_ Git - rust-lightning/blob - lightning-background-processor/src/lib.rs

   1 //! Utilities that take care of tasks that (1) need to happen periodically to keep Rust-Lightning
   2 //! running properly, and (2) either can or should be run in the background. See docs for
   3 //! [`BackgroundProcessor`] for more details on the nitty-gritty.
   4
   5 #![deny(broken_intra_doc_links)]
   6 #![deny(missing_docs)]
   7 #![deny(unsafe_code)]
   8
   9 #[macro_use] extern crate lightning;
  10
  11 use lightning::chain;
  12 use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
  13 use lightning::chain::keysinterface::{Sign, KeysInterface};
  14 use lightning::ln::channelmanager::ChannelManager;
  15 use lightning::ln::msgs::{ChannelMessageHandler, RoutingMessageHandler};
  16 use lightning::ln::peer_handler::{PeerManager, SocketDescriptor};
  17 use lightning::util::events::{EventHandler, EventsProvider};
  18 use lightning::util::logger::Logger;
  19 use std::sync::Arc;
  20 use std::sync::atomic::{AtomicBool, Ordering};
  21 use std::thread;
  22 use std::thread::JoinHandle;
  23 use std::time::{Duration, Instant};
  24 use std::ops::Deref;
  25
  26 /// BackgroundProcessor takes care of tasks that (1) need to happen periodically to keep
  27 /// Rust-Lightning running properly, and (2) either can or should be run in the background. Its
  28 /// responsibilities are:
  29 /// * Monitoring whether the ChannelManager needs to be re-persisted to disk, and if so,
  30 ///   writing it to disk/backups by invoking the callback given to it at startup.
  31 ///   ChannelManager persistence should be done in the background.
  32 /// * Calling `ChannelManager::timer_tick_occurred()` and
  33 ///   `PeerManager::timer_tick_occurred()` every minute (can be done in the
  34 ///   background).
  35 ///
  36 /// Note that if ChannelManager persistence fails and the persisted manager becomes out-of-date,
  37 /// then there is a risk of channels force-closing on startup when the manager realizes it's
  38 /// outdated. However, as long as `ChannelMonitor` backups are sound, no funds besides those used
  39 /// for unilateral chain closure fees are at risk.
  40 pub struct BackgroundProcessor {
  41         stop_thread: Arc<AtomicBool>,
  42         /// May be used to retrieve and handle the error if `BackgroundProcessor`'s thread
  43         /// exits due to an error while persisting.
  44         pub thread_handle: JoinHandle<Result<(), std::io::Error>>,
  45 }
  46
  47 #[cfg(not(test))]
  48 const FRESHNESS_TIMER: u64 = 60;
  49 #[cfg(test)]
  50 const FRESHNESS_TIMER: u64 = 1;
  51
  52 /// Trait which handles persisting a [`ChannelManager`] to disk.
  53 ///
  54 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
  55 pub trait ChannelManagerPersister<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
  56 where
  57         M::Target: 'static + chain::Watch<Signer>,
  58         T::Target: 'static + BroadcasterInterface,
  59         K::Target: 'static + KeysInterface<Signer = Signer>,
  60         F::Target: 'static + FeeEstimator,
  61         L::Target: 'static + Logger,
  62 {
  63         /// Persist the given [`ChannelManager`] to disk, returning an error if persistence failed
  64         /// (which will cause the [`BackgroundProcessor`] which called this method to exit.
  65         ///
  66         /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
  67         fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error>;
  68 }
  69
  70 impl<Fun, Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref>
  71 ChannelManagerPersister<Signer, M, T, K, F, L> for Fun where
  72         M::Target: 'static + chain::Watch<Signer>,
  73         T::Target: 'static + BroadcasterInterface,
  74         K::Target: 'static + KeysInterface<Signer = Signer>,
  75         F::Target: 'static + FeeEstimator,
  76         L::Target: 'static + Logger,
  77         Fun: Fn(&ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error>,
  78 {
  79         fn persist_manager(&self, channel_manager: &ChannelManager<Signer, M, T, K, F, L>) -> Result<(), std::io::Error> {
  80                 self(channel_manager)
  81         }
  82 }
  83
  84 impl BackgroundProcessor {
  85         /// Start a background thread that takes care of responsibilities enumerated in the top-level
  86         /// documentation.
