1 //! Utilities to assist in the initial sync required to initialize or reload Rust-Lightning objects
4 use crate::{BlockSource, BlockSourceResult, Cache, ChainNotifier};
5 use crate::poll::{ChainPoller, Validate, ValidatedBlockHeader};
7 use bitcoin::blockdata::block::BlockHeader;
8 use bitcoin::hash_types::BlockHash;
9 use bitcoin::network::constants::Network;
15 /// Returns a validated block header of the source's best chain tip.
17 /// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
18 /// start when there are no chain listeners to sync yet.
20 /// [`SpvClient`]: crate::SpvClient
21 pub async fn validate_best_block_header<B: Deref>(block_source: B) ->
22 BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
23 let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
25 .get_header(&best_block_hash, best_block_height).await?
26 .validate(best_block_hash)
29 /// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
30 /// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
32 /// Upon success, the returned header can be used to initialize [`SpvClient`]. In the case of
33 /// failure, each listener may be left at a different block hash than the one it was originally
36 /// Useful during startup to bring the [`ChannelManager`] and each [`ChannelMonitor`] in sync before
37 /// switching to [`SpvClient`]. For example:
40 /// use bitcoin::hash_types::BlockHash;
41 /// use bitcoin::network::constants::Network;
43 /// use lightning::chain;
44 /// use lightning::chain::Watch;
45 /// use lightning::chain::chainmonitor;
46 /// use lightning::chain::chainmonitor::ChainMonitor;
47 /// use lightning::chain::channelmonitor::ChannelMonitor;
48 /// use lightning::chain::chaininterface::BroadcasterInterface;
49 /// use lightning::chain::chaininterface::FeeEstimator;
50 /// use lightning::chain::keysinterface;
51 /// use lightning::chain::keysinterface::KeysInterface;
52 /// use lightning::ln::channelmanager::ChannelManager;
53 /// use lightning::ln::channelmanager::ChannelManagerReadArgs;
54 /// use lightning::util::config::UserConfig;
55 /// use lightning::util::logger::Logger;
56 /// use lightning::util::ser::ReadableArgs;
58 /// use lightning_block_sync::*;
60 /// use std::io::Cursor;
62 /// async fn init_sync<
64 /// K: KeysInterface<Signer = S>,
65 /// S: keysinterface::Sign,
66 /// T: BroadcasterInterface,
70 /// P: chainmonitor::Persist<S>,
73 /// chain_monitor: &ChainMonitor<S, &C, &T, &F, &L, &P>,
74 /// config: UserConfig,
76 /// tx_broadcaster: &T,
77 /// fee_estimator: &F,
81 /// // Read a serialized channel monitor paired with the block hash when it was persisted.
82 /// let serialized_monitor = "...";
83 /// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<S>)>::read(
84 /// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
86 /// // Read the channel manager paired with the block hash when it was persisted.
87 /// let serialized_manager = "...";
88 /// let (manager_block_hash, mut manager) = {
89 /// let read_args = ChannelManagerReadArgs::new(
96 /// vec![&mut monitor],
98 /// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
99 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
102 /// // Synchronize any channel monitors and the channel manager to be on the best block.
103 /// let mut cache = UnboundedCache::new();
104 /// let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
105 /// let listeners = vec![
106 /// (monitor_block_hash, &monitor_listener as &dyn chain::Listen),
107 /// (manager_block_hash, &manager as &dyn chain::Listen),
109 /// let chain_tip = init::synchronize_listeners(
110 /// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
112 /// // Allow the chain monitor to watch any channels.
113 /// let monitor = monitor_listener.0;
114 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
116 /// // Create an SPV client to notify the chain monitor and channel manager of block events.
117 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
118 /// let mut chain_listener = (chain_monitor, &manager);
119 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
123 /// [`SpvClient`]: crate::SpvClient
124 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
125 /// [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
126 pub async fn synchronize_listeners<B: Deref + Sized + Send + Sync, C: Cache, L: chain::Listen + ?Sized>(
129 header_cache: &mut C,
130 mut chain_listeners: Vec<(BlockHash, &L)>,
131 ) -> BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
132 let best_header = validate_best_block_header(&*block_source).await?;
134 // Fetch the header for the block hash paired with each listener.
