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 /// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
11 /// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
13 /// Upon success, the returned header can be used to initialize [`SpvClient`]. In the case of
14 /// failure, each listener may be left at a different block hash than the one it was originally
17 /// Useful during startup to bring the [`ChannelManager`] and each [`ChannelMonitor`] in sync before
18 /// switching to [`SpvClient`]. For example:
21 /// use bitcoin::hash_types::BlockHash;
22 /// use bitcoin::network::constants::Network;
24 /// use lightning::chain;
25 /// use lightning::chain::Watch;
26 /// use lightning::chain::chainmonitor::ChainMonitor;
27 /// use lightning::chain::channelmonitor;
28 /// use lightning::chain::channelmonitor::ChannelMonitor;
29 /// use lightning::chain::chaininterface::BroadcasterInterface;
30 /// use lightning::chain::chaininterface::FeeEstimator;
31 /// use lightning::chain::keysinterface;
32 /// use lightning::chain::keysinterface::KeysInterface;
33 /// use lightning::ln::channelmanager::ChannelManager;
34 /// use lightning::ln::channelmanager::ChannelManagerReadArgs;
35 /// use lightning::util::config::UserConfig;
36 /// use lightning::util::logger::Logger;
37 /// use lightning::util::ser::ReadableArgs;
39 /// use lightning_block_sync::*;
41 /// use std::cell::RefCell;
42 /// use std::io::Cursor;
44 /// async fn init_sync<
46 /// K: KeysInterface<Signer = S>,
47 /// S: keysinterface::Sign,
48 /// T: BroadcasterInterface,
52 /// P: channelmonitor::Persist<S>,
54 /// block_source: &mut B,
55 /// chain_monitor: &ChainMonitor<S, &C, &T, &F, &L, &P>,
56 /// config: UserConfig,
58 /// tx_broadcaster: &T,
59 /// fee_estimator: &F,
63 /// // Read a serialized channel monitor paired with the block hash when it was persisted.
64 /// let serialized_monitor = "...";
65 /// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<S>)>::read(
66 /// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
68 /// // Read the channel manager paired with the block hash when it was persisted.
69 /// let serialized_manager = "...";
70 /// let (manager_block_hash, mut manager) = {
71 /// let read_args = ChannelManagerReadArgs::new(
78 /// vec![&mut monitor],
80 /// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
81 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
84 /// // Synchronize any channel monitors and the channel manager to be on the best block.
85 /// let mut cache = UnboundedCache::new();
86 /// let mut monitor_listener = (RefCell::new(monitor), &*tx_broadcaster, &*fee_estimator, &*logger);
87 /// let listeners = vec![
88 /// (monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
89 /// (manager_block_hash, &mut manager as &mut dyn chain::Listen),
91 /// let chain_tip = init::synchronize_listeners(
92 /// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
94 /// // Allow the chain monitor to watch any channels.
95 /// let monitor = monitor_listener.0.into_inner();
96 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
98 /// // Create an SPV client to notify the chain monitor and channel manager of block events.
99 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
100 /// let mut chain_listener = (chain_monitor, &manager);
101 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
105 /// [`SpvClient`]: ../struct.SpvClient.html
106 /// [`ChannelManager`]: ../../lightning/ln/channelmanager/struct.ChannelManager.html
107 /// [`ChannelMonitor`]: ../../lightning/chain/channelmonitor/struct.ChannelMonitor.html
108 pub async fn synchronize_listeners<B: BlockSource, C: Cache>(
109 block_source: &mut B,
111 header_cache: &mut C,
112 mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
113 ) -> BlockSourceResult<ValidatedBlockHeader> {
114 let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
115 let best_header = block_source
116 .get_header(&best_block_hash, best_block_height).await?
117 .validate(best_block_hash)?;
119 // Fetch the header for the block hash paired with each listener.
