [`KVStore`]
+       ///   - The number of pending updates exceeds `maximum_pending_updates` as given to [`Self::new`]
+       ///   - LDK commands re-persisting the entire monitor through this function, specifically when
+       ///     `update` is `None`.
+       ///   - The update is at [`CLOSED_CHANNEL_UPDATE_ID`]
+       fn update_persisted_channel(
+               &self, funding_txo: OutPoint, update: Option<&ChannelMonitorUpdate>,
+               monitor: &ChannelMonitor<ChannelSigner>, monitor_update_call_id: MonitorUpdateId,
+       ) -> chain::ChannelMonitorUpdateStatus {
+               // IMPORTANT: monitor_update_call_id: MonitorUpdateId is not to be confused with
+               // ChannelMonitorUpdate's update_id.
+               if let Some(update) = update {
+                       if update.update_id != CLOSED_CHANNEL_UPDATE_ID
+                               && update.update_id % self.maximum_pending_updates != 0
+                       {
+                               let monitor_name = MonitorName::from(funding_txo);
+                               let update_name = UpdateName::from(update.update_id);
+                               match self.kv_store.write(
+                                       CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                                       monitor_name.as_str(),
+                                       update_name.as_str(),
+                                       &update.encode(),
+                               ) {
+                                       Ok(()) => chain::ChannelMonitorUpdateStatus::Completed,
+                                       Err(e) => {
+                                               log_error!(
+                                                       self.logger,
+                                                       "Failed to write ChannelMonitorUpdate {}/{}/{} reason: {}",
+                                                       CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                                                       monitor_name.as_str(),
+                                                       update_name.as_str(),
+                                                       e
+                                               );
+                                               chain::ChannelMonitorUpdateStatus::UnrecoverableError
+                                       }
+                               }
+                       } else {
+                               let monitor_name = MonitorName::from(funding_txo);
+                               // In case of channel-close monitor update, we need to read old monitor before persisting
+                               // the new one in order to determine the cleanup range.
+                               let maybe_old_monitor = match monitor.get_latest_update_id() {
+                                       CLOSED_CHANNEL_UPDATE_ID => self.read_monitor(&monitor_name).ok(),
+                                       _ => None
+                               };
+
+                               // We could write this update, but it meets criteria of our design that calls for a full monitor write.
+                               let monitor_update_status = self.persist_new_channel(funding_txo, monitor, monitor_update_call_id);
+
+                               if let chain::ChannelMonitorUpdateStatus::Completed = monitor_update_status {
+                                       let cleanup_range = if monitor.get_latest_update_id() == CLOSED_CHANNEL_UPDATE_ID {
+                                               // If there is an error while reading old monitor, we skip clean up.
+                                               maybe_old_monitor.map(|(_, ref old_monitor)| {
+                                                       let start = old_monitor.get_latest_update_id();
+                                                       // We never persist an update with update_id = CLOSED_CHANNEL_UPDATE_ID
+                                                       let end = cmp::min(
+                                                               start.saturating_add(self.maximum_pending_updates),
+                                                               CLOSED_CHANNEL_UPDATE_ID - 1,
+                                                       );
+                                                       (start, end)
+                                               })
+                                       } else {
+                                               let end = monitor.get_latest_update_id();
+                                               let start = end.saturating_sub(self.maximum_pending_updates);
+                                               Some((start, end))
+                                       };
+
+                                       if let Some((start, end)) = cleanup_range {
+                                               self.cleanup_in_range(monitor_name, start, end);
+                                       }
+                               }
+
+                               monitor_update_status
+                       }
+               } else {
+                       // There is no update given, so we must persist a new monitor.
+                       self.persist_new_channel(funding_txo, monitor, monitor_update_call_id)
+               }
+       }
+
+       fn archive_persisted_channel(&self, funding_txo: OutPoint) {
+               let monitor_name = MonitorName::from(funding_txo);
+               let monitor = match self.read_monitor(&monitor_name) {
+                       Ok((_block_hash, monitor)) => monitor,
+                       Err(_) => return
+               };
+               match self.kv_store.write(
+                       ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       ARCHIVED_CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       &monitor.encode()
+               ) {
+                       Ok(()) => {},
+                       Err(_e) => return,
+               };
+               let _ = self.kv_store.remove(
+                       CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE,
+                       CHANNEL_MONITOR_PERSISTENCE_SECONDARY_NAMESPACE,
+                       monitor_name.as_str(),
+                       true,
+               );
+       }
+}
+
+impl<K: Deref, L: Deref, ES: Deref, SP: Deref> MonitorUpdatingPersister<K, L, ES, SP>
+where
+       ES::Target: EntropySource + Sized,
+       K::Target: KVStore,
+       L::Target: Logger,
+       SP::Target: SignerProvider + Sized
+{
+       // Cleans up monitor updates for given monitor in range `start..=end`.