  87         ///
  88         /// If `persist_manager` returns an error, then this thread will return said error (and
  89         /// `start()` will need to be called again to restart the `BackgroundProcessor`). Users should
  90         /// wait on [`thread_handle`]'s `join()` method to be able to tell if and when an error is
  91         /// returned, or implement `persist_manager` such that an error is never returned to the
  92         /// `BackgroundProcessor`
  93         ///
  94         /// `persist_manager` is responsible for writing out the [`ChannelManager`] to disk, and/or
  95         /// uploading to one or more backup services. See [`ChannelManager::write`] for writing out a
  96         /// [`ChannelManager`]. See [`FilesystemPersister::persist_manager`] for Rust-Lightning's
  97         /// provided implementation.
  98         ///
  99         /// [`thread_handle`]: BackgroundProcessor::thread_handle
 100         /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
 101         /// [`ChannelManager::write`]: lightning::ln::channelmanager::ChannelManager#impl-Writeable
 102         /// [`FilesystemPersister::persist_manager`]: lightning_persister::FilesystemPersister::persist_manager
 103         pub fn start<
 104                 Signer: 'static + Sign,
 105                 M: 'static + Deref + Send + Sync,
 106                 T: 'static + Deref + Send + Sync,
 107                 K: 'static + Deref + Send + Sync,
 108                 F: 'static + Deref + Send + Sync,
 109                 L: 'static + Deref + Send + Sync,
 110                 Descriptor: 'static + SocketDescriptor + Send + Sync,
 111                 CMH: 'static + Deref + Send + Sync,
 112                 RMH: 'static + Deref + Send + Sync,
 113                 EH: 'static + EventHandler + Send + Sync,
 114                 CMP: 'static + Send + ChannelManagerPersister<Signer, M, T, K, F, L>,
 115                 CM: 'static + Deref<Target = ChannelManager<Signer, M, T, K, F, L>> + Send + Sync,
 116                 PM: 'static + Deref<Target = PeerManager<Descriptor, CMH, RMH, L>> + Send + Sync,
 117         >
 118         (persister: CMP, event_handler: EH, channel_manager: CM, peer_manager: PM, logger: L) -> Self
 119         where
 120                 M::Target: 'static + chain::Watch<Signer>,
 121                 T::Target: 'static + BroadcasterInterface,
 122                 K::Target: 'static + KeysInterface<Signer = Signer>,
 123                 F::Target: 'static + FeeEstimator,
 124                 L::Target: 'static + Logger,
 125                 CMH::Target: 'static + ChannelMessageHandler,
 126                 RMH::Target: 'static + RoutingMessageHandler,
 127         {
 128                 let stop_thread = Arc::new(AtomicBool::new(false));
 129                 let stop_thread_clone = stop_thread.clone();
 130                 let handle = thread::spawn(move || -> Result<(), std::io::Error> {
 131                         let mut current_time = Instant::now();
 132                         loop {
 133                                 peer_manager.process_events();
 134                                 channel_manager.process_pending_events(&event_handler);
 135                                 let updates_available =
 136                                         channel_manager.await_persistable_update_timeout(Duration::from_millis(100));
 137                                 if updates_available {
 138                                         persister.persist_manager(&*channel_manager)?;
 139                                 }
 140                                 // Exit the loop if the background processor was requested to stop.
 141                                 if stop_thread.load(Ordering::Acquire) == true {
 142                                         log_trace!(logger, "Terminating background processor.");
 143                                         return Ok(());
 144                                 }
 145                                 if current_time.elapsed().as_secs() > FRESHNESS_TIMER {
 146                                         log_trace!(logger, "Calling ChannelManager's and PeerManager's timer_tick_occurred");
 147                                         channel_manager.timer_tick_occurred();
 148                                         peer_manager.timer_tick_occurred();
 149                                         current_time = Instant::now();
 150                                 }
 151                         }
 152                 });
 153                 Self { stop_thread: stop_thread_clone, thread_handle: handle }
 154         }
 155
 156         /// Stop `BackgroundProcessor`'s thread.
