Michael Sproul
99d2c33387
## Issue Addressed This PR fixes the unnecessary `WARN Single block lookup failed` messages described here: https://github.com/sigp/lighthouse/pull/2866#issuecomment-1008442640 ## Proposed Changes Add a new cache to the `BeaconChain` that tracks the block roots of blocks from before finalization. These could be blocks from the canonical chain (which might need to be read from disk), or old pre-finalization blocks that have been forked out. The cache also stores a set of block roots for in-progress single block lookups, which duplicates some of the information from sync's `single_block_lookups` hashmap: https://github.com/sigp/lighthouse/blob/a836e180f9ad51f31767c5ffb33bebdeff1a9f3f/beacon_node/network/src/sync/manager.rs#L192-L196 On a live node you can confirm that the cache is working by grepping logs for the message: `Rejected attestation to finalized block`.