+       fn cleanup_in_range(&self, monitor_name: MonitorName, start: u64, end: u64) {
+               for update_id in start..=end {
+                       let update_name = UpdateName::from(update_id);
+                       if let Err(e) = self.kv_store.remove(
+                               CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                               monitor_name.as_str(),
+                               update_name.as_str(),
+                               true,
+                       ) {
+                               log_error!(
+                                       self.logger,
+                                       "Failed to clean up channel monitor updates for monitor {}, reason: {}",
+                                       monitor_name.as_str(),
+                                       e
+                               );
+                       };
+               }
+       }
+}
+
+/// A struct representing a name for a monitor.
+#[derive(Debug)]
+struct MonitorName(String);
+
+impl MonitorName {
+       /// Constructs a [`MonitorName`], after verifying that an [`OutPoint`] can
+       /// be formed from the given `name`.
+       pub fn new(name: String) -> Result<Self, io::Error> {
+               MonitorName::do_try_into_outpoint(&name)?;
+               Ok(Self(name))
+       }
+       /// Convert this monitor name to a str.
+       pub fn as_str(&self) -> &str {
+               &self.0
+       }
+       /// Attempt to form a valid [`OutPoint`] from a given name string.
+       fn do_try_into_outpoint(name: &str) -> Result<OutPoint, io::Error> {
+               let mut parts = name.splitn(2, '_');
+               let txid = if let Some(part) = parts.next() {
+                       Txid::from_str(part).map_err(|_| {
+                               io::Error::new(io::ErrorKind::InvalidData, "Invalid tx ID in stored key")
+                       })?
+               } else {
+                       return Err(io::Error::new(
+                               io::ErrorKind::InvalidData,
+                               "Stored monitor key is not a splittable string",
+                       ));
+               };
+               let index = if let Some(part) = parts.next() {
+                       part.parse().map_err(|_| {
+                               io::Error::new(io::ErrorKind::InvalidData, "Invalid tx index in stored key")
+                       })?
+               } else {
+                       return Err(io::Error::new(
+                               io::ErrorKind::InvalidData,
+                               "No tx index value found after underscore in stored key",
+                       ));
+               };
+               Ok(OutPoint { txid, index })
+       }
+}
+
+impl TryFrom<&MonitorName> for OutPoint {
+       type Error = io::Error;
+
+       fn try_from(value: &MonitorName) -> Result<Self, io::Error> {
+               MonitorName::do_try_into_outpoint(&value.0)
+       }
+}
+
+impl From<OutPoint> for MonitorName {
+       fn from(value: OutPoint) -> Self {
+               MonitorName(format!("{}_{}", value.txid.to_string(), value.index))
+       }
+}
+
+/// A struct representing a name for an update.
+#[derive(Debug)]
+struct UpdateName(u64, String);
+
+impl UpdateName {
+       /// Constructs an [`UpdateName`], after verifying that an update sequence ID
+       /// can be derived from the given `name`.
