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add current_epoch helper

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Danny Ryan 2019-01-26 07:31:09 -07:00
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specs/core/0_beacon-chain.md
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@ -61,6 +61,7 @@
- [`hash`](#hash)
- [`hash_tree_root`](#hash_tree_root)
- [`slot_to_epoch`](#slot_to_epoch)
- [`current_epoch`](#current_epoch)
- [`is_active_validator`](#is_active_validator)
- [`get_active_validator_indices`](#get_active_validator_indices)
- [`shuffle`](#shuffle)
@ -770,6 +771,14 @@ def slot_to_epoch(slot: int) -> int:
return slot // EPOCH_LENGTH
```
#### `current_epoch`
```python
def current_epoch(state: BeaconState) -> int:
return slot_to_epoch(state.slot)
```
#### `is_active_validator`
```python
def is_active_validator(validator: Validator, slot: int) -> bool:
@ -893,7 +902,7 @@ def get_shuffling(seed: Bytes32,
return split(shuffled_active_validator_indices, committees_per_slot * EPOCH_LENGTH)
```
**Invariant**: if `get_shuffling(seed, validators, epoch)` returns some value `x` for some `epoch <= slot_to_epoch(state.slot) + ENTRY_EXIT_DELAY`, it should return the same value `x` for the same `seed` and `epoch` and possible future modifications of `validators` forever in phase 0, and until the ~1 year deletion delay in phase 2 and in the future.
**Invariant**: if `get_shuffling(seed, validators, epoch)` returns some value `x` for some `epoch <= current_epoch(state) + ENTRY_EXIT_DELAY`, it should return the same value `x` for the same `seed` and `epoch` and possible future modifications of `validators` forever in phase 0, and until the ~1 year deletion delay in phase 2 and in the future.
**Note**: this definition and the next few definitions make heavy use of repetitive computing. Production implementations are expected to appropriately use caching/memoization to avoid redoing work.
@ -997,9 +1006,8 @@ def get_active_index_root(state: BeaconState,
"""
Returns the index root at a recent ``slot``.
"""
state_epoch = slot_to_epoch(state.slot)
assert state_epoch < epoch + LATEST_INDEX_ROOTS_LENGTH
assert epoch <= state_epoch
assert current_epoch(state) < epoch + LATEST_INDEX_ROOTS_LENGTH
assert epoch <= current_epoch(state)
return state.latest_index_roots[epoch % LATEST_INDEX_ROOTS_LENGTH]
```
@ -1428,13 +1436,13 @@ def exit_validator(state: BeaconState, index: int) -> None:
def penalize_validator(state: BeaconState, index: int) -> None:
exit_validator(state, index)
validator = state.validator_registry[index]
state.latest_penalized_balances[slot_to_epoch(state.slot) % LATEST_PENALIZED_EXIT_LENGTH] += get_effective_balance(state, index)
state.latest_penalized_balances[current_epoch(state) % LATEST_PENALIZED_EXIT_LENGTH] += get_effective_balance(state, index)
whistleblower_index = get_beacon_proposer_index(state, state.slot)
whistleblower_reward = get_effective_balance(state, index) // WHISTLEBLOWER_REWARD_QUOTIENT
state.validator_balances[whistleblower_index] += whistleblower_reward
state.validator_balances[index] -= whistleblower_reward
validator.penalized_epoch = slot_to_epoch(state.slot)
validator.penalized_epoch = current_epoch(state)
```
```python
@ -1594,16 +1602,15 @@ The steps below happen when `(state.slot + 1) % EPOCH_LENGTH == 0`.
### Helpers
* Let `current_epoch = slot_to_epoch(state.slot)`.
* Let `current_epoch_start_slot = current_epoch * EPOCH_LENGTH`.
* Let `next_epoch = slot_to_epoch(state.slot + 1)`.
* Let `current_epoch_start_slot = current_epoch(state) * EPOCH_LENGTH`.
* Let `next_epoch = current_epoch(state) + 1`.
* Let `next_epoch_start_slot = next_epoch * EPOCH_LENGTH`.
* Let `previous_epoch = current_epoch - 1 if current_epoch > slot_to_epoch(GENESIS_SLOT) else current_epoch`.
* Let `previous_epoch = current_epoch(state) - 1 if current_epoch(state) > slot_to_epoch(GENESIS_SLOT) else current_epoch(state)`.
* Let `previous_epoch_start_slot = previous_epoch * EPOCH_LENGTH`.
All [validators](#dfn-validator):
* Let `active_validator_indices = get_active_validator_indices(state.validator_registry, current_epoch)`.
* Let `active_validator_indices = get_active_validator_indices(state.validator_registry, current_epoch(state))`.
* Let `total_balance = sum([get_effective_balance(state, i) for i in active_validator_indices])`.
[Validators](#dfn-Validator) attesting during the current epoch:
@ -1650,7 +1657,7 @@ Define the following helpers to process attestation inclusion rewards and inclus
### Eth1 data
If `slot_to_epoch(state.slot) % ETH1_DATA_VOTING_PERIOD == 0`:
If `current_epoch(state) % ETH1_DATA_VOTING_PERIOD == 0`:
* Set `state.latest_eth1_data = eth1_data_vote.data` if `eth1_data_vote.vote_count * 2 > ETH1_DATA_VOTING_PERIOD * EPOCH_LENGTH` for some `eth1_data_vote` in `state.eth1_data_votes`.
