1 use crate::{BlockSource, BlockSourceResult, Cache, ChainNotifier};
2 use crate::poll::{ChainPoller, Validate, ValidatedBlockHeader};
4 use bitcoin::blockdata::block::{Block, BlockHeader};
5 use bitcoin::hash_types::BlockHash;
6 use bitcoin::network::constants::Network;
10 /// Returns a validated block header of the source's best chain tip.
12 /// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
13 /// start when there are no chain listeners to sync yet.
15 /// [`SpvClient`]: crate::SpvClient
16 pub async fn validate_best_block_header<B: BlockSource>(block_source: &mut B) ->
17 BlockSourceResult<ValidatedBlockHeader> {
18 let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
20 .get_header(&best_block_hash, best_block_height).await?
21 .validate(best_block_hash)
24 /// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
25 /// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
27 /// Upon success, the returned header can be used to initialize [`SpvClient`]. In the case of
28 /// failure, each listener may be left at a different block hash than the one it was originally
31 /// Useful during startup to bring the [`ChannelManager`] and each [`ChannelMonitor`] in sync before
32 /// switching to [`SpvClient`]. For example:
35 /// use bitcoin::hash_types::BlockHash;
36 /// use bitcoin::network::constants::Network;
38 /// use lightning::chain;
39 /// use lightning::chain::Watch;
40 /// use lightning::chain::chainmonitor::ChainMonitor;
41 /// use lightning::chain::channelmonitor;
42 /// use lightning::chain::channelmonitor::ChannelMonitor;
43 /// use lightning::chain::chaininterface::BroadcasterInterface;
44 /// use lightning::chain::chaininterface::FeeEstimator;
45 /// use lightning::chain::keysinterface;
46 /// use lightning::chain::keysinterface::KeysInterface;
47 /// use lightning::ln::channelmanager::ChannelManager;
48 /// use lightning::ln::channelmanager::ChannelManagerReadArgs;
49 /// use lightning::util::config::UserConfig;
50 /// use lightning::util::logger::Logger;
51 /// use lightning::util::ser::ReadableArgs;
53 /// use lightning_block_sync::*;
55 /// use std::io::Cursor;
57 /// async fn init_sync<
59 /// K: KeysInterface<Signer = S>,
60 /// S: keysinterface::Sign,
61 /// T: BroadcasterInterface,
65 /// P: channelmonitor::Persist<S>,
67 /// block_source: &mut B,
68 /// chain_monitor: &ChainMonitor<S, &C, &T, &F, &L, &P>,
69 /// config: UserConfig,
71 /// tx_broadcaster: &T,
72 /// fee_estimator: &F,
76 /// // Read a serialized channel monitor paired with the block hash when it was persisted.
77 /// let serialized_monitor = "...";
78 /// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<S>)>::read(
79 /// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
81 /// // Read the channel manager paired with the block hash when it was persisted.
82 /// let serialized_manager = "...";
83 /// let (manager_block_hash, mut manager) = {
84 /// let read_args = ChannelManagerReadArgs::new(
91 /// vec![&mut monitor],
93 /// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
94 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
97 /// // Synchronize any channel monitors and the channel manager to be on the best block.
98 /// let mut cache = UnboundedCache::new();
99 /// let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
100 /// let listeners = vec![
101 /// (monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
102 /// (manager_block_hash, &mut manager as &mut dyn chain::Listen),
104 /// let chain_tip = init::synchronize_listeners(
105 /// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
107 /// // Allow the chain monitor to watch any channels.
108 /// let monitor = monitor_listener.0;
109 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
111 /// // Create an SPV client to notify the chain monitor and channel manager of block events.
112 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
113 /// let mut chain_listener = (chain_monitor, &manager);
114 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
118 /// [`SpvClient`]: crate::SpvClient
119 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
120 /// [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
121 pub async fn synchronize_listeners<B: BlockSource, C: Cache>(
122 block_source: &mut B,
124 header_cache: &mut C,
125 mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
126 ) -> BlockSourceResult<ValidatedBlockHeader> {
127 let best_header = validate_best_block_header(block_source).await?;
129 // Fetch the header for the block hash paired with each listener.
