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Merge branch 'master' into signature-scheme-update

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This commit is contained in:
Kirk Baird
2019-02-23 13:34:57 +11:00
parent 673c8ea388 c040ed7b11
commit a5cbda0b60
15 changed files with 636 additions and 187 deletions
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211
eth2/fork_choice/src/optimised_lmd_ghost.rs → eth2/fork_choice/src/bitwise_lmd_ghost.rs
View File

@@ -1,49 +1,25 @@
// 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 bit_vec;
extern crate fast_math;
use crate::{ForkChoice, ForkChoiceError};
use byteorder::{BigEndian, ByteOrder};
use bit_vec::BitVec;
use db::{
stores::{BeaconBlockStore, BeaconStateStore},
ClientDB,
};
use fast_math::log2_raw;
use log::{debug, trace};
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.
/// The optimised bitwise 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.
@@ -51,6 +27,13 @@ const EPOCH_LENGTH: u64 = 64;
// the comparison. Log2_raw takes 2ns according to the documentation.
#[inline]
fn log2_int(x: u32) -> u32 {
if x == 0 {
return 0;
}
assert!(
x <= std::f32::MAX as u32,
"Height too large for fast log in bitwise fork choice"
);
log2_raw(x as f32) as u32
}
@@ -58,8 +41,8 @@ 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> {
/// Stores the necessary data structures to run the optimised bitwise lmd ghost algorithm.
pub struct BitwiseLMDGhost<T: ClientDB + Sized> {
/// A cache of known ancestors at given heights for a specific block.
//TODO: Consider FnvHashMap
cache: HashMap<CacheKey<u32>, Hash256>,
@@ -78,7 +61,7 @@ pub struct OptimisedLMDGhost<T: ClientDB + Sized> {
max_known_height: SlotHeight,
}
impl<T> OptimisedLMDGhost<T>
impl<T> BitwiseLMDGhost<T>
where
T: ClientDB + Sized,
{
@@ -86,7 +69,7 @@ where
block_store: Arc<BeaconBlockStore<T>>,
state_store: Arc<BeaconStateStore<T>>,
) -> Self {
OptimisedLMDGhost {
BitwiseLMDGhost {
cache: HashMap::new(),
ancestors: vec![HashMap::new(); 16],
latest_attestation_targets: HashMap::new(),
@@ -103,6 +86,7 @@ where
&self,
state_root: &Hash256,
block_slot: Slot,
spec: &ChainSpec,
) -> Result<HashMap<Hash256, u64>, ForkChoiceError> {
// get latest votes
// Note: Votes are weighted by min(balance, MAX_DEPOSIT_AMOUNT) //
@@ -117,25 +101,31 @@ where
let active_validator_indices = get_active_validator_indices(
&current_state.validator_registry[..],
block_slot.epoch(EPOCH_LENGTH),
block_slot.epoch(spec.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;
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;
}
}
}
trace!("Latest votes: {:?}", latest_votes);
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: SlotHeight) -> Option<Hash256> {
fn get_ancestor(
&mut self,
block_hash: Hash256,
target_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
@@ -145,32 +135,31 @@ where
.expect("Should have returned already if None")
.slot;
block_slot.height(Slot::from(GENESIS_SLOT))
block_slot.height(spec.genesis_slot)
};
// verify we haven't exceeded the block height
if at_height >= block_height {
if at_height > block_height {
if target_height >= block_height {
if target_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());
let cache_key = CacheKey::new(&block_hash, target_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]
[log2_int((block_height - target_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)
self.get_ancestor(*ancestor_lookup, target_height, &spec)
} {
// add the result to the cache
self.cache.insert(cache_key, ancestor);
@@ -185,15 +174,17 @@ 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();
let mut total_vote_count = 0;
trace!("Clear winner at block height: {}", block_height);
// 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;
@@ -210,54 +201,62 @@ where
None
}
// Finds the best child, splitting children into a binary tree, based on their hashes
// Finds the best child, splitting children into a binary tree, based on their hashes (Bitwise
// LMD Ghost)
fn choose_best_child(&self, votes: &HashMap<Hash256, u64>) -> Option<Hash256> {
let mut bitmask = 0;
for bit in (0..=255).rev() {
if votes.is_empty() {
return None;
}
let mut bitmask: BitVec = BitVec::new();
// loop through all bits
for bit in 0..=256 {
let mut zero_votes = 0;
let mut one_votes = 0;
let mut single_candidate = None;
let mut single_candidate = (None, false);
trace!("Child vote length: {}", votes.len());
for (candidate, votes) in votes.iter() {
let candidate_uint = BigEndian::read_u32(candidate);
if candidate_uint >> (bit + 1) != bitmask {
let candidate_bit: BitVec = BitVec::from_bytes(&candidate);
// if the bitmasks don't match, exclude candidate
if !bitmask.iter().eq(candidate_bit.iter().take(bit)) {
trace!(
