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Merge pull request #195 from sigp/fork-choices

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[WIP] Generalise Fork Choice Algorithms and implement optimised version.
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Age Manning 2019-02-13 18:56:44 +11:00 committed by GitHub
commit 1da06c156c
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22 changed files with 949 additions and 345 deletions
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2
Cargo.toml
View File

@ -2,7 +2,7 @@
members = [
"eth2/attester",
"eth2/block_producer",
"eth2/naive_fork_choice",
"eth2/fork_choice",
"eth2/state_processing",
"eth2/types",
"eth2/utils/bls",

1
beacon_node/Cargo.toml
View File

@ -14,6 +14,7 @@ clap = "2.32.0"
db = { path = "db" }
dirs = "1.0.3"
futures = "0.1.23"
fork_choice = { path = "../eth2/fork_choice" }
slog = "^2.2.3"
slot_clock = { path = "../eth2/utils/slot_clock" }
slog-term = "^2.4.0"

1
beacon_node/beacon_chain/Cargo.toml
View File

@ -12,6 +12,7 @@ db = { path = "../db" }
failure = "0.1"
failure_derive = "0.1"
hashing = { path = "../../eth2/utils/hashing" }
fork_choice = { path = "../../eth2/fork_choice" }
parking_lot = "0.7"
log = "0.4"
env_logger = "0.6"

23
beacon_node/beacon_chain/src/attestation_targets.rs
View File

@ -1,23 +0,0 @@
use std::collections::HashMap;
use types::Hash256;
#[derive(Default)]
pub struct AttestationTargets {
map: HashMap<u64, Hash256>,
}
impl AttestationTargets {
pub fn new() -> Self {
Self {
map: HashMap::new(),
}
}
pub fn get(&self, validator_index: u64) -> Option<&Hash256> {
self.map.get(&validator_index)
}
pub fn insert(&mut self, validator_index: u64, block_hash: Hash256) -> Option<Hash256> {
self.map.insert(validator_index, block_hash)
}
}

109
beacon_node/beacon_chain/src/beacon_chain.rs
View File

@ -1,11 +1,10 @@
use crate::attestation_aggregator::{AttestationAggregator, Outcome as AggregationOutcome};
use crate::attestation_targets::AttestationTargets;
use crate::block_graph::BlockGraph;
use crate::checkpoint::CheckPoint;
use db::{
stores::{BeaconBlockStore, BeaconStateStore},
ClientDB, DBError,
};
use fork_choice::{ForkChoice, ForkChoiceError};
use log::{debug, trace};
use parking_lot::{RwLock, RwLockReadGuard};
use slot_clock::SlotClock;
@ -28,11 +27,14 @@ pub enum Error {
CommitteesError(CommitteesError),
DBInconsistent(String),
DBError(String),
ForkChoiceError(ForkChoiceError),
MissingBeaconBlock(Hash256),
MissingBeaconState(Hash256),
}
#[derive(Debug, PartialEq)]
pub enum ValidBlock {
/// The block was sucessfully processed.
/// The block was successfully processed.
Processed,
}
@ -53,29 +55,29 @@ pub enum InvalidBlock {
#[derive(Debug, PartialEq)]
pub enum BlockProcessingOutcome {
/// The block was sucessfully validated.
/// The block was successfully validated.
ValidBlock(ValidBlock),
/// The block was not sucessfully validated.
/// The block was not successfully validated.
InvalidBlock(InvalidBlock),
}
pub struct BeaconChain<T: ClientDB + Sized, U: SlotClock> {
pub struct BeaconChain<T: ClientDB + Sized, U: SlotClock, F: ForkChoice> {
pub block_store: Arc<BeaconBlockStore<T>>,
pub state_store: Arc<BeaconStateStore<T>>,
pub slot_clock: U,
pub block_graph: BlockGraph,
pub attestation_aggregator: RwLock<AttestationAggregator>,
canonical_head: RwLock<CheckPoint>,
finalized_head: RwLock<CheckPoint>,
pub state: RwLock<BeaconState>,
pub latest_attestation_targets: RwLock<AttestationTargets>,
pub spec: ChainSpec,
pub fork_choice: RwLock<F>,
}
impl<T, U> BeaconChain<T, U>
impl<T, U, F> BeaconChain<T, U, F>
where
T: ClientDB,
U: SlotClock,
F: ForkChoice,
{
/// Instantiate a new Beacon Chain, from genesis.
pub fn genesis(
@ -86,6 +88,7 @@ where
latest_eth1_data: Eth1Data,
initial_validator_deposits: Vec<Deposit>,
spec: ChainSpec,
fork_choice: F,
) -> Result<Self, Error> {
if initial_validator_deposits.is_empty() {
return Err(Error::InsufficientValidators);
@ -104,9 +107,6 @@ where
let block_root = genesis_block.canonical_root();
block_store.put(&block_root, &ssz_encode(&genesis_block)[..])?;
let block_graph = BlockGraph::new();
block_graph.add_leaf(&Hash256::zero(), block_root);
let finalized_head = RwLock::new(CheckPoint::new(
genesis_block.clone(),
block_root,
@ -121,19 +121,16 @@ where
));
let attestation_aggregator = RwLock::new(AttestationAggregator::new());
let latest_attestation_targets = RwLock::new(AttestationTargets::new());
Ok(Self {
block_store,
state_store,
slot_clock,
block_graph,
attestation_aggregator,
state: RwLock::new(genesis_state.clone()),
finalized_head,
canonical_head,
latest_attestation_targets,
spec,
fork_choice: RwLock::new(fork_choice),
})
}
@ -208,7 +205,7 @@ where
Ok(())
}
/// Returns the the validator index (if any) for the given public key.
/// Returns the validator index (if any) for the given public key.
///
/// Information is retrieved from the present `beacon_state.validator_registry`.
pub fn validator_index(&self, pubkey: &PublicKey) -> Option<usize> {
@ -332,26 +329,24 @@ where
&self,
free_attestation: FreeAttestation,
) -> Result<AggregationOutcome, Error> {
self.attestation_aggregator
let aggregation_outcome = self
.attestation_aggregator
.write()
.process_free_attestation(&self.state.read(), &free_attestation, &self.spec)
.map_err(|e| e.into())
}
.process_free_attestation(&self.state.read(), &free_attestation, &self.spec)?;
// TODO: Check this comment
//.map_err(|e| e.into())?;
/// Set the latest attestation target for some validator.
pub fn insert_latest_attestation_target(&self, validator_index: u64, block_root: Hash256) {
let mut targets = self.latest_attestation_targets.write();
targets.insert(validator_index, block_root);
}
/// Get the latest attestation target for some validator.
pub fn get_latest_attestation_target(&self, validator_index: u64) -> Option<Hash256> {
let targets = self.latest_attestation_targets.read();
match targets.get(validator_index) {
Some(hash) => Some(*hash),
None => None,
// return if the attestation is invalid
if !aggregation_outcome.valid {
return Ok(aggregation_outcome);
}
// valid attestation, proceed with fork-choice logic
self.fork_choice.write().add_attestation(
free_attestation.validator_index,
&free_attestation.data.beacon_block_root,
)?;
Ok(aggregation_outcome)
}
/// Dumps the entire canonical chain, from the head to genesis to a vector for analysis.
@ -458,7 +453,7 @@ where
}
}
// Apply the recieved block to its parent state (which has been transitioned into this
// Apply the received block to its parent state (which has been transitioned into this
// slot).
if let Err(e) = state.per_block_processing(&block, &self.spec) {
return Ok(BlockProcessingOutcome::InvalidBlock(
@ -478,15 +473,20 @@ where
self.block_store.put(&block_root, &ssz_encode(&block)[..])?;
self.state_store.put(&state_root, &ssz_encode(&state)[..])?;
// Update the block DAG.
self.block_graph.add_leaf(&parent_block_root, block_root);
// run the fork_choice add_block logic
self.fork_choice.write().add_block(&block, &block_root)?;
// If the parent block was the parent_block, automatically update the canonical head.
//
// TODO: this is a first-in-best-dressed scenario that is not ideal; fork_choice should be
// run instead.
if self.head().beacon_block_root == parent_block_root {
self.update_canonical_head(block.clone(), block_root, state.clone(), state_root);
self.update_canonical_head(
block.clone(),
block_root.clone(),
state.clone(),
state_root,
);
// Update the local state variable.
*self.state.write() = state.clone();
}
@ -496,7 +496,7 @@ where
/// Produce a new block at the present slot.
///
/// The produced block will not be inheriently valid, it must be signed by a block producer.
/// The produced block will not be inherently valid, it must be signed by a block producer.
/// Block signing is out of the scope of this function and should be done by a separate program.
pub fn produce_block(&self, randao_reveal: Signature) -> Option<(BeaconBlock, BeaconState)> {
debug!("Producing block at slot {}...", self.state.read().slot);
@ -549,6 +549,31 @@ where
Some((block, state))
}
// TODO: Left this as is, modify later
pub fn fork_choice(&self) -> Result<(), Error> {
let present_head = self.finalized_head().beacon_block_root;
let new_head = self.fork_choice.write().find_head(&present_head)?;
if new_head != present_head {
let block = self
.block_store
.get_deserialized(&new_head)?
.ok_or_else(|| Error::MissingBeaconBlock(new_head))?;
let block_root = block.canonical_root();
let state = self
.state_store
.get_deserialized(&block.state_root)?
.ok_or_else(|| Error::MissingBeaconState(block.state_root))?;
let state_root = state.canonical_root();
self.update_canonical_head(block, block_root, state, state_root);
}
Ok(())
}
}
impl From<DBError> for Error {
@ -557,6 +582,12 @@ impl From<DBError> for Error {
}
}
impl From<ForkChoiceError> for Error {
fn from(e: ForkChoiceError) -> Error {
Error::ForkChoiceError(e)
}
}
impl From<CommitteesError> for Error {
fn from(e: CommitteesError) -> Error {
Error::CommitteesError(e)

