86 lines
2.6 KiB
Rust
86 lines
2.6 KiB
Rust
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use super::WinningRootError;
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use types::*;
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#[derive(Clone)]
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pub struct WinningRoot {
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pub shard_block_root: Hash256,
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pub attesting_validator_indices: Vec<usize>,
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pub total_balance: u64,
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pub total_attesting_balance: u64,
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}
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fn winning_root(
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state: &BeaconState,
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shard: u64,
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current_epoch_attestations: &[&PendingAttestation],
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previous_epoch_attestations: &[&PendingAttestation],
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spec: &ChainSpec,
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) -> Result<WinningRoot, WinningRootError> {
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let mut attestations = current_epoch_attestations.to_vec();
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attestations.append(&mut previous_epoch_attestations.to_vec());
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let mut candidates: HashMap<Hash256, WinningRoot> = HashMap::new();
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let mut highest_seen_balance = 0;
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for a in &attestations {
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if a.data.shard != shard {
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continue;
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}
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let shard_block_root = &a.data.shard_block_root;
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if candidates.contains_key(shard_block_root) {
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continue;
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}
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let attesting_validator_indices = attestations
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.iter()
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.try_fold::<_, _, Result<_, BeaconStateError>>(vec![], |mut acc, a| {
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if (a.data.shard == shard) && (a.data.shard_block_root == *shard_block_root) {
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acc.append(&mut state.get_attestation_participants(
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&a.data,
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&a.aggregation_bitfield,
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spec,
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)?);
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}
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Ok(acc)
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})?;
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let total_balance: u64 = attesting_validator_indices
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.iter()
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.fold(0, |acc, i| acc + state.get_effective_balance(*i, spec));
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let total_attesting_balance: u64 = attesting_validator_indices
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.iter()
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.fold(0, |acc, i| acc + state.get_effective_balance(*i, spec));
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if total_attesting_balance > highest_seen_balance {
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highest_seen_balance = total_attesting_balance;
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}
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let candidate_root = WinningRoot {
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shard_block_root: *shard_block_root,
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attesting_validator_indices,
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total_attesting_balance,
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total_balance,
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};
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candidates.insert(*shard_block_root, candidate_root);
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}
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Ok(candidates
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.iter()
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.filter_map(|(_hash, candidate)| {
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if candidate.total_attesting_balance == highest_seen_balance {
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Some(candidate)
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} else {
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None
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}
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})
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.min_by_key(|candidate| candidate.shard_block_root)
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.ok_or_else(|| WinningRootError::NoWinningRoot)?
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// TODO: avoid clone.
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.clone())
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}
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