"Child: {} was removed in bit: {} with the bitmask: {:?}",
candidate,
bit,
bitmask
);
continue;
}
if (candidate_uint >> bit) % 2 == 0 {
if candidate_bit.get(bit) == Some(false) {
zero_votes += votes;
} else {
one_votes += votes;
}
if single_candidate.is_none() {
single_candidate = Some(candidate);
if single_candidate.0.is_none() {
single_candidate.0 = Some(candidate);
single_candidate.1 = true;
} else {
single_candidate = None;
single_candidate.1 = false;
}
}
bitmask = (bitmask * 2) + {
if one_votes > zero_votes {
1
} else {
0
}
};
if let Some(candidate) = single_candidate {
return Some(*candidate);
bitmask.push(one_votes > zero_votes);
if single_candidate.1 {
return Some(*single_candidate.0.expect("Cannot reach this"));
}
//TODO Remove this during benchmark after testing
assert!(bit >= 1);
}
// should never reach here
None
}
}
impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
impl<T: ClientDB + Sized> ForkChoice for BitwiseLMDGhost<T> {
fn add_block(
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
spec: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// get the height of the parent
let parent_height = self
@@ -265,7 +264,7 @@ 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(spec.genesis_slot);
let parent_hash = &block.parent_root;
@@ -295,22 +294,29 @@ 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
trace!(
"Adding attestation of validator: {:?} for block: {}",
validator_index,
target_block_root
);
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 {
trace!("Old attestation found: {:?}", attestation_target);
// 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));
.height(spec.genesis_slot);
// get the height of the past target block
let past_block_height = self
@@ -318,9 +324,10 @@ 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(spec.genesis_slot);
// update the attestation only if the new target is higher
if past_block_height < block_height {
trace!("Updating old attestation");
*attestation_target = *target_block_root;
}
}
@@ -328,25 +335,39 @@ 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> {
debug!(
"Starting optimised fork choice at block: {}",
justified_block_start
);
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 block_height = block_slot.height(spec.genesis_slot);
let mut current_head = *justified_block_start;
let mut latest_votes = self.get_latest_votes(&state_root, block_slot)?;
let mut latest_votes = self.get_latest_votes(&state_root, block_slot, spec)?;
// 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));
// begin searching for the head
loop {
debug!(
"Iteration for block: {} with vote length: {}",
current_head,
latest_votes.len()
);
// if there are no children, we are done, return the current_head
let children = match self.children.get(&current_head) {
Some(children) => children.clone(),
@@ -358,9 +379,11 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
let mut step =
power_of_2_below(self.max_known_height.saturating_sub(block_height).as_u32()) / 2;
while step > 0 {
trace!("Current Step: {}", step);
if let Some(clear_winner) = self.get_clear_winner(
&latest_votes,
block_height - (block_height % u64::from(step)) + u64::from(step),
spec,
) {
current_head = clear_winner;
break;
@@ -368,17 +391,23 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
step /= 2;
}
if step > 0 {
trace!("Found clear winner in log lookup");
}
// if our skip lookup failed and we only have one child, progress to that child
else if children.len() == 1 {
current_head = children[0];
trace!(
"Lookup failed, only one child, proceeding to child: {}",
current_head
);
}
// we need to find the best child path to progress down.
else {
trace!("Searching for best child");
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;
}
@@ -387,22 +416,30 @@ impl<T: ClientDB + Sized> ForkChoice for OptimisedLMDGhost<T> {
current_head = self
.choose_best_child(&child_votes)
.ok_or(ForkChoiceError::CannotFindBestChild)?;
trace!("Best child found: {}", current_head);
}
// No head was found, re-iterate
// update the block height for the next iteration
let block_height = self
// didn't find head yet, proceed to next iteration
// update block height
block_height = self
.block_store
.get_deserialized(&current_head)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*justified_block_start))?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(current_head))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(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));
for hash in latest_votes.keys() {
trace!(
"Ancestor for vote: {} at height: {} is: {:?}",
hash,
block_height,
self.get_ancestor(*hash, block_height, spec)
);
}
latest_votes.retain(|hash, _| {
self.get_ancestor(*hash, block_height, spec) == Some(current_head)
});
}
}
}