45
beacon_node/beacon_chain/src/block_graph.rs
View File

@ -1,45 +0,0 @@
use parking_lot::{RwLock, RwLockReadGuard};
use std::collections::HashSet;
use types::Hash256;
/// Maintains a view of the block DAG, also known as the "blockchain" (except, it tracks multiple
/// chains eminating from a single root instead of just the head of some canonical chain).
///
/// The BlockGraph does not store the blocks, instead it tracks the block hashes of blocks at the
/// tip of the DAG. It is out of the scope of the object to retrieve blocks.
///
/// Presently, the DAG root (genesis block) is not tracked.
///
/// The BlogGraph is thread-safe due to internal RwLocks.
#[derive(Default)]
pub struct BlockGraph {
pub leaves: RwLock<HashSet<Hash256>>,
}
impl BlockGraph {
/// Create a new block graph without any leaves.
pub fn new() -> Self {
Self {
leaves: RwLock::new(HashSet::new()),
}
}
/// Add a new leaf to the block hash graph. Returns `true` if the leaf was built upon another
/// leaf.
pub fn add_leaf(&self, parent: &Hash256, leaf: Hash256) -> bool {
let mut leaves = self.leaves.write();
if leaves.contains(parent) {
leaves.remove(parent);
leaves.insert(leaf);
true
} else {
leaves.insert(leaf);
false
}
}
/// Returns a read-guarded HashSet of all leaf blocks.
pub fn leaves(&self) -> RwLockReadGuard<HashSet<Hash256>> {
self.leaves.read()
}
}

4
beacon_node/beacon_chain/src/lib.rs
View File

@ -1,9 +1,7 @@
mod attestation_aggregator;
mod attestation_targets;
mod beacon_chain;
mod block_graph;
mod checkpoint;
mod lmd_ghost;
pub use self::beacon_chain::{BeaconChain, Error};
pub use self::checkpoint::CheckPoint;
pub use fork_choice::{ForkChoice, ForkChoiceAlgorithms, ForkChoiceError};

