implement Persist and Persister with generic PersistObject trait

johncantrell97 · johncantrell97 · commit 324fbd5a4dbb · 2022-04-11T15:12:46.000-04:00
diff --git a/lightning-background-processor/src/lib.rs b/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<
diff --git a/lightning-persister/src/lib.rs b/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};
@@ -28,10 +27,39 @@ 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};
 
+/// 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>;
+}
+
+/// Trait for a key-value store for persisting some writeable object at some key
+pub trait PersistObject<W: Writeable> {
+	/// Persist the given writeable using the provided key
+	fn persist_object(&self, key: String, object: &W) -> std::io::Result<()>;
+}
+
+impl<W: Writeable> PersistObject<W> for FilesystemPersister {
+	fn persist_object(&self, key: String, object: &W) -> std::io::Result<()> {
+		util::write_to_file(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)
 	}
 
 	/// 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.clone())).exists() {
 			return Ok(Vec::new());
 		}
 		let mut res = Vec::new();
@@ -187,18 +164,43 @@ 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!("{}/{}_{}", self.path_to_monitor_data(), funding_txo.txid.to_hex(), funding_txo.index);
+		self.persist_object(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!("{}/{}_{}", self.path_to_monitor_data(), funding_txo.txid.to_hex(), funding_txo.index);
+		self.persist_object(key, monitor)
 			.map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
 	}
 }
 
+impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> Persister<Signer, M, T, K, F, L> for FilesystemPersister
+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> {
+		let key = format!("{}/manager", self.get_data_dir());
+		self.persist_object(key, channel_manager)
+	}
+
+	fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), std::io::Error> {
+		let key = format!("{}/network_graph", self.get_data_dir());
+		if self.persist_object(key, 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;
diff --git a/lightning-persister/src/util.rs b/lightning-persister/src/util.rs
@@ -7,21 +7,14 @@ use std::path::{Path, PathBuf};
 #[cfg(not(target_os = "windows"))]
 use std::os::unix::io::AsRawFd;
 
+use lightning::util::ser::Writeable;
+
 #[cfg(target_os = "windows")]
 use {
 	std::ffi::OsStr,
 	std::os::windows::ffi::OsStrExt
 };
 
-pub(crate) trait DiskWriteable {
-	fn write_to_file(&self, writer: &mut fs::File) -> Result<(), std::io::Error>;
-}
-
-pub(crate) fn get_full_filepath(mut filepath: PathBuf, filename: String) -> String {
-	filepath.push(filename);
-	filepath.to_str().unwrap().to_string()
-}
-
 #[cfg(target_os = "windows")]
 macro_rules! call {
 	($e: expr) => (
@@ -39,21 +32,23 @@ fn path_to_windows_str<T: AsRef<OsStr>>(path: T) -> Vec<winapi::shared::ntdef::W
 }
 
 #[allow(bare_trait_objects)]
-pub(crate) fn write_to_file<D: DiskWriteable>(path: PathBuf, filename: String, data: &D) -> std::io::Result<()> {
-	fs::create_dir_all(path.clone())?;
+pub(crate) fn write_to_file<W: Writeable>(filename_with_path: String, data: &W) -> std::io::Result<()> {
+	let mut path_parts: Vec<&str> = filename_with_path.split("/").collect();
+	let _filename = path_parts.pop();
+	let path = path_parts.join("/");
+	fs::create_dir_all(path)?;
 	// Do a crazy dance with lots of fsync()s to be overly cautious here...
 	// We never want to end up in a state where we've lost the old data, or end up using the
 	// old data on power loss after we've returned.
 	// The way to atomically write a file on Unix platforms is:
 	// open(tmpname), write(tmpfile), fsync(tmpfile), close(tmpfile), rename(), fsync(dir)
-	let filename_with_path = get_full_filepath(path, filename);
 	let tmp_filename = format!("{}.tmp", filename_with_path.clone());
 
 	{
 		// Note that going by rust-lang/rust@d602a6b, on MacOS it is only safe to use
 		// rust stdlib 1.36 or higher.
 		let mut f = fs::File::create(&tmp_filename)?;
-		data.write_to_file(&mut f)?;
+		data.write(&mut f)?;
 		f.sync_all()?;
 	}
 	// Fsync the parent directory on Unix.
@@ -87,15 +82,17 @@ pub(crate) fn write_to_file<D: DiskWriteable>(path: PathBuf, filename: String, d
 
 #[cfg(test)]
 mod tests {
-	use super::{DiskWriteable, get_full_filepath, write_to_file};
+	use lightning::util::ser::Writeable;
+
+use super::{write_to_file};
 	use std::fs;
 	use std::io;
 	use std::io::Write;
 	use std::path::PathBuf;
 
 	struct TestWriteable{}
-	impl DiskWriteable for TestWriteable {
-		fn write_to_file(&self, writer: &mut fs::File) -> Result<(), io::Error> {
+	impl Writeable for TestWriteable {
+		fn write(&self, writer: &mut fs::File) -> Result<(), io::Error> {
 			writer.write_all(&[42; 1])
 		}
 	}
