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

// 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)
	}
}