implement Persist and Persister with generic KVStorePersister trait

Author: johncantrell97

lightning-background-processor/src/lib.rs

@@ -20,6 +20,7 @@ use lightning::ln::peer_handler::{CustomMessageHandler, PeerManager, SocketDescr
 use lightning::routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
 use lightning::util::events::{Event, EventHandler, EventsProvider};
 use lightning::util::logger::Logger;
+use lightning_persister::Persister;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::thread;
@@ -80,22 +81,7 @@ const FIRST_NETWORK_PRUNE_TIMER: u64 = 60;
 #[cfg(test)]
 const FIRST_NETWORK_PRUNE_TIMER: u64 = 1;
 
-/// Trait that handles persisting a [`ChannelManager`] and [`NetworkGraph`] to disk.
-pub trait Persister<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
-where
-	M::Target: 'static + chain::Watch<Signer>,
-	T::Target: 'static + BroadcasterInterface,
-	K::Target: 'static + KeysInterface<Signer = Signer>,
-	F::Target: 'static + FeeEstimator,
-	L::Target: 'static + Logger,
-{
-	/// Persist the given [`ChannelManager`] to disk, returning an error if persistence failed
-	/// (which will cause the [`BackgroundProcessor`] which called this method to exit).
-	fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error>;
-
-	/// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
-	fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), std::io::Error>;
-}
+
 
 /// Decorates an [`EventHandler`] with common functionality provided by standard [`EventHandler`]s.
 struct DecoratingEventHandler<
@@ -142,7 +128,7 @@ impl BackgroundProcessor {
 	/// provided implementation.
 	///
 	/// [`Persister::persist_graph`] is responsible for writing out the [`NetworkGraph`] to disk. See
-	/// [`NetworkGraph::write`] for writing out a [`NetworkGraph`]. See [`FilesystemPersister::persist_network_graph`]
+	/// [`NetworkGraph::write`] for writing out a [`NetworkGraph`]. See [`FilesystemPersister::persist_graph`]
 	/// for Rust-Lightning's provided implementation.
 	///
 	/// Typically, users should either implement [`Persister::persist_manager`] to never return an
@@ -161,8 +147,8 @@ impl BackgroundProcessor {
 	/// [`stop`]: Self::stop
 	/// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
 	/// [`ChannelManager::write`]: lightning::ln::channelmanager::ChannelManager#impl-Writeable
-	/// [`FilesystemPersister::persist_manager`]: lightning_persister::FilesystemPersister::persist_manager
-	/// [`FilesystemPersister::persist_network_graph`]: lightning_persister::FilesystemPersister::persist_network_graph
+	/// [`FilesystemPersister::persist_manager`]: lightning_persister::FilesystemPersister#impl-Persister
+	/// [`FilesystemPersister::persist_graph`]: lightning_persister::FilesystemPersister#impl-Persister
 	/// [`NetworkGraph`]: lightning::routing::network_graph::NetworkGraph
 	/// [`NetworkGraph::write`]: lightning::routing::network_graph::NetworkGraph#impl-Writeable
 	pub fn start<
@@ -180,7 +166,7 @@ impl BackgroundProcessor {
 		CMH: 'static + Deref + Send + Sync,
 		RMH: 'static + Deref + Send + Sync,
 		EH: 'static + EventHandler + Send,
-		PS: 'static + Send + Persister<Signer, CW, T, K, F, L>,
+		PS: 'static + Send + Persister,
 		M: 'static + Deref<Target = ChainMonitor<Signer, CF, T, F, L, P>> + Send + Sync,
 		CM: 'static + Deref<Target = ChannelManager<Signer, CW, T, K, F, L>> + Send + Sync,
 		NG: 'static + Deref<Target = NetGraphMsgHandler<G, CA, L>> + Send + Sync,
@@ -367,8 +353,8 @@ mod tests {
 	use lightning::util::test_utils;
 	use lightning_invoice::payment::{InvoicePayer, RetryAttempts};
 	use lightning_invoice::utils::DefaultRouter;
-	use lightning_persister::FilesystemPersister;
-	use std::fs;
+	use lightning_persister::{FilesystemPersister, Persister as LPPersister};
+	use std::fs::{self, File};
 	use std::ops::Deref;
 	use std::path::PathBuf;
 	use std::sync::{Arc, Mutex};
@@ -414,12 +400,14 @@ mod tests {
 	struct Persister {
 		data_dir: String,
 		graph_error: Option<(std::io::ErrorKind, &'static str)>,
-		manager_error: Option<(std::io::ErrorKind, &'static str)>
+		manager_error: Option<(std::io::ErrorKind, &'static str)>,
+		filesystem_persister: FilesystemPersister
 	}
 