120 let mut chain_listeners_with_old_headers = Vec::new();
121 for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
122 let old_header = match header_cache.look_up(&old_block_hash) {
123 Some(header) => *header,
125 .get_header(&old_block_hash, None).await?
126 .validate(old_block_hash)?
128 chain_listeners_with_old_headers.push((old_header, chain_listener))
131 // Find differences and disconnect blocks for each listener individually.
132 let mut chain_poller = ChainPoller::new(block_source, network);
133 let mut chain_listeners_at_height = Vec::new();
134 let mut most_common_ancestor = None;
135 let mut most_connected_blocks = Vec::new();
136 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
137 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
138 let header_cache = &mut ReadOnlyCache(header_cache);
139 let (common_ancestor, connected_blocks) = {
140 let chain_listener = &DynamicChainListener(chain_listener);
141 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
143 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
144 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
145 (difference.common_ancestor, difference.connected_blocks)
148 // Keep track of the most common ancestor and all blocks connected across all listeners.
149 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
150 if connected_blocks.len() > most_connected_blocks.len() {
151 most_common_ancestor = Some(common_ancestor);
152 most_connected_blocks = connected_blocks;
156 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
157 if let Some(common_ancestor) = most_common_ancestor {
158 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
159 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
160 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
161 .await.or_else(|(e, _)| Err(e))?;
167 /// A wrapper to make a cache read-only.
169 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
171 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
173 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
174 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
175 self.0.look_up(block_hash)
178 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
182 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
187 /// Wrapper for supporting dynamically sized chain listeners.
188 struct DynamicChainListener<'a>(&'a mut dyn chain::Listen);
190 impl<'a> chain::Listen for DynamicChainListener<'a> {
191 fn block_connected(&self, _block: &Block, _height: u32) {
195 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
196 self.0.block_disconnected(header, height)
200 /// A set of dynamically sized chain listeners, each paired with a starting block height.
201 struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn chain::Listen)>);
203 impl<'a> chain::Listen for ChainListenerSet<'a> {
204 fn block_connected(&self, block: &Block, height: u32) {
205 for (starting_height, chain_listener) in self.0.iter() {
206 if height > *starting_height {
207 chain_listener.block_connected(block, height);
212 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
219 use crate::test_utils::{Blockchain, MockChainListener};
222 use bitcoin::network::constants::Network;
225 async fn sync_from_same_chain() {
226 let mut chain = Blockchain::default().with_height(4);
228 let mut listener_1 = MockChainListener::new()
229 .expect_block_connected(*chain.at_height(2))
230 .expect_block_connected(*chain.at_height(3))
231 .expect_block_connected(*chain.at_height(4));
232 let mut listener_2 = MockChainListener::new()
233 .expect_block_connected(*chain.at_height(3))
234 .expect_block_connected(*chain.at_height(4));
235 let mut listener_3 = MockChainListener::new()
236 .expect_block_connected(*chain.at_height(4));
238 let listeners = vec![
239 (chain.at_height(1).block_hash, &mut listener_1 as &mut dyn chain::Listen),
240 (chain.at_height(2).block_hash, &mut listener_2 as &mut dyn chain::Listen),
241 (chain.at_height(3).block_hash, &mut listener_3 as &mut dyn chain::Listen),
243 let mut cache = chain.header_cache(0..=4);
244 match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
245 Ok(header) => assert_eq!(header, chain.tip()),
246 Err(e) => panic!("Unexpected error: {:?}", e),
251 async fn sync_from_different_chains() {