 157         pub fn stop(self) -> Result<(), std::io::Error> {
 158                 self.stop_thread.store(true, Ordering::Release);
 159                 self.thread_handle.join().unwrap()
 160         }
 161 }
 162
 163 #[cfg(test)]
 164 mod tests {
 165         use bitcoin::blockdata::constants::genesis_block;
 166         use bitcoin::blockdata::transaction::{Transaction, TxOut};
 167         use bitcoin::network::constants::Network;
 168         use lightning::chain::chainmonitor;
 169         use lightning::chain::keysinterface::{InMemorySigner, KeysInterface, KeysManager};
 170         use lightning::chain::transaction::OutPoint;
 171         use lightning::get_event_msg;
 172         use lightning::ln::channelmanager::{BestBlock, ChainParameters, ChannelManager, SimpleArcChannelManager};
 173         use lightning::ln::features::InitFeatures;
 174         use lightning::ln::msgs::ChannelMessageHandler;
 175         use lightning::ln::peer_handler::{PeerManager, MessageHandler, SocketDescriptor};
 176         use lightning::util::config::UserConfig;
 177         use lightning::util::events::{Event, MessageSendEventsProvider, MessageSendEvent};
 178         use lightning::util::ser::Writeable;
 179         use lightning::util::test_utils;
 180         use lightning_persister::FilesystemPersister;
 181         use std::fs;
 182         use std::path::PathBuf;
 183         use std::sync::{Arc, Mutex};
 184         use std::time::Duration;
 185         use super::{BackgroundProcessor, FRESHNESS_TIMER};
 186
 187         #[derive(Clone, Eq, Hash, PartialEq)]
 188         struct TestDescriptor{}
 189         impl SocketDescriptor for TestDescriptor {
 190                 fn send_data(&mut self, _data: &[u8], _resume_read: bool) -> usize {
 191                         0
 192                 }
 193
 194                 fn disconnect_socket(&mut self) {}
 195         }
 196
 197         type ChainMonitor = chainmonitor::ChainMonitor<InMemorySigner, Arc<test_utils::TestChainSource>, Arc<test_utils::TestBroadcaster>, Arc<test_utils::TestFeeEstimator>, Arc<test_utils::TestLogger>, Arc<FilesystemPersister>>;
 198
 199         struct Node {
 200                 node: Arc<SimpleArcChannelManager<ChainMonitor, test_utils::TestBroadcaster, test_utils::TestFeeEstimator, test_utils::TestLogger>>,
 201                 peer_manager: Arc<PeerManager<TestDescriptor, Arc<test_utils::TestChannelMessageHandler>, Arc<test_utils::TestRoutingMessageHandler>, Arc<test_utils::TestLogger>>>,
 202                 persister: Arc<FilesystemPersister>,
 203                 logger: Arc<test_utils::TestLogger>,
 204         }
 205
 206         impl Drop for Node {
 207                 fn drop(&mut self) {
 208                         let data_dir = self.persister.get_data_dir();
 209                         match fs::remove_dir_all(data_dir.clone()) {
 210                                 Err(e) => println!("Failed to remove test persister directory {}: {}", data_dir, e),
 211                                 _ => {}
 212                         }
 213                 }
 214         }
 215
 216         fn get_full_filepath(filepath: String, filename: String) -> String {
 217                 let mut path = PathBuf::from(filepath);
 218                 path.push(filename);
 219                 path.to_str().unwrap().to_string()
 220         }
 221
 222         fn create_nodes(num_nodes: usize, persist_dir: String) -> Vec<Node> {
 223                 let mut nodes = Vec::new();
 224                 for i in 0..num_nodes {
 225                         let tx_broadcaster = Arc::new(test_utils::TestBroadcaster{txn_broadcasted: Mutex::new(Vec::new())});
 226                         let fee_estimator = Arc::new(test_utils::TestFeeEstimator { sat_per_kw: 253 });
 227                         let chain_source = Arc::new(test_utils::TestChainSource::new(Network::Testnet));
 228                         let logger = Arc::new(test_utils::TestLogger::with_id(format!("node {}", i)));
 229                         let persister = Arc::new(FilesystemPersister::new(format!("{}_persister_{}", persist_dir, i)));
 230                         let seed = [i as u8; 32];
 231                         let network = Network::Testnet;
 232                         let now = Duration::from_secs(genesis_block(network).header.time as u64);
 233                         let keys_manager = Arc::new(KeysManager::new(&seed, now.as_secs(), now.subsec_nanos()));
 234                         let chain_monitor = Arc::new(chainmonitor::ChainMonitor::new(Some(chain_source.clone()), tx_broadcaster.clone(), logger.clone(), fee_estimator.clone(), persister.clone()));
 235                         let params = ChainParameters {
 236                                 network,
 237                                 best_block: BestBlock::from_genesis(network),
 238                         };
 239                         let manager = Arc::new(ChannelManager::new(fee_estimator.clone(), chain_monitor.clone(), tx_broadcaster, logger.clone(), keys_manager.clone(), UserConfig::default(), params));
 240                         let msg_handler = MessageHandler { chan_handler: Arc::new(test_utils::TestChannelMessageHandler::new()), route_handler: Arc::new(test_utils::TestRoutingMessageHandler::new() )};
 241                         let peer_manager = Arc::new(PeerManager::new(msg_handler, keys_manager.get_node_secret(), &seed, logger.clone()));
 242                         let node = Node { node: manager, peer_manager, persister, logger };
 243                         nodes.push(node);
 244                 }
 245                 nodes
 246         }
 247
 248         macro_rules! open_channel {
 249                 ($node_a: expr, $node_b: expr, $channel_value: expr) => {{
 250                         begin_open_channel!($node_a, $node_b, $channel_value);
