eth2fastspec

Eth2fastspec is an extension to eth2spec, utilizing the same types, configuration and dependencies, but optimized for transition speed.

Usage

A few new objects are introduced for precomputed data, speeding up the transition:

• ShufflingEpoch: Committee shuffling information for a single epoch
• EpochsContext: A collection of contextual information to re-use during an epoch, and rotating precomputed data of the next epoch into the current epoch. This includes shuffling, but also proposer information is available.
  • epochs_ctx.load_state(state) precomputes the data for the given state.
  • sync_pubkeys() checks the precomputed data against a state, and then adds missing pubkeys (strictly append-only however, not meant to fork this information)
  • copy() if a fork occurs, the context will have to be copied. To avoid copying the immutable parts, the copy() implements a specialized copy routine.
  • rotate_epochs() to re-use information, such as the shuffling of the next epoch, after transitioning into a new epoch, the rotate_epochs() is called. The transition function takes care of epoch-context data rotation.
• FlatValidator: A copy of the regular Validator, but in a simple object instead of a tree-representation. For intermediate computation the remerkleable representation slows things down, so a regular object is used instead.
• AttesterStatus: During the epoch transition, additional data is precomputed to avoid traversing any state a second time. Attestations are a big part of this, and each validator has an "status" to represent its precomputed participation.
• EpochProcess: The AttesterStatus (and FlatValidator under status.validator) objects and EpochStakeSummary are tracked in the EpochProcess and made available as additional context in the epoch transition.
  • prepare_epoch_process_state(epochs_ctx, state) computes this data.

Method signatures in the spec changed to utilize precomputed data:

• state_transition, process_slots, process_slot, process_epoch, every epoch sub-process, process_block, every block sub-process, and verify_block_signature all have an additional epochs_ctx (EpochsContext) argument.
• every epoch sub-process has an additional process (EpochProcess) argument.

The argument order is generally: epochs_ctx, proces, state, remaining args.

from eth2spec.config.config_util import prepare_config
# Example: load a config, loading it in `eth2spec` as well as `eth2fastspec`, before loading the spec modules.
prepare_config("./lighthouse", "config")

import eth2fastspec as spec

state: spec.BeaconState = ...  # BeaconState.deserialize(stream, size), or some other source.
block: spec.SignedBeaconBlock = ...

epochs_ctx = spec.EpochsContext()
epochs_ctx.load_state(state)

spec.state_transition(epochs_ctx, state, block)

print(state.hash_tree_root().hex())

License

MIT, see LICENSE file.