130 let mut chain_listeners_with_old_headers = Vec::new();
131 for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
132 let old_header = match header_cache.look_up(&old_block_hash) {
133 Some(header) => *header,
135 .get_header(&old_block_hash, None).await?
136 .validate(old_block_hash)?
138 chain_listeners_with_old_headers.push((old_header, chain_listener))
141 // Find differences and disconnect blocks for each listener individually.
142 let mut chain_poller = ChainPoller::new(block_source, network);
143 let mut chain_listeners_at_height = Vec::new();
144 let mut most_common_ancestor = None;
145 let mut most_connected_blocks = Vec::new();
146 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
147 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
148 let header_cache = &mut ReadOnlyCache(header_cache);
149 let (common_ancestor, connected_blocks) = {
150 let chain_listener = &DynamicChainListener(chain_listener);
151 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
153 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
154 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
155 (difference.common_ancestor, difference.connected_blocks)
158 // Keep track of the most common ancestor and all blocks connected across all listeners.
159 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
160 if connected_blocks.len() > most_connected_blocks.len() {
161 most_common_ancestor = Some(common_ancestor);
162 most_connected_blocks = connected_blocks;
166 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
167 if let Some(common_ancestor) = most_common_ancestor {
168 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
169 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
170 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
171 .await.or_else(|(e, _)| Err(e))?;
177 /// A wrapper to make a cache read-only.
179 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
181 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
183 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
184 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
185 self.0.look_up(block_hash)
188 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
192 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
197 /// Wrapper for supporting dynamically sized chain listeners.
198 struct DynamicChainListener<'a>(&'a mut dyn chain::Listen);
200 impl<'a> chain::Listen for DynamicChainListener<'a> {
201 fn block_connected(&self, _block: &Block, _height: u32) {
205 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
206 self.0.block_disconnected(header, height)
210 /// A set of dynamically sized chain listeners, each paired with a starting block height.
211 struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn chain::Listen)>);
213 impl<'a> chain::Listen for ChainListenerSet<'a> {
214 fn block_connected(&self, block: &Block, height: u32) {
215 for (starting_height, chain_listener) in self.0.iter() {
216 if height > *starting_height {
217 chain_listener.block_connected(block, height);
222 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
229 use crate::test_utils::{Blockchain, MockChainListener};
232 use bitcoin::network::constants::Network;
235 async fn sync_from_same_chain() {
236 let mut chain = Blockchain::default().with_height(4);
238 let mut listener_1 = MockChainListener::new()
239 .expect_block_connected(*chain.at_height(2))
240 .expect_block_connected(*chain.at_height(3))
241 .expect_block_connected(*chain.at_height(4));
242 let mut listener_2 = MockChainListener::new()
243 .expect_block_connected(*chain.at_height(3))
244 .expect_block_connected(*chain.at_height(4));
245 let mut listener_3 = MockChainListener::new()
246 .expect_block_connected(*chain.at_height(4));
248 let listeners = vec![
249 (chain.at_height(1).block_hash, &mut listener_1 as &mut dyn chain::Listen),
250 (chain.at_height(2).block_hash, &mut listener_2 as &mut dyn chain::Listen),
251 (chain.at_height(3).block_hash, &mut listener_3 as &mut dyn chain::Listen),
253 let mut cache = chain.header_cache(0..=4);
254 match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
255 Ok(header) => assert_eq!(header, chain.tip()),
256 Err(e) => panic!("Unexpected error: {:?}", e),
261 async fn sync_from_different_chains() {