252 let mut main_chain = Blockchain::default().with_height(4);
253 let fork_chain_1 = main_chain.fork_at_height(1);
254 let fork_chain_2 = main_chain.fork_at_height(2);
255 let fork_chain_3 = main_chain.fork_at_height(3);
257 let mut listener_1 = MockChainListener::new()
258 .expect_block_disconnected(*fork_chain_1.at_height(4))
259 .expect_block_disconnected(*fork_chain_1.at_height(3))
260 .expect_block_disconnected(*fork_chain_1.at_height(2))
261 .expect_block_connected(*main_chain.at_height(2))
262 .expect_block_connected(*main_chain.at_height(3))
263 .expect_block_connected(*main_chain.at_height(4));
264 let mut listener_2 = MockChainListener::new()
265 .expect_block_disconnected(*fork_chain_2.at_height(4))
266 .expect_block_disconnected(*fork_chain_2.at_height(3))
267 .expect_block_connected(*main_chain.at_height(3))
268 .expect_block_connected(*main_chain.at_height(4));
269 let mut listener_3 = MockChainListener::new()
270 .expect_block_disconnected(*fork_chain_3.at_height(4))
271 .expect_block_connected(*main_chain.at_height(4));
273 let listeners = vec![
274 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
275 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
276 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
278 let mut cache = fork_chain_1.header_cache(2..=4);
279 cache.extend(fork_chain_2.header_cache(3..=4));
280 cache.extend(fork_chain_3.header_cache(4..=4));
281 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
282 Ok(header) => assert_eq!(header, main_chain.tip()),
283 Err(e) => panic!("Unexpected error: {:?}", e),
288 async fn sync_from_overlapping_chains() {
289 let mut main_chain = Blockchain::default().with_height(4);
290 let fork_chain_1 = main_chain.fork_at_height(1);
291 let fork_chain_2 = fork_chain_1.fork_at_height(2);
292 let fork_chain_3 = fork_chain_2.fork_at_height(3);
294 let mut listener_1 = MockChainListener::new()
295 .expect_block_disconnected(*fork_chain_1.at_height(4))
296 .expect_block_disconnected(*fork_chain_1.at_height(3))
297 .expect_block_disconnected(*fork_chain_1.at_height(2))
298 .expect_block_connected(*main_chain.at_height(2))
299 .expect_block_connected(*main_chain.at_height(3))
300 .expect_block_connected(*main_chain.at_height(4));
301 let mut listener_2 = MockChainListener::new()
302 .expect_block_disconnected(*fork_chain_2.at_height(4))
303 .expect_block_disconnected(*fork_chain_2.at_height(3))
304 .expect_block_disconnected(*fork_chain_2.at_height(2))
305 .expect_block_connected(*main_chain.at_height(2))
306 .expect_block_connected(*main_chain.at_height(3))
307 .expect_block_connected(*main_chain.at_height(4));
308 let mut listener_3 = MockChainListener::new()
309 .expect_block_disconnected(*fork_chain_3.at_height(4))
310 .expect_block_disconnected(*fork_chain_3.at_height(3))
311 .expect_block_disconnected(*fork_chain_3.at_height(2))
312 .expect_block_connected(*main_chain.at_height(2))
313 .expect_block_connected(*main_chain.at_height(3))
314 .expect_block_connected(*main_chain.at_height(4));
316 let listeners = vec![
317 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
318 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
319 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
321 let mut cache = fork_chain_1.header_cache(2..=4);
322 cache.extend(fork_chain_2.header_cache(3..=4));
323 cache.extend(fork_chain_3.header_cache(4..=4));
324 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
325 Ok(header) => assert_eq!(header, main_chain.tip()),
326 Err(e) => panic!("Unexpected error: {:?}", e),
331 async fn cache_connected_and_keep_disconnected_blocks() {
332 let mut main_chain = Blockchain::default().with_height(2);
333 let fork_chain = main_chain.fork_at_height(1);
334 let new_tip = main_chain.tip();
335 let old_tip = fork_chain.tip();
337 let mut listener = MockChainListener::new()
338 .expect_block_disconnected(*old_tip)
339 .expect_block_connected(*new_tip);
341 let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn chain::Listen)];
342 let mut cache = fork_chain.header_cache(2..=2);
343 match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
345 assert!(cache.contains_key(&new_tip.block_hash));
346 assert!(cache.contains_key(&old_tip.block_hash));
348 Err(e) => panic!("Unexpected error: {:?}", e),