+       pub fn new(name: String) -> Result<Self, io::Error> {
+               match name.parse::<u64>() {
+                       Ok(u) => Ok(u.into()),
+                       Err(_) => {
+                               Err(io::Error::new(io::ErrorKind::InvalidData, "cannot parse u64 from update name"))
+                       }
+               }
+       }
+
+       /// Convert this monitor update name to a &str
+       pub fn as_str(&self) -> &str {
+               &self.1
+       }
+}
+
+impl From<u64> for UpdateName {
+       fn from(value: u64) -> Self {
+               Self(value, value.to_string())
+       }
+}
+
+#[cfg(test)]
+mod tests {
+       use super::*;
+       use crate::chain::ChannelMonitorUpdateStatus;
+       use crate::events::{ClosureReason, MessageSendEventsProvider};
+       use crate::ln::functional_test_utils::*;
+       use crate::util::test_utils::{self, TestLogger, TestStore};
+       use crate::{check_added_monitors, check_closed_broadcast};
+       use crate::sync::Arc;
+       use crate::util::test_channel_signer::TestChannelSigner;
+
+       const EXPECTED_UPDATES_PER_PAYMENT: u64 = 5;
+
+       #[test]
+       fn converts_u64_to_update_name() {
+               assert_eq!(UpdateName::from(0).as_str(), "0");
+               assert_eq!(UpdateName::from(21).as_str(), "21");
+               assert_eq!(UpdateName::from(u64::MAX).as_str(), "18446744073709551615");
+       }
+
+       #[test]
+       fn bad_update_name_fails() {
+               assert!(UpdateName::new("deadbeef".to_string()).is_err());
+               assert!(UpdateName::new("-1".to_string()).is_err());
+       }
+
+       #[test]
+       fn monitor_from_outpoint_works() {
+               let monitor_name1 = MonitorName::from(OutPoint {
+                       txid: Txid::from_str("deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef").unwrap(),
+                       index: 1,
+               });
+               assert_eq!(monitor_name1.as_str(), "deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1");
+
+               let monitor_name2 = MonitorName::from(OutPoint {
+                       txid: Txid::from_str("f33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeef").unwrap(),
+                       index: u16::MAX,
+               });
+               assert_eq!(monitor_name2.as_str(), "f33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeeff33dbeef_65535");
+       }
+
+       #[test]
+       fn bad_monitor_string_fails() {
+               assert!(MonitorName::new("deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef".to_string()).is_err());
+               assert!(MonitorName::new("deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_65536".to_string()).is_err());
+               assert!(MonitorName::new("deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_21".to_string()).is_err());
+       }
+
+       // Exercise the `MonitorUpdatingPersister` with real channels and payments.
+       #[test]
+       fn persister_with_real_monitors() {
+               // This value is used later to limit how many iterations we perform.
+               let persister_0_max_pending_updates = 7;
+               // Intentionally set this to a smaller value to test a different alignment.
+               let persister_1_max_pending_updates = 3;
+               let chanmon_cfgs = create_chanmon_cfgs(4);
+               let persister_0 = MonitorUpdatingPersister {
+                       kv_store: &TestStore::new(false),
+                       logger: &TestLogger::new(),
+                       maximum_pending_updates: persister_0_max_pending_updates,
+                       entropy_source: &chanmon_cfgs[0].keys_manager,
+                       signer_provider: &chanmon_cfgs[0].keys_manager,
+               };
+               let persister_1 = MonitorUpdatingPersister {
+                       kv_store: &TestStore::new(false),
+                       logger: &TestLogger::new(),
+                       maximum_pending_updates: persister_1_max_pending_updates,
+                       entropy_source: &chanmon_cfgs[1].keys_manager,
+                       signer_provider: &chanmon_cfgs[1].keys_manager,
+               };
+               let mut node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let chain_mon_0 = test_utils::TestChainMonitor::new(
+                       Some(&chanmon_cfgs[0].chain_source),
+                       &chanmon_cfgs[0].tx_broadcaster,
+                       &chanmon_cfgs[0].logger,
+                       &chanmon_cfgs[0].fee_estimator,
+                       &persister_0,
+                       &chanmon_cfgs[0].keys_manager,
+               );
+               let chain_mon_1 = test_utils::TestChainMonitor::new(
+                       Some(&chanmon_cfgs[1].chain_source),
+                       &chanmon_cfgs[1].tx_broadcaster,
+                       &chanmon_cfgs[1].logger,
+                       &chanmon_cfgs[1].fee_estimator,
+                       &persister_1,
+                       &chanmon_cfgs[1].keys_manager,
+               );
+               node_cfgs[0].chain_monitor = chain_mon_0;
+               node_cfgs[1].chain_monitor = chain_mon_1;
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+               let broadcaster_0 = &chanmon_cfgs[2].tx_broadcaster;
+               let broadcaster_1 = &chanmon_cfgs[3].tx_broadcaster;
+
+               // Check that the persisted channel data is empty before any channels are
+               // open.
+               let mut persisted_chan_data_0 = persister_0.read_all_channel_monitors_with_updates(
+                       &broadcaster_0, &&chanmon_cfgs[0].fee_estimator).unwrap();
+               assert_eq!(persisted_chan_data_0.len(), 0);
+               let mut persisted_chan_data_1 = persister_1.read_all_channel_monitors_with_updates(
+                       &broadcaster_1, &&chanmon_cfgs[1].fee_estimator).unwrap();
+               assert_eq!(persisted_chan_data_1.len(), 0);
+
+               // Helper to make sure the channel is on the expected update ID.
