From 9d18760521ae05c1edfd0ca6a1fb104c02506af9 Mon Sep 17 00:00:00 2001 From: Danny Ryan Date: Sun, 27 Jan 2019 09:56:26 -0700 Subject: [PATCH] convert some functions to be per epoch --- specs/core/0_beacon-chain.md | 39 ++++++++++++++++++------------------ 1 file changed, 20 insertions(+), 19 deletions(-) diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md index 97e7a7dd1..2ead71784 100644 --- a/specs/core/0_beacon-chain.md +++ b/specs/core/0_beacon-chain.md @@ -68,10 +68,10 @@ - [`get_active_validator_indices`](#get_active_validator_indices) - [`shuffle`](#shuffle) - [`split`](#split) - - [`get_committee_count_per_slot`](#get_committee_count_per_slot) + - [`get_epoch_committee_count`](#get_epoch_committee_count) - [`get_shuffling`](#get_shuffling) - - [`get_previous_epoch_committee_count_per_slot`](#get_previous_epoch_committee_count_per_slot) - - [`get_current_epoch_committee_count_per_slot`](#get_current_epoch_committee_count_per_slot) + - [`get_previous_epoch_committee_count`](#get_previous_epoch_committee_count) + - [`get_current_epoch_committee_count`](#get_current_epoch_committee_count) - [`get_crosslink_committees_at_slot`](#get_crosslink_committees_at_slot) - [`get_block_root`](#get_block_root) - [`get_randao_mix`](#get_randao_mix) @@ -899,17 +899,17 @@ def split(values: List[Any], split_count: int) -> List[List[Any]]: ] ``` -#### `get_committee_count_per_slot` +#### `get_epoch_committee_count` ```python -def get_committee_count_per_slot(active_validator_count: int) -> int: +def get_epoch_committee_count(active_validator_count: int) -> int: return max( 1, min( SHARD_COUNT // EPOCH_LENGTH, active_validator_count // EPOCH_LENGTH // TARGET_COMMITTEE_SIZE, ) - ) + ) * EPOCH_LENGTH ``` #### `get_shuffling` @@ -926,40 +926,40 @@ def get_shuffling(seed: Bytes32, active_validator_indices = get_active_validator_indices(validators, epoch) - committees_per_slot = get_committee_count_per_slot(len(active_validator_indices)) + committees_per_epoch = get_epoch_committee_count(len(active_validator_indices)) # Shuffle seed = xor(seed, int_to_bytes32(epoch)) shuffled_active_validator_indices = shuffle(active_validator_indices, seed) - # Split the shuffled list into epoch_length * committees_per_slot pieces - return split(shuffled_active_validator_indices, committees_per_slot * EPOCH_LENGTH) + # Split the shuffled list into committees_per_epoch pieces + return split(shuffled_active_validator_indices, committees_per_epoch) ``` **Invariant**: if `get_shuffling(seed, validators, epoch)` returns some value `x` for some `epoch <= get_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. -#### `get_previous_epoch_committee_count_per_slot` +#### `get_previous_epoch_committee_count` ```python -def get_previous_epoch_committee_count_per_slot(state: BeaconState) -> int: +def get_previous_epoch_committee_count(state: BeaconState) -> int: previous_active_validators = get_active_validator_indices( state.validator_registry, state.previous_calculation_epoch, ) - return get_committee_count_per_slot(len(previous_active_validators)) + return get_epoch_committee_count(len(previous_active_validators)) ``` -#### `get_current_epoch_committee_count_per_slot` +#### `get_current_epoch_committee_count` ```python -def get_current_epoch_committee_count_per_slot(state: BeaconState) -> int: +def get_current_epoch_committee_count(state: BeaconState) -> int: current_active_validators = get_active_validator_indices( state.validator_registry, state.current_calculation_epoch, ) - return get_committee_count_per_slot(len(current_active_validators)) + return get_epoch_committee_count(len(current_active_validators)) ``` #### `get_crosslink_committees_at_slot` @@ -978,12 +978,12 @@ def get_crosslink_committees_at_slot(state: BeaconState, assert previous_epoch <= epoch < next_epoch if epoch < current_epoch: - committees_per_slot = get_previous_epoch_committee_count_per_slot(state) + committees_per_epoch = get_previous_epoch_committee_count(state) seed = state.previous_epoch_seed shuffling_epoch = state.previous_calculation_epoch shuffling_start_shard = state.previous_epoch_start_shard else: - committees_per_slot = get_current_epoch_committee_count_per_slot(state) + committees_per_epoch = get_current_epoch_committee_count(state) seed = state.current_epoch_seed shuffling_epoch = state.current_calculation_epoch shuffling_start_shard = state.current_epoch_start_shard @@ -994,6 +994,7 @@ def get_crosslink_committees_at_slot(state: BeaconState, shuffling_epoch, ) offset = slot % EPOCH_LENGTH + committees_per_slot = committees_per_epoch // EPOCH_LENGTH slot_start_shard = (shuffling_start_shard + committees_per_slot * offset) % SHARD_COUNT return [ @@ -1795,7 +1796,7 @@ First, update the following: If the following are satisfied: * `state.finalized_epoch > state.validator_registry_update_epoch` -* `state.latest_crosslinks[shard].epoch > state.validator_registry_update_epoch` for every shard number `shard` in `[(state.current_epoch_start_shard + i) % SHARD_COUNT for i in range(get_current_epoch_committee_count_per_slot(state) * EPOCH_LENGTH)]` (that is, for every shard in the current committees) +* `state.latest_crosslinks[shard].epoch > state.validator_registry_update_epoch` for every shard number `shard` in `[(state.current_epoch_start_shard + i) % SHARD_COUNT for i in range(get_current_epoch_committee_count(state))]` (that is, for every shard in the current committees) update the validator registry and associated fields by running @@ -1847,7 +1848,7 @@ def update_validator_registry(state: BeaconState) -> None: and perform the following updates: * Set `state.current_calculation_epoch = next_epoch` -* Set `state.current_epoch_start_shard = (state.current_epoch_start_shard + get_current_epoch_committee_count_per_slot(state) * EPOCH_LENGTH) % SHARD_COUNT` +* Set `state.current_epoch_start_shard = (state.current_epoch_start_shard + get_current_epoch_committee_count(state)) % SHARD_COUNT` * Set `state.current_epoch_seed = generate_seed(state, state.current_calculation_epoch)` If a validator registry update does _not_ happen do the following: