99 lines
2.8 KiB
Rust
99 lines
2.8 KiB
Rust
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use crate::BeaconChain;
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use lmd_ghost::LmdGhost;
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use state_processing::common::get_attesting_indices_unsorted;
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use std::marker::PhantomData;
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use std::sync::Arc;
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use store::Store;
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use types::{Attestation, BeaconBlock, BeaconState, BeaconStateError, EthSpec, Hash256};
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type Result<T> = std::result::Result<T, Error>;
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#[derive(Debug, PartialEq)]
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pub enum Error {
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BackendError(String),
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BeaconStateError(BeaconStateError),
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}
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pub struct ForkChoice<L, S, E> {
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backend: L,
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_phantom_a: PhantomData<S>,
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_phantom_b: PhantomData<E>,
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}
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impl<L, S, E> ForkChoice<L, S, E>
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where
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L: LmdGhost<S, E>,
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S: Store,
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E: EthSpec,
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{
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pub fn new(store: Arc<S>) -> Self {
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Self {
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backend: L::new(store),
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_phantom_a: PhantomData,
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_phantom_b: PhantomData,
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}
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}
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pub fn find_head(&self) -> Result<Hash256> {
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self.backend.find_head().map_err(Into::into)
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}
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pub fn process_attestation(
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&self,
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state: &BeaconState<E>,
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attestation: &Attestation,
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) -> Result<()> {
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// Note: `get_attesting_indices_unsorted` requires that the beacon state caches be built.
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let validator_indices = get_attesting_indices_unsorted(
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state,
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&attestation.data,
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&attestation.aggregation_bitfield,
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)?;
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let block_hash = attestation.data.target_root;
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// TODO: what happens when the target root is not the same slot as the block?
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let block_slot = attestation
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.data
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.target_epoch
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.start_slot(E::slots_per_epoch());
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for validator_index in validator_indices {
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self.backend
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.process_message(validator_index, block_hash, block_slot)?;
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}
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Ok(())
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}
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/// A helper function which runs `self.process_attestation` on all `Attestation` in the given `BeaconBlock`.
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///
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/// Assumes the block (and therefore it's attestations) are valid. It is a logic error to
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/// provide an invalid block.
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pub fn process_block(&self, state: &BeaconState<E>, block: &BeaconBlock) -> Result<()> {
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// Note: we never count the block as a latest message, only attestations.
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//
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// I (Paul H) do not have an explicit reference to this, however I derive it from this
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// document:
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//
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// https://github.com/ethereum/eth2.0-specs/blob/v0.7.0/specs/core/0_fork-choice.md
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for attestation in &block.body.attestations {
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self.process_attestation(state, attestation)?;
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}
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Ok(())
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}
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}
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impl From<BeaconStateError> for Error {
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fn from(e: BeaconStateError) -> Error {
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Error::BeaconStateError(e)
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}
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}
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impl From<String> for Error {
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fn from(e: String) -> Error {
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Error::BackendError(e)
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}
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}
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