Merge pull request #597 from ethereum/reward-clarifications

Reward clarifications/fix
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Danny Ryan 2019-02-13 08:21:30 -07:00 committed by GitHub
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@ -1826,24 +1826,21 @@ The steps below happen when `(state.slot + 1) % EPOCH_LENGTH == 0`.
[Validators](#dfn-Validator) attesting during the current epoch:
* Let `current_total_balance = get_total_balance(state, get_active_validator_indices(state.validator_registry, current_epoch))`.
* Let `current_epoch_attestations = [a for a in state.latest_attestations if current_epoch == slot_to_epoch(a.data.slot)]`. (Note: this is the set of attestations of slots in the epoch `current_epoch`, _not_ attestations that got included in the chain during the epoch `current_epoch`.)
* Let `current_epoch_attestations = [a for a in state.latest_attestations if current_epoch == slot_to_epoch(a.data.slot)]`. (Note: Each of these attestations votes for the current justified epoch/block root because of the [attestation block validity rules](#attestations-1).)
* Validators justifying the epoch boundary block at the start of the current epoch:
* Let `current_epoch_boundary_attestations = [a for a in current_epoch_attestations if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(current_epoch)) and a.data.justified_epoch == state.justified_epoch]`.
* Let `current_epoch_boundary_attestations = [a for a in current_epoch_attestations if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(current_epoch))]`.
* Let `current_epoch_boundary_attester_indices` be the union of the [validator](#dfn-validator) index sets given by `[get_attestation_participants(state, a.data, a.aggregation_bitfield) for a in current_epoch_boundary_attestations]`.
* Let `current_epoch_boundary_attesting_balance = get_total_balance(state, current_epoch_boundary_attester_indices)`.
[Validators](#dfn-Validator) attesting during the previous epoch:
* Let `previous_total_balance = get_total_balance(state, get_active_validator_indices(state.validator_registry, previous_epoch))`.
* Validators that made an attestation during the previous epoch:
* Let `previous_epoch_attestations = [a for a in state.latest_attestations if previous_epoch == slot_to_epoch(a.data.slot)]`.
* Validators that made an attestation during the previous epoch, targeting the previous justified slot:
* Let `previous_epoch_attestations = [a for a in state.latest_attestations if previous_epoch == slot_to_epoch(a.data.slot)]`. (Note: Each of these attestations votes for the previous justified epoch/block root because of the [attestation block validity rules](#attestations-1).)
* Let `previous_epoch_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.aggregation_bitfield) for a in previous_epoch_attestations]`.
* Validators targeting the previous justified slot:
* Let `previous_epoch_justified_attestations = [a for a in current_epoch_attestations + previous_epoch_attestations if a.data.justified_epoch == state.previous_justified_epoch]`.
* Let `previous_epoch_justified_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.aggregation_bitfield) for a in previous_epoch_justified_attestations]`.
* Let `previous_epoch_justified_attesting_balance = get_total_balance(state, previous_epoch_justified_attester_indices)`.
* Let `previous_epoch_attesting_balance = get_total_balance(state, previous_epoch_attester_indices)`.
* Validators justifying the epoch boundary block at the start of the previous epoch:
* Let `previous_epoch_boundary_attestations = [a for a in previous_epoch_justified_attestations if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(previous_epoch))]`.
* Let `previous_epoch_boundary_attestations = [a for a in previous_epoch_attestations if a.data.epoch_boundary_root == get_block_root(state, get_epoch_start_slot(previous_epoch))]`.
* Let `previous_epoch_boundary_attester_indices` be the union of the validator index sets given by `[get_attestation_participants(state, a.data, a.aggregation_bitfield) for a in previous_epoch_boundary_attestations]`.
* Let `previous_epoch_boundary_attesting_balance = get_total_balance(state, previous_epoch_boundary_attester_indices)`.
* Validators attesting to the expected beacon chain head during the previous epoch:
@ -1908,17 +1905,19 @@ First, we define some additional helpers:
* Let `base_reward(state, index) = get_effective_balance(state, index) // base_reward_quotient // 5` for any validator with the given `index`.
* Let `inactivity_penalty(state, index, epochs_since_finality) = base_reward(state, index) + get_effective_balance(state, index) * epochs_since_finality // INACTIVITY_PENALTY_QUOTIENT // 2` for any validator with the given `index`.
Note: When applying penalties in the following balance recalculations implementers should make sure the `uint64` does not underflow.
##### Justification and finalization
Note: When applying penalties in the following balance recalculations implementers should make sure the `uint64` does not underflow.
Note: Rewards and penalties are for participation in the previous epoch, so the "active validator" set is drawn from `get_active_validator_indices(state.validator_registry, previous_epoch)`.
* Let `epochs_since_finality = next_epoch - state.finalized_epoch`.
Case 1: `epochs_since_finality <= 4`:
* Expected FFG source:
* Any [validator](#dfn-validator) `index` in `previous_epoch_justified_attester_indices` gains `base_reward(state, index) * previous_epoch_justified_attesting_balance // previous_total_balance`.
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_justified_attester_indices` loses `base_reward(state, index)`.
* Any [validator](#dfn-validator) `index` in `previous_epoch_attester_indices` gains `base_reward(state, index) * previous_epoch_attesting_balance // previous_total_balance`.
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_attester_indices` loses `base_reward(state, index)`.
* Expected FFG target:
* Any [validator](#dfn-validator) `index` in `previous_epoch_boundary_attester_indices` gains `base_reward(state, index) * previous_epoch_boundary_attesting_balance // previous_total_balance`.
* Any [active validator](#dfn-active-validator) `index` not in `previous_epoch_boundary_attester_indices` loses `base_reward(state, index)`.
@ -1930,10 +1929,10 @@ Case 1: `epochs_since_finality <= 4`:
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_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`, 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