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nimbus-eth2/beacon_chain/gossip_processing
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Jacek Sieka 4ed2e34a9e Revamp attestation pool 
This is a revamp of the attestation pool that cleans up several aspects
of attestation processing as the network grows larger and block space
becomes more precious.

The aim is to better exploit the divide between attestation subnets and
aggregations by keeping the two kinds separate until it's time to either
produce a block or aggregate. This means we're no longer eagerly
combining single-vote attestations, but rather wait until the last
moment, and then try to add singles to all aggregates, including those
coming from the network.

Importantly, the branch improves on poor aggregate quality and poor
attestation packing in cases where block space is running out.

A basic greed scoring mechanism is used to select attestations for
blocks - attestations are added based on how much many new votes they
bring to the table.

* Collect single-vote attestations separately and store these until it's
time to make aggregates
* Create aggregates based on single-vote attestations
* Select _best_ aggregate rather than _first_ aggregate when on
aggregation duty
* Top up all aggregates with singles when it's time make the attestation
cut, thus improving the chances of grabbing the best aggregates out
there
* Improve aggregation test coverage
* Improve bitseq operations
* Simplify aggregate signature creation
* Make attestation cache temporary instead of storing it in attestation
pool - most of the time, blocks are not being produced, no need to keep
the data around
* Remove redundant aggregate storage that was used only for RPC
* Use tables to avoid some linear seeks when looking up attestation data
* Fix long cleanup on large slot jumps
* Avoid some pointers
* Speed up iterating all attestations for a slot (fixes #2490)
 		2021-04-13 20:24:02 +03:00
..
README.md Reorg (5/5) (#2377) 2021-03-05 14:12:00 +01:00
batch_validation.nim only deserialize attestation and aggregation gossiped signatures once (#2472) 2021-04-09 14:59:24 +02:00
consensus_manager.nim add metric for nextActionWait (#2399) 2021-03-12 09:46:26 +00:00
eth2_processor.nim Rebase and fixes. 2021-04-09 21:42:13 +03:00
gossip_to_consensus.nim only deserialize attestation and aggregation gossiped signatures once (#2472) 2021-04-09 14:59:24 +02:00
gossip_validation.nim Revamp attestation pool 2021-04-13 20:24:02 +03:00

README.md

Gossip Processing

This folders hold a collection of modules to:

  • validate raw gossip data before
    • rebroadcasting them (potentially aggregated)
    • sending it to one of the consensus object pool

Validation

Gossip Validation is different from consensus verification in particular for blocks.

There are 2 consumers of validated consensus objects:

  • a ValidationResult.Accept output triggers rebroadcasting in libp2p
    • method validate(PubSub, message) in libp2p/protocols/pubsub/pubsub.nim in the
    • which was called by rpcHandler(GossipSub, PubSubPeer, RPCMsg)
  • a xyzValidator message enqueues the validated object in one of the processing queue in eth2_processor
    • blocksQueue: AsyncQueue[BlockEntry], (shared with request_manager and sync_manager)
    • attestationsQueue: AsyncQueue[AttestationEntry]
    • aggregatesQueue: AsyncQueue[AggregateEntry]

Those queues are then regularly processed to be made available to the consensus object pools.

Security concerns

As the first line of defense in Nimbus, modules must be able to handle burst of data that may come:

  • from malicious nodes trying to DOS us
  • from long periods of non-finality, creating lots of forks, attestations, forks