Changed crosslink mechanics (#111)
* Changed crosslink mechanics * Update beacon-chain.md * make start_shard clearer
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vbuterin
Danny Ryan
parent
b8d85ef8bd
commit
024ba75fb3
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@ -210,6 +210,8 @@ The `CrystallizedState` has the following fields:
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# Persistent shard committees
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'persistent_committees': [['uint24']],
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'persistent_committee_reassignments': [ShardReassignmentRecord],
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# Randao seed used for next shuffling
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'next_shuffling_seed': 'hash32',
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# Total deposits penalized in the given withdrawal period
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'deposits_penalized_in_period': ['uint32'],
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# Hash chain of validator set changes (for light clients to easily track deltas)
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@ -249,8 +251,6 @@ A `CrosslinkRecord` has the following fields:
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```python
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{
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# Flag indicating if crosslink was updated since most recent validator change
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'recently_changed': 'bool',
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# Slot number
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'slot': 'uint64',
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# Shard chain block hash
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@ -526,7 +526,6 @@ def on_startup(initial_validator_entries: List[Any]) -> Tuple[CrystallizedState,
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x = get_new_shuffling(bytes([0] * 32), validators, 0)
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crosslinks = [
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CrosslinkRecord(
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recently_changed=False,
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slot=0,
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hash=bytes([0] * 32)
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)
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@ -544,6 +543,7 @@ def on_startup(initial_validator_entries: List[Any]) -> Tuple[CrystallizedState,
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persistent_committees=split(shuffle(validators, bytes([0] * 32)), SHARD_COUNT),
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persistent_committee_reassignments=[],
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deposits_penalized_in_period=[],
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next_shuffling_seed=b'\x00'*32,
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validator_set_delta_hash_chain=bytes([0] * 32), # stub
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pre_fork_version=INITIAL_FORK_VERSION,
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post_fork_version=INITIAL_FORK_VERSION,
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@ -702,7 +702,7 @@ For every `(shard, shard_block_hash)` tuple:
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* Let `total_balance_attesting_to_h` be the total balance of validators that attested to the shard block with hash `shard_block_hash`.
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* Let `total_committee_balance` be the total balance in the committee of validators that could have attested to the shard block with hash `shard_block_hash`.
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* If `3 * total_balance_attesting_to_h >= 2 * total_committee_balance` and `recently_changed is False`, set `crosslinks[shard] = CrosslinkRecord(recently_changed=True, slot=last_state_recalculation_slot + CYCLE_LENGTH, hash=shard_block_hash)`.
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* If `3 * total_balance_attesting_to_h >= 2 * total_committee_balance`, set `crosslinks[shard] = CrosslinkRecord(slot=last_state_recalculation_slot + CYCLE_LENGTH, hash=shard_block_hash)`.
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#### Balance recalculations related to FFG rewards
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@ -732,13 +732,13 @@ In addition, validators with `status == PENALIZED` lose `B // reward_quotient +
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For every shard number `shard` for which a crosslink committee exists in the cycle prior to the most recent cycle (`last_state_recalculation_slot - CYCLE_LENGTH ... last_state_recalculation_slot - 1`), let `V` be the corresponding validator set. Let `B` be the balance of any given validator whose balance we are adjusting, not including any balance changes from this round of state recalculation. For each `shard`, `V`:
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* Let `total_balance_of_v` be the total balance of `V`.
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* Let `winning_shard_hash` be the hash that the largest total deposits signed for the `shard` during the cycle.
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* Define a "participating validator" as a member of `V` that signed a crosslink of `winning_shard_hash`.
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* Let `total_balance_of_v_participating` be the total balance of the subset of `V` that participated.
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* Let `time_since_last_confirmation = block.slot - crosslinks[shard].slot`.
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* If `recently_changed is False`, adjust balances as follows:
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* Adjust balances as follows:
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* Participating validators gain `B // reward_quotient * (2 * total_balance_of_v_participating - total_balance_of_v) // total_balance_of_v`.
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* Non-participating validators lose `B // reward_quotient + B * time_since_last_confirmation // quadratic_penalty_quotient`.
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In addition, validators with `status == PENALIZED` lose `B // reward_quotient + B * sum([time_since_last_confirmation(c) for c in committees]) // len(committees) // quadratic_penalty_quotient`, where `committees` is the set of committees processed and `time_since_last_confirmation(c)` is the value of `time_since_last_confirmation` in committee `c`.
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* Non-participating validators lose `B // reward_quotient`.
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#### Process penalties, logouts and other special objects
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@ -815,10 +815,17 @@ def change_validators(validators: List[ValidatorRecord]) -> None:
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```
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* Set `crystallized_state.validator_set_change_slot = crystallized_state.last_state_recalculation_slot`
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* For all `c` in `crystallized_state.crosslinks`, set `c.recently_changed = False`
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* Set `shard_and_committee_for_slots[:CYCLE_LENGTH] = shard_and_committee_for_slots[CYCLE_LENGTH:]`
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* Let `next_start_shard = (shard_and_committee_for_slots[-1][-1].shard + 1) % SHARD_COUNT`
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* Set `shard_and_committee_for_slots[CYCLE_LENGTH:] = get_new_shuffling(active_state.randao_mix, validators, next_start_shard)`
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* Set `shard_and_committee_for_slots[CYCLE_LENGTH:] = get_new_shuffling(crystallized_state.next_shuffling_seed, validators, next_start_shard)`
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* Set `crystallized_state.next_shuffling_seed = active_state.randao_mix`
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### If a validator set change does NOT happen
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* Set `shard_and_committee_for_slots[:CYCLE_LENGTH] = shard_and_committee_for_slots[CYCLE_LENGTH:]`
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* Let `time_since_finality = block.slot - crystallized_state.validator_set_change_slot`
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* Let `start_shard = shard_and_committee_for_slots[0][0].shard`
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* If `time_since_finality * CYCLE_LENGTH <= MIN_VALIDATOR_SET_CHANGE_INTERVAL` or `time_since_finality` is an exact power of 2, set `shard_and_committee_for_slots[CYCLE_LENGTH:] = get_new_shuffling(crystallized_state.next_shuffling_seed, validators, start_shard)` and set `crystallized_state.next_shuffling_seed = active_state.randao_mix`. Note that `start_shard` is not changed from last cycle.
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#### Finally...
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@ -826,7 +833,6 @@ def change_validators(validators: List[ValidatorRecord]) -> None:
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* Empty the `active_state.pending_specials` list
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* For any validator with index `v` with balance less than `MIN_ONLINE_DEPOSIT_SIZE` and status `ACTIVE`, run `exit_validator(v, crystallized_state, penalize=False, current_slot=block.slot)`
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* Set `active_state.recent_block_hashes = active_state.recent_block_hashes[CYCLE_LENGTH:]`
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* If a validator set change did _not_ occur during this state recalculation, set `shard_and_committee_for_slots[:CYCLE_LENGTH] = shard_and_committee_for_slots[CYCLE_LENGTH:]`
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* Set `crystallized_state.last_state_recalculation_slot += CYCLE_LENGTH`
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For any validator that was added or removed from the active validator list during this state recalculation:
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