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Implement light client friendliness changes #234

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Jan 29, 2019
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Implement light client friendliness changes #234

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Implement light client friendliness changes
hwwhww Jan 28, 2019
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hwwhww Jan 29, 2019
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hwwhww Jan 29, 2019
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5 changes: 0 additions & 5 deletions eth2/beacon/enums.py
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Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,6 @@ class ValidatorStatusFlags(IntEnum):
WITHDRAWABLE = 2


class ValidatorRegistryDeltaFlag(IntEnum):
ACTIVATION = 0
EXIT = 1


class SignatureDomain(IntEnum):
DOMAIN_DEPOSIT = 0
DOMAIN_ATTESTATION = 1
Expand Down
62 changes: 57 additions & 5 deletions eth2/beacon/helpers.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,9 @@
from eth2._utils.numeric import (
bitwise_xor,
)
from eth2.beacon._utils.hash import (
hash_eth2,
)
from eth2.beacon._utils.random import (
shuffle,
split,
Expand All @@ -43,6 +46,7 @@
ValidatorIndex,
)
from eth2.beacon.validation import (
validate_epoch_for_active_index_root,
validate_slot_for_state_slot,
)

Expand Down Expand Up @@ -108,6 +112,7 @@ def get_randao_mix(state: 'BeaconState',
"""
Return the randao mix at a recent ``slot``.
"""
# TODO: update to epoch version
assert state.slot < slot + latest_randao_mixes_length
assert slot <= state.slot
return state.latest_randao_mixes[slot % latest_randao_mixes_length]
Expand Down Expand Up @@ -243,7 +248,7 @@ def get_crosslink_committees_at_slot(
target_committee_size=target_committee_size,
)

seed = state.previous_epoch_randao_mix
seed = state.previous_epoch_seed
shuffling_slot = state.previous_epoch_calculation_slot
shuffling_start_shard = state.previous_epoch_start_shard
else:
Expand All @@ -253,7 +258,7 @@ def get_crosslink_committees_at_slot(
epoch_length=epoch_length,
target_committee_size=target_committee_size,
)
seed = state.current_epoch_randao_mix
seed = state.current_epoch_seed
shuffling_slot = state.current_epoch_calculation_slot
shuffling_start_shard = state.current_epoch_start_shard

Expand All @@ -279,9 +284,45 @@ def get_crosslink_committees_at_slot(
)


#
# Get proposer position
#
def get_active_index_root(state: 'BeaconState',
slot: SlotNumber,
epoch_length: int,
latest_index_roots_length: int) -> Hash32:
"""
Return the index root at a recent ``slot``.
"""
state_epoch = state.slot // epoch_length
given_epoch = slot // epoch_length

validate_epoch_for_active_index_root(state_epoch, given_epoch, latest_index_roots_length)

return state.latest_index_roots[given_epoch % latest_index_roots_length]


def generate_seed(state: 'BeaconState',
slot: SlotNumber,
epoch_length: int,
seed_lookahead: int,
latest_index_roots_length: int,
latest_randao_mixes_length: int) -> Hash32:
"""
Generate a seed for the given ``slot``.

TODO: it's slot version, will be changed to epoch version.
"""
return hash_eth2(
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get_randao_mix(
state,
SlotNumber(slot - seed_lookahead),
latest_randao_mixes_length=latest_randao_mixes_length,
) + get_active_index_root(
state,
slot,
epoch_length=epoch_length,
latest_index_roots_length=latest_index_roots_length,
)
)


def get_beacon_proposer_index(state: 'BeaconState',
slot: SlotNumber,
Expand Down Expand Up @@ -506,3 +547,14 @@ def is_surround_vote(attestation_data_1: 'AttestationData',
(attestation_data_2.justified_slot + 1 == attestation_data_2.slot) and
(attestation_data_2.slot < attestation_data_1.slot)
)


def get_entry_exit_effect_slot(slot: SlotNumber,
epoch_length: int,
entry_exit_delay: int) -> SlotNumber:
"""
An entry or exit triggered in the slot given by the input takes effect at
the slot given by the output.
"""
# TODO: update to epoch version
return SlotNumber((slot - slot % epoch_length) + epoch_length + entry_exit_delay)
11 changes: 6 additions & 5 deletions eth2/beacon/on_startup.py
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Expand Up @@ -66,8 +66,8 @@ def get_initial_beacon_state(*,
genesis_start_shard: ShardNumber,
shard_count: int,
latest_block_roots_length: int,
latest_index_roots_length: int,
epoch_length: int,
target_committee_size: int,
max_deposit: Ether,
latest_penalized_exit_length: int,
latest_randao_mixes_length: int,
Expand All @@ -87,7 +87,6 @@ def get_initial_beacon_state(*,
validator_balances=(),
validator_registry_update_slot=genesis_slot,
validator_registry_exit_count=0,
validator_registry_delta_chain_tip=ZERO_HASH32,

