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::{Block, BlockHeader};
8 use bitcoin::hash_types::BlockHash;
9 use bitcoin::network::constants::Network;
13 /// Returns a validated block header of the source's best chain tip.
15 /// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
16 /// start when there are no chain listeners to sync yet.
18 /// [`SpvClient`]: crate::SpvClient
19 pub async fn validate_best_block_header<B: BlockSource>(block_source: &B) ->
20 BlockSourceResult<ValidatedBlockHeader> {
21 let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
23 .get_header(&best_block_hash, best_block_height).await?
24 .validate(best_block_hash)
27 /// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
28 /// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
30 /// Upon success, the returned header can be used to initialize [`SpvClient`]. In the case of
31 /// failure, each listener may be left at a different block hash than the one it was originally
34 /// Useful during startup to bring the [`ChannelManager`] and each [`ChannelMonitor`] in sync before
35 /// switching to [`SpvClient`]. For example:
38 /// use bitcoin::hash_types::BlockHash;
39 /// use bitcoin::network::constants::Network;
41 /// use lightning::chain;
42 /// use lightning::chain::Watch;
43 /// use lightning::chain::chainmonitor;
44 /// use lightning::chain::chainmonitor::ChainMonitor;
45 /// use lightning::chain::channelmonitor::ChannelMonitor;
46 /// use lightning::chain::chaininterface::BroadcasterInterface;
47 /// use lightning::chain::chaininterface::FeeEstimator;
48 /// use lightning::chain::keysinterface;
49 /// use lightning::chain::keysinterface::KeysInterface;
50 /// use lightning::ln::channelmanager::ChannelManager;
51 /// use lightning::ln::channelmanager::ChannelManagerReadArgs;
52 /// use lightning::util::config::UserConfig;
53 /// use lightning::util::logger::Logger;
54 /// use lightning::util::ser::ReadableArgs;
56 /// use lightning_block_sync::*;
58 /// use std::io::Cursor;
60 /// async fn init_sync<
62 /// K: KeysInterface<Signer = S>,
63 /// S: keysinterface::Sign,
64 /// T: BroadcasterInterface,
68 /// P: chainmonitor::Persist<S>,
71 /// chain_monitor: &ChainMonitor<S, &C, &T, &F, &L, &P>,
72 /// config: UserConfig,
74 /// tx_broadcaster: &T,
75 /// fee_estimator: &F,
79 /// // Read a serialized channel monitor paired with the block hash when it was persisted.
80 /// let serialized_monitor = "...";
81 /// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<S>)>::read(
82 /// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
84 /// // Read the channel manager paired with the block hash when it was persisted.
85 /// let serialized_manager = "...";
86 /// let (manager_block_hash, mut manager) = {
87 /// let read_args = ChannelManagerReadArgs::new(
94 /// vec![&mut monitor],
96 /// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
97 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
100 /// // Synchronize any channel monitors and the channel manager to be on the best block.
101 /// let mut cache = UnboundedCache::new();
102 /// let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
103 /// let listeners = vec![
104 /// (monitor_block_hash, &monitor_listener as &dyn chain::Listen),
105 /// (manager_block_hash, &manager as &dyn chain::Listen),
107 /// let chain_tip = init::synchronize_listeners(
108 /// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
110 /// // Allow the chain monitor to watch any channels.
111 /// let monitor = monitor_listener.0;
112 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
114 /// // Create an SPV client to notify the chain monitor and channel manager of block events.
115 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
116 /// let mut chain_listener = (chain_monitor, &manager);
117 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
121 /// [`SpvClient`]: crate::SpvClient
122 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
123 /// [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
124 pub async fn synchronize_listeners<'a, B: BlockSource, C: Cache, L: chain::Listen + ?Sized>(
127 header_cache: &mut C,
128 mut chain_listeners: Vec<(BlockHash, &'a L)>,
129 ) -> BlockSourceResult<ValidatedBlockHeader> {
130 let best_header = validate_best_block_header(block_source).await?;
132 // Fetch the header for the block hash paired with each listener.
