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eth2.0-specs
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bitvector[8] -> uint8, for efficient packing in flags merkle tree

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protolambda 2021-02-01 21:46:27 +01:00
parent 1ba4917119
commit 3677073812
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5 changed files with 63 additions and 31 deletions
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53
specs/lightclient/beacon-chain.md
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@ -55,15 +55,26 @@ This is a patch implementing the first hard fork to the beacon chain, tentativel
and [TODO] reducing the cost of processing chains that have very little or zero participation for a long span of epochs
* Fork choice rule changes to address weaknesses recently discovered in the existing fork choice
## Custom types
| Name | SSZ equivalent | Description |
| - | - | - |
| `ValidatorFlags` | `uint8` | Bitflags to track validator actions with |
## Constants
### Participation flags
### Validator action flags
This is formatted as an enum, with values `2**i` that can be combined as bit-flags.
The `0` value is reserved as default. Remaining bits in `ValidatorFlags` may be used in future hardforks.
**Note**: unlike Phase0, a `TIMELY_TARGET_FLAG` does not imply a `TIMELY_SOURCE_FLAG`.
| Name | Value |
| - | - |
| `TIMELY_HEAD_FLAG` | `0` |
| `TIMELY_SOURCE_FLAG` | `1` |
| `TIMELY_TARGET_FLAG` | `2` |
| `TIMELY_HEAD_FLAG` | `ValidatorFlags(2**0)` (= 1) |
| `TIMELY_SOURCE_FLAG` | `ValidatorFlags(2**1)` (= 2) |
| `TIMELY_TARGET_FLAG` | `ValidatorFlags(2**2)` (= 4) |
### Participation rewards
@ -80,7 +91,6 @@ The reward fractions add up to 7/8, leaving the remaining 1/8 for proposer rewar
| Name | Value |
| - | - |
| `PARTICIPATION_FLAGS_LENGTH` | `8` |
| `G2_POINT_AT_INFINITY` | `BLSSignature(b'\xc0' + b'\x00' * 95)` |
## Configuration
@ -146,8 +156,8 @@ class BeaconState(Container):
# Slashings
slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR] # Per-epoch sums of slashed effective balances
# Participation
previous_epoch_participation: List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT]
current_epoch_participation: List[Bitvector[PARTICIPATION_FLAGS_LENGTH], VALIDATOR_REGISTRY_LIMIT]
previous_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
current_epoch_participation: List[ValidatorFlags, VALIDATOR_REGISTRY_LIMIT]
# Finality
justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH] # Bit set for every recent justified epoch
previous_justified_checkpoint: Checkpoint
@ -197,7 +207,15 @@ def get_flags_and_numerators() -> Sequence[Tuple[int, int]]:
)
```
```python
def add_flags(flags: ValidatorFlags, add: ValidatorFlags) -> ValidatorFlags:
return flags | add
```
```python
def has_flags(flags: ValidatorFlags, has: ValidatorFlags) -> bool:
return flags & has == has
```
### Beacon state accessors
@ -257,7 +275,10 @@ def get_base_reward(state: BeaconState, index: ValidatorIndex) -> Gwei:
#### `get_unslashed_participating_indices`
```python
def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch: Epoch) -> Set[ValidatorIndex]:
def get_unslashed_participating_indices(state: BeaconState, flags: ValidatorFlags, epoch: Epoch) -> Set[ValidatorIndex]:
"""
Retrieves the active validator indices of the given epoch, who are not slashed, and have all of the given flags.
"""
assert epoch in (get_previous_epoch(state), get_current_epoch(state))
if epoch == get_current_epoch(state):
epoch_participation = state.current_epoch_participation
@ -265,7 +286,7 @@ def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch:
epoch_participation = state.previous_epoch_participation
participating_indices = [
index for index in get_active_validator_indices(state, epoch)
if epoch_participation[index][flag]
if has_flags(epoch_participation[index], flags)
]
return set(filter(lambda index: not state.validators[index].slashed, participating_indices))
```
@ -273,7 +294,9 @@ def get_unslashed_participating_indices(state: BeaconState, flag: uint8, epoch:
#### `get_flag_deltas`
```python
def get_flag_deltas(state: BeaconState, flag: uint8, numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
def get_flag_deltas(state: BeaconState,
flag: ValidatorFlags,
numerator: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
"""
Computes the rewards and penalties associated with a particular duty, by scanning through the participation
flags to determine who participated and who did not and assigning them the appropriate rewards and penalties.
