use lightning::chain;
+/// Returns a validated block header of the source's best chain tip.
+///
+/// Upon success, the returned header can be used to initialize [`SpvClient`]. Useful during a fresh
+/// start when there are no chain listeners to sync yet.
+pub async fn validate_best_block_header<B: BlockSource>(block_source: &mut B) ->
+BlockSourceResult<ValidatedBlockHeader> {
+ let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
+ block_source
+ .get_header(&best_block_hash, best_block_height).await?
+ .validate(best_block_hash)
+}
+
/// Performs a one-time sync of chain listeners using a single *trusted* block source, bringing each
/// listener's view of the chain from its paired block hash to `block_source`'s best chain tip.
///
/// ) {
/// // Read a serialized channel monitor paired with the block hash when it was persisted.
/// let serialized_monitor = "...";
-/// let (monitor_block_hash, mut monitor) = <(BlockHash, ChannelMonitor<S>)>::read(
+/// let (monitor_block_hash_option, mut monitor) = <(Option<BlockHash>, ChannelMonitor<S>)>::read(
/// &mut Cursor::new(&serialized_monitor), keys_manager).unwrap();
///
/// // Read the channel manager paired with the block hash when it was persisted.
/// let serialized_manager = "...";
-/// let (manager_block_hash, mut manager) = {
+/// let (manager_block_hash_option, mut manager) = {
/// let read_args = ChannelManagerReadArgs::new(
/// keys_manager,
/// fee_estimator,
/// config,
/// vec![&mut monitor],
/// );
-/// <(BlockHash, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
+/// <(Option<BlockHash>, ChannelManager<S, &ChainMonitor<S, &C, &T, &F, &L, &P>, &T, &K, &F, &L>)>::read(
/// &mut Cursor::new(&serialized_manager), read_args).unwrap()
/// };
///
/// // Synchronize any channel monitors and the channel manager to be on the best block.
/// let mut cache = UnboundedCache::new();
/// let mut monitor_listener = (monitor, &*tx_broadcaster, &*fee_estimator, &*logger);
-/// let listeners = vec![
-/// (monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen),
-/// (manager_block_hash, &mut manager as &mut dyn chain::Listen),
-/// ];
+/// let mut listeners = vec![];
+/// if let Some(monitor_block_hash) = monitor_block_hash_option {
+/// listeners.push((monitor_block_hash, &mut monitor_listener as &mut dyn chain::Listen))
+/// }
+/// if let Some(manager_block_hash) = manager_block_hash_option {
+/// listeners.push((manager_block_hash, &mut manager as &mut dyn chain::Listen))
+/// }
/// let chain_tip = init::synchronize_listeners(
/// block_source, Network::Bitcoin, &mut cache, listeners).await.unwrap();
///
header_cache: &mut C,
mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
) -> BlockSourceResult<ValidatedBlockHeader> {
- let (best_block_hash, best_block_height) = block_source.get_best_block().await?;
- let best_header = block_source
- .get_header(&best_block_hash, best_block_height).await?
- .validate(best_block_hash)?;
+ let best_header = validate_best_block_header(block_source).await?;
// Fetch the header for the block hash paired with each listener.
let mut chain_listeners_with_old_headers = Vec::new();