68 lines
3.0 KiB
Nim
68 lines
3.0 KiB
Nim
# beacon_chain
|
|
# Copyright (c) 2018-2023 Status Research & Development GmbH
|
|
# Licensed and distributed under either of
|
|
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
|
|
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
|
|
# at your option. This file may not be copied, modified, or distributed except according to those terms.
|
|
|
|
{.push raises: [].}
|
|
|
|
import
|
|
./datatypes/base, ./beaconstate, ./forks, ./helpers
|
|
|
|
# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.0/specs/phase0/weak-subjectivity.md#configuration
|
|
const SAFETY_DECAY* = 10'u64
|
|
|
|
# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.0/specs/phase0/weak-subjectivity.md#compute_weak_subjectivity_period
|
|
func compute_weak_subjectivity_period(
|
|
cfg: RuntimeConfig, state: ForkyBeaconState): uint64 =
|
|
## Returns the weak subjectivity period for the current ``state``.
|
|
## This computation takes into account the effect of:
|
|
## - validator set churn
|
|
## (bounded by ``get_validator_churn_limit()`` per epoch), and
|
|
## - validator balance top-ups
|
|
## (bounded by ``MAX_DEPOSITS * SLOTS_PER_EPOCH`` per epoch).
|
|
## A detailed calculation can be found at:
|
|
## https://github.com/runtimeverification/beacon-chain-verification/blob/master/weak-subjectivity/weak-subjectivity-analysis.pdf
|
|
var
|
|
cache: StateCache
|
|
ws_period = cfg.MIN_VALIDATOR_WITHDRAWABILITY_DELAY
|
|
let
|
|
N = get_active_validator_indices_len(state, get_current_epoch(state))
|
|
t = (get_total_active_balance(state, cache) div N).toEther
|
|
const T = MAX_EFFECTIVE_BALANCE.toEther
|
|
let delta = cfg.get_validator_churn_limit(state, cache)
|
|
const
|
|
Delta = MAX_DEPOSITS * SLOTS_PER_EPOCH
|
|
D = SAFETY_DECAY
|
|
|
|
if T * (200 + 3 * D) < t * (200 + 12 * D):
|
|
let
|
|
epochs_for_validator_set_churn =
|
|
N * (t * (200 + 12 * D) - T * (200 + 3 * D)) div
|
|
(600 * delta * (2 * t + T))
|
|
epochs_for_balance_top_ups =
|
|
N * (200 + 3 * D) div (600 * Delta)
|
|
ws_period += max(epochs_for_validator_set_churn, epochs_for_balance_top_ups)
|
|
else:
|
|
ws_period += 3 * N * D * t div (200 * Delta * (T - t))
|
|
|
|
ws_period
|
|
|
|
# https://github.com/ethereum/consensus-specs/blob/v1.4.0-beta.0/specs/phase0/weak-subjectivity.md#is_within_weak_subjectivity_period
|
|
func is_within_weak_subjectivity_period*(cfg: RuntimeConfig, current_slot: Slot,
|
|
ws_state: ForkedHashedBeaconState,
|
|
ws_checkpoint: Checkpoint): bool =
|
|
## Clients may choose to validate the input state against the input Weak Subjectivity Checkpoint
|
|
doAssert getStateField(ws_state, latest_block_header).state_root ==
|
|
ws_checkpoint.root
|
|
doAssert epoch(getStateField(ws_state, slot)) == ws_checkpoint.epoch
|
|
|
|
let
|
|
ws_period = withState(ws_state):
|
|
cfg.compute_weak_subjectivity_period(forkyState.data)
|
|
ws_state_epoch = epoch(getStateField(ws_state, slot))
|
|
current_epoch = epoch(current_slot)
|
|
|
|
current_epoch <= ws_state_epoch + ws_period
|