electra_weak_subjectivity_table.py

"""
An updated version of the Eth2 Weak Subjectivity Period Calculation:
https://gist.github.com/adiasg/3aceab409b36aa9a9d9156c1baa3c248
"""

from remerkleable.basic import uint64

CHURN_LIMIT_QUOTIENT = uint64(65536)
EFFECTIVE_BALANCE_INCREMENT = uint64(1000000000)
ETH_TO_GWEI = uint64(10**9)
MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA = uint64(128000000000)
MIN_VALIDATOR_WITHDRAWABILITY_DELAY = uint64(256)
SAFETY_DECAY = uint64(10)

def get_balance_churn_limit(total_active_balance) -> uint64:
    """
    Return the churn limit for the current epoch.
    """
    churn = max(
        MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA,
        total_active_balance // CHURN_LIMIT_QUOTIENT
    )
    return churn - churn % EFFECTIVE_BALANCE_INCREMENT

def compute_weak_subjectivity_period(total_active_balance: uint64, balance_churn_limit: uint64) -> uint64:
    """
    Returns the weak subjectivity period for the current ``state``.
    This computation takes into account the effect of:
        - validator set churn (bounded by ``get_balance_churn_limit()`` per epoch)
    A detailed calculation can be found at:
    https://notes.ethereum.org/@CarlBeek/electra_weak_subjectivity
    """
    t = total_active_balance
    delta = balance_churn_limit
    epochs_for_validator_set_churn = SAFETY_DECAY * t // (2 * delta * 100)
    return MIN_VALIDATOR_WITHDRAWABILITY_DELAY + epochs_for_validator_set_churn

print("| Safety Decay | Total Active Balance (ETH) | Weak Sub. Period (Epochs) |")
print("| ----: | ----: | ----: |")
for exp in range(20, 26):
    total_active_balance_eth = uint64(2**exp)
    total_active_balance_gwei = total_active_balance_eth * ETH_TO_GWEI
    balance_churn_limit = get_balance_churn_limit(total_active_balance_gwei)
    weak_subjectivity_period = compute_weak_subjectivity_period(total_active_balance_gwei, balance_churn_limit)
    print(f"| {SAFETY_DECAY} | {total_active_balance_eth:,} | {weak_subjectivity_period:,} |")