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Merge pull request #112 from ethereum/vitalik9 

Implementation of alternate withdrawal mechanism (issue #91)
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Hsiao-Wei Wang 2018-11-19 12:51:57 +09:00 committed by GitHub
parent e5a9d4e547 54eeb49831
commit a274432889
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1 changed files with 27 additions and 14 deletions
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41
specs/core/0_beacon-chain.md
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@ -44,7 +44,9 @@ The primary source of load on the beacon chain are "attestations". Attestations
| `MIN_VALIDATOR_SET_CHANGE_INTERVAL` | 2**8 (= 256) | slots | ~1.1 hours | | `MIN_VALIDATOR_SET_CHANGE_INTERVAL` | 2**8 (= 256) | slots | ~1.1 hours |
| `RANDAO_SLOTS_PER_LAYER` | 2**12 (= 4096) | slots | ~18 hours | | `RANDAO_SLOTS_PER_LAYER` | 2**12 (= 4096) | slots | ~18 hours |
| `SQRT_E_DROP_TIME` | 2**16 (= 65,536) | slots | ~12 days | | `SQRT_E_DROP_TIME` | 2**16 (= 65,536) | slots | ~12 days |
| `WITHDRAWAL_PERIOD` | 2**19 (= 524,288) | slots | ~97 days | | `MIN_WITHDRAWAL_PERIOD` | 2**12 (= 4096) | slots | ~18 hours |
| `WITHDRAWALS_PER_CYCLE` | 8 | - | 4.3m ETH in ~6 months |
| `COLLECTIVE_PENALTY_CALCULATION_PERIOD` | 2**19 (= 524,288) | slots | ~3 months |
| `DELETION_PERIOD` | 2**21 (= 2,097,152) | slots | ~1.06 years | | `DELETION_PERIOD` | 2**21 (= 2,097,152) | slots | ~1.06 years |
| `SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD` | 2**16 (= 65,536) | slots | ~12 days | | `SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD` | 2**16 (= 65,536) | slots | ~12 days |
| `BASE_REWARD_QUOTIENT` | 2**15 (= 32,768) | — | | `BASE_REWARD_QUOTIENT` | 2**15 (= 32,768) | — |
@ -211,6 +213,8 @@ The `BeaconState` has the following fields:
'deposits_penalized_in_period': ['uint32'], 'deposits_penalized_in_period': ['uint32'],
# Hash chain of validator set changes (for light clients to easily track deltas) # Hash chain of validator set changes (for light clients to easily track deltas)
'validator_set_delta_hash_chain': 'hash32' 'validator_set_delta_hash_chain': 'hash32'
# Current sequence number for withdrawals
'current_exit_seq': 'uint64',
# Genesis time # Genesis time
'genesis_time': 'uint64', 'genesis_time': 'uint64',
# PoW chain reference # PoW chain reference
@ -251,6 +255,8 @@ A `ValidatorRecord` has the following fields:
'status': 'uint8', 'status': 'uint8',
# Slot when validator exited (or 0) # Slot when validator exited (or 0)
'exit_slot': 'uint64' 'exit_slot': 'uint64'
# Sequence number when validator exited (or 0)
'exit_seq': 'uint64'
} }
``` ```
@ -622,6 +628,7 @@ def on_startup(initial_validator_entries: List[Any], genesis_time: uint64, pow_h
deposits_penalized_in_period=[], deposits_penalized_in_period=[],
next_shuffling_seed=b'\x00'*32, next_shuffling_seed=b'\x00'*32,
validator_set_delta_hash_chain=bytes([0] * 32), # stub validator_set_delta_hash_chain=bytes([0] * 32), # stub
current_exit_seq=0,
genesis_time=genesis_time, genesis_time=genesis_time,
known_pow_hash_chain_tip=pow_hash_chain_tip, known_pow_hash_chain_tip=pow_hash_chain_tip,
processed_pow_hash_chain_tip=pow_hash_chain_tip, processed_pow_hash_chain_tip=pow_hash_chain_tip,
@ -682,7 +689,8 @@ def add_validator(validators: List[ValidatorRecord],
randao_last_change=current_slot, randao_last_change=current_slot,
