103 lines
3.1 KiB
Rust
103 lines
3.1 KiB
Rust
use crate::{ForkChoice, ForkChoiceError};
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use db::{stores::BeaconBlockStore, ClientDB};
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use std::sync::Arc;
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use types::{BeaconBlock, Hash256, Slot};
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pub struct LongestChain<T>
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where
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T: ClientDB + Sized,
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{
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/// List of head block hashes
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head_block_hashes: Vec<Hash256>,
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/// Block storage access.
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block_store: Arc<BeaconBlockStore<T>>,
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}
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impl<T> LongestChain<T>
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where
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T: ClientDB + Sized,
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{
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pub fn new(block_store: Arc<BeaconBlockStore<T>>) -> Self {
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LongestChain {
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head_block_hashes: Vec::new(),
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block_store,
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}
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}
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}
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impl<T: ClientDB + Sized> ForkChoice for LongestChain<T> {
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fn add_block(
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&mut self,
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block: &BeaconBlock,
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block_hash: &Hash256,
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) -> Result<(), ForkChoiceError> {
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// add the block hash to head_block_hashes removing the parent if it exists
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self.head_block_hashes
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.retain(|hash| *hash != block.parent_root);
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self.head_block_hashes.push(*block_hash);
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Ok(())
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}
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fn add_attestation(&mut self, _: u64, _: &Hash256) -> Result<(), ForkChoiceError> {
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// do nothing
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Ok(())
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}
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fn find_head(&mut self, _: &Hash256) -> Result<Hash256, ForkChoiceError> {
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let mut head_blocks: Vec<(usize, BeaconBlock)> = vec![];
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/*
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* Load all the head_block hashes from the DB as SszBeaconBlocks.
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*/
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for (index, block_hash) in self.head_block_hashes.iter().enumerate() {
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let block = self
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.block_store
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.get_deserialized(&block_hash)?
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.ok_or(ForkChoiceError::MissingBeaconBlock(*block_hash))?;
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head_blocks.push((index, block));
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}
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/*
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* Loop through all the head blocks and find the highest slot.
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*/
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let highest_slot = head_blocks
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.iter()
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.fold(Slot::from(0u64), |highest, (_, block)| {
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std::cmp::max(block.slot, highest)
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});
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// if we find no blocks, return Error
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if highest_slot == 0 {
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return Err(ForkChoiceError::HeadNotFound);
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}
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/*
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* Loop through all the highest blocks and sort them by highest hash.
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*
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* Ultimately, the index of the head_block hash with the highest slot and highest block
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* hash will be the winner.
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*/
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let head_index: Option<usize> =
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head_blocks
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.iter()
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.fold(None, |smallest_index, (index, block)| {
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if block.slot == highest_slot {
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if smallest_index.is_none() {
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return Some(*index);
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}
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return Some(std::cmp::min(
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*index,
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smallest_index.expect("Cannot be None"),
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));
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}
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smallest_index
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});
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if head_index.is_none() {
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return Err(ForkChoiceError::HeadNotFound);
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}
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Ok(self.head_block_hashes[head_index.unwrap()])
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}
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}
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