198
beacon_node/beacon_chain/src/lmd_ghost.rs
View File

@ -1,198 +0,0 @@
use crate::BeaconChain;
use db::{
stores::{BeaconBlockAtSlotError, BeaconBlockStore},
ClientDB, DBError,
};
use slot_clock::{SlotClock, TestingSlotClockError};
use std::collections::HashSet;
use std::sync::Arc;
use types::{
readers::{BeaconBlockReader, BeaconStateReader},
validator_registry::get_active_validator_indices,
Hash256, Slot,
};
#[derive(Debug, PartialEq)]
pub enum Error {
DBError(String),
MissingBeaconState(Hash256),
InvalidBeaconState(Hash256),
MissingBeaconBlock(Hash256),
InvalidBeaconBlock(Hash256),
}
impl<T, U> BeaconChain<T, U>
where
T: ClientDB,
U: SlotClock,
Error: From<<U as SlotClock>::Error>,
{
/// Run the fork-choice rule on the current chain, updating the canonical head, if required.
pub fn fork_choice(&self) -> Result<(), Error> {
let present_head = &self.finalized_head().beacon_block_root;
let new_head = self.slow_lmd_ghost(&self.finalized_head().beacon_block_root)?;
if new_head != *present_head {
let block = self
.block_store
.get_deserialized(&new_head)?
.ok_or_else(|| Error::MissingBeaconBlock(new_head))?;
let block_root = block.canonical_root();
let state = self
.state_store
.get_deserialized(&block.state_root)?
.ok_or_else(|| Error::MissingBeaconState(block.state_root))?;
let state_root = state.canonical_root();
self.update_canonical_head(block, block_root, state, state_root);
}
Ok(())
}
/// A very inefficient implementation of LMD ghost.
pub fn slow_lmd_ghost(&self, start_hash: &Hash256) -> Result<Hash256, Error> {
let start = self
.block_store
.get_reader(&start_hash)?
.ok_or_else(|| Error::MissingBeaconBlock(*start_hash))?;
let start_state_root = start.state_root();
let state = self
.state_store
.get_reader(&start_state_root)?
.ok_or_else(|| Error::MissingBeaconState(start_state_root))?
.into_beacon_state()
.ok_or_else(|| Error::InvalidBeaconState(start_state_root))?;
let active_validator_indices = get_active_validator_indices(
&state.validator_registry,
start.slot().epoch(self.spec.epoch_length),
);
let mut attestation_targets = Vec::with_capacity(active_validator_indices.len());
for i in active_validator_indices {
if let Some(target) = self.get_latest_attestation_target(i as u64) {
attestation_targets.push(target);
}
}
let mut head_hash = Hash256::zero();
let mut head_vote_count = 0;
loop {
let child_hashes_and_slots = get_child_hashes_and_slots(
&self.block_store,
&head_hash,
&self.block_graph.leaves(),
)?;
if child_hashes_and_slots.is_empty() {
break;
}
for (child_hash, child_slot) in child_hashes_and_slots {
let vote_count = get_vote_count(
&self.block_store,
&attestation_targets[..],
&child_hash,
child_slot,
)?;
if vote_count > head_vote_count {
head_hash = child_hash;
head_vote_count = vote_count;
}
}
}
Ok(head_hash)
}
}
/// Get the total number of votes for some given block root.
///
/// The vote count is incrememented each time an attestation target votes for a block root.
fn get_vote_count<T: ClientDB>(
block_store: &Arc<BeaconBlockStore<T>>,
attestation_targets: &[Hash256],
block_root: &Hash256,
slot: Slot,
) -> Result<u64, Error> {
let mut count = 0;
for target in attestation_targets {
let (root_at_slot, _) = block_store
.block_at_slot(&block_root, slot)?
.ok_or_else(|| Error::MissingBeaconBlock(*block_root))?;
if root_at_slot == *target {
count += 1;
}
}
Ok(count)
}
/// Starting from some `leaf_hashes`, recurse back down each branch until the `root_hash`, adding
/// each `block_root` and `slot` to a HashSet.
fn get_child_hashes_and_slots<T: ClientDB>(
block_store: &Arc<BeaconBlockStore<T>>,
root_hash: &Hash256,
leaf_hashes: &HashSet<Hash256>,
) -> Result<HashSet<(Hash256, Slot)>, Error> {
let mut hash_set = HashSet::new();
for leaf_hash in leaf_hashes {
let mut current_hash = *leaf_hash;
loop {
if let Some(block_reader) = block_store.get_reader(&current_hash)? {
let parent_root = block_reader.parent_root();
let new_hash = hash_set.insert((current_hash, block_reader.slot()));
// If the hash just added was already in the set, break the loop.
//
// In such a case, the present branch has merged with a branch that is already in
// the set.
if !new_hash {
break;
}
// The branch is exhausted if the parent of this block is the root_hash.
if parent_root == *root_hash {
break;
}
current_hash = parent_root;
} else {
return Err(Error::MissingBeaconBlock(current_hash));
}
}
}
Ok(hash_set)
}
impl From<DBError> for Error {
fn from(e: DBError) -> Error {
Error::DBError(e.message)
}
}
impl From<BeaconBlockAtSlotError> for Error {
fn from(e: BeaconBlockAtSlotError) -> Error {
match e {
BeaconBlockAtSlotError::UnknownBeaconBlock(h) => Error::MissingBeaconBlock(h),
BeaconBlockAtSlotError::InvalidBeaconBlock(h) => Error::InvalidBeaconBlock(h),
BeaconBlockAtSlotError::DBError(msg) => Error::DBError(msg),
}
}
}
impl From<TestingSlotClockError> for Error {
fn from(_: TestingSlotClockError) -> Error {
unreachable!(); // Testing clock never throws an error.
}
}

1
beacon_node/beacon_chain/test_harness/Cargo.toml
View File

@ -21,6 +21,7 @@ db = { path = "../../db" }
parking_lot = "0.7"
failure = "0.1"
failure_derive = "0.1"
fork_choice = { path = "../../../eth2/fork_choice" }
hashing = { path = "../../../eth2/utils/hashing" }
log = "0.4"
env_logger = "0.6.0"

8
beacon_node/beacon_chain/test_harness/src/beacon_chain_harness.rs
View File

@ -6,6 +6,7 @@ use db::{
stores::{BeaconBlockStore, BeaconStateStore},
MemoryDB,
};
use fork_choice::{optimised_lmd_ghost::OptimisedLMDGhost, slow_lmd_ghost::SlowLMDGhost}; // import all the algorithms
use log::debug;
use rayon::prelude::*;
use slot_clock::TestingSlotClock;
@ -21,13 +22,13 @@ use types::{
/// The beacon chain harness simulates a single beacon node with `validator_count` validators connected
/// to it. Each validator is provided a borrow to the beacon chain, where it may read
/// information and submit blocks/attesations for processing.
/// information and submit blocks/attestations for processing.
///
/// This test harness is useful for testing validator and internal state transition logic. It
/// is not useful for testing that multiple beacon nodes can reach consensus.
pub struct BeaconChainHarness {
pub db: Arc<MemoryDB>,
pub beacon_chain: Arc<BeaconChain<MemoryDB, TestingSlotClock>>,
pub beacon_chain: Arc<BeaconChain<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>>,
pub block_store: Arc<BeaconBlockStore<MemoryDB>>,
pub state_store: Arc<BeaconStateStore<MemoryDB>>,
pub validators: Vec<ValidatorHarness>,
@ -43,9 +44,9 @@ impl BeaconChainHarness {
let db = Arc::new(MemoryDB::open());
let block_store = Arc::new(BeaconBlockStore::new(db.clone()));
let state_store = Arc::new(BeaconStateStore::new(db.clone()));
let genesis_time = 1_549_935_547; // 12th Feb 2018 (arbitrary value in the past).
let slot_clock = TestingSlotClock::new(spec.genesis_slot.as_u64());
let fork_choice = OptimisedLMDGhost::new(block_store.clone(), state_store.clone());
let latest_eth1_data = Eth1Data {
deposit_root: Hash256::zero(),
block_hash: Hash256::zero(),
@ -90,6 +91,7 @@ impl BeaconChainHarness {
latest_eth1_data,
initial_validator_deposits,
spec.clone(),
fork_choice,
)
.unwrap(),
);