 251                         let events = $node_a.node.get_and_clear_pending_events();
 252                         assert_eq!(events.len(), 1);
 253                         let (temporary_channel_id, tx) = handle_funding_generation_ready!(events[0], $channel_value);
 254                         end_open_channel!($node_a, $node_b, temporary_channel_id, tx);
 255                         tx
 256                 }}
 257         }
 258
 259         macro_rules! begin_open_channel {
 260                 ($node_a: expr, $node_b: expr, $channel_value: expr) => {{
 261                         $node_a.node.create_channel($node_b.node.get_our_node_id(), $channel_value, 100, 42, None).unwrap();
 262                         $node_b.node.handle_open_channel(&$node_a.node.get_our_node_id(), InitFeatures::known(), &get_event_msg!($node_a, MessageSendEvent::SendOpenChannel, $node_b.node.get_our_node_id()));
 263                         $node_a.node.handle_accept_channel(&$node_b.node.get_our_node_id(), InitFeatures::known(), &get_event_msg!($node_b, MessageSendEvent::SendAcceptChannel, $node_a.node.get_our_node_id()));
 264                 }}
 265         }
 266
 267         macro_rules! handle_funding_generation_ready {
 268                 ($event: expr, $channel_value: expr) => {{
 269                         match $event {
 270                                 Event::FundingGenerationReady { ref temporary_channel_id, ref channel_value_satoshis, ref output_script, user_channel_id } => {
 271                                         assert_eq!(*channel_value_satoshis, $channel_value);
 272                                         assert_eq!(user_channel_id, 42);
 273
 274                                         let tx = Transaction { version: 1 as i32, lock_time: 0, input: Vec::new(), output: vec![TxOut {
 275                                                 value: *channel_value_satoshis, script_pubkey: output_script.clone(),
 276                                         }]};
 277                                         (*temporary_channel_id, tx)
 278                                 },
 279                                 _ => panic!("Unexpected event"),
 280                         }
 281                 }}
 282         }
 283
 284         macro_rules! end_open_channel {
 285                 ($node_a: expr, $node_b: expr, $temporary_channel_id: expr, $tx: expr) => {{
 286                         $node_a.node.funding_transaction_generated(&$temporary_channel_id, $tx.clone()).unwrap();
 287                         $node_b.node.handle_funding_created(&$node_a.node.get_our_node_id(), &get_event_msg!($node_a, MessageSendEvent::SendFundingCreated, $node_b.node.get_our_node_id()));
 288                         $node_a.node.handle_funding_signed(&$node_b.node.get_our_node_id(), &get_event_msg!($node_b, MessageSendEvent::SendFundingSigned, $node_a.node.get_our_node_id()));
 289                 }}
 290         }
 291
 292         #[test]
 293         fn test_background_processor() {
 294                 // Test that when a new channel is created, the ChannelManager needs to be re-persisted with
 295                 // updates. Also test that when new updates are available, the manager signals that it needs
 296                 // re-persistence and is successfully re-persisted.
 297                 let nodes = create_nodes(2, "test_background_processor".to_string());
 298
 299                 // Go through the channel creation process so that each node has something to persist. Since
 300                 // open_channel consumes events, it must complete before starting BackgroundProcessor to
 301                 // avoid a race with processing events.
 302                 let tx = open_channel!(nodes[0], nodes[1], 100000);
 303
 304                 // Initiate the background processors to watch each node.
 305                 let data_dir = nodes[0].persister.get_data_dir();
 306                 let persister = move |node: &ChannelManager<InMemorySigner, Arc<ChainMonitor>, Arc<test_utils::TestBroadcaster>, Arc<KeysManager>, Arc<test_utils::TestFeeEstimator>, Arc<test_utils::TestLogger>>| FilesystemPersister::persist_manager(data_dir.clone(), node);
 307                 let event_handler = |_| {};
 308                 let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 309
 310                 macro_rules! check_persisted_data {
 311                         ($node: expr, $filepath: expr, $expected_bytes: expr) => {
 312                                 match $node.write(&mut $expected_bytes) {
 313                                         Ok(()) => {
 314                                                 loop {
 315                                                         match std::fs::read($filepath) {
 316                                                                 Ok(bytes) => {
 317                                                                         if bytes == $expected_bytes {
 318                                                                                 break
 319                                                                         } else {
 320                                                                                 continue
 321                                                                         }
 322                                                                 },
 323                                                                 Err(_) => continue
 324                                                         }
 325                                                 }
 326                                         },
 327                                         Err(e) => panic!("Unexpected error: {}", e)
 328                                 }
 329                         }
 330                 }
 331
 332                 // Check that the initial channel manager data is persisted as expected.
