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, ChannelManagerReadArgs};
53 /// use lightning::routing::router::Router;
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<
65 /// T: BroadcasterInterface,
70 /// P: chainmonitor::Persist<K::Signer>,
73 /// chain_monitor: &ChainMonitor<K::Signer, &C, &T, &F, &L, &P>,
74 /// config: UserConfig,
76 /// tx_broadcaster: &T,
77 /// fee_estimator: &F,
82 /// // Read a serialized channel monitor paired with the block hash when it was persisted.
83 /// let serialized_monitor = "...";
84 /// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<K::Signer>)>::read(
85 /// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
87 /// // Read the channel manager paired with the block hash when it was persisted.
88 /// let serialized_manager = "...";
89 /// let (manager_block_hash, mut manager) = {
90 /// let read_args = ChannelManagerReadArgs::new(
98 /// vec![&mut monitor],
100 /// <(BlockHash, ChannelManager<&ChainMonitor<K::Signer, &C, &T, &F, &L, &P>, &T, &K, &F, &R, &L>)>::read(
101 /// &mut Cursor::new(&serialized_manager), read_args).unwrap()
104 /// // Synchronize any channel monitors and the channel manager to be on the best block.
105 /// let mut cache = UnboundedCache::new();
106 /// let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
107 /// let listeners = vec![
108 /// (monitor_block_hash, &monitor_listener as &dyn chain::Listen),
109 /// (manager_block_hash, &manager as &dyn chain::Listen),
111 /// let chain_tip = init::synchronize_listeners(
112 /// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
114 /// // Allow the chain monitor to watch any channels.
115 /// let monitor = monitor_listener.0;
116 /// chain_monitor.watch_channel(monitor.get_funding_txo().0, monitor);
118 /// // Create an SPV client to notify the chain monitor and channel manager of block events.
119 /// let chain_poller = poll::ChainPoller::new(block_source, Network::Bitcoin);
120 /// let mut chain_listener = (chain_monitor, &manager);
121 /// let spv_client = SpvClient::new(chain_tip, chain_poller, &mut cache, &chain_listener);
125 /// [`SpvClient`]: crate::SpvClient
126 /// [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
127 /// [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
128 pub async fn synchronize_listeners<B: Deref + Sized + Send + Sync, C: Cache, L: chain::Listen + ?Sized>(
131 header_cache: &mut C,
132 mut chain_listeners: Vec<(BlockHash, &L)>,
133 ) -> BlockSourceResult<ValidatedBlockHeader> where B::Target: BlockSource {
134 let best_header = validate_best_block_header(&*block_source).await?;
136 // Fetch the header for the block hash paired with each listener.
137 let mut chain_listeners_with_old_headers = Vec::new();
138 for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
139 let old_header = match header_cache.look_up(&old_block_hash) {
140 Some(header) => *header,
142 .get_header(&old_block_hash, None).await?
143 .validate(old_block_hash)?
145 chain_listeners_with_old_headers.push((old_header, chain_listener))
148 // Find differences and disconnect blocks for each listener individually.
149 let mut chain_poller = ChainPoller::new(block_source, network);
150 let mut chain_listeners_at_height = Vec::new();
151 let mut most_common_ancestor = None;
152 let mut most_connected_blocks = Vec::new();
153 for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
154 // Disconnect any stale blocks, but keep them in the cache for the next iteration.
155 let header_cache = &mut ReadOnlyCache(header_cache);
156 let (common_ancestor, connected_blocks) = {
157 let chain_listener = &DynamicChainListener(chain_listener);
158 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
160 chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
161 chain_notifier.disconnect_blocks(difference.disconnected_blocks);
162 (difference.common_ancestor, difference.connected_blocks)
165 // Keep track of the most common ancestor and all blocks connected across all listeners.
166 chain_listeners_at_height.push((common_ancestor.height, chain_listener));
167 if connected_blocks.len() > most_connected_blocks.len() {
168 most_common_ancestor = Some(common_ancestor);
169 most_connected_blocks = connected_blocks;
173 // Connect new blocks for all listeners at once to avoid re-fetching blocks.
