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Only check for epoch underflow just before peer communication

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During state processing epochs can underflow (hence why we have a non-zero arbitrary genesis epoch)
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Mamy André-Ratsimbazafy 2019-03-26 13:58:34 +01:00 committed by zah
parent e189c1d3cd
commit 57c693c88f
1 changed files with 4 additions and 3 deletions
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7
beacon_chain/spec/validator.nim
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@ -7,7 +7,7 @@
# Helpers and functions pertaining to managing the validator set
import
options, nimcrypto, sequtils, math,
options, nimcrypto, sequtils, math, chronicles,
eth/common,
../ssz,
./crypto, ./datatypes, ./digest, ./helpers
@ -125,9 +125,10 @@ func get_next_epoch_committee_count(state: BeaconState): uint64 =
# https://github.com/ethereum/eth2.0-specs/blob/v0.5.0/specs/core/0_beacon-chain.md#get_previous_epoch
func get_previous_epoch*(state: BeaconState): Epoch =
## Return the previous epoch of the given ``state``.
# Note: This is allowed to underflow internally (this is why GENESIS_EPOCH != 0)
# however when interfacing with peers for example for attestations
# this should not underflow.
let epoch = get_current_epoch(state)
if epoch == GENESIS_EPOCH:
raise newException(OverflowError, "Underflow: trying to get the previous epoch of epoch 0 (genesis).")
epoch - 1