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Updates optimised ghost to use chainspec for consts.

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Age Manning 2019-02-18 17:42:07 +11:00
parent 8b34bc490b
commit 6e6d451978
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2 changed files with 44 additions and 28 deletions
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10
eth2/fork_choice/src/lib.rs
View File

@ -50,7 +50,7 @@ pub mod slow_lmd_ghost;
use db::stores::BeaconBlockAtSlotError;
use db::DBError;
use types::{BeaconBlock, Hash256};
use types::{BeaconBlock, ChainSpec, Hash256};
pub use longest_chain::LongestChain;
pub use optimised_lmd_ghost::OptimisedLMDGhost;
@ -65,6 +65,7 @@ pub trait ForkChoice: Send + Sync {
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
spec: &ChainSpec,
) -> Result<(), ForkChoiceError>;
/// Called when an attestation has been added. Allows generic attestation-level data structures to be built for a given fork choice.
// This can be generalised to a full attestation if required later.
@ -72,10 +73,15 @@ pub trait ForkChoice: Send + Sync {
&mut self,
validator_index: u64,
target_block_hash: &Hash256,
spec: &ChainSpec,
) -> Result<(), ForkChoiceError>;
/// The fork-choice algorithm to find the current canonical head of the chain.
// TODO: Remove the justified_start_block parameter and make it internal
fn find_head(&mut self, justified_start_block: &Hash256) -> Result<Hash256, ForkChoiceError>;
fn find_head(
&mut self,
justified_start_block: &Hash256,
spec: &ChainSpec,
) -> Result<Hash256, ForkChoiceError>;
}
/// Possible fork choice errors that can occur.