 333                 let filepath = get_full_filepath("test_background_processor_persister_0".to_string(), "manager".to_string());
 334                 let mut expected_bytes = Vec::new();
 335                 check_persisted_data!(nodes[0].node, filepath.clone(), expected_bytes);
 336                 loop {
 337                         if !nodes[0].node.get_persistence_condvar_value() { break }
 338                 }
 339
 340                 // Force-close the channel.
 341                 nodes[0].node.force_close_channel(&OutPoint { txid: tx.txid(), index: 0 }.to_channel_id()).unwrap();
 342
 343                 // Check that the force-close updates are persisted.
 344                 let mut expected_bytes = Vec::new();
 345                 check_persisted_data!(nodes[0].node, filepath.clone(), expected_bytes);
 346                 loop {
 347                         if !nodes[0].node.get_persistence_condvar_value() { break }
 348                 }
 349
 350                 assert!(bg_processor.stop().is_ok());
 351         }
 352
 353         #[test]
 354         fn test_timer_tick_called() {
 355                 // Test that ChannelManager's and PeerManager's `timer_tick_occurred` is called every
 356                 // `FRESHNESS_TIMER`.
 357                 let nodes = create_nodes(1, "test_timer_tick_called".to_string());
 358                 let data_dir = nodes[0].persister.get_data_dir();
 359                 let persister = move |node: &ChannelManager<InMemorySigner, Arc<ChainMonitor>, Arc<test_utils::TestBroadcaster>, Arc<KeysManager>, Arc<test_utils::TestFeeEstimator>, Arc<test_utils::TestLogger>>| FilesystemPersister::persist_manager(data_dir.clone(), node);
 360                 let event_handler = |_| {};
 361                 let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 362                 loop {
 363                         let log_entries = nodes[0].logger.lines.lock().unwrap();
 364                         let desired_log = "Calling ChannelManager's and PeerManager's timer_tick_occurred".to_string();
 365                         if log_entries.get(&("lightning_background_processor".to_string(), desired_log)).is_some() {
 366                                 break
 367                         }
 368                 }
 369
 370                 assert!(bg_processor.stop().is_ok());
 371         }
 372
 373         #[test]
 374         fn test_persist_error() {
 375                 // Test that if we encounter an error during manager persistence, the thread panics.
 376                 let nodes = create_nodes(2, "test_persist_error".to_string());
 377                 open_channel!(nodes[0], nodes[1], 100000);
 378
 379                 let persister = |_: &_| Err(std::io::Error::new(std::io::ErrorKind::Other, "test"));
 380                 let event_handler = |_| {};
 381                 let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 382                 let _ = bg_processor.thread_handle.join().unwrap().expect_err("Errored persisting manager: test");
 383         }
 384
 385         #[test]
 386         fn test_background_event_handling() {
 387                 let nodes = create_nodes(2, "test_background_event_handling".to_string());
 388                 let channel_value = 100000;
 389                 let data_dir = nodes[0].persister.get_data_dir();
 390                 let persister = move |node: &_| FilesystemPersister::persist_manager(data_dir.clone(), node);
 391
 392                 // Set up a background event handler for FundingGenerationReady events.
 393                 let (sender, receiver) = std::sync::mpsc::sync_channel(1);
 394                 let event_handler = move |event| {
 395                         sender.send(handle_funding_generation_ready!(event, channel_value)).unwrap();
 396                 };
 397                 let bg_processor = BackgroundProcessor::start(persister, event_handler, nodes[0].node.clone(), nodes[0].peer_manager.clone(), nodes[0].logger.clone());
 398
 399                 // Open a channel and check that the FundingGenerationReady event was handled.
 400                 begin_open_channel!(nodes[0], nodes[1], channel_value);
 401                 let timeout = Duration::from_secs(5 * FRESHNESS_TIMER);
 402                 let (temporary_channel_id, tx) = receiver
 403                         .recv_timeout(timeout)
 404                         .expect("FundingGenerationReady not handled within deadline");
 405                 end_open_channel!(nodes[0], nodes[1], temporary_channel_id, tx);
 406
 407                 assert!(bg_processor.stop().is_ok());
 408         }
 409 }