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;
8 use lightning::chain::ChainListener;
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::ChainListener;
26 /// use lightning::chain::Watch;
27 /// use lightning::chain::chainmonitor::ChainMonitor;
28 /// use lightning::chain::channelmonitor;
29 /// use lightning::chain::channelmonitor::ChannelMonitor;
30 /// use lightning::chain::chaininterface::BroadcasterInterface;
31 /// use lightning::chain::chaininterface::FeeEstimator;
32 /// use lightning::chain::keysinterface;
33 /// use lightning::chain::keysinterface::KeysInterface;
34 /// use lightning::ln::channelmanager::ChannelManager;
35 /// use lightning::ln::channelmanager::ChannelManagerReadArgs;
36 /// use lightning::util::config::UserConfig;
37 /// use lightning::util::logger::Logger;
38 /// use lightning::util::ser::ReadableArgs;
40 /// use lightning_block_sync::*;
42 /// use std::cell::RefCell;
43 /// use std::io::Cursor;
45 /// async fn init_sync<
47 /// K: KeysInterface<Signer = S>,
48 /// S: keysinterface::Sign,
49 /// T: BroadcasterInterface,
53 /// P: channelmonitor::Persist<S>,
55 /// block_source: &mut B,
56 /// chain_monitor: &ChainMonitor<S, &C, &T, &F, &L, &P>,
57 /// config: UserConfig,
59 /// tx_broadcaster: &T,
60 /// fee_estimator: &F,
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 /// let serialized_manager = "...";
69 /// let (manager_block_hash, mut manager) = {
70 /// let read_args = ChannelManagerReadArgs::new(
77 /// vec![&mut monitor],
79 /// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
80 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
83 /// let mut cache = UnboundedCache::new();
84 /// let mut monitor_listener = (RefCell::new(monitor), &*tx_broadcaster, &*fee_estimator, &*logger);
85 /// let listeners = vec![
86 /// (monitor_block_hash, &mut monitor_listener as &mut dyn ChainListener),
87 /// (manager_block_hash, &mut manager as &mut dyn ChainListener),
90 /// init::sync_listeners(block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
92 /// let monitor = monitor_listener.0.into_inner();
93 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
95 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
96 /// let mut chain_listener = (chain_monitor, &manager);
97 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
101 /// [`SpvClient`]: ../struct.SpvClient.html
102 /// [`ChannelManager`]: ../../lightning/ln/channelmanager/struct.ChannelManager.html
103 /// [`ChannelMonitor`]: ../../lightning/chain/channelmonitor/struct.ChannelMonitor.html
104 pub async fn sync_listeners<B: BlockSource, C: Cache>(
105 block_source: &mut B,
107 header_cache: &mut C,
108 mut chain_listeners: Vec<(BlockHash, &mut dyn ChainListener)>,
109 ) -> BlockSourceResult<ValidatedBlockHeader> {
110 let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
111 let new_header = block_source
112 .get_header(&best_block_hash, best_block_height).await?
113 .validate(best_block_hash)?;
115 // Fetch the header for the block hash paired with each listener.
116 let mut chain_listeners_with_old_headers = Vec::new();
117 for (old_block, chain_listener) in chain_listeners.drain(..) {
118 let old_header = match header_cache.look_up(&old_block) {
119 Some(header) => *header,
121 .get_header(&old_block, None).await?
122 .validate(old_block)?
124 chain_listeners_with_old_headers.push((old_header, chain_listener))
127 // Find differences and disconnect blocks for each listener individually.
128 let mut chain_poller = ChainPoller::new(block_source, network);
129 let mut chain_listeners_at_height = Vec::new();
130 let mut most_common_ancestor = None;
131 let mut most_connected_blocks = Vec::new();
132 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
133 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
134 let header_cache = &mut ReadOnlyCache(header_cache);
135 let (common_ancestor, connected_blocks) = {
136 let chain_listener = &DynamicChainListener(chain_listener);
137 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
139 chain_notifier.find_difference(new_header, &old_header, &mut chain_poller).await?;
140 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
141 (difference.common_ancestor, difference.connected_blocks)
144 // Keep track of the most common ancestor and all blocks connected across all listeners.
145 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
146 if connected_blocks.len() > most_connected_blocks.len() {
147 most_common_ancestor = Some(common_ancestor);
148 most_connected_blocks = connected_blocks;
152 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
153 if let Some(common_ancestor) = most_common_ancestor {
154 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
155 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
156 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
157 .await.or_else(|(e, _)| Err(e))?;
163 /// A wrapper to make a cache read-only.
165 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
167 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
169 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
170 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
171 self.0.look_up(block_hash)
174 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
178 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
183 /// Wrapper for supporting dynamically sized chain listeners.
184 struct DynamicChainListener<'a>(&'a mut dyn ChainListener);
186 impl<'a> ChainListener for DynamicChainListener<'a> {
187 fn block_connected(&self, _block: &Block, _height: u32) {
191 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
192 self.0.block_disconnected(header, height)
196 /// A set of dynamically sized chain listeners, each paired with a starting block height.
