During custody backfill sync there could be an edge case where we update CGC at the same time where we are importing a batch of columns which may cause us to incorrectly overwrite values when calling `backfill_validator_custody_requirements`. To prevent this race condition, the expected cgc is now passed into this function and is used to check if the expected cgc == the current validator cgc. If the values arent equal, this probably indicates that a very recent CGC occurred so we do not prune/update values in the `epoch_validator_custody_requirements` map.
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
#7603
#### Custody backfill sync service
Similar in many ways to the current backfill service. There may be ways to unify the two services. The difficulty there is that the current backfill service tightly couples blocks and their associated blobs/data columns. Any attempts to unify the two services should be left to a separate PR in my opinion.
#### `SyncNeworkContext`
`SyncNetworkContext` manages custody sync data columns by range requests separetly from other sync RPC requests. I think this is a nice separation considering that custody backfill is its own service.
#### Data column import logic
The import logic verifies KZG committments and that the data columns block root matches the block root in the nodes store before importing columns
#### New channel to send messages to `SyncManager`
Now external services can communicate with the `SyncManager`. In this PR this channel is used to trigger a custody sync. Alternatively we may be able to use the existing `mpsc` channel that the `SyncNetworkContext` uses to communicate with the `SyncManager`. I will spend some time reviewing this.
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