133 let mut chain_listeners_with_old_headers = Vec::new();
134 for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
135 let old_header = match header_cache.look_up(&old_block_hash) {
136 Some(header) => *header,
138 .get_header(&old_block_hash, None).await?
139 .validate(old_block_hash)?
141 chain_listeners_with_old_headers.push((old_header, chain_listener))
144 // Find differences and disconnect blocks for each listener individually.
145 let mut chain_poller = ChainPoller::new(block_source, network);
146 let mut chain_listeners_at_height = Vec::new();
147 let mut most_common_ancestor = None;
148 let mut most_connected_blocks = Vec::new();
149 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
150 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
151 let header_cache = &mut ReadOnlyCache(header_cache);
152 let (common_ancestor, connected_blocks) = {
153 let chain_listener = &DynamicChainListener(chain_listener);
154 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
156 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
157 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
158 (difference.common_ancestor, difference.connected_blocks)
161 // Keep track of the most common ancestor and all blocks connected across all listeners.
162 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
163 if connected_blocks.len() > most_connected_blocks.len() {
164 most_common_ancestor = Some(common_ancestor);
165 most_connected_blocks = connected_blocks;
169 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
170 if let Some(common_ancestor) = most_common_ancestor {
171 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
172 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
173 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
174 .await.or_else(|(e, _)| Err(e))?;
180 /// A wrapper to make a cache read-only.
182 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
184 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
186 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
187 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
188 self.0.look_up(block_hash)
191 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
195 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
200 /// Wrapper for supporting dynamically sized chain listeners.
201 struct DynamicChainListener<'a, L: chain::Listen + ?Sized>(&'a L);
203 impl<'a, L: chain::Listen + ?Sized> chain::Listen for DynamicChainListener<'a, L> {
204 fn block_connected(&self, _block: &Block, _height: u32) {
208 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
209 self.0.block_disconnected(header, height)
213 /// A set of dynamically sized chain listeners, each paired with a starting block height.
214 struct ChainListenerSet<'a, L: chain::Listen + ?Sized>(Vec<(u32, &'a L)>);
216 impl<'a, L: chain::Listen + ?Sized> chain::Listen for ChainListenerSet<'a, L> {
217 fn block_connected(&self, block: &Block, height: u32) {
218 for (starting_height, chain_listener) in self.0.iter() {
219 if height > *starting_height {
220 chain_listener.block_connected(block, height);
225 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
232 use crate::test_utils::{Blockchain, MockChainListener};
235 use bitcoin::network::constants::Network;
238 async fn sync_from_same_chain() {
239 let mut chain = Blockchain::default().with_height(4);
241 let listener_1 = MockChainListener::new()
242 .expect_block_connected(*chain.at_height(2))
243 .expect_block_connected(*chain.at_height(3))
244 .expect_block_connected(*chain.at_height(4));
245 let listener_2 = MockChainListener::new()
246 .expect_block_connected(*chain.at_height(3))
247 .expect_block_connected(*chain.at_height(4));
248 let listener_3 = MockChainListener::new()
249 .expect_block_connected(*chain.at_height(4));
251 let listeners = vec![
252 (chain.at_height(1).block_hash, &listener_1 as &dyn chain::Listen),
253 (chain.at_height(2).block_hash, &listener_2 as &dyn chain::Listen),
254 (chain.at_height(3).block_hash, &listener_3 as &dyn chain::Listen),
256 let mut cache = chain.header_cache(0..=4);
257 match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
258 Ok(header) => assert_eq!(header, chain.tip()),
259 Err(e) => panic!("Unexpected error: {:?}", e),