197 struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn ChainListener)>);
199 impl<'a> ChainListener for ChainListenerSet<'a> {
200 fn block_connected(&self, block: &Block, height: u32) {
201 for (starting_height, chain_listener) in self.0.iter() {
202 if height > *starting_height {
203 chain_listener.block_connected(block, height);
208 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
215 use crate::test_utils::{Blockchain, MockChainListener};
218 use bitcoin::network::constants::Network;
221 async fn sync_from_same_chain() {
222 let mut chain = Blockchain::default().with_height(4);
224 let mut listener_1 = MockChainListener::new()
225 .expect_block_connected(*chain.at_height(2))
226 .expect_block_connected(*chain.at_height(3))
227 .expect_block_connected(*chain.at_height(4));
228 let mut listener_2 = MockChainListener::new()
229 .expect_block_connected(*chain.at_height(3))
230 .expect_block_connected(*chain.at_height(4));
231 let mut listener_3 = MockChainListener::new()
232 .expect_block_connected(*chain.at_height(4));
234 let listeners = vec![
235 (chain.at_height(1).block_hash, &mut listener_1 as &mut dyn ChainListener),
236 (chain.at_height(2).block_hash, &mut listener_2 as &mut dyn ChainListener),
237 (chain.at_height(3).block_hash, &mut listener_3 as &mut dyn ChainListener),
239 let mut cache = chain.header_cache(0..=4);
240 match sync_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
241 Ok(header) => assert_eq!(header, chain.tip()),
242 Err(e) => panic!("Unexpected error: {:?}", e),
247 async fn sync_from_different_chains() {
248 let mut main_chain = Blockchain::default().with_height(4);
249 let fork_chain_1 = main_chain.fork_at_height(1);
250 let fork_chain_2 = main_chain.fork_at_height(2);
251 let fork_chain_3 = main_chain.fork_at_height(3);
253 let mut listener_1 = MockChainListener::new()
254 .expect_block_disconnected(*fork_chain_1.at_height(4))
255 .expect_block_disconnected(*fork_chain_1.at_height(3))
256 .expect_block_disconnected(*fork_chain_1.at_height(2))
257 .expect_block_connected(*main_chain.at_height(2))
258 .expect_block_connected(*main_chain.at_height(3))
259 .expect_block_connected(*main_chain.at_height(4));
260 let mut listener_2 = MockChainListener::new()
261 .expect_block_disconnected(*fork_chain_2.at_height(4))
262 .expect_block_disconnected(*fork_chain_2.at_height(3))
263 .expect_block_connected(*main_chain.at_height(3))
264 .expect_block_connected(*main_chain.at_height(4));
265 let mut listener_3 = MockChainListener::new()
266 .expect_block_disconnected(*fork_chain_3.at_height(4))
267 .expect_block_connected(*main_chain.at_height(4));
269 let listeners = vec![
270 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn ChainListener),
271 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn ChainListener),
272 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn ChainListener),
274 let mut cache = fork_chain_1.header_cache(2..=4);
275 cache.extend(fork_chain_2.header_cache(3..=4));
276 cache.extend(fork_chain_3.header_cache(4..=4));
277 match sync_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
278 Ok(header) => assert_eq!(header, main_chain.tip()),
279 Err(e) => panic!("Unexpected error: {:?}", e),
284 async fn sync_from_overlapping_chains() {
285 let mut main_chain = Blockchain::default().with_height(4);
286 let fork_chain_1 = main_chain.fork_at_height(1);
287 let fork_chain_2 = fork_chain_1.fork_at_height(2);
288 let fork_chain_3 = fork_chain_2.fork_at_height(3);
290 let mut listener_1 = MockChainListener::new()
291 .expect_block_disconnected(*fork_chain_1.at_height(4))
292 .expect_block_disconnected(*fork_chain_1.at_height(3))
293 .expect_block_disconnected(*fork_chain_1.at_height(2))
294 .expect_block_connected(*main_chain.at_height(2))
295 .expect_block_connected(*main_chain.at_height(3))
296 .expect_block_connected(*main_chain.at_height(4));
297 let mut listener_2 = MockChainListener::new()
298 .expect_block_disconnected(*fork_chain_2.at_height(4))
299 .expect_block_disconnected(*fork_chain_2.at_height(3))
300 .expect_block_disconnected(*fork_chain_2.at_height(2))
301 .expect_block_connected(*main_chain.at_height(2))
302 .expect_block_connected(*main_chain.at_height(3))
303 .expect_block_connected(*main_chain.at_height(4));
304 let mut listener_3 = MockChainListener::new()
305 .expect_block_disconnected(*fork_chain_3.at_height(4))
306 .expect_block_disconnected(*fork_chain_3.at_height(3))
307 .expect_block_disconnected(*fork_chain_3.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));
312 let listeners = vec![
313 (fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn ChainListener),
314 (fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn ChainListener),
315 (fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn ChainListener),
317 let mut cache = fork_chain_1.header_cache(2..=4);
318 cache.extend(fork_chain_2.header_cache(3..=4));
319 cache.extend(fork_chain_3.header_cache(4..=4));
320 match sync_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
321 Ok(header) => assert_eq!(header, main_chain.tip()),
322 Err(e) => panic!("Unexpected error: {:?}", e),
327 async fn cache_connected_and_keep_disconnected_blocks() {
328 let mut main_chain = Blockchain::default().with_height(2);
329 let fork_chain = main_chain.fork_at_height(1);
330 let new_tip = main_chain.tip();
331 let old_tip = fork_chain.tip();
333 let mut listener = MockChainListener::new()
334 .expect_block_disconnected(*old_tip)
335 .expect_block_connected(*new_tip);
337 let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn ChainListener)];
338 let mut cache = fork_chain.header_cache(2..=2);
339 match sync_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
341 assert!(cache.contains_key(&new_tip.block_hash));
342 assert!(cache.contains_key(&old_tip.block_hash));
344 Err(e) => panic!("Unexpected error: {:?}", e),