# Randomness and committees
latest_randao_mixes=tuple(ZERO_HASH32 for _ in range(latest_randao_mixes_length)),
Expand All @@ -101,8 +100,8 @@ def get_initial_beacon_state(*,
current_epoch_start_shard=genesis_start_shard,
previous_epoch_calculation_slot=genesis_slot,
current_epoch_calculation_slot=genesis_slot,
previous_epoch_randao_mix=ZERO_HASH32,
current_epoch_randao_mix=ZERO_HASH32,
previous_epoch_seed=ZERO_HASH32,
current_epoch_seed=ZERO_HASH32,

# Custody challenges
custody_challenges=(),
Expand All @@ -119,6 +118,7 @@ def get_initial_beacon_state(*,
for _ in range(shard_count)
]),
latest_block_roots=tuple(ZERO_HASH32 for _ in range(latest_block_roots_length)),
latest_index_roots=tuple(ZERO_HASH32 for _ in range(latest_index_roots_length)),
latest_penalized_balances=tuple(
Gwei(0)
for _ in range(latest_penalized_exit_length)
Expand Down Expand Up @@ -154,8 +154,9 @@ def get_initial_beacon_state(*,
state = activate_validator(
state,
validator_index,
genesis=True,
is_genesis=True,
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👍

genesis_slot=genesis_slot,
epoch_length=epoch_length,
entry_exit_delay=entry_exit_delay,
)

Expand Down
1 change: 1 addition & 0 deletions eth2/beacon/state_machines/configs.py
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Expand Up @@ -24,6 +24,7 @@
('BEACON_CHAIN_SHARD_NUMBER', ShardNumber),
('MAX_CASPER_VOTES', int),
('LATEST_BLOCK_ROOTS_LENGTH', int),
('LATEST_INDEX_ROOTS_LENGTH', int),
('LATEST_RANDAO_MIXES_LENGTH', int),
('LATEST_PENALIZED_EXIT_LENGTH', int),
# EMPTY_SIGNATURE is defined in constants.py
Expand Down
1 change: 1 addition & 0 deletions eth2/beacon/state_machines/forks/serenity/configs.py
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Expand Up @@ -19,6 +19,7 @@
BEACON_CHAIN_SHARD_NUMBER=ShardNumber(2**64 - 1),
MAX_CASPER_VOTES=2**10, # (= 1,024) votes
LATEST_BLOCK_ROOTS_LENGTH=2**13, # (= 8,192) block roots
LATEST_INDEX_ROOTS_LENGTH=2**13, # (= 8,192) index roots
LATEST_RANDAO_MIXES_LENGTH=2**13, # (= 8,192) randao mixes
LATEST_PENALIZED_EXIT_LENGTH=2**13, # (= 8,192) randao mixes
# Deposit contract
Expand Down
72 changes: 59 additions & 13 deletions eth2/beacon/state_machines/forks/serenity/epoch_processing.py
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Expand Up @@ -8,16 +8,20 @@
from eth2._utils.tuple import (
update_tuple_item,
)
from eth2.beacon._utils.hash import (
hash_eth2,
)
from eth2.beacon import helpers
from eth2.beacon.helpers import (
get_active_validator_indices,
get_current_epoch_committee_count_per_slot,
get_randao_mix,
)
from eth2.beacon.types.states import BeaconState
from eth2.beacon.state_machines.configs import BeaconConfig


#
# Validator Registry
# Validator registry and shuffling seed data
#
def _check_if_update_validator_registry(state: BeaconState,
config: BeaconConfig) -> Tuple[bool, int]:
Expand Down Expand Up @@ -48,13 +52,41 @@ def update_validator_registry(state: BeaconState) -> BeaconState:
return state


def _update_latest_index_roots(state: BeaconState,
config: BeaconConfig) -> BeaconState:
"""
Return the BeaconState with updated `latest_index_roots`.
"""
next_epoch = state.next_epoch(config.EPOCH_LENGTH)

# TODO: chanege to hash_tree_root
index_root = hash_eth2(
bytes(
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Is it guaranteed that get_active_validator_indices() will only return values in the range 0-255? A glance at the implementation doesn't appear it has that guarantee. If not, then this call will fail if any of the indices are outside of this range.