62
eth2/fork_choice/src/optimised_lmd_ghost.rs
View File

@ -11,18 +11,12 @@ use std::collections::HashMap;
use std::sync::Arc;
use types::{
readers::BeaconBlockReader, validator_registry::get_active_validator_indices, BeaconBlock,
Hash256, Slot, SlotHeight,
ChainSpec, Hash256, Slot, SlotHeight,
};
//TODO: Pruning - Children
//TODO: Handle Syncing
//TODO: Sort out global constants
const GENESIS_SLOT: u64 = 0;
const FORK_CHOICE_BALANCE_INCREMENT: u64 = 1e9 as u64;
const MAX_DEPOSIT_AMOUNT: u64 = 32e9 as u64;
const EPOCH_LENGTH: u64 = 64;
/// The optimised LMD-GHOST fork choice rule.
/// NOTE: This uses u32 to represent difference between block heights. Thus this is only
/// applicable for block height differences in the range of a u32.
@ -82,7 +76,8 @@ where
pub fn get_latest_votes(
&self,
state_root: &Hash256,
block_slot: Slot,
block_slot: &Slot,
spec: &ChainSpec,
) -> Result<HashMap<Hash256, u64>, ForkChoiceError> {
// get latest votes
// Note: Votes are weighted by min(balance, MAX_DEPOSIT_AMOUNT) //
@ -98,7 +93,7 @@ where
let active_validator_indices = get_active_validator_indices(
&current_state.validator_registry[..],
block_slot.epoch(EPOCH_LENGTH),
block_slot.epoch(spec.epoch_length),
);
trace!(
"FORKCHOICE: Active validator indicies: {:?}",
@ -106,9 +101,10 @@ where
);
for index in active_validator_indices {
let balance =
std::cmp::min(current_state.validator_balances[index], MAX_DEPOSIT_AMOUNT)
/ FORK_CHOICE_BALANCE_INCREMENT;
let balance = std::cmp::min(
current_state.validator_balances[index],
spec.max_deposit_amount,
) / spec.fork_choice_balance_increment;
if balance > 0 {
if let Some(target) = self.latest_attestation_targets.get(&(index as u64)) {
*latest_votes.entry(*target).or_insert_with(|| 0) += balance;
@ -120,7 +116,12 @@ where
}
/// Gets the ancestor at a given height `at_height` of a block specified by `block_hash`.
fn get_ancestor(&mut self, block_hash: Hash256, at_height: SlotHeight) -> Option<Hash256> {
fn get_ancestor(
&mut self,
block_hash: Hash256,
at_height: SlotHeight,
spec: &ChainSpec,
) -> Option<Hash256> {
// return None if we can't get the block from the db.
let block_height = {
let block_slot = self
@ -130,7 +131,7 @@ where
.expect("Should have returned already if None")
.slot;
block_slot.height(Slot::from(GENESIS_SLOT))
block_slot.height(Slot::from(spec.genesis_slot))
};
// verify we haven't exceeded the block height
@ -155,7 +156,7 @@ where
.get(&block_hash)
//TODO: Panic if we can't lookup and fork choice fails
.expect("All blocks should be added to the ancestor log lookup table");
self.get_ancestor(*ancestor_lookup, at_height)
self.get_ancestor(*ancestor_lookup, at_height, &spec)
} {
// add the result to the cache
self.cache.insert(cache_key, ancestor);
@ -170,6 +171,7 @@ where
&mut self,
latest_votes: &HashMap<Hash256, u64>,
block_height: SlotHeight,
spec: &ChainSpec,
) -> Option<Hash256> {
// map of vote counts for every hash at this height
let mut current_votes: HashMap<Hash256, u64> = HashMap::new();
@ -178,7 +180,7 @@ where
// loop through the latest votes and count all votes
// these have already been weighted by balance
for (hash, votes) in latest_votes.iter() {
if let Some(ancestor) = self.get_ancestor(*hash, block_height) {
if let Some(ancestor) = self.get_ancestor(*hash, block_height, spec) {
let current_vote_value = current_votes.get(&ancestor).unwrap_or_else(|| &0);
current_votes.insert(ancestor, current_vote_value + *votes);
total_vote_count += votes;
@ -244,6 +246,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
spec: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// get the height of the parent
let parent_height = self
@ -251,7 +254,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
.get_deserialized(&block.parent_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(block.parent_root))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(Slot::from(spec.genesis_slot));
let parent_hash = &block.parent_root;
@ -281,6 +284,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
&mut self,
validator_index: u64,
target_block_root: &Hash256,
spec: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// simply add the attestation to the latest_attestation_target if the block_height is
// larger
@ -305,7 +309,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
.get_deserialized(&target_block_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*target_block_root))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(Slot::from(spec.genesis_slot));
// get the height of the past target block
let past_block_height = self
@ -313,7 +317,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
.get_deserialized(&attestation_target)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*attestation_target))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(Slot::from(spec.genesis_slot));
trace!("FORKCHOICE: Old block height: {:?}", past_block_height);
trace!("FORKCHOICE: New block height: {:?}", block_height);
// update the attestation only if the new target is higher
@ -326,7 +330,11 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
}
/// Perform lmd_ghost on the current chain to find the head.
fn find_head(&mut self, justified_block_start: &Hash256) -> Result<Hash256, ForkChoiceError> {
fn find_head(
&mut self,
justified_block_start: &Hash256,
spec: &ChainSpec,
) -> Result<Hash256, ForkChoiceError> {
trace!("Starting optimised fork choice");
let block = self
.block_store
@ -334,7 +342,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?;
let block_slot = block.slot();
let block_height = block_slot.height(Slot::from(GENESIS_SLOT));
let block_height = block_slot.height(Slot::from(spec.genesis_slot));
let state_root = block.state_root();
let mut current_head = *justified_block_start;
@ -342,7 +350,8 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
let mut latest_votes = self.get_latest_votes(&state_root, block_slot)?;
// remove any votes that don't relate to our current head.
latest_votes.retain(|hash, _| self.get_ancestor(*hash, block_height) == Some(current_head));
latest_votes
.retain(|hash, _| self.get_ancestor(*hash, block_height, spec) == Some(current_head));
trace!("FORKCHOICE: Latest votes: {:?}", latest_votes);
// begin searching for the head
@ -384,7 +393,7 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
let mut child_votes = HashMap::new();
for (voted_hash, vote) in latest_votes.iter() {
// if the latest votes correspond to a child
if let Some(child) = self.get_ancestor(*voted_hash, block_height + 1) {
if let Some(child) = self.get_ancestor(*voted_hash, block_height + 1, spec) {
// add up the votes for each child
*child_votes.entry(child).or_insert_with(|| 0) += vote;
}
@ -404,12 +413,13 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
.get_deserialized(&current_head)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(Slot::from(spec.genesis_slot));
// prune the latest votes for votes that are not part of current chosen chain
// more specifically, only keep votes that have head as an ancestor
latest_votes
.retain(|hash, _| self.get_ancestor(*hash, block_height) == Some(current_head));
latest_votes.retain(|hash, _| {
self.get_ancestor(*hash, block_height, spec) == Some(current_head)
});
}
}
}