264 async fn sync_from_different_chains() {
265 let mut main_chain = Blockchain::default().with_height(4);
266 let fork_chain_1 = main_chain.fork_at_height(1);
267 let fork_chain_2 = main_chain.fork_at_height(2);
268 let fork_chain_3 = main_chain.fork_at_height(3);
270 let listener_1 = MockChainListener::new()
271 .expect_block_disconnected(*fork_chain_1.at_height(4))
272 .expect_block_disconnected(*fork_chain_1.at_height(3))
273 .expect_block_disconnected(*fork_chain_1.at_height(2))
274 .expect_block_connected(*main_chain.at_height(2))
275 .expect_block_connected(*main_chain.at_height(3))
276 .expect_block_connected(*main_chain.at_height(4));
277 let listener_2 = MockChainListener::new()
278 .expect_block_disconnected(*fork_chain_2.at_height(4))
279 .expect_block_disconnected(*fork_chain_2.at_height(3))
280 .expect_block_connected(*main_chain.at_height(3))
281 .expect_block_connected(*main_chain.at_height(4));
282 let listener_3 = MockChainListener::new()
283 .expect_block_disconnected(*fork_chain_3.at_height(4))
284 .expect_block_connected(*main_chain.at_height(4));
286 let listeners = vec![
287 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
288 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
289 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
291 let mut cache = fork_chain_1.header_cache(2..=4);
292 cache.extend(fork_chain_2.header_cache(3..=4));
293 cache.extend(fork_chain_3.header_cache(4..=4));
294 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
295 Ok(header) => assert_eq!(header, main_chain.tip()),
296 Err(e) => panic!("Unexpected error: {:?}", e),
301 async fn sync_from_overlapping_chains() {
302 let mut main_chain = Blockchain::default().with_height(4);
303 let fork_chain_1 = main_chain.fork_at_height(1);
304 let fork_chain_2 = fork_chain_1.fork_at_height(2);
305 let fork_chain_3 = fork_chain_2.fork_at_height(3);
307 let listener_1 = MockChainListener::new()
308 .expect_block_disconnected(*fork_chain_1.at_height(4))
309 .expect_block_disconnected(*fork_chain_1.at_height(3))
310 .expect_block_disconnected(*fork_chain_1.at_height(2))
311 .expect_block_connected(*main_chain.at_height(2))
312 .expect_block_connected(*main_chain.at_height(3))
313 .expect_block_connected(*main_chain.at_height(4));
314 let listener_2 = MockChainListener::new()
315 .expect_block_disconnected(*fork_chain_2.at_height(4))
316 .expect_block_disconnected(*fork_chain_2.at_height(3))
317 .expect_block_disconnected(*fork_chain_2.at_height(2))
318 .expect_block_connected(*main_chain.at_height(2))
319 .expect_block_connected(*main_chain.at_height(3))
320 .expect_block_connected(*main_chain.at_height(4));
321 let listener_3 = MockChainListener::new()
322 .expect_block_disconnected(*fork_chain_3.at_height(4))
323 .expect_block_disconnected(*fork_chain_3.at_height(3))
324 .expect_block_disconnected(*fork_chain_3.at_height(2))
325 .expect_block_connected(*main_chain.at_height(2))
326 .expect_block_connected(*main_chain.at_height(3))
327 .expect_block_connected(*main_chain.at_height(4));
329 let listeners = vec![
330 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
331 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
332 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
334 let mut cache = fork_chain_1.header_cache(2..=4);
335 cache.extend(fork_chain_2.header_cache(3..=4));
336 cache.extend(fork_chain_3.header_cache(4..=4));
337 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
338 Ok(header) => assert_eq!(header, main_chain.tip()),
339 Err(e) => panic!("Unexpected error: {:?}", e),
344 async fn cache_connected_and_keep_disconnected_blocks() {
345 let mut main_chain = Blockchain::default().with_height(2);
346 let fork_chain = main_chain.fork_at_height(1);
347 let new_tip = main_chain.tip();
348 let old_tip = fork_chain.tip();
350 let listener = MockChainListener::new()
351 .expect_block_disconnected(*old_tip)
352 .expect_block_connected(*new_tip);
354 let listeners = vec![(old_tip.block_hash, &listener as &dyn chain::Listen)];
355 let mut cache = fork_chain.header_cache(2..=2);
356 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
358 assert!(cache.contains_key(&new_tip.block_hash));
359 assert!(cache.contains_key(&old_tip.block_hash));
361 Err(e) => panic!("Unexpected error: {:?}", e),