13
beacon_node/beacon_chain/test_harness/src/validator_harness/direct_beacon_node.rs
View File

@ -8,6 +8,7 @@ use block_producer::{
PublishOutcome as BlockPublishOutcome,
};
use db::ClientDB;
use fork_choice::ForkChoice;
use parking_lot::RwLock;
use slot_clock::SlotClock;
use std::sync::Arc;
@ -22,14 +23,14 @@ use types::{AttestationData, BeaconBlock, FreeAttestation, Signature, Slot};
/// `BeaconBlock`s and `FreeAttestation`s are not actually published to the `BeaconChain`, instead
/// they are stored inside this struct. This is to allow one to benchmark the submission of the
/// block/attestation directly, or modify it before submission.
pub struct DirectBeaconNode<T: ClientDB, U: SlotClock> {
beacon_chain: Arc<BeaconChain<T, U>>,
pub struct DirectBeaconNode<T: ClientDB, U: SlotClock, F: ForkChoice> {
beacon_chain: Arc<BeaconChain<T, U, F>>,
published_blocks: RwLock<Vec<BeaconBlock>>,
published_attestations: RwLock<Vec<FreeAttestation>>,
}
impl<T: ClientDB, U: SlotClock> DirectBeaconNode<T, U> {
pub fn new(beacon_chain: Arc<BeaconChain<T, U>>) -> Self {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> DirectBeaconNode<T, U, F> {
pub fn new(beacon_chain: Arc<BeaconChain<T, U, F>>) -> Self {
Self {
beacon_chain,
published_blocks: RwLock::new(vec![]),
@ -48,7 +49,7 @@ impl<T: ClientDB, U: SlotClock> DirectBeaconNode<T, U> {
}
}
impl<T: ClientDB, U: SlotClock> AttesterBeaconNode for DirectBeaconNode<T, U> {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> AttesterBeaconNode for DirectBeaconNode<T, U, F> {
fn produce_attestation_data(
&self,
_slot: Slot,
@ -69,7 +70,7 @@ impl<T: ClientDB, U: SlotClock> AttesterBeaconNode for DirectBeaconNode<T, U> {
}
}
impl<T: ClientDB, U: SlotClock> BeaconBlockNode for DirectBeaconNode<T, U> {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> BeaconBlockNode for DirectBeaconNode<T, U, F> {
/// Requests a new `BeaconBlock from the `BeaconChain`.
fn produce_beacon_block(
&self,

13
beacon_node/beacon_chain/test_harness/src/validator_harness/direct_duties.rs
View File

@ -6,19 +6,20 @@ use block_producer::{
DutiesReader as ProducerDutiesReader, DutiesReaderError as ProducerDutiesReaderError,
};
use db::ClientDB;
use fork_choice::ForkChoice;
use slot_clock::SlotClock;
use std::sync::Arc;
use types::{PublicKey, Slot};
/// Connects directly to a borrowed `BeaconChain` and reads attester/proposer duties directly from
/// it.
pub struct DirectDuties<T: ClientDB, U: SlotClock> {
beacon_chain: Arc<BeaconChain<T, U>>,
pub struct DirectDuties<T: ClientDB, U: SlotClock, F: ForkChoice> {
beacon_chain: Arc<BeaconChain<T, U, F>>,
pubkey: PublicKey,
}
impl<T: ClientDB, U: SlotClock> DirectDuties<T, U> {
pub fn new(pubkey: PublicKey, beacon_chain: Arc<BeaconChain<T, U>>) -> Self {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> DirectDuties<T, U, F> {
pub fn new(pubkey: PublicKey, beacon_chain: Arc<BeaconChain<T, U, F>>) -> Self {
Self {
beacon_chain,
pubkey,
@ -26,7 +27,7 @@ impl<T: ClientDB, U: SlotClock> DirectDuties<T, U> {
}
}
impl<T: ClientDB, U: SlotClock> ProducerDutiesReader for DirectDuties<T, U> {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> ProducerDutiesReader for DirectDuties<T, U, F> {
fn is_block_production_slot(&self, slot: Slot) -> Result<bool, ProducerDutiesReaderError> {
let validator_index = self
.beacon_chain
@ -41,7 +42,7 @@ impl<T: ClientDB, U: SlotClock> ProducerDutiesReader for DirectDuties<T, U> {
}
}
impl<T: ClientDB, U: SlotClock> AttesterDutiesReader for DirectDuties<T, U> {
impl<T: ClientDB, U: SlotClock, F: ForkChoice> AttesterDutiesReader for DirectDuties<T, U, F> {
fn validator_index(&self) -> Option<u64> {
match self.beacon_chain.validator_index(&self.pubkey) {
Some(index) => Some(index as u64),

15
beacon_node/beacon_chain/test_harness/src/validator_harness/mod.rs
View File

@ -10,6 +10,7 @@ use block_producer::{BlockProducer, Error as BlockPollError};
use db::MemoryDB;
use direct_beacon_node::DirectBeaconNode;
use direct_duties::DirectDuties;
use fork_choice::{optimised_lmd_ghost::OptimisedLMDGhost, slow_lmd_ghost::SlowLMDGhost};
use local_signer::LocalSigner;
use slot_clock::TestingSlotClock;
use std::sync::Arc;
@ -35,20 +36,20 @@ pub enum AttestationProduceError {
pub struct ValidatorHarness {
pub block_producer: BlockProducer<
TestingSlotClock,
DirectBeaconNode<MemoryDB, TestingSlotClock>,
DirectDuties<MemoryDB, TestingSlotClock>,
DirectBeaconNode<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>,
DirectDuties<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>,
LocalSigner,
>,
pub attester: Attester<
TestingSlotClock,
DirectBeaconNode<MemoryDB, TestingSlotClock>,
DirectDuties<MemoryDB, TestingSlotClock>,
DirectBeaconNode<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>,
DirectDuties<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>,
LocalSigner,
>,
pub spec: Arc<ChainSpec>,
pub epoch_map: Arc<DirectDuties<MemoryDB, TestingSlotClock>>,
pub epoch_map: Arc<DirectDuties<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>>,
pub keypair: Keypair,
pub beacon_node: Arc<DirectBeaconNode<MemoryDB, TestingSlotClock>>,
pub beacon_node: Arc<DirectBeaconNode<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>>,
pub slot_clock: Arc<TestingSlotClock>,
pub signer: Arc<LocalSigner>,
}
@ -60,7 +61,7 @@ impl ValidatorHarness {
/// A `BlockProducer` and `Attester` is created..
pub fn new(
keypair: Keypair,
beacon_chain: Arc<BeaconChain<MemoryDB, TestingSlotClock>>,
beacon_chain: Arc<BeaconChain<MemoryDB, TestingSlotClock, OptimisedLMDGhost<MemoryDB>>>,
spec: Arc<ChainSpec>,
) -> Self {
let slot_clock = Arc::new(TestingSlotClock::new(spec.genesis_slot.as_u64()));