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ohhh good point!!!!
(Note that it's a workaround before we add tree hashing.) I'm changing it to:

    # TODO: chanege to hash_tree_root
    index_root = hash_eth2(
        b''.join(
            [
                index.to_bytes(32, 'big')
                for index in get_active_validator_indices(
                    state.validator_registry,
                    # TODO: change to `per-epoch` version
                    state.slot,
                )
            ]
        )
    )

(p.s. The upper-bound of the size of ValidatorIndex is uint64.)

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Hrm, a uint64 should fit within 8 bytes right?

get_active_validator_indices(
state.validator_registry,
state.slot,
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)
)
)
latest_index_roots = update_tuple_item(
state.latest_index_roots,
next_epoch,
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index_root,
)

return state.copy(
latest_index_roots=latest_index_roots,
)


def process_validator_registry(state: BeaconState,
config: BeaconConfig) -> BeaconState:
state = state.copy(
previous_epoch_calculation_slot=state.current_epoch_calculation_slot,
previous_epoch_start_shard=state.current_epoch_start_shard,
previous_epoch_randao_mix=state.current_epoch_randao_mix,
previous_epoch_seed=state.current_epoch_seed,
)
state = _update_latest_index_roots(state, config)

need_to_update, num_shards_in_committees = _check_if_update_validator_registry(state, config)

Expand All @@ -71,12 +103,18 @@ def process_validator_registry(state: BeaconState,
state.current_epoch_start_shard + num_shards_in_committees
) % config.SHARD_COUNT,
)

# `helpers.generate_seed` path for mocking tests
current_epoch_seed = helpers.generate_seed(
state=state,
slot=state.current_epoch_calculation_slot,
epoch_length=config.EPOCH_LENGTH,
seed_lookahead=config.SEED_LOOKAHEAD,
latest_index_roots_length=config.LATEST_INDEX_ROOTS_LENGTH,
latest_randao_mixes_length=config.LATEST_RANDAO_MIXES_LENGTH,
)
state = state.copy(
current_epoch_randao_mix=get_randao_mix(
state,
state.current_epoch_calculation_slot - config.SEED_LOOKAHEAD,
config.LATEST_RANDAO_MIXES_LENGTH,
),
current_epoch_seed=current_epoch_seed,
)
else:
epochs_since_last_registry_change = (
Expand All @@ -88,13 +126,21 @@ def process_validator_registry(state: BeaconState,
state = state.copy(
current_epoch_calculation_slot=state.slot,
)

# `helpers.generate_seed` path for mocking tests
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I think know what this comment is indicating but could we maybe make it a bit more explicit. Here's what I think it is trying to say.

The helpers.generate_seed function is only present to provide an entry point for mocking this out in tests.

current_epoch_seed = helpers.generate_seed(
state=state,
slot=state.current_epoch_calculation_slot,
epoch_length=config.EPOCH_LENGTH,
seed_lookahead=config.SEED_LOOKAHEAD,
latest_index_roots_length=config.LATEST_INDEX_ROOTS_LENGTH,
latest_randao_mixes_length=config.LATEST_RANDAO_MIXES_LENGTH,
)
state = state.copy(
current_epoch_randao_mix=get_randao_mix(
state,
state.current_epoch_calculation_slot - config.SEED_LOOKAHEAD,
config.LATEST_RANDAO_MIXES_LENGTH,
),
current_epoch_seed=current_epoch_seed,
)
else:
pass

return state

Expand Down
2 changes: 1 addition & 1 deletion eth2/beacon/tools/builder/initializer.py
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Expand Up @@ -112,8 +112,8 @@ def create_mock_genesis(
genesis_start_shard=config.GENESIS_START_SHARD,
shard_count=config.SHARD_COUNT,
latest_block_roots_length=config.LATEST_BLOCK_ROOTS_LENGTH,
latest_index_roots_length=config.LATEST_INDEX_ROOTS_LENGTH,
epoch_length=config.EPOCH_LENGTH,
target_committee_size=config.TARGET_COMMITTEE_SIZE,
max_deposit=config.MAX_DEPOSIT,
latest_penalized_exit_length=config.LATEST_PENALIZED_EXIT_LENGTH,
latest_randao_mixes_length=config.LATEST_RANDAO_MIXES_LENGTH,
Expand Down
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