174 if let Some(common_ancestor) = most_common_ancestor {
175 let chain_listener = &ChainListenerSet(chain_listeners_at_height);
176 let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
177 chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
178 .await.or_else(|(e, _)| Err(e))?;
184 /// A wrapper to make a cache read-only.
186 /// Used to prevent losing headers that may be needed to disconnect blocks common to more than one
188 struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
190 impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
191 fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
192 self.0.look_up(block_hash)
195 fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
199 fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
204 /// Wrapper for supporting dynamically sized chain listeners.
205 struct DynamicChainListener<'a, L: chain::Listen + ?Sized>(&'a L);
207 impl<'a, L: chain::Listen + ?Sized> chain::Listen for DynamicChainListener<'a, L> {
208 fn filtered_block_connected(&self, _header: &BlockHeader, _txdata: &chain::transaction::TransactionData, _height: u32) {
212 fn block_disconnected(&self, header: &BlockHeader, height: u32) {
213 self.0.block_disconnected(header, height)
217 /// A set of dynamically sized chain listeners, each paired with a starting block height.
218 struct ChainListenerSet<'a, L: chain::Listen + ?Sized>(Vec<(u32, &'a L)>);
220 impl<'a, L: chain::Listen + ?Sized> chain::Listen for ChainListenerSet<'a, L> {
221 // Needed to differentiate test expectations.
223 fn block_connected(&self, block: &bitcoin::Block, height: u32) {
224 for (starting_height, chain_listener) in self.0.iter() {
225 if height > *starting_height {
226 chain_listener.block_connected(block, height);
231 fn filtered_block_connected(&self, header: &BlockHeader, txdata: &chain::transaction::TransactionData, height: u32) {
232 for (starting_height, chain_listener) in self.0.iter() {
233 if height > *starting_height {
234 chain_listener.filtered_block_connected(header, txdata, height);
239 fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
246 use crate::test_utils::{Blockchain, MockChainListener};
249 use bitcoin::network::constants::Network;
252 async fn sync_from_same_chain() {
253 let chain = Blockchain::default().with_height(4);
255 let listener_1 = MockChainListener::new()
256 .expect_block_connected(*chain.at_height(2))
257 .expect_block_connected(*chain.at_height(3))
258 .expect_block_connected(*chain.at_height(4));
259 let listener_2 = MockChainListener::new()
260 .expect_block_connected(*chain.at_height(3))
261 .expect_block_connected(*chain.at_height(4));
262 let listener_3 = MockChainListener::new()
263 .expect_block_connected(*chain.at_height(4));
265 let listeners = vec![
266 (chain.at_height(1).block_hash, &listener_1 as &dyn chain::Listen),
267 (chain.at_height(2).block_hash, &listener_2 as &dyn chain::Listen),
268 (chain.at_height(3).block_hash, &listener_3 as &dyn chain::Listen),
270 let mut cache = chain.header_cache(0..=4);
271 match synchronize_listeners(&chain, Network::Bitcoin, &mut cache, listeners).await {
272 Ok(header) => assert_eq!(header, chain.tip()),
273 Err(e) => panic!("Unexpected error: {:?}", e),
278 async fn sync_from_different_chains() {
279 let main_chain = Blockchain::default().with_height(4);
280 let fork_chain_1 = main_chain.fork_at_height(1);
281 let fork_chain_2 = main_chain.fork_at_height(2);
282 let fork_chain_3 = main_chain.fork_at_height(3);
284 let listener_1 = MockChainListener::new()
285 .expect_block_disconnected(*fork_chain_1.at_height(4))
286 .expect_block_disconnected(*fork_chain_1.at_height(3))
287 .expect_block_disconnected(*fork_chain_1.at_height(2))
