Replace the lookahead limit panic with a warning
And decrease the minimum to 400 blocks
@@ -57,8 +57,8 @@ const BLOCK_DOWNLOAD_RETRY_LIMIT: usize = 3;
/// A lower bound on the user-specified lookahead limit.
///
-/// Set to two checkpoint intervals, so that we're sure that the lookahead
-/// limit always contains at least one complete checkpoint.
+/// Set to the maximum checkpoint interval, so the pipeline holds at least one checkpoint's
+/// worth of blocks.
///
/// ## Security
///
@@ -74,7 +74,7 @@ const BLOCK_DOWNLOAD_RETRY_LIMIT: usize = 3;
/// Once these malicious blocks start failing validation, the syncer will cancel all
/// the pending download and verify tasks, drop all the blocks, and start a new
/// ObtainTips with a new set of peers.
-pub const MIN_LOOKAHEAD_LIMIT: usize = zebra_consensus::MAX_CHECKPOINT_HEIGHT_GAP * 2;
+pub const MIN_LOOKAHEAD_LIMIT: usize = zebra_consensus::MAX_CHECKPOINT_HEIGHT_GAP;
/// The default for the user-specified lookahead limit.
///
@@ -318,24 +318,27 @@ where
// We apply a timeout to the verifier to avoid hangs due to missing earlier blocks.
let verifier = Timeout::new(verifier, BLOCK_VERIFY_TIMEOUT);
- assert!(
- config.sync.lookahead_limit >= MIN_LOOKAHEAD_LIMIT,
- "configured lookahead limit {} too low, must be at least {}",
- config.sync.lookahead_limit,
- MIN_LOOKAHEAD_LIMIT
+ let mut lookahead_limit = config.sync.lookahead_limit;
+ if lookahead_limit < MIN_LOOKAHEAD_LIMIT {
+ warn!(
+ "configured lookahead limit {} too low, increasing to {}",
+ config.sync.lookahead_limit, MIN_LOOKAHEAD_LIMIT,
);
+ lookahead_limit = MIN_LOOKAHEAD_LIMIT;
+ }
+
let (sync_status, recent_syncs) = SyncStatus::new();
let new_syncer = Self {
genesis_hash: genesis_hash(config.network.network),
- lookahead_limit: config.sync.lookahead_limit,
+ lookahead_limit,
tip_network,
downloads: Box::pin(Downloads::new(
block_network,
verifier,
latest_chain_tip.clone(),
- config.sync.lookahead_limit,
+ lookahead_limit,
)),
state,
latest_chain_tip,