balance=DEPOSIT_SIZE * GWEI_PER_ETH, balance=DEPOSIT_SIZE * GWEI_PER_ETH,
status=status, status=status,
exit_slot=0 exit_slot=0,
exit_seq=0
) )
index = min_empty_validator(validators) index = min_empty_validator(validators)
if index is None: if index is None:
@ -699,9 +707,11 @@ def add_validator(validators: List[ValidatorRecord],
def exit_validator(index, state, penalize, current_slot): def exit_validator(index, state, penalize, current_slot):
validator = state.validators[index] validator = state.validators[index]
validator.exit_slot = current_slot validator.exit_slot = current_slot
validator.exit_seq = state.current_exit_seq
state.current_exit_seq += 1
if penalize: if penalize:
validator.status = PENALIZED validator.status = PENALIZED
state.deposits_penalized_in_period[current_slot // WITHDRAWAL_PERIOD] += validator.balance state.deposits_penalized_in_period[current_slot // COLLECTIVE_PENALTY_CALCULATION_PERIOD] += validator.balance
else: else:
validator.status = PENDING_EXIT validator.status = PENDING_EXIT
add_validator_set_change_record(state, index, validator.pubkey, EXIT) add_validator_set_change_record(state, index, validator.pubkey, EXIT)
@ -1006,7 +1016,7 @@ def change_validators(validators: List[ValidatorRecord], current_slot: int) -> N
break break
# Calculate the total ETH that has been penalized in the last ~2-3 withdrawal periods # Calculate the total ETH that has been penalized in the last ~2-3 withdrawal periods
period_index = current_slot // WITHDRAWAL_PERIOD period_index = current_slot // COLLECTIVE_PENALTY_CALCULATION_PERIOD
total_penalties = ( total_penalties = (
(state.deposits_penalized_in_period[period_index]) + (state.deposits_penalized_in_period[period_index]) +
(state.deposits_penalized_in_period[period_index - 1] if period_index >= 1 else 0) + (state.deposits_penalized_in_period[period_index - 1] if period_index >= 1 else 0) +
@ -1014,17 +1024,20 @@ def change_validators(validators: List[ValidatorRecord], current_slot: int) -> N
) )
# Separate loop to withdraw validators that have been logged out for long enough, and # Separate loop to withdraw validators that have been logged out for long enough, and
# calculate their penalties if they were slashed # calculate their penalties if they were slashed
for i in range(len(validators)):
if validators[i].status in (PENDING_WITHDRAW, PENALIZED) and current_slot >= validators[i].exit_slot + WITHDRAWAL_PERIOD:
if validators[i].status == PENALIZED:
validators[i].balance -= validators[i].balance * min(total_penalties * 3, total_balance) // total_balance
validators[i].status = WITHDRAWN
validators[i].exit_slot = current_slot
withdraw_amount = validators[i].balance def withdrawable(v):
... return v.status in (PENDING_WITHDRAW, PENALIZED) and current_slot >= v.exit_slot + MIN_WITHDRAWAL_PERIOD
# STUB: withdraw to shard chain
withdrawable_validators = sorted(filter(withdrawable, validators), key=lambda v: v.exit_seq)
for v in withdrawable_validators[:WITHDRAWALS_PER_CYCLE]:
if v.status == PENALIZED:
v.balance -= v.balance * min(total_penalties * 3, total_balance) // total_balance
v.status = WITHDRAWN
v.exit_slot = current_slot
withdraw_amount = v.balance
...
# STUB: withdraw to shard chain
``` ```
* Set `state.validator_set_change_slot = state.last_state_recalculation_slot` * Set `state.validator_set_change_slot = state.last_state_recalculation_slot`