use crate::{BlockSource, BlockSourceResult, Cache, ChainNotifier};
use crate::poll::{ChainPoller, Validate, ValidatedBlockHeader};
use bitcoin::blockdata::block::{Block, BlockHeader};
use bitcoin::hash_types::BlockHash;
use bitcoin::network::constants::Network;
use lightning::chain;
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)
}
pub async fn synchronize_listeners<B: BlockSource, C: Cache>(
block_source: &mut B,
network: Network,
header_cache: &mut C,
mut chain_listeners: Vec<(BlockHash, &mut dyn chain::Listen)>,
) -> BlockSourceResult<ValidatedBlockHeader> {
let best_header = validate_best_block_header(block_source).await?;
let mut chain_listeners_with_old_headers = Vec::new();
for (old_block_hash, chain_listener) in chain_listeners.drain(..) {
let old_header = match header_cache.look_up(&old_block_hash) {
Some(header) => *header,
None => block_source
.get_header(&old_block_hash, None).await?
.validate(old_block_hash)?
};
chain_listeners_with_old_headers.push((old_header, chain_listener))
}
let mut chain_poller = ChainPoller::new(block_source, network);
let mut chain_listeners_at_height = Vec::new();
let mut most_common_ancestor = None;
let mut most_connected_blocks = Vec::new();
for (old_header, chain_listener) in chain_listeners_with_old_headers.drain(..) {
let header_cache = &mut ReadOnlyCache(header_cache);
let (common_ancestor, connected_blocks) = {
let chain_listener = &DynamicChainListener(chain_listener);
let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
let difference =
chain_notifier.find_difference(best_header, &old_header, &mut chain_poller).await?;
chain_notifier.disconnect_blocks(difference.disconnected_blocks);
(difference.common_ancestor, difference.connected_blocks)
};
chain_listeners_at_height.push((common_ancestor.height, chain_listener));
if connected_blocks.len() > most_connected_blocks.len() {
most_common_ancestor = Some(common_ancestor);
most_connected_blocks = connected_blocks;
}
}
if let Some(common_ancestor) = most_common_ancestor {
let chain_listener = &ChainListenerSet(chain_listeners_at_height);
let mut chain_notifier = ChainNotifier { header_cache, chain_listener };
chain_notifier.connect_blocks(common_ancestor, most_connected_blocks, &mut chain_poller)
.await.or_else(|(e, _)| Err(e))?;
}
Ok(best_header)
}
struct ReadOnlyCache<'a, C: Cache>(&'a mut C);
impl<'a, C: Cache> Cache for ReadOnlyCache<'a, C> {
fn look_up(&self, block_hash: &BlockHash) -> Option<&ValidatedBlockHeader> {
self.0.look_up(block_hash)
}
fn block_connected(&mut self, _block_hash: BlockHash, _block_header: ValidatedBlockHeader) {
unreachable!()
}
fn block_disconnected(&mut self, _block_hash: &BlockHash) -> Option<ValidatedBlockHeader> {
None
}
}
struct DynamicChainListener<'a>(&'a mut dyn chain::Listen);
impl<'a> chain::Listen for DynamicChainListener<'a> {
fn block_connected(&self, _block: &Block, _height: u32) {
unreachable!()
}
fn block_disconnected(&self, header: &BlockHeader, height: u32) {
self.0.block_disconnected(header, height)
}
}
struct ChainListenerSet<'a>(Vec<(u32, &'a mut dyn chain::Listen)>);
impl<'a> chain::Listen for ChainListenerSet<'a> {
fn block_connected(&self, block: &Block, height: u32) {
for (starting_height, chain_listener) in self.0.iter() {
if height > *starting_height {
chain_listener.block_connected(block, height);
}
}
}
fn block_disconnected(&self, _header: &BlockHeader, _height: u32) {
unreachable!()
}
}
#[cfg(test)]
mod tests {
use crate::test_utils::{Blockchain, MockChainListener};
use super::*;
use bitcoin::network::constants::Network;
#[tokio::test]
async fn sync_from_same_chain() {
let mut chain = Blockchain::default().with_height(4);
let mut listener_1 = MockChainListener::new()
.expect_block_connected(*chain.at_height(2))
.expect_block_connected(*chain.at_height(3))
.expect_block_connected(*chain.at_height(4));
let mut listener_2 = MockChainListener::new()
.expect_block_connected(*chain.at_height(3))
.expect_block_connected(*chain.at_height(4));
let mut listener_3 = MockChainListener::new()
.expect_block_connected(*chain.at_height(4));
let listeners = vec![
(chain.at_height(1).block_hash, &mut listener_1 as &mut dyn chain::Listen),
(chain.at_height(2).block_hash, &mut listener_2 as &mut dyn chain::Listen),
(chain.at_height(3).block_hash, &mut listener_3 as &mut dyn chain::Listen),
];
let mut cache = chain.header_cache(0..=4);