4
beacon_node/src/main.rs
View File

@ -14,6 +14,7 @@ use db::{
stores::{BeaconBlockStore, BeaconStateStore},
MemoryDB,
};
use fork_choice::optimised_lmd_ghost::OptimisedLMDGhost;
use slog::{error, info, o, Drain};
use slot_clock::SystemTimeSlotClock;
use std::sync::Arc;
@ -79,6 +80,8 @@ fn main() {
let genesis_time = 1_549_935_547; // 12th Feb 2018 (arbitrary value in the past).
let slot_clock = SystemTimeSlotClock::new(genesis_time, spec.slot_duration)
.expect("Unable to load SystemTimeSlotClock");
// Choose the fork choice
let fork_choice = OptimisedLMDGhost::new(block_store.clone(), state_store.clone());
/*
* Generate some random data to start a chain with.
@ -120,6 +123,7 @@ fn main() {
latest_eth1_data,
initial_validator_deposits,
spec,
fork_choice,
);
let _server = start_server(log.clone());

6
eth2/naive_fork_choice/Cargo.toml → eth2/fork_choice/Cargo.toml
View File

@ -1,10 +1,12 @@
[package]
name = "naive_fork_choice"
name = "fork_choice"
version = "0.1.0"
authors = ["Paul Hauner <paul@paulhauner.com>"]
authors = ["Age Manning <Age@AgeManning.com>"]
edition = "2018"
[dependencies]
db = { path = "../../beacon_node/db" }
ssz = { path = "../utils/ssz" }
types = { path = "../types" }
fast-math = "0.1.1"
byteorder = "1.3.1"

118
eth2/fork_choice/src/lib.rs Normal file
View File

@ -0,0 +1,118 @@
// Copyright 2019 Sigma Prime Pty Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//! This crate stores the various implementations of fork-choice rules that can be used for the
//! beacon blockchain.
//!
//! There are four implementations. One is the naive longest chain rule (primarily for testing
//! purposes). The other three are proposed implementations of the LMD-GHOST fork-choice rule with various forms of optimisation.
//!
//! The current implementations are:
//! - [`longest-chain`]: Simplistic longest-chain fork choice - primarily for testing, **not for
//! production**.
//! - [`slow_lmd_ghost`]: This is a simple and very inefficient implementation given in the ethereum 2.0
//! specifications (https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_block_root).
//! - [`optimised_lmd_ghost`]: This is an optimised version of the naive implementation as proposed
//! by Vitalik. The reference implementation can be found at: https://github.com/ethereum/research/blob/master/ghost/ghost.py
//! - [`protolambda_lmd_ghost`]: Another optimised version of LMD-GHOST designed by @protolambda.
//! The go implementation can be found here: https://github.com/protolambda/lmd-ghost.
//!
//! [`slow_lmd_ghost`]: struct.SlowLmdGhost.html
//! [`optimised_lmd_ghost`]: struct.OptimisedLmdGhost.html
//! [`protolambda_lmd_ghost`]: struct.ProtolambdaLmdGhost.html
extern crate db;
extern crate ssz;
extern crate types;
pub mod longest_chain;
pub mod optimised_lmd_ghost;
pub mod protolambda_lmd_ghost;
pub mod slow_lmd_ghost;
use db::stores::BeaconBlockAtSlotError;
use db::DBError;
use types::{BeaconBlock, Hash256};
/// Defines the interface for Fork Choices. Each Fork choice will define their own data structures
/// which can be built in block processing through the `add_block` and `add_attestation` functions.
/// The main fork choice algorithm is specified in `find_head
pub trait ForkChoice: Send + Sync {
/// Called when a block has been added. Allows generic block-level data structures to be
/// built for a given fork-choice.
fn add_block(
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
) -> 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.
fn add_attestation(
&mut self,
validator_index: u64,
target_block_hash: &Hash256,
) -> 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>;
}
/// Possible fork choice errors that can occur.
#[derive(Debug, PartialEq)]
pub enum ForkChoiceError {
MissingBeaconBlock(Hash256),
MissingBeaconState(Hash256),
IncorrectBeaconState(Hash256),
CannotFindBestChild,
ChildrenNotFound,
StorageError(String),
}
impl From<DBError> for ForkChoiceError {
fn from(e: DBError) -> ForkChoiceError {
ForkChoiceError::StorageError(e.message)
}
}
impl From<BeaconBlockAtSlotError> for ForkChoiceError {
fn from(e: BeaconBlockAtSlotError) -> ForkChoiceError {
match e {
BeaconBlockAtSlotError::UnknownBeaconBlock(hash) => {
ForkChoiceError::MissingBeaconBlock(hash)
}
BeaconBlockAtSlotError::InvalidBeaconBlock(hash) => {
ForkChoiceError::MissingBeaconBlock(hash)
}
BeaconBlockAtSlotError::DBError(string) => ForkChoiceError::StorageError(string),
}
}
}
/// Fork choice options that are currently implemented.
pub enum ForkChoiceAlgorithms {
/// Chooses the longest chain becomes the head. Not for production.
LongestChain,
/// A simple and highly inefficient implementation of LMD ghost.
SlowLMDGhost,
/// An optimised version of LMD-GHOST by Vitalik.
OptimisedLMDGhost,
/// An optimised version of LMD-GHOST by Protolambda.
ProtoLMDGhost,
}

6
eth2/naive_fork_choice/src/lib.rs → eth2/fork_choice/src/longest_chain.rs
View File

@ -1,7 +1,3 @@
extern crate db;
extern crate ssz;
extern crate types;
use db::stores::BeaconBlockStore;
use db::{ClientDB, DBError};
use ssz::{Decodable, DecodeError};
@ -14,7 +10,7 @@ pub enum ForkChoiceError {
DBError(String),
}
pub fn naive_fork_choice<T>(
pub fn longest_chain<T>(
head_block_hashes: &[Hash256],
block_store: &Arc<BeaconBlockStore<T>>,
) -> Result<Option<usize>, ForkChoiceError>