135 let mut chain_listeners_with_old_headers = Vec::new();
136 for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
137 let old_header = match header_cache.look_up(&old_block_hash) {
138 Some(header) => *header,
140 .get_header(&old_block_hash, None).await?
141 .validate(old_block_hash)?
143 chain_listeners_with_old_headers.push((old_header, chain_listener))
146 // Find differences and disconnect blocks for each listener individually.
147 let mut chain_poller = ChainPoller::new(block_source, network);
148 let mut chain_listeners_at_height = Vec::new();
149 let mut most_common_ancestor = None;
150 let mut most_connected_blocks = Vec::new();
151 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
152 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
153 let header_cache = &mut ReadOnlyCache(header_cache);
154 let (common_ancestor, connected_blocks) = {
155 let chain_listener = &DynamicChainListener(chain_listener);
156 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
158 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
159 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
160 (difference.common_ancestor, difference.connected_blocks)
163 // Keep track of the most common ancestor and all blocks connected across all listeners.
164 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
165 if connected_blocks.len() > most_connected_blocks.len() {
166 most_common_ancestor = Some(common_ancestor);
167 most_connected_blocks = connected_blocks;
171 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
172 if let Some(common_ancestor) = most_common_ancestor {
173 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
174 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
175 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
176 .await.or_else(|(e, _)| Err(e))?;
182 /// A wrapper to make a cache read-only.
184 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
186 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
188 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
189 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
190 self.0.look_up(block_hash)
193 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
197 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
202 /// Wrapper for supporting dynamically sized chain listeners.
203 struct DynamicChainListener<'a, L: chain::Listen + ?Sized>(&'a L);
205 impl<'a, L: chain::Listen + ?Sized> chain::Listen for DynamicChainListener<'a, L> {
206 fn filtered_block_connected(&self, _header: &BlockHeader, _txdata: &chain::transaction::TransactionData, _height: u32) {
210 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
211 self.0.block_disconnected(header, height)
215 /// A set of dynamically sized chain listeners, each paired with a starting block height.
216 struct ChainListenerSet<'a, L: chain::Listen + ?Sized>(Vec<(u32, &'a L)>);
218 impl<'a, L: chain::Listen + ?Sized> chain::Listen for ChainListenerSet<'a, L> {
219 fn filtered_block_connected(&self, header: &BlockHeader, txdata: &chain::transaction::TransactionData, height: u32) {
220 for (starting_height, chain_listener) in self.0.iter() {
221 if height > *starting_height {
222 chain_listener.filtered_block_connected(header, txdata, height);
227 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
234 use crate::test_utils::{Blockchain, MockChainListener};
237 use bitcoin::network::constants::Network;
240 async fn sync_from_same_chain() {
241 let chain = Blockchain::default().with_height(4);
243 let listener_1 = MockChainListener::new()
244 .expect_block_connected(*chain.at_height(2))
245 .expect_block_connected(*chain.at_height(3))
246 .expect_block_connected(*chain.at_height(4));
247 let listener_2 = MockChainListener::new()
248 .expect_block_connected(*chain.at_height(3))
249 .expect_block_connected(*chain.at_height(4));
250 let listener_3 = MockChainListener::new()
251 .expect_block_connected(*chain.at_height(4));
253 let listeners = vec![
254 (chain.at_height(1).block_hash, &listener_1 as &dyn chain::Listen),
255 (chain.at_height(2).block_hash, &listener_2 as &dyn chain::Listen),
256 (chain.at_height(3).block_hash, &listener_3 as &dyn chain::Listen),
258 let mut cache = chain.header_cache(0..=4);
259 match synchronize_listeners(&chain, Network::Bitcoin, &mut cache, listeners).await {
260 Ok(header) => assert_eq!(header, chain.tip()),