* Set `state.eth1_data_votes = []`.
@ -1715,7 +1722,7 @@ Case 2: `epochs_since_finality > 4`:
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_justified_attester_indices`, loses `inactivity_penalty(state, index, epochs_since_finality)`.
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_boundary_attester_indices`, loses `inactivity_penalty(state, index, epochs_since_finality)`.
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_head_attester_indices`, loses `base_reward(state, index)`.
* Any [active_validator](#dfn-active-validator) `index` with `validator.penalized_epoch <= current_epoch`, loses `2 * inactivity_penalty(state, index, epochs_since_finality) + base_reward(state, index)`.
* Any [active_validator](#dfn-active-validator) `index` with `validator.penalized_epoch <= current_epoch(state)`, loses `2 * inactivity_penalty(state, index, epochs_since_finality) + base_reward(state, index)`.
* Any [validator](#dfn-validator) `index` in `previous_epoch_attester_indices` loses `base_reward(state, index) - base_reward(state, index) * MIN_ATTESTATION_INCLUSION_DELAY // inclusion_distance(state, index)`
#### Attestation inclusion
@ -1739,7 +1746,7 @@ def process_ejections(state: BeaconState) -> None:
Iterate through the validator registry
and eject active validators with balance below ``EJECTION_BALANCE``.
"""
for index in get_active_validator_indices(state.validator_registry, current_epoch):
for index in get_active_validator_indices(state.validator_registry, current_epoch(state)):
if state.validator_balances[index] < EJECTION_BALANCE:
exit_validator(state, index)
```
@ -1767,7 +1774,7 @@ def update_validator_registry(state: BeaconState) -> None:
Note that this function mutates ``state``.
"""
# The active validators
active_validator_indices = get_active_validator_indices(state.validator_registry, current_epoch)
active_validator_indices = get_active_validator_indices(state.validator_registry, current_epoch(state))
# The total effective balance of active validators
total_balance = sum([get_effective_balance(state, i) for i in active_validator_indices])
@ -1801,7 +1808,7 @@ def update_validator_registry(state: BeaconState) -> None:
# Exit validator
exit_validator(state, index)
state.validator_registry_update_epoch = slot_to_epoch(state.slot)
state.validator_registry_update_epoch = current_epoch(state)
```
and perform the following updates:
@ -1812,7 +1819,7 @@ and perform the following updates:
If a validator registry update does _not_ happen do the following:
* Let `epochs_since_last_registry_change = current_epoch - state.validator_registry_update_epoch`.
* Let `epochs_since_last_registry_change = current_epoch(state) - state.validator_registry_update_epoch`.
* If `epochs_since_last_registry_change` is an exact power of 2:
* Set `state.current_calculation_epoch = next_epoch`.
* Set `state.current_epoch_seed = generate_seed(state, state.current_calculation_epoch)`
@ -1830,8 +1837,8 @@ def process_penalties_and_exits(state: BeaconState) -> None:
total_balance = sum([get_effective_balance(state, i) for i in active_validator_indices])
for index, validator in enumerate(state.validator_registry):
if slot_to_epoch(state.slot) == validator.penalized_epoch + LATEST_PENALIZED_EXIT_LENGTH // 2:
e = slot_to_epoch(state.slot) % LATEST_PENALIZED_EXIT_LENGTH
if current_epoch(state) == validator.penalized_epoch + LATEST_PENALIZED_EXIT_LENGTH // 2:
e = current_epoch(state) % LATEST_PENALIZED_EXIT_LENGTH
total_at_start = state.latest_penalized_balances[(e + 1) % LATEST_PENALIZED_EXIT_LENGTH]
total_at_end = state.latest_penalized_balances[e]
total_penalties = total_at_end - total_at_start
@ -1840,11 +1847,11 @@ def process_penalties_and_exits(state: BeaconState) -> None:
def eligible(index):
validator = state.validator_registry[index]
if validator.penalized_epoch <= slot_to_epoch(state.slot):
if validator.penalized_epoch <= current_epoch(state):
PENALIZED_WITHDRAWAL_EPOCHS = LATEST_PENALIZED_EXIT_LENGTH // 2
return slot_to_epoch(state.slot) >= validator.penalized_epoch + PENALIZED_WITHDRAWAL_EPOCHS
return current_epoch(state) >= validator.penalized_epoch + PENALIZED_WITHDRAWAL_EPOCHS
else:
return slot_to_epoch(state.slot) >= validator.exit_epoch + MIN_VALIDATOR_WITHDRAWAL_EPOCHS
return current_epoch(state) >= validator.exit_epoch + MIN_VALIDATOR_WITHDRAWAL_EPOCHS
all_indices = list(range(len(state.validator_registry)))
eligible_indices = filter(eligible, all_indices)
@ -1859,7 +1866,7 @@ def process_penalties_and_exits(state: BeaconState) -> None:
### Final updates
* Set `state.latest_penalized_balances[(next_epoch) % LATEST_PENALIZED_EXIT_LENGTH] = state.latest_penalized_balances[current_epoch % LATEST_PENALIZED_EXIT_LENGTH]`.
* Set `state.latest_penalized_balances[(next_epoch) % LATEST_PENALIZED_EXIT_LENGTH] = state.latest_penalized_balances[current_epoch(state) % LATEST_PENALIZED_EXIT_LENGTH]`.
* Remove any `attestation` in `state.latest_attestations` such that `attestation.data.slot < current_epoch_start_slot`.
## State root processing