443
eth2/fork_choice/src/optimised_lmd_ghost.rs Normal file
View File

@ -0,0 +1,443 @@
// Copyright 2019 Sigma Prime Pty Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
extern crate byteorder;
extern crate fast_math;
use crate::{ForkChoice, ForkChoiceError};
use byteorder::{BigEndian, ByteOrder};
use db::{
stores::{BeaconBlockStore, BeaconStateStore},
ClientDB,
};
use fast_math::log2_raw;
use std::collections::HashMap;
use std::sync::Arc;
use types::{
readers::BeaconBlockReader,
slot_epoch_height::{Height, Slot},
validator_registry::get_active_validator_indices,
BeaconBlock, Hash256,
};
//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.
/// This can potentially be parallelized in some parts.
// we use fast log2, a log2 lookup table is implemented in Vitaliks code, potentially do
// the comparison. Log2_raw takes 2ns according to the documentation.
#[inline]
fn log2_int(x: u32) -> u32 {
log2_raw(x as f32) as u32
}
fn power_of_2_below(x: u32) -> u32 {
2u32.pow(log2_int(x))
}
/// Stores the necessary data structures to run the optimised lmd ghost algorithm.
pub struct OptimisedLMDGhost<T: ClientDB + Sized> {
/// A cache of known ancestors at given heights for a specific block.
//TODO: Consider FnvHashMap
cache: HashMap<CacheKey<u32>, Hash256>,
/// Log lookup table for blocks to their ancestors.
//TODO: Verify we only want/need a size 16 log lookup
ancestors: Vec<HashMap<Hash256, Hash256>>,
/// Stores the children for any given parent.
children: HashMap<Hash256, Vec<Hash256>>,
/// The latest attestation targets as a map of validator index to block hash.
//TODO: Could this be a fixed size vec
latest_attestation_targets: HashMap<u64, Hash256>,
/// Block storage access.
block_store: Arc<BeaconBlockStore<T>>,
/// State storage access.
state_store: Arc<BeaconStateStore<T>>,
max_known_height: Height,
}
impl<T> OptimisedLMDGhost<T>
where
T: ClientDB + Sized,
{
pub fn new(
block_store: Arc<BeaconBlockStore<T>>,
state_store: Arc<BeaconStateStore<T>>,
) -> Self {
OptimisedLMDGhost {
cache: HashMap::new(),
ancestors: vec![HashMap::new(); 16],
latest_attestation_targets: HashMap::new(),
children: HashMap::new(),
max_known_height: Height::new(0),
block_store,
state_store,
}
}
/// Finds the latest votes weighted by validator balance. Returns a hashmap of block_hash to
/// weighted votes.
pub fn get_latest_votes(
&self,
state_root: &Hash256,
block_slot: Slot,
) -> Result<HashMap<Hash256, u64>, ForkChoiceError> {
// get latest votes
// Note: Votes are weighted by min(balance, MAX_DEPOSIT_AMOUNT) //
// FORK_CHOICE_BALANCE_INCREMENT
// build a hashmap of block_hash to weighted votes
let mut latest_votes: HashMap<Hash256, u64> = HashMap::new();
// gets the current weighted votes
let current_state = self
.state_store
.get_deserialized(&state_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
let active_validator_indices = get_active_validator_indices(
&current_state.validator_registry,
block_slot.epoch(EPOCH_LENGTH),
);
for index in active_validator_indices {
let balance =
std::cmp::min(current_state.validator_balances[index], MAX_DEPOSIT_AMOUNT)
/ 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;
}
}
}
Ok(latest_votes)
}
/// 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: Height) -> Option<Hash256> {
// return None if we can't get the block from the db.
let block_height = {
let block_slot = self
.block_store
.get_deserialized(&block_hash)
.ok()?
.expect("Should have returned already if None")
.slot;
block_slot.height(Slot::from(GENESIS_SLOT))
};
// verify we haven't exceeded the block height
if at_height >= block_height {
if at_height > block_height {
return None;
} else {
return Some(block_hash);
}
}
// check if the result is stored in our cache
let cache_key = CacheKey::new(&block_hash, at_height.as_u32());
if let Some(ancestor) = self.cache.get(&cache_key) {
return Some(*ancestor);
}
// not in the cache recursively search for ancestors using a log-lookup
if let Some(ancestor) = {
let ancestor_lookup = self.ancestors
[log2_int((block_height - at_height - 1u64).as_u32()) as usize]
.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)
} {
// add the result to the cache
self.cache.insert(cache_key, ancestor);
return Some(ancestor);
}
None
}
// looks for an obvious block winner given the latest votes for a specific height
fn get_clear_winner(
&mut self,
latest_votes: &HashMap<Hash256, u64>,
block_height: Height,
) -> Option<Hash256> {
// map of vote counts for every hash at this height
let mut current_votes: HashMap<Hash256, u64> = HashMap::new();
let mut total_vote_count = 0;
// 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) {
let current_vote_value = current_votes.get(&ancestor).unwrap_or_else(|| &0);
current_votes.insert(ancestor, current_vote_value + *votes);
total_vote_count += votes;
}
}
// Check if there is a clear block winner at this height. If so return it.
for (hash, votes) in current_votes.iter() {
if *votes >= total_vote_count / 2 {
// we have a clear winner, return it
return Some(*hash);
}
}
// didn't find a clear winner
None
}
// Finds the best child, splitting children into a binary tree, based on their hashes
fn choose_best_child(&self, votes: &HashMap<Hash256, u64>) -> Option<Hash256> {
let mut bitmask = 0;
for bit in (0..=255).rev() {
let mut zero_votes = 0;
let mut one_votes = 0;
let mut single_candidate = None;
for (candidate, votes) in votes.iter() {
let candidate_uint = BigEndian::read_u32(candidate);
if candidate_uint >> (bit + 1) != bitmask {
continue;
}
if (candidate_uint >> bit) % 2 == 0 {
zero_votes += votes;
} else {
one_votes += votes;
}
if single_candidate.is_none() {
single_candidate = Some(candidate);
} else {
single_candidate = None;
}
}
bitmask = (bitmask * 2) + {
if one_votes > zero_votes {
1
} else {
0
}
};
if let Some(candidate) = single_candidate {
return Some(*candidate);
}
//TODO Remove this during benchmark after testing
assert!(bit >= 1);
}
// should never reach here
None
}
}
impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
fn add_block(
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
) -> Result<(), ForkChoiceError> {
// get the height of the parent
let parent_height = self
.block_store
.get_deserialized(&block.parent_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(block.parent_root))?
.slot()
.height(Slot::from(GENESIS_SLOT));
let parent_hash = &block.parent_root;
// add the new block to the children of parent
(*self
.children
.entry(block.parent_root)
.or_insert_with(|| vec![]))
.push(block_hash.clone());
// build the ancestor data structure
for index in 0..16 {
if parent_height % (1 << index) == 0 {
self.ancestors[index].insert(*block_hash, *parent_hash);
} else {
// TODO: This is unsafe. Will panic if parent_hash doesn't exist. Using it for debugging
let parent_ancestor = self.ancestors[index][parent_hash];
self.ancestors[index].insert(*block_hash, parent_ancestor);
}
}
// update the max height
self.max_known_height = std::cmp::max(self.max_known_height, parent_height + 1);
Ok(())
}
fn add_attestation(
&mut self,
validator_index: u64,
target_block_root: &Hash256,
) -> Result<(), ForkChoiceError> {
// simply add the attestation to the latest_attestation_target if the block_height is
// larger
let attestation_target = self
.latest_attestation_targets
.entry(validator_index)
.or_insert_with(|| *target_block_root);
// if we already have a value
if attestation_target != target_block_root {
// get the height of the target block
let block_height = self
.block_store
.get_deserialized(&target_block_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*target_block_root))?
.slot()
.height(Slot::from(GENESIS_SLOT));
// get the height of the past target block
let past_block_height = self
.block_store
.get_deserialized(&attestation_target)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*attestation_target))?
.slot()
.height(Slot::from(GENESIS_SLOT));
// update the attestation only if the new target is higher
if past_block_height < block_height {
*attestation_target = *target_block_root;
}
}
Ok(())
}
/// Perform lmd_ghost on the current chain to find the head.
fn find_head(&mut self, justified_block_start: &Hash256) -> Result<Hash256, ForkChoiceError> {
let block = self
.block_store
.get_deserialized(&justified_block_start)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?;
let block_slot = block.slot();
let block_height = block_slot.height(Slot::from(GENESIS_SLOT));
let state_root = block.state_root();
let mut current_head = *justified_block_start;
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));
// begin searching for the head
loop {
// if there are no children, we are done, return the current_head
let children = match self.children.get(&current_head) {
Some(children) => children.clone(),
None => return Ok(current_head),
};
// logarithmic lookup blocks to see if there are obvious winners, if so,
// progress to the next iteration.
let mut step =
power_of_2_below(self.max_known_height.saturating_sub(block_height).as_u32()) / 2;
while step > 0 {
if let Some(clear_winner) = self.get_clear_winner(
&latest_votes,
block_height - (block_height % u64::from(step)) + u64::from(step),
) {
current_head = clear_winner;
break;
}
step /= 2;
}
if step > 0 {
}
// if our skip lookup failed and we only have one child, progress to that child
else if children.len() == 1 {
current_head = children[0];
}
// we need to find the best child path to progress down.
else {
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) {
// add up the votes for each child
*child_votes.entry(child).or_insert_with(|| 0) += vote;
}
}
// given the votes on the children, find the best child
current_head = self
.choose_best_child(&child_votes)
.ok_or(ForkChoiceError::CannotFindBestChild)?;
}
// No head was found, re-iterate
// update the block height for the next iteration
let block_height = self
.block_store
.get_deserialized(&current_head)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?
.slot()
.height(Slot::from(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));
}
}
}
/// Type for storing blocks in a memory cache. Key is comprised of block-hash plus the height.
#[derive(PartialEq, Eq, Hash)]
pub struct CacheKey<T> {
block_hash: Hash256,
block_height: T,
}
impl<T> CacheKey<T> {
pub fn new(block_hash: &Hash256, block_height: T) -> Self {
CacheKey {
block_hash: *block_hash,
block_height,
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
pub fn test_power_of_2_below() {
println!("{:?}", std::f32::MAX);
assert_eq!(power_of_2_below(4), 4);
assert_eq!(power_of_2_below(5), 4);
assert_eq!(power_of_2_below(7), 4);
assert_eq!(power_of_2_below(24), 16);
assert_eq!(power_of_2_below(32), 32);
assert_eq!(power_of_2_below(33), 32);
assert_eq!(power_of_2_below(63), 32);
}
}