53
eth2/fork_choice/src/lib.rs
View File

@@ -1,57 +1,36 @@
// 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.
//! There are three implementations. One is the naive longest chain rule (primarily for testing
//! purposes). The other two 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
//! - [`bitwise_lmd_ghost`]: This is an optimised version of bitwise LMD-GHOST 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.
//!
//! [`longest-chain`]: struct.LongestChain.html
//! [`slow_lmd_ghost`]: struct.SlowLmdGhost.html
//! [`optimised_lmd_ghost`]: struct.OptimisedLmdGhost.html
//! [`protolambda_lmd_ghost`]: struct.ProtolambdaLmdGhost.html
//! [`bitwise_lmd_ghost`]: struct.OptimisedLmdGhost.html
extern crate db;
extern crate ssz;
extern crate types;
pub mod bitwise_lmd_ghost;
pub mod longest_chain;
pub mod optimised_lmd_ghost;
pub mod slow_lmd_ghost;
use db::stores::BeaconBlockAtSlotError;
use db::DBError;
use types::{BeaconBlock, Hash256};
use types::{BeaconBlock, ChainSpec, Hash256};
pub use bitwise_lmd_ghost::BitwiseLMDGhost;
pub use longest_chain::LongestChain;
pub use optimised_lmd_ghost::OptimisedLMDGhost;
pub use slow_lmd_ghost::SlowLMDGhost;
/// 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.
@@ -63,6 +42,7 @@ 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.
@@ -70,10 +50,15 @@ 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.
@@ -109,11 +94,11 @@ impl From<BeaconBlockAtSlotError> for ForkChoiceError {
}
/// Fork choice options that are currently implemented.
pub enum ForkChoiceAlgorithms {
pub enum ForkChoiceAlgorithm {
/// 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 bitwise LMD-GHOST by Vitalik.
BitwiseLMDGhost,
}

12
eth2/fork_choice/src/longest_chain.rs
View File

@@ -1,7 +1,7 @@
use crate::{ForkChoice, ForkChoiceError};
use db::{stores::BeaconBlockStore, ClientDB};
use std::sync::Arc;
use types::{BeaconBlock, Hash256, Slot};
use types::{BeaconBlock, ChainSpec, Hash256, Slot};
pub struct LongestChain<T>
where
@@ -30,6 +30,7 @@ impl<T: ClientDB + Sized> ForkChoice for LongestChain<T> {
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
_: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// add the block hash to head_block_hashes removing the parent if it exists
self.head_block_hashes
@@ -38,12 +39,17 @@ impl<T: ClientDB + Sized> ForkChoice for LongestChain<T> {
Ok(())
}
fn add_attestation(&mut self, _: u64, _: &Hash256) -> Result<(), ForkChoiceError> {
fn add_attestation(
&mut self,
_: u64,
_: &Hash256,
_: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// do nothing
Ok(())
}
fn find_head(&mut self, _: &Hash256) -> Result<Hash256, ForkChoiceError> {
fn find_head(&mut self, _: &Hash256, _: &ChainSpec) -> Result<Hash256, ForkChoiceError> {
let mut head_blocks: Vec<(usize, BeaconBlock)> = vec![];
/*
* Load all the head_block hashes from the DB as SszBeaconBlocks.