+               macro_rules! check_persisted_data {
+                       ($expected_update_id: expr) => {
+                               persisted_chan_data_0 = persister_0.read_all_channel_monitors_with_updates(
+                                       &broadcaster_0, &&chanmon_cfgs[0].fee_estimator).unwrap();
+                               // check that we stored only one monitor
+                               assert_eq!(persisted_chan_data_0.len(), 1);
+                               for (_, mon) in persisted_chan_data_0.iter() {
+                                       // check that when we read it, we got the right update id
+                                       assert_eq!(mon.get_latest_update_id(), $expected_update_id);
+
+                                       // if the CM is at consolidation threshold, ensure no updates are stored.
+                                       let monitor_name = MonitorName::from(mon.get_funding_txo().0);
+                                       if mon.get_latest_update_id() % persister_0_max_pending_updates == 0
+                                                       || mon.get_latest_update_id() == CLOSED_CHANNEL_UPDATE_ID {
+                                               assert_eq!(
+                                                       persister_0.kv_store.list(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                                                               monitor_name.as_str()).unwrap().len(),
+                                                       0,
+                                                       "updates stored when they shouldn't be in persister 0"
+                                               );
+                                       }
+                               }
+                               persisted_chan_data_1 = persister_1.read_all_channel_monitors_with_updates(
+                                       &broadcaster_1, &&chanmon_cfgs[1].fee_estimator).unwrap();
+                               assert_eq!(persisted_chan_data_1.len(), 1);
+                               for (_, mon) in persisted_chan_data_1.iter() {
+                                       assert_eq!(mon.get_latest_update_id(), $expected_update_id);
+                                       let monitor_name = MonitorName::from(mon.get_funding_txo().0);
+                                       // if the CM is at consolidation threshold, ensure no updates are stored.
+                                       if mon.get_latest_update_id() % persister_1_max_pending_updates == 0
+                                                       || mon.get_latest_update_id() == CLOSED_CHANNEL_UPDATE_ID {
+                                               assert_eq!(
+                                                       persister_1.kv_store.list(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE,
+                                                               monitor_name.as_str()).unwrap().len(),
+                                                       0,
+                                                       "updates stored when they shouldn't be in persister 1"
+                                               );
+                                       }
+                               }
+                       };
+               }
+
+               // Create some initial channel and check that a channel was persisted.
+               let _ = create_announced_chan_between_nodes(&nodes, 0, 1);
+               check_persisted_data!(0);
+
+               // Send a few payments and make sure the monitors are updated to the latest.
+               send_payment(&nodes[0], &vec![&nodes[1]][..], 8_000_000);
+               check_persisted_data!(EXPECTED_UPDATES_PER_PAYMENT);
+               send_payment(&nodes[1], &vec![&nodes[0]][..], 4_000_000);
+               check_persisted_data!(2 * EXPECTED_UPDATES_PER_PAYMENT);
+
+               // Send a few more payments to try all the alignments of max pending updates with
+               // updates for a payment sent and received.
+               let mut sender = 0;
+               for i in 3..=persister_0_max_pending_updates * 2 {
+                       let receiver;
+                       if sender == 0 {
+                               sender = 1;
+                               receiver = 0;
+                       } else {
+                               sender = 0;
+                               receiver = 1;
+                       }
+                       send_payment(&nodes[sender], &vec![&nodes[receiver]][..], 21_000);
+                       check_persisted_data!(i * EXPECTED_UPDATES_PER_PAYMENT);
+               }
+
+               // Force close because cooperative close doesn't result in any persisted
+               // updates.
+               nodes[0].node.force_close_broadcasting_latest_txn(&nodes[0].node.list_channels()[0].channel_id, &nodes[1].node.get_our_node_id()).unwrap();
+
+               check_closed_event(&nodes[0], 1, ClosureReason::HolderForceClosed, false, &[nodes[1].node.get_our_node_id()], 100000);
+               check_closed_broadcast!(nodes[0], true);
+               check_added_monitors!(nodes[0], 1);
+
+               let node_txn = nodes[0].tx_broadcaster.txn_broadcast();
+               assert_eq!(node_txn.len(), 1);
+
+               connect_block(&nodes[1], &create_dummy_block(nodes[0].best_block_hash(), 42, vec![node_txn[0].clone(), node_txn[0].clone()]));
+
+               check_closed_broadcast!(nodes[1], true);
+               check_closed_event(&nodes[1], 1, ClosureReason::CommitmentTxConfirmed, false, &[nodes[0].node.get_our_node_id()], 100000);
+               check_added_monitors!(nodes[1], 1);
+
+               // Make sure everything is persisted as expected after close.