0
eth2/fork_choice/src/protolambda_lmd_ghost.rs Normal file
View File

223
eth2/fork_choice/src/slow_lmd_ghost.rs Normal file
View File

@ -0,0 +1,223 @@
// Copyright 2019 Sigma Prime Pty Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
extern crate db;
use crate::{ForkChoice, ForkChoiceError};
use db::{
stores::{BeaconBlockStore, BeaconStateStore},
ClientDB,
};
use std::collections::HashMap;
use std::sync::Arc;
use types::{
readers::{BeaconBlockReader, BeaconStateReader},
slot_epoch_height::Slot,
validator_registry::get_active_validator_indices,
BeaconBlock, Hash256,
};
//TODO: Pruning and 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;
pub struct SlowLMDGhost<T: ClientDB + Sized> {
/// The latest attestation targets as a map of validator index to block hash.
//TODO: Could this be a fixed size vec
latest_attestation_targets: HashMap<u64, Hash256>,
/// Stores the children for any given parent.
children: HashMap<Hash256, Vec<Hash256>>,
/// Block storage access.
block_store: Arc<BeaconBlockStore<T>>,
/// State storage access.
state_store: Arc<BeaconStateStore<T>>,
}
impl<T> SlowLMDGhost<T>
where
T: ClientDB + Sized,
{
pub fn new(block_store: BeaconBlockStore<T>, state_store: BeaconStateStore<T>) -> Self {
SlowLMDGhost {
latest_attestation_targets: HashMap::new(),
children: HashMap::new(),
block_store: Arc::new(block_store),
state_store: Arc::new(state_store),
}
}
/// Finds the latest votes weighted by validator balance. Returns a hashmap of block_hash to
/// weighted votes.
pub fn get_latest_votes(
&self,
state_root: &Hash256,
block_slot: Slot,
) -> Result<HashMap<Hash256, u64>, ForkChoiceError> {
// get latest votes
// Note: Votes are weighted by min(balance, MAX_DEPOSIT_AMOUNT) //
// FORK_CHOICE_BALANCE_INCREMENT
// build a hashmap of block_hash to weighted votes
let mut latest_votes: HashMap<Hash256, u64> = HashMap::new();
// gets the current weighted votes
let current_state = self
.state_store
.get_deserialized(&state_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
let active_validator_indices = get_active_validator_indices(
&current_state.validator_registry,
block_slot.epoch(EPOCH_LENGTH),
);
for index in active_validator_indices {
let balance =
std::cmp::min(current_state.validator_balances[index], MAX_DEPOSIT_AMOUNT)
/ 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;
}
}
}
Ok(latest_votes)
}
/// Get the total number of votes for some given block root.
///
/// The vote count is incremented each time an attestation target votes for a block root.
fn get_vote_count(
&self,
latest_votes: &HashMap<Hash256, u64>,
block_root: &Hash256,
) -> Result<u64, ForkChoiceError> {
let mut count = 0;
let block_slot = self
.block_store
.get_deserialized(&block_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*block_root))?
.slot();
for (target_hash, votes) in latest_votes.iter() {
let (root_at_slot, _) = self
.block_store
.block_at_slot(&block_root, block_slot)?
.ok_or(ForkChoiceError::MissingBeaconBlock(*block_root))?;
if root_at_slot == *target_hash {
count += votes;
}
}
Ok(count)
}
}
impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
/// Process when a block is added
fn add_block(
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
) -> Result<(), ForkChoiceError> {
// build the children hashmap
// add the new block to the children of parent
(*self
.children
.entry(block.parent_root)
.or_insert_with(|| vec![]))
.push(block_hash.clone());
// complete
Ok(())
}
fn add_attestation(
&mut self,
validator_index: u64,
target_block_root: &Hash256,
) -> Result<(), ForkChoiceError> {
// simply add the attestation to the latest_attestation_target if the block_height is
// larger
let attestation_target = self
.latest_attestation_targets
.entry(validator_index)
.or_insert_with(|| *target_block_root);
// if we already have a value
if attestation_target != target_block_root {
// get the height of the target block
let block_height = self
.block_store
.get_deserialized(&target_block_root)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*target_block_root))?
.slot()
.height(Slot::from(GENESIS_SLOT));
// get the height of the past target block
let past_block_height = self
.block_store
.get_deserialized(&attestation_target)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*attestation_target))?
.slot()
.height(Slot::from(GENESIS_SLOT));
// update the attestation only if the new target is higher
if past_block_height < block_height {
*attestation_target = *target_block_root;
}
}
Ok(())
}
/// A very inefficient implementation of LMD ghost.
fn find_head(&mut self, justified_block_start: &Hash256) -> Result<Hash256, ForkChoiceError> {
let start = self
.block_store
.get_deserialized(&justified_block_start)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?;
let start_state_root = start.state_root();
let latest_votes = self.get_latest_votes(&start_state_root, start.slot())?;
let mut head_hash = Hash256::zero();
loop {
let mut head_vote_count = 0;
let children = match self.children.get(&head_hash) {
Some(children) => children,
// we have found the head, exit
None => break,
};
for child_hash in children {
let vote_count = self.get_vote_count(&latest_votes, &child_hash)?;
if vote_count > head_vote_count {
head_hash = *child_hash;
head_vote_count = vote_count;
}
}
}
Ok(head_hash)
}
}

