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Merge pull request #1027 from ethereum/fix-underflows

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Fix underflows from #1017
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Danny Ryan 2019-05-03 08:48:17 -06:00 committed by GitHub
commit 8942fac7ec
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2 changed files with 4 additions and 5 deletions
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2
scripts/phase0/build_spec.py
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@ -48,10 +48,8 @@ def compute_committee(indices: List[ValidatorIndex], seed: Bytes32, index: int,
param_hash = (hash_tree_root(indices), seed, index, count)
if param_hash in committee_cache:
print("Cache hit, param_hash: ", param_hash)
return committee_cache[param_hash]
else:
print("Cache miss, param_hash: ", param_hash)
ret = _compute_committee(indices, seed, index, count)
committee_cache[param_hash] = ret
return ret

7
specs/core/0_beacon-chain.md
View File

@ -799,8 +799,8 @@ def get_randao_mix(state: BeaconState,
epoch: Epoch) -> Bytes32:
"""
Return the randao mix at a recent ``epoch``.
``epoch`` expected to be between (current_epoch - LATEST_RANDAO_MIXES_LENGTH, current_epoch].
"""
assert get_current_epoch(state) - LATEST_RANDAO_MIXES_LENGTH < epoch <= get_current_epoch(state)
return state.latest_randao_mixes[epoch % LATEST_RANDAO_MIXES_LENGTH]
```
@ -811,8 +811,9 @@ def get_active_index_root(state: BeaconState,
epoch: Epoch) -> Bytes32:
"""
Return the index root at a recent ``epoch``.
``epoch`` expected to be between
(current_epoch - LATEST_ACTIVE_INDEX_ROOTS_LENGTH + ACTIVATION_EXIT_DELAY, current_epoch + ACTIVATION_EXIT_DELAY].
"""
assert get_current_epoch(state) - LATEST_ACTIVE_INDEX_ROOTS_LENGTH + ACTIVATION_EXIT_DELAY < epoch <= get_current_epoch(state) + ACTIVATION_EXIT_DELAY
return state.latest_active_index_roots[epoch % LATEST_ACTIVE_INDEX_ROOTS_LENGTH]
```
@ -825,7 +826,7 @@ def generate_seed(state: BeaconState,
Generate a seed for the given ``epoch``.
"""
return hash(
get_randao_mix(state, epoch - MIN_SEED_LOOKAHEAD) +
get_randao_mix(state, epoch + LATEST_RANDAO_MIXES_LENGTH - MIN_SEED_LOOKAHEAD) +
get_active_index_root(state, epoch) +
int_to_bytes32(epoch)
)