96
eth2/fork_choice/src/slow_lmd_ghost.rs
View File

@@ -1,23 +1,3 @@
// 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};
@@ -25,21 +5,16 @@ use db::{
stores::{BeaconBlockStore, BeaconStateStore},
ClientDB,
};
use log::{debug, trace};
use std::collections::HashMap;
use std::sync::Arc;
use types::{
readers::BeaconBlockReader, validator_registry::get_active_validator_indices, BeaconBlock,
Hash256, Slot,
ChainSpec, Hash256, Slot,
};
//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
@@ -56,12 +31,15 @@ impl<T> SlowLMDGhost<T>
where
T: ClientDB + Sized,
{
pub fn new(block_store: BeaconBlockStore<T>, state_store: BeaconStateStore<T>) -> Self {
pub fn new(
block_store: Arc<BeaconBlockStore<T>>,
state_store: Arc<BeaconStateStore<T>>,
) -> Self {
SlowLMDGhost {
latest_attestation_targets: HashMap::new(),
children: HashMap::new(),
block_store: Arc::new(block_store),
state_store: Arc::new(state_store),
block_store,
state_store,
}
}
@@ -71,6 +49,7 @@ where
&self,
state_root: &Hash256,
block_slot: Slot,
spec: &ChainSpec,
) -> Result<HashMap<Hash256, u64>, ForkChoiceError> {
// get latest votes
// Note: Votes are weighted by min(balance, MAX_DEPOSIT_AMOUNT) //
@@ -84,21 +63,22 @@ where
.ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
let active_validator_indices = get_active_validator_indices(
&current_state.validator_registry,
block_slot.epoch(EPOCH_LENGTH),
&current_state.validator_registry[..],
block_slot.epoch(spec.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;
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;
}
}
}
trace!("Latest votes: {:?}", latest_votes);
Ok(latest_votes)
}
@@ -117,12 +97,12 @@ where
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*block_root))?
.slot();
for (target_hash, votes) in latest_votes.iter() {
for (vote_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 {
.block_at_slot(&vote_hash, block_slot)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*block_root))?;
if root_at_slot == *block_root {
count += votes;
}
}
@@ -136,6 +116,7 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
&mut self,
block: &BeaconBlock,
block_hash: &Hash256,
_: &ChainSpec,
) -> Result<(), ForkChoiceError> {
// build the children hashmap
// add the new block to the children of parent
@@ -153,22 +134,29 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<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
trace!(
"Adding attestation of validator: {:?} for block: {}",
validator_index,
target_block_root
);
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 {
trace!("Old attestation found: {:?}", attestation_target);
// 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));
.height(spec.genesis_slot);
// get the height of the past target block
let past_block_height = self
@@ -176,9 +164,10 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
.get_deserialized(&attestation_target)?
.ok_or_else(|| ForkChoiceError::MissingBeaconBlock(*attestation_target))?
.slot()
.height(Slot::from(GENESIS_SLOT));
.height(spec.genesis_slot);
// update the attestation only if the new target is higher
if past_block_height < block_height {
trace!("Updating old attestation");
*attestation_target = *target_block_root;
}
}
@@ -186,7 +175,12 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
}
/// A very inefficient implementation of LMD ghost.
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> {
debug!("Running LMD Ghost Fork-choice rule");
let start = self
.block_store
.get_deserialized(&justified_block_start)?
@@ -194,12 +188,12 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
let start_state_root = start.state_root();
let latest_votes = self.get_latest_votes(&start_state_root, start.slot())?;
let latest_votes = self.get_latest_votes(&start_state_root, start.slot(), spec)?;
let mut head_hash = Hash256::zero();
let mut head_hash = *justified_block_start;
loop {
let mut head_vote_count = 0;
debug!("Iteration for block: {}", head_hash);
let children = match self.children.get(&head_hash) {
Some(children) => children,
@@ -207,8 +201,18 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
None => break,
};
// if we only have one child, use it
if children.len() == 1 {
trace!("Single child found.");
head_hash = children[0];
continue;
}
trace!("Children found: {:?}", children);
let mut head_vote_count = 0;
for child_hash in children {
let vote_count = self.get_vote_count(&latest_votes, &child_hash)?;
trace!("Vote count for child: {} is: {}", child_hash, vote_count);
if vote_count > head_vote_count {
head_hash = *child_hash;