implement Persist and Persister with generic KVStorePersister trait

[rust-lightning] / lightning / src / util / persist.rs

diff --git a/lightning/src/util/persist.rs b/lightning/src/util/persist.rs
new file mode 100644 (file)
index 0000000..9476331
--- /dev/null
+++ b/lightning/src/util/persist.rs
@@ -0,0 +1,77 @@
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+//! This module contains a simple key-value store trait KVStorePersister that
+//! allows one to implement the persistence for [`ChannelManager`], [`NetworkGraph`],
+//! and [`ChannelMonitor`] all in one place.
+
+use core::ops::Deref;
+use bitcoin::hashes::hex::ToHex;
+use io::{self};
+
+use crate::{chain::{keysinterface::{Sign, KeysInterface}, self, transaction::{OutPoint}, chaininterface::{BroadcasterInterface, FeeEstimator}, chainmonitor::{Persist, MonitorUpdateId}, channelmonitor::{ChannelMonitor, ChannelMonitorUpdate}}, ln::channelmanager::ChannelManager, routing::network_graph::NetworkGraph};
+use super::{logger::Logger, ser::Writeable};
+
+/// Trait for a key-value store for persisting some writeable object at some key
+/// Implementing `KVStorePersister` provides auto-implementations for [`Persister`]
+/// and [`Persist`] traits.  It uses "manager", "network_graph",
+/// and "monitors/{funding_txo_id}_{funding_txo_index}" for keys.
+pub trait KVStorePersister {
+       /// Persist the given writeable using the provided key
+       fn persist<W: Writeable>(&self, key: &str, object: &W) -> io::Result<()>;
+}
+
+/// 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.
+       fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), io::Error>;
+
+       /// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
+       fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), io::Error>;
+}
+
+impl<A: KVStorePersister, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> Persister<Signer, M, T, K, F, L> for A
+       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.
+       fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), io::Error> {
+               self.persist("manager", channel_manager)
+       }
+
+       /// Persist the given [`NetworkGraph`] to disk, returning an error if persistence failed.
+       fn persist_graph(&self, network_graph: &NetworkGraph) -> Result<(), io::Error> {
+               self.persist("network_graph", network_graph)
+       }
+}
+
+impl<ChannelSigner: Sign, K: KVStorePersister> 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 need to shut down since we're force-closing channels without
+       // even broadcasting!
+
+       fn persist_new_channel(&self, funding_txo: OutPoint, monitor: &ChannelMonitor<ChannelSigner>, _update_id: MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
+               let key = format!("monitors/{}_{}", 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: MonitorUpdateId) -> Result<(), chain::ChannelMonitorUpdateErr> {
+               let key = format!("monitors/{}_{}", funding_txo.txid.to_hex(), funding_txo.index);
+               self.persist(&key, monitor)
+                       .map_err(|_| chain::ChannelMonitorUpdateErr::PermanentFailure)
+       }
+}