When the network is partitioned for a long time, e.g., Goerli, branches
start forming where different peers have distinct views about the chain
state. The current syncing solution with sync manager doesn't handle the
case well, as it is optimized for a healthy network where syncing can be
parallelized across different peers. To support sync manager discovering
additional branches, a new module is added that pulls in histories from
peers on unknown branches in a backwards manner.
Using a dedicated branch for researching the effectiveness of split view
scenario handling simplifies testing and avoids having partial work on
`unstable`. If we want, we can reintroduce it under a `--debug` flag at
a later time. But for now, Goerli is a rare opoprtunity to test this,
maybe just for another week or so.
- https://github.com/status-im/infra-nimbus/pull/179
In split view situation, the canonical chain may only be served by a
tiny amount of peers, and branches may span long durations. Minority
branches may still have a large weight from attestations and should
be discovered. To assist with that, add a branch discovery module that
assists in such a situation by specifically targeting peers with unknown
histories and downloading from them, in addition to sync manager work
which handles popular branches.