4
eth2/types/src/lib.rs
View File

@ -24,7 +24,7 @@ pub mod readers;
pub mod shard_reassignment_record;
pub mod slashable_attestation;
pub mod slashable_vote_data;
pub mod slot_epoch;
pub mod slot_epoch_height;
pub mod spec;
pub mod validator;
pub mod validator_registry;
@ -55,7 +55,7 @@ pub use crate::proposal_signed_data::ProposalSignedData;
pub use crate::proposer_slashing::ProposerSlashing;
pub use crate::slashable_attestation::SlashableAttestation;
pub use crate::slashable_vote_data::SlashableVoteData;
pub use crate::slot_epoch::{Epoch, Slot};
pub use crate::slot_epoch_height::{Epoch, Slot};
pub use crate::spec::ChainSpec;
pub use crate::validator::{StatusFlags as ValidatorStatusFlags, Validator};
pub use crate::validator_registry_delta_block::ValidatorRegistryDeltaBlock;

57
eth2/types/src/slot_epoch.rs → eth2/types/src/slot_epoch_height.rs
View File

@ -1,14 +1,14 @@
/// The `Slot` and `Epoch` types are defined as newtypes over u64 to enforce type-safety between
/// the two types.
/// The `Slot` `Epoch`, `Height` types are defined as newtypes over u64 to enforce type-safety between
/// the three types.
///
/// `Slot` and `Epoch` have implementations which permit conversion, comparison and math operations
/// `Slot`, `Epoch` and `Height` have implementations which permit conversion, comparison and math operations
/// between each and `u64`, however specifically not between each other.
///
/// All math operations on `Slot` and `Epoch` are saturating, they never wrap.
///
/// It would be easy to define `PartialOrd` and other traits generically across all types which
/// implement `Into<u64>`, however this would allow operations between `Slots` and `Epochs` which
/// may lead to programming errors which are not detected by the compiler.
/// implement `Into<u64>`, however this would allow operations between `Slots`, `Epochs` and
/// `Heights` which may lead to programming errors which are not detected by the compiler.
use crate::test_utils::TestRandom;
use rand::RngCore;
use serde_derive::Serialize;
@ -42,6 +42,23 @@ macro_rules! impl_from_into_u64 {
};
}
// need to truncate for some fork-choice algorithms
macro_rules! impl_into_u32 {
($main: ident) => {
impl Into<u32> for $main {
fn into(self) -> u32 {
self.0 as u32
}
}
impl $main {
pub fn as_u32(&self) -> u32 {
self.0 as u32
}
}
};
}
macro_rules! impl_from_into_usize {
($main: ident) => {
impl From<usize> for $main {
@ -269,13 +286,21 @@ macro_rules! impl_common {
};
}
/// Beacon block slot.
#[derive(Eq, Debug, Clone, Copy, Default, Serialize)]
pub struct Slot(u64);
/// Beacon block height, effectively `Slot/GENESIS_START_BLOCK`.
#[derive(Eq, Debug, Clone, Copy, Default, Serialize)]
pub struct Height(u64);
/// Beacon Epoch, effectively `Slot / EPOCH_LENGTH`.
#[derive(Eq, Debug, Clone, Copy, Default, Serialize)]
pub struct Epoch(u64);
impl_common!(Slot);
impl_common!(Height);
impl_into_u32!(Height); // height can be converted to u32
impl_common!(Epoch);
impl Slot {
@ -287,11 +312,33 @@ impl Slot {
Epoch::from(self.0 / epoch_length)
}
pub fn height(self, genesis_slot: Slot) -> Height {
Height::from(self.0.saturating_sub(genesis_slot.as_u64()))
}
pub fn max_value() -> Slot {
Slot(u64::max_value())
}
}
impl Height {
pub fn new(slot: u64) -> Height {
Height(slot)
}
pub fn slot(self, genesis_slot: Slot) -> Slot {
Slot::from(self.0.saturating_add(genesis_slot.as_u64()))
}
pub fn epoch(self, genesis_slot: u64, epoch_length: u64) -> Epoch {
Epoch::from(self.0.saturating_add(genesis_slot) / epoch_length)
}
pub fn max_value() -> Height {
Height(u64::max_value())
}
}
impl Epoch {
pub fn new(slot: u64) -> Epoch {
Epoch(slot)