 	impl Persister {
 		fn new(data_dir: String) -> Self {
-			Self { data_dir, graph_error: None, manager_error: None }
+			let filesystem_persister = FilesystemPersister::new(data_dir.clone());
+			Self { data_dir, graph_error: None, manager_error: None, filesystem_persister }
 		}
 
 		fn with_graph_error(self, error: std::io::ErrorKind, message: &'static str) -> Self {
@@ -431,23 +419,24 @@ mod tests {
 		}
 	}
 
-	impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L:Deref> super::Persister<Signer, M, T, K, F, L> for Persister where
+	impl LPPersister for Persister 
+	{
+		fn persist_manager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> where
 		M::Target: 'static + chain::Watch<Signer>,
 		T::Target: 'static + BroadcasterInterface,
 		K::Target: 'static + KeysInterface<Signer = Signer>,
 		F::Target: 'static + FeeEstimator,
 		L::Target: 'static + Logger,
-	{
-		fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> {
+		{
 			match self.manager_error {
-				None => FilesystemPersister::persist_manager(self.data_dir.clone(), channel_manager),
+				None => self.filesystem_persister.persist_manager(channel_manager),
 				Some((error, message)) => Err(std::io::Error::new(error, message)),
 			}
 		}
 
 		fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), std::io::Error> {
 			match self.graph_error {
-				None => FilesystemPersister::persist_network_graph(self.data_dir.clone(), network_graph),
+				None => self.filesystem_persister.persist_graph(network_graph),
 				Some((error, message)) => Err(std::io::Error::new(error, message)),
 			}
 		}

lightning-persister/src/lib.rs

@@ -17,7 +17,6 @@ extern crate libc;
 use bitcoin::hash_types::{BlockHash, Txid};
 use bitcoin::hashes::hex::{FromHex, ToHex};
 use lightning::routing::network_graph::NetworkGraph;
-use crate::util::DiskWriteable;
 use lightning::chain;
 use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 use lightning::chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate};
@@ -28,9 +27,38 @@ use lightning::ln::channelmanager::ChannelManager;
 use lightning::util::logger::Logger;
 use lightning::util::ser::{ReadableArgs, Writeable};
 use std::fs;
-use std::io::{Cursor, Error};
+use std::io::{Cursor, Error, Write};
 use std::ops::Deref;
-use std::path::{Path, PathBuf};
+use std::path::{Path, PathBuf, MAIN_SEPARATOR};
+
+
+/// Trait that handles persisting a [`ChannelManager`] and [`NetworkGraph`] to disk.
+pub trait Persister
+{
+	/// Persist the given [`ChannelManager`] to disk, returning an error if persistence failed
+	/// (which will cause the BackgroundProcessor which called this method to exit).
+	fn persist_manager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> where
+	M::Target: 'static + chain::Watch<Signer>,
+	T::Target: 'static + BroadcasterInterface,
+	K::Target: 'static + KeysInterface<Signer = Signer>,
+	F::Target: 'static + FeeEstimator,
+	L::Target: 'static + Logger;
+
+	/// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
+	fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), std::io::Error>;
+}
+
+/// Trait for a key-value store for persisting some writeable object at some key
+pub trait KVStorePersister<W: Writeable> {
+	/// Persist the given writeable using the provided key
+	fn persist(&self, key: String, object: &W) -> std::io::Result<()>;
+}
+
+impl<W: Writeable> KVStorePersister<W> for FilesystemPersister {
+	fn persist(&self, key: String, object: &W) -> std::io::Result<()> {
+		util::write_to_file(format!("{}{}{}", self.path_to_channel_data, MAIN_SEPARATOR, key), object)
+	}
+}
 
 /// FilesystemPersister persists channel data on disk, where each channel's
 /// data is stored in a file named after its funding outpoint.
@@ -48,31 +76,6 @@ pub struct FilesystemPersister {
 	path_to_channel_data: String,
 }
 