261 Err(e) => panic!("Unexpected error: {:?}", e),
266 async fn sync_from_different_chains() {
267 let main_chain = Blockchain::default().with_height(4);
268 let fork_chain_1 = main_chain.fork_at_height(1);
269 let fork_chain_2 = main_chain.fork_at_height(2);
270 let fork_chain_3 = main_chain.fork_at_height(3);
272 let listener_1 = MockChainListener::new()
273 .expect_block_disconnected(*fork_chain_1.at_height(4))
274 .expect_block_disconnected(*fork_chain_1.at_height(3))
275 .expect_block_disconnected(*fork_chain_1.at_height(2))
276 .expect_block_connected(*main_chain.at_height(2))
277 .expect_block_connected(*main_chain.at_height(3))
278 .expect_block_connected(*main_chain.at_height(4));
279 let listener_2 = MockChainListener::new()
280 .expect_block_disconnected(*fork_chain_2.at_height(4))
281 .expect_block_disconnected(*fork_chain_2.at_height(3))
282 .expect_block_connected(*main_chain.at_height(3))
283 .expect_block_connected(*main_chain.at_height(4));
284 let listener_3 = MockChainListener::new()
285 .expect_block_disconnected(*fork_chain_3.at_height(4))
286 .expect_block_connected(*main_chain.at_height(4));
288 let listeners = vec![
289 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
290 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
291 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
293 let mut cache = fork_chain_1.header_cache(2..=4);
294 cache.extend(fork_chain_2.header_cache(3..=4));
295 cache.extend(fork_chain_3.header_cache(4..=4));
296 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
297 Ok(header) => assert_eq!(header, main_chain.tip()),
298 Err(e) => panic!("Unexpected error: {:?}", e),
303 async fn sync_from_overlapping_chains() {
304 let main_chain = Blockchain::default().with_height(4);
305 let fork_chain_1 = main_chain.fork_at_height(1);
306 let fork_chain_2 = fork_chain_1.fork_at_height(2);
307 let fork_chain_3 = fork_chain_2.fork_at_height(3);
309 let listener_1 = MockChainListener::new()
310 .expect_block_disconnected(*fork_chain_1.at_height(4))
311 .expect_block_disconnected(*fork_chain_1.at_height(3))
312 .expect_block_disconnected(*fork_chain_1.at_height(2))
313 .expect_block_connected(*main_chain.at_height(2))
314 .expect_block_connected(*main_chain.at_height(3))
315 .expect_block_connected(*main_chain.at_height(4));
316 let listener_2 = MockChainListener::new()
317 .expect_block_disconnected(*fork_chain_2.at_height(4))
318 .expect_block_disconnected(*fork_chain_2.at_height(3))
319 .expect_block_disconnected(*fork_chain_2.at_height(2))
320 .expect_block_connected(*main_chain.at_height(2))
321 .expect_block_connected(*main_chain.at_height(3))
322 .expect_block_connected(*main_chain.at_height(4));
323 let listener_3 = MockChainListener::new()
324 .expect_block_disconnected(*fork_chain_3.at_height(4))
325 .expect_block_disconnected(*fork_chain_3.at_height(3))
326 .expect_block_disconnected(*fork_chain_3.at_height(2))
327 .expect_block_connected(*main_chain.at_height(2))
328 .expect_block_connected(*main_chain.at_height(3))
329 .expect_block_connected(*main_chain.at_height(4));
331 let listeners = vec![
332 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
333 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
334 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
336 let mut cache = fork_chain_1.header_cache(2..=4);
337 cache.extend(fork_chain_2.header_cache(3..=4));
338 cache.extend(fork_chain_3.header_cache(4..=4));
339 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
340 Ok(header) => assert_eq!(header, main_chain.tip()),
341 Err(e) => panic!("Unexpected error: {:?}", e),
346 async fn cache_connected_and_keep_disconnected_blocks() {
347 let main_chain = Blockchain::default().with_height(2);
348 let fork_chain = main_chain.fork_at_height(1);
349 let new_tip = main_chain.tip();
350 let old_tip = fork_chain.tip();
352 let listener = MockChainListener::new()
353 .expect_block_disconnected(*old_tip)
354 .expect_block_connected(*new_tip);
356 let listeners = vec![(old_tip.block_hash, &listener as &dyn chain::Listen)];
357 let mut cache = fork_chain.header_cache(2..=2);
358 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
360 assert!(cache.contains_key(&new_tip.block_hash));
361 assert!(cache.contains_key(&old_tip.block_hash));
363 Err(e) => panic!("Unexpected error: {:?}", e),