@ -385,8 +408,8 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
proposer_reward_numerator = 0
for index in get_attesting_indices(state, data, attestation.aggregation_bits):
for flag, numerator in get_flags_and_numerators():
if flag in participation_flags and not epoch_participation[index][flag]:
epoch_participation[index][flag] = True
if flag in participation_flags and not has_flags(epoch_participation[index], flag):
epoch_participation[index] = add_flags(epoch_participation[index], flag)
proposer_reward_numerator += get_base_reward(state, index) * numerator
# Reward proposer
@ -432,8 +455,8 @@ def process_deposit(state: BeaconState, deposit: Deposit) -> None:
state.validators.append(get_validator_from_deposit(state, deposit))
state.balances.append(amount)
# [Added in hf-1] Initialize empty participation flags for new validator
state.previous_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
state.current_epoch_participation.append(Bitvector[PARTICIPATION_FLAGS_LENGTH]())
state.previous_epoch_participation.append(ValidatorFlags(0))
state.current_epoch_participation.append(ValidatorFlags(0))
else:
# Increase balance by deposit amount
index = ValidatorIndex(validator_pubkeys.index(pubkey))
@ -572,5 +595,5 @@ def process_participation_flag_updates(state: BeaconState) -> None:
Call to ``process_participation_flag_updates`` added to ``process_epoch`` in HF1
"""
state.previous_epoch_participation = state.current_epoch_participation
state.current_epoch_participation = [Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(state.validators))]
state.current_epoch_participation = [ValidatorFlags(0) for _ in range(len(state.validators))]
```

4
specs/lightclient/lightclient-fork.md
View File

@ -67,8 +67,8 @@ def upgrade_to_lightclient_patch(pre: phase0.BeaconState) -> BeaconState:
# Slashings
slashings=pre.slashings,
# Attestations
previous_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
current_epoch_participation=[Bitvector[PARTICIPATION_FLAGS_LENGTH]() for _ in range(len(pre.validators))],
previous_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
current_epoch_participation=[ValidatorFlags(0) for _ in range(len(pre.validators))],
# Finality
justification_bits=pre.justification_bits,
previous_justified_checkpoint=pre.previous_justified_checkpoint,

29
tests/core/pyspec/eth2spec/test/helpers/rewards.py
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@ -6,7 +6,7 @@ from eth2spec.test.context import is_post_lightclient_patch
from eth2spec.test.helpers.attestations import cached_prepare_state_with_attestations
from eth2spec.test.helpers.deposits import mock_deposit
from eth2spec.test.helpers.state import next_epoch
from eth2spec.utils.ssz.ssz_typing import Container, uint64, List, Bitvector
from eth2spec.utils.ssz.ssz_typing import Container, uint64, List
class Deltas(Container):
@ -314,7 +314,7 @@ def run_test_full_but_partial_participation(spec, state, rng=Random(5522)):
else:
for index in range(len(state.validators)):
if rng.choice([True, False]):
state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
yield from run_deltas(spec, state)
@ -328,7 +328,7 @@ def run_test_partial(spec, state, fraction_filled):
state.previous_epoch_attestations = state.previous_epoch_attestations[:num_attestations]
else:
for index in range(int(len(state.validators) * fraction_filled)):
state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
yield from run_deltas(spec, state)
@ -394,7 +394,7 @@ def run_test_some_very_low_effective_balances_that_did_not_attest(spec, state):
else:
index = 0
state.validators[index].effective_balance = 1
state.previous_epoch_participation[index] = Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
state.previous_epoch_participation[index] = spec.ValidatorFlags(0)
yield from run_deltas(spec, state)
@ -519,16 +519,25 @@ def run_test_full_random(spec, state, rng=Random(8020)):
for index in range(len(state.validators)):
# ~1/3 have bad head or bad target or not timely enough
is_timely_correct_head = rng.randint(0, 2) != 0
state.previous_epoch_participation[index][spec.TIMELY_HEAD_FLAG] = is_timely_correct_head
flags = state.previous_epoch_participation[index]
def set_flag(f, v):
nonlocal flags
if v:
flags |= f
else:
flags &= 0xff ^ f
set_flag(spec.TIMELY_HEAD_FLAG, is_timely_correct_head)
if is_timely_correct_head:
# If timely head, then must be timely target
state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = True
set_flag(spec.TIMELY_TARGET_FLAG, True)
# If timely head, then must be timely source
state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = True
set_flag(spec.TIMELY_SOURCE_FLAG, True)
else:
# ~50% of remaining have bad target or not timely enough
state.previous_epoch_participation[index][spec.TIMELY_TARGET_FLAG] = rng.choice([True, False])
set_flag(spec.TIMELY_TARGET_FLAG, rng.choice([True, False]))
# ~50% of remaining have bad source or not timely enough
state.previous_epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = rng.choice([True, False])
set_flag(spec.TIMELY_SOURCE_FLAG, rng.choice([True, False]))
state.previous_epoch_participation[index] = flags
yield from run_deltas(spec, state)

6
tests/core/pyspec/eth2spec/test/phase0/epoch_processing/test_process_justification_and_finalization.py
View File

@ -78,10 +78,10 @@ def add_mock_attestations(spec, state, epoch, source, target, sufficient_support
else:
for i, index in enumerate(committee):
if aggregation_bits[i]:
epoch_participation[index][spec.TIMELY_HEAD_FLAG] = True
epoch_participation[index][spec.TIMELY_SOURCE_FLAG] = True
epoch_participation[index] |= spec.TIMELY_HEAD_FLAG
epoch_participation[index] |= spec.TIMELY_SOURCE_FLAG
if not messed_up_target:
epoch_participation[index][spec.TIMELY_TARGET_FLAG] = True
epoch_participation[index] |= spec.TIMELY_TARGET_FLAG
def get_checkpoints(spec, epoch):

2
tests/core/pyspec/eth2spec/test/phase0/sanity/test_blocks.py
View File

@ -806,7 +806,7 @@ def test_attestation(spec, state):
assert spec.hash_tree_root(state.previous_epoch_attestations) == pre_current_attestations_root
else:
for index in range(len(state.validators)):
assert state.current_epoch_participation[index] == spec.Bitvector[spec.PARTICIPATION_FLAGS_LENGTH]()
assert state.current_epoch_participation[index] == 0
assert spec.hash_tree_root(state.previous_epoch_participation) == pre_current_epoch_participation_root