288 .expect_block_connected(*main_chain.at_height(2))
289 .expect_block_connected(*main_chain.at_height(3))
290 .expect_block_connected(*main_chain.at_height(4));
291 let listener_2 = MockChainListener::new()
292 .expect_block_disconnected(*fork_chain_2.at_height(4))
293 .expect_block_disconnected(*fork_chain_2.at_height(3))
294 .expect_block_connected(*main_chain.at_height(3))
295 .expect_block_connected(*main_chain.at_height(4));
296 let listener_3 = MockChainListener::new()
297 .expect_block_disconnected(*fork_chain_3.at_height(4))
298 .expect_block_connected(*main_chain.at_height(4));
300 let listeners = vec![
301 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
302 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
303 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
305 let mut cache = fork_chain_1.header_cache(2..=4);
306 cache.extend(fork_chain_2.header_cache(3..=4));
307 cache.extend(fork_chain_3.header_cache(4..=4));
308 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
309 Ok(header) => assert_eq!(header, main_chain.tip()),
310 Err(e) => panic!("Unexpected error: {:?}", e),
315 async fn sync_from_overlapping_chains() {
316 let main_chain = Blockchain::default().with_height(4);
317 let fork_chain_1 = main_chain.fork_at_height(1);
318 let fork_chain_2 = fork_chain_1.fork_at_height(2);
319 let fork_chain_3 = fork_chain_2.fork_at_height(3);
321 let listener_1 = MockChainListener::new()
322 .expect_block_disconnected(*fork_chain_1.at_height(4))
323 .expect_block_disconnected(*fork_chain_1.at_height(3))
324 .expect_block_disconnected(*fork_chain_1.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));
328 let listener_2 = MockChainListener::new()
329 .expect_block_disconnected(*fork_chain_2.at_height(4))
330 .expect_block_disconnected(*fork_chain_2.at_height(3))
331 .expect_block_disconnected(*fork_chain_2.at_height(2))
332 .expect_block_connected(*main_chain.at_height(2))
333 .expect_block_connected(*main_chain.at_height(3))
334 .expect_block_connected(*main_chain.at_height(4));
335 let listener_3 = MockChainListener::new()
336 .expect_block_disconnected(*fork_chain_3.at_height(4))
337 .expect_block_disconnected(*fork_chain_3.at_height(3))
338 .expect_block_disconnected(*fork_chain_3.at_height(2))
339 .expect_block_connected(*main_chain.at_height(2))
340 .expect_block_connected(*main_chain.at_height(3))
341 .expect_block_connected(*main_chain.at_height(4));
343 let listeners = vec![
344 (fork_chain_1.tip().block_hash, &listener_1 as &dyn chain::Listen),
345 (fork_chain_2.tip().block_hash, &listener_2 as &dyn chain::Listen),
346 (fork_chain_3.tip().block_hash, &listener_3 as &dyn chain::Listen),
348 let mut cache = fork_chain_1.header_cache(2..=4);
349 cache.extend(fork_chain_2.header_cache(3..=4));
350 cache.extend(fork_chain_3.header_cache(4..=4));
351 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
352 Ok(header) => assert_eq!(header, main_chain.tip()),
353 Err(e) => panic!("Unexpected error: {:?}", e),
358 async fn cache_connected_and_keep_disconnected_blocks() {
359 let main_chain = Blockchain::default().with_height(2);
360 let fork_chain = main_chain.fork_at_height(1);
361 let new_tip = main_chain.tip();
362 let old_tip = fork_chain.tip();
364 let listener = MockChainListener::new()
365 .expect_block_disconnected(*old_tip)
366 .expect_block_connected(*new_tip);
368 let listeners = vec![(old_tip.block_hash, &listener as &dyn chain::Listen)];
369 let mut cache = fork_chain.header_cache(2..=2);
370 match synchronize_listeners(&main_chain, Network::Bitcoin, &mut cache, listeners).await {
372 assert!(cache.contains_key(&new_tip.block_hash));
373 assert!(cache.contains_key(&old_tip.block_hash));
375 Err(e) => panic!("Unexpected error: {:?}", e),