Currently, we have a bit of a convoluted flow where when sending
attestations, we start broadcasting them over gossip then pass them to
the attestation validation to include them in the local attestation pool
- it should be the other way around: we should be checking attestations
_before_ gossipping them - this serves as an additional safety net to
ensure that we don't publish junk - this becomes more important when
publishing attestations from the API.
Also, the REST API was performing its own validation meaning
attestations coming from REST would be validated twice - finally, the
JSON RPC wasn't pre-validating and would happily broadcast invalid
attestations.
* Unified attestation production pipeline with the same flow for gossip,
locally and API-produced attestations: all are now validated and entered
into the pool, then broadcast/republished
* Refactor subnet handling with specific SubnetId alias, streamlining
where subnets are computed, avoiding the need to pass around the number
of active validators
* Move some of the subnet handling code to eth2_network
* Use BitArray throughout for subnet handling
With the introduction of batching and lazy attestation aggregation, it
no longer makes sense to enqueue attestations between the signature
check and adding them to the attestation pool - this only takes up
valuable CPU without any real benefit.
* add successfully validated attestations to attestion pool directly
* avoid copying participant list around for single-vote attestations,
pass single validator index instead
* release decompressed gossip memory earlier, specially during async
message validation
* use cooked signatures in a few more places to avoid reloads and errors
* remove some Defect-raising versions of signature-loading
* release decompressed data memory before validating message