262 let mut main_chain = Blockchain::default().with_height(4);
263 let fork_chain_1 = main_chain.fork_at_height(1);
264 let fork_chain_2 = main_chain.fork_at_height(2);
265 let fork_chain_3 = main_chain.fork_at_height(3);
267 let mut listener_1 = MockChainListener::new()
268 .expect_block_disconnected(*fork_chain_1.at_height(4))
269 .expect_block_disconnected(*fork_chain_1.at_height(3))
270 .expect_block_disconnected(*fork_chain_1.at_height(2))
271 .expect_block_connected(*main_chain.at_height(2))
272 .expect_block_connected(*main_chain.at_height(3))
273 .expect_block_connected(*main_chain.at_height(4));
274 let mut listener_2 = MockChainListener::new()
275 .expect_block_disconnected(*fork_chain_2.at_height(4))
276 .expect_block_disconnected(*fork_chain_2.at_height(3))
277 .expect_block_connected(*main_chain.at_height(3))
278 .expect_block_connected(*main_chain.at_height(4));
279 let mut listener_3 = MockChainListener::new()
280 .expect_block_disconnected(*fork_chain_3.at_height(4))
281 .expect_block_connected(*main_chain.at_height(4));
283 let listeners = vec![
284 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
285 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
286 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
288 let mut cache = fork_chain_1.header_cache(2..=4);
289 cache.extend(fork_chain_2.header_cache(3..=4));
290 cache.extend(fork_chain_3.header_cache(4..=4));
291 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
292 Ok(header) => assert_eq!(header, main_chain.tip()),
293 Err(e) => panic!("Unexpected error: {:?}", e),
298 async fn sync_from_overlapping_chains() {
299 let mut main_chain = Blockchain::default().with_height(4);
300 let fork_chain_1 = main_chain.fork_at_height(1);
301 let fork_chain_2 = fork_chain_1.fork_at_height(2);
302 let fork_chain_3 = fork_chain_2.fork_at_height(3);
304 let mut listener_1 = MockChainListener::new()
305 .expect_block_disconnected(*fork_chain_1.at_height(4))
306 .expect_block_disconnected(*fork_chain_1.at_height(3))
307 .expect_block_disconnected(*fork_chain_1.at_height(2))
308 .expect_block_connected(*main_chain.at_height(2))
309 .expect_block_connected(*main_chain.at_height(3))
310 .expect_block_connected(*main_chain.at_height(4));
311 let mut listener_2 = MockChainListener::new()
312 .expect_block_disconnected(*fork_chain_2.at_height(4))
313 .expect_block_disconnected(*fork_chain_2.at_height(3))
314 .expect_block_disconnected(*fork_chain_2.at_height(2))
315 .expect_block_connected(*main_chain.at_height(2))
316 .expect_block_connected(*main_chain.at_height(3))
317 .expect_block_connected(*main_chain.at_height(4));
318 let mut listener_3 = MockChainListener::new()
319 .expect_block_disconnected(*fork_chain_3.at_height(4))
320 .expect_block_disconnected(*fork_chain_3.at_height(3))
321 .expect_block_disconnected(*fork_chain_3.at_height(2))
322 .expect_block_connected(*main_chain.at_height(2))
323 .expect_block_connected(*main_chain.at_height(3))
324 .expect_block_connected(*main_chain.at_height(4));
326 let listeners = vec![
327 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
328 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
329 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
331 let mut cache = fork_chain_1.header_cache(2..=4);
332 cache.extend(fork_chain_2.header_cache(3..=4));
333 cache.extend(fork_chain_3.header_cache(4..=4));
334 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
335 Ok(header) => assert_eq!(header, main_chain.tip()),
336 Err(e) => panic!("Unexpected error: {:?}", e),
341 async fn cache_connected_and_keep_disconnected_blocks() {
342 let mut main_chain = Blockchain::default().with_height(2);
343 let fork_chain = main_chain.fork_at_height(1);
344 let new_tip = main_chain.tip();
345 let old_tip = fork_chain.tip();
347 let mut listener = MockChainListener::new()
348 .expect_block_disconnected(*old_tip)
349 .expect_block_connected(*new_tip);
351 let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn chain::Listen)];
352 let mut cache = fork_chain.header_cache(2..=2);
353 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
355 assert!(cache.contains_key(&new_tip.block_hash));
356 assert!(cache.contains_key(&old_tip.block_hash));
358 Err(e) => panic!("Unexpected error: {:?}", e),