+               check_persisted_data!(CLOSED_CHANNEL_UPDATE_ID);
+
+               // Make sure the expected number of stale updates is present.
+               let persisted_chan_data = persister_0.read_all_channel_monitors_with_updates(&broadcaster_0, &&chanmon_cfgs[0].fee_estimator).unwrap();
+               let (_, monitor) = &persisted_chan_data[0];
+               let monitor_name = MonitorName::from(monitor.get_funding_txo().0);
+               // The channel should have 0 updates, as it wrote a full monitor and consolidated.
+               assert_eq!(persister_0.kv_store.list(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str()).unwrap().len(), 0);
+               assert_eq!(persister_1.kv_store.list(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str()).unwrap().len(), 0);
+       }
+
+       // Test that if the `MonitorUpdatingPersister`'s can't actually write, trying to persist a
+       // monitor or update with it results in the persister returning an UnrecoverableError status.
+       #[test]
+       fn unrecoverable_error_on_write_failure() {
+               // Set up a dummy channel and force close. This will produce a monitor
+               // that we can then use to test persistence.
+               let chanmon_cfgs = create_chanmon_cfgs(2);
+               let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+               let chan = create_announced_chan_between_nodes(&nodes, 0, 1);
+               nodes[1].node.force_close_broadcasting_latest_txn(&chan.2, &nodes[0].node.get_our_node_id()).unwrap();
+               check_closed_event(&nodes[1], 1, ClosureReason::HolderForceClosed, false, &[nodes[0].node.get_our_node_id()], 100000);
+               {
+                       let mut added_monitors = nodes[1].chain_monitor.added_monitors.lock().unwrap();
+                       let update_map = nodes[1].chain_monitor.latest_monitor_update_id.lock().unwrap();
+                       let update_id = update_map.get(&added_monitors[0].1.channel_id()).unwrap();
+                       let cmu_map = nodes[1].chain_monitor.monitor_updates.lock().unwrap();
+                       let cmu = &cmu_map.get(&added_monitors[0].1.channel_id()).unwrap()[0];
+                       let test_txo = OutPoint { txid: Txid::from_str("8984484a580b825b9972d7adb15050b3ab624ccd731946b3eeddb92f4e7ef6be").unwrap(), index: 0 };
+
+                       let ro_persister = MonitorUpdatingPersister {
+                               kv_store: &TestStore::new(true),
+                               logger: &TestLogger::new(),
+                               maximum_pending_updates: 11,
+                               entropy_source: node_cfgs[0].keys_manager,
+                               signer_provider: node_cfgs[0].keys_manager,
+                       };
+                       match ro_persister.persist_new_channel(test_txo, &added_monitors[0].1, update_id.2) {
+                               ChannelMonitorUpdateStatus::UnrecoverableError => {
+                                       // correct result
+                               }
+                               ChannelMonitorUpdateStatus::Completed => {
+                                       panic!("Completed persisting new channel when shouldn't have")
+                               }
+                               ChannelMonitorUpdateStatus::InProgress => {
+                                       panic!("Returned InProgress when shouldn't have")
+                               }
+                       }
+                       match ro_persister.update_persisted_channel(test_txo, Some(cmu), &added_monitors[0].1, update_id.2) {
+                               ChannelMonitorUpdateStatus::UnrecoverableError => {
+                                       // correct result
+                               }
+                               ChannelMonitorUpdateStatus::Completed => {
+                                       panic!("Completed persisting new channel when shouldn't have")
+                               }
+                               ChannelMonitorUpdateStatus::InProgress => {
+                                       panic!("Returned InProgress when shouldn't have")
+                               }
+                       }
+                       added_monitors.clear();
+               }
+               nodes[1].node.get_and_clear_pending_msg_events();
+       }
+
+       // Confirm that the `clean_stale_updates` function finds and deletes stale updates.