match synchronize_listeners(&mut chain, Network::Bitcoin, &mut cache, listeners).await {
Ok(header) => assert_eq!(header, chain.tip()),
Err(e) => panic!("Unexpected error: {:?}", e),
}
}
#[tokio::test]
async fn sync_from_different_chains() {
let mut main_chain = Blockchain::default().with_height(4);
let fork_chain_1 = main_chain.fork_at_height(1);
let fork_chain_2 = main_chain.fork_at_height(2);
let fork_chain_3 = main_chain.fork_at_height(3);
let mut listener_1 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_1.at_height(4))
.expect_block_disconnected(*fork_chain_1.at_height(3))
.expect_block_disconnected(*fork_chain_1.at_height(2))
.expect_block_connected(*main_chain.at_height(2))
.expect_block_connected(*main_chain.at_height(3))
.expect_block_connected(*main_chain.at_height(4));
let mut listener_2 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_2.at_height(4))
.expect_block_disconnected(*fork_chain_2.at_height(3))
.expect_block_connected(*main_chain.at_height(3))
.expect_block_connected(*main_chain.at_height(4));
let mut listener_3 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_3.at_height(4))
.expect_block_connected(*main_chain.at_height(4));
let listeners = vec![
(fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
(fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
(fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
];
let mut cache = fork_chain_1.header_cache(2..=4);
cache.extend(fork_chain_2.header_cache(3..=4));
cache.extend(fork_chain_3.header_cache(4..=4));
match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
Ok(header) => assert_eq!(header, main_chain.tip()),
Err(e) => panic!("Unexpected error: {:?}", e),
}
}
#[tokio::test]
async fn sync_from_overlapping_chains() {
let mut main_chain = Blockchain::default().with_height(4);
let fork_chain_1 = main_chain.fork_at_height(1);
let fork_chain_2 = fork_chain_1.fork_at_height(2);
let fork_chain_3 = fork_chain_2.fork_at_height(3);
let mut listener_1 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_1.at_height(4))
.expect_block_disconnected(*fork_chain_1.at_height(3))
.expect_block_disconnected(*fork_chain_1.at_height(2))
.expect_block_connected(*main_chain.at_height(2))
.expect_block_connected(*main_chain.at_height(3))
.expect_block_connected(*main_chain.at_height(4));
let mut listener_2 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_2.at_height(4))
.expect_block_disconnected(*fork_chain_2.at_height(3))
.expect_block_disconnected(*fork_chain_2.at_height(2))
.expect_block_connected(*main_chain.at_height(2))
.expect_block_connected(*main_chain.at_height(3))
.expect_block_connected(*main_chain.at_height(4));
let mut listener_3 = MockChainListener::new()
.expect_block_disconnected(*fork_chain_3.at_height(4))
.expect_block_disconnected(*fork_chain_3.at_height(3))
.expect_block_disconnected(*fork_chain_3.at_height(2))
.expect_block_connected(*main_chain.at_height(2))
.expect_block_connected(*main_chain.at_height(3))
.expect_block_connected(*main_chain.at_height(4));
let listeners = vec![
(fork_chain_1.tip().block_hash, &mut listener_1 as &mut dyn chain::Listen),
(fork_chain_2.tip().block_hash, &mut listener_2 as &mut dyn chain::Listen),
(fork_chain_3.tip().block_hash, &mut listener_3 as &mut dyn chain::Listen),
];
let mut cache = fork_chain_1.header_cache(2..=4);
cache.extend(fork_chain_2.header_cache(3..=4));
cache.extend(fork_chain_3.header_cache(4..=4));
match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
Ok(header) => assert_eq!(header, main_chain.tip()),
Err(e) => panic!("Unexpected error: {:?}", e),
}
}
#[tokio::test]
async fn cache_connected_and_keep_disconnected_blocks() {
let mut main_chain = Blockchain::default().with_height(2);
let fork_chain = main_chain.fork_at_height(1);
let new_tip = main_chain.tip();
let old_tip = fork_chain.tip();
let mut listener = MockChainListener::new()
.expect_block_disconnected(*old_tip)
.expect_block_connected(*new_tip);
let listeners = vec![(old_tip.block_hash, &mut listener as &mut dyn chain::Listen)];
let mut cache = fork_chain.header_cache(2..=2);
match synchronize_listeners(&mut main_chain, Network::Bitcoin, &mut cache, listeners).await {
Ok(_) => {
assert!(cache.contains_key(&new_tip.block_hash));
assert!(cache.contains_key(&old_tip.block_hash));
},
Err(e) => panic!("Unexpected error: {:?}", e),
}
}
}