-impl<Signer: Sign> DiskWriteable for ChannelMonitor<Signer> {
-	fn write_to_file(&self, writer: &mut fs::File) -> Result<(), Error> {
-		self.write(writer)
-	}
-}
-
-impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> DiskWriteable 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 write_to_file(&self, writer: &mut fs::File) -> Result<(), std::io::Error> {
-		self.write(writer)
-	}
-}
-
-impl DiskWriteable for NetworkGraph {
-	fn write_to_file(&self, writer: &mut fs::File) -> Result<(), std::io::Error> {
-		self.write(writer)
-	}
-}
-
 impl FilesystemPersister {
 	/// Initialize a new FilesystemPersister and set the path to the individual channels'
 	/// files.
@@ -87,34 +90,8 @@ impl FilesystemPersister {
 		self.path_to_channel_data.clone()
 	}
 
-	pub(crate) fn path_to_monitor_data(&self) -> PathBuf {
-		let mut path = PathBuf::from(self.path_to_channel_data.clone());
-		path.push("monitors");
-		path
-	}
-
-	/// Writes the provided `ChannelManager` to the path provided at `FilesystemPersister`
-	/// initialization, within a file called "manager".
-	pub fn persist_manager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>(
-		data_dir: String,
-		manager: &ChannelManager<Signer, M, T, K, F, L>
-	) -> Result<(), std::io::Error>
-	where
-		M::Target: chain::Watch<Signer>,
-		T::Target: BroadcasterInterface,
-		K::Target: KeysInterface<Signer=Signer>,
-		F::Target: FeeEstimator,
-		L::Target: Logger,
-	{
-		let path = PathBuf::from(data_dir);
-		util::write_to_file(path, "manager".to_string(), manager)
-	}
-
-	/// Write the provided `NetworkGraph` to the path provided at `FilesystemPersister`
-	/// initialization, within a file called "network_graph"
-	pub fn persist_network_graph(data_dir: String, network_graph: &NetworkGraph) -> Result<(), std::io::Error> {
-		let path = PathBuf::from(data_dir);
-		util::write_to_file(path, "network_graph".to_string(), network_graph)
+	pub(crate) fn path_to_monitor_data(&self) -> String {
+			format!("{}{}monitors", self.path_to_channel_data, MAIN_SEPARATOR)
 	}
 
 	/// Read `ChannelMonitor`s from disk.
@@ -124,7 +101,7 @@ impl FilesystemPersister {
 		where K::Target: KeysInterface<Signer=Signer> + Sized,
 	{
 		let path = self.path_to_monitor_data();
-		if !Path::new(&path).exists() {
+		if !Path::new(&PathBuf::from(&path)).exists() {
 			return Ok(Vec::new());
 		}
 		let mut res = Vec::new();
@@ -187,18 +164,39 @@ impl<ChannelSigner: Sign> chainmonitor::Persist<ChannelSigner> for FilesystemPer
 	// even broadcasting!
 
 	fn persist_new_channel(&self, funding_txo: OutPoint, monitor: &ChannelMonitor<ChannelSigner>, _update_id: chainmonitor::MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
-		let filename = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
-		util::write_to_file(self.path_to_monitor_data(), filename, monitor)
+		let key = format!("monitors{}{}_{}", MAIN_SEPARATOR, funding_txo.txid.to_hex(), funding_txo.index);
+		self.persist(key, monitor)
 			.map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
 	}
 
 	fn update_persisted_channel(&self, funding_txo: OutPoint, _update: &Option<ChannelMonitorUpdate>, monitor: &ChannelMonitor<ChannelSigner>, _update_id: chainmonitor::MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
-		let filename = format!("{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
-		util::write_to_file(self.path_to_monitor_data(), filename, monitor)
+		let key = format!("monitors{}{}_{}", MAIN_SEPARATOR, funding_txo.txid.to_hex(), funding_txo.index);
+		self.persist(key, monitor)
 			.map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
 	}
 }
 
+impl Persister for FilesystemPersister {
+	fn persist_manager<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> where
+	M::Target: 'static + chain::Watch<Signer>,
+	T::Target: 'static + BroadcasterInterface,
+	K::Target: 'static + KeysInterface<Signer=Signer>,
+	F::Target: 'static + FeeEstimator,
+	L::Target: 'static + Logger {
+		self.persist("manager".to_string(), channel_manager)
+	}
+
+	fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), std::io::Error> {
+		if self.persist("network_graph".to_string(), network_graph).is_err()
+		{
+			// Persistence errors here are non-fatal as we can just fetch the routing graph
+			// again later, but they may indicate a disk error which could be fatal elsewhere.
+			eprintln!("Warning: Failed to persist network graph, check your disk and permissions");
+		}
+		Ok(())
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	extern crate lightning;