+       #[test]
+       fn clean_stale_updates_works() {
+               let test_max_pending_updates = 7;
+               let chanmon_cfgs = create_chanmon_cfgs(3);
+               let persister_0 = MonitorUpdatingPersister {
+                       kv_store: &TestStore::new(false),
+                       logger: &TestLogger::new(),
+                       maximum_pending_updates: test_max_pending_updates,
+                       entropy_source: &chanmon_cfgs[0].keys_manager,
+                       signer_provider: &chanmon_cfgs[0].keys_manager,
+               };
+               let persister_1 = MonitorUpdatingPersister {
+                       kv_store: &TestStore::new(false),
+                       logger: &TestLogger::new(),
+                       maximum_pending_updates: test_max_pending_updates,
+                       entropy_source: &chanmon_cfgs[1].keys_manager,
+                       signer_provider: &chanmon_cfgs[1].keys_manager,
+               };
+               let mut node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+               let chain_mon_0 = test_utils::TestChainMonitor::new(
+                       Some(&chanmon_cfgs[0].chain_source),
+                       &chanmon_cfgs[0].tx_broadcaster,
+                       &chanmon_cfgs[0].logger,
+                       &chanmon_cfgs[0].fee_estimator,
+                       &persister_0,
+                       &chanmon_cfgs[0].keys_manager,
+               );
+               let chain_mon_1 = test_utils::TestChainMonitor::new(
+                       Some(&chanmon_cfgs[1].chain_source),
+                       &chanmon_cfgs[1].tx_broadcaster,
+                       &chanmon_cfgs[1].logger,
+                       &chanmon_cfgs[1].fee_estimator,
+                       &persister_1,
+                       &chanmon_cfgs[1].keys_manager,
+               );
+               node_cfgs[0].chain_monitor = chain_mon_0;
+               node_cfgs[1].chain_monitor = chain_mon_1;
+               let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+               let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+               let broadcaster_0 = &chanmon_cfgs[2].tx_broadcaster;
+
+               // Check that the persisted channel data is empty before any channels are
+               // open.
+               let persisted_chan_data = persister_0.read_all_channel_monitors_with_updates(&broadcaster_0, &&chanmon_cfgs[0].fee_estimator).unwrap();
+               assert_eq!(persisted_chan_data.len(), 0);
+
+               // Create some initial channel
+               let _ = create_announced_chan_between_nodes(&nodes, 0, 1);
+
+               // Send a few payments to advance the updates a bit
+               send_payment(&nodes[0], &vec![&nodes[1]][..], 8_000_000);
+               send_payment(&nodes[1], &vec![&nodes[0]][..], 4_000_000);
+
+               // Get the monitor and make a fake stale update at update_id=1 (lowest height of an update possible)
+               let persisted_chan_data = persister_0.read_all_channel_monitors_with_updates(&broadcaster_0, &&chanmon_cfgs[0].fee_estimator).unwrap();
+               let (_, monitor) = &persisted_chan_data[0];
+               let monitor_name = MonitorName::from(monitor.get_funding_txo().0);
+               persister_0
+                       .kv_store
+                       .write(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str(), UpdateName::from(1).as_str(), &[0u8; 1])
+                       .unwrap();
+
+               // Do the stale update cleanup
+               persister_0.cleanup_stale_updates(false).unwrap();
+
+               // Confirm the stale update is unreadable/gone
+               assert!(persister_0
+                       .kv_store
+                       .read(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str(), UpdateName::from(1).as_str())
+                       .is_err());
+
+               // Force close.
+               nodes[0].node.force_close_broadcasting_latest_txn(&nodes[0].node.list_channels()[0].channel_id, &nodes[1].node.get_our_node_id()).unwrap();
+               check_closed_event(&nodes[0], 1, ClosureReason::HolderForceClosed, false, &[nodes[1].node.get_our_node_id()], 100000);
+               check_closed_broadcast!(nodes[0], true);
+               check_added_monitors!(nodes[0], 1);
+
+               // Write an update near u64::MAX
+               persister_0
+                       .kv_store
+                       .write(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str(), UpdateName::from(u64::MAX - 1).as_str(), &[0u8; 1])
+                       .unwrap();
+
+               // Do the stale update cleanup
+               persister_0.cleanup_stale_updates(false).unwrap();
+
+               // Confirm the stale update is unreadable/gone
+               assert!(persister_0
+                       .kv_store
+                       .read(CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE, monitor_name.as_str(), UpdateName::from(u64::MAX - 1).as_str())
+                       .is_err());
+       }
+
+       fn persist_fn<P: Deref, ChannelSigner: WriteableEcdsaChannelSigner>(_persist: P) -> bool where P::Target: Persist<ChannelSigner> {
+               true
+       }
+
+       #[test]
+       fn kvstore_trait_object_usage() {
+               let store: Arc<dyn KVStore + Send + Sync> = Arc::new(TestStore::new(false));
+               assert!(persist_fn::<_, TestChannelSigner>(store.clone()));
+       }
+}