nimbus-eth2/research/state_sim.nim

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# beacon_chain
# Copyright (c) 2019-2020 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
# `state_sim` runs the state transition function in isolation, creating blocks
# and attesting to them as if the network was running as a whole.
import
confutils, stats, times,
strformat,
options, sequtils, random, tables,
../tests/testblockutil,
../beacon_chain/spec/[beaconstate, crypto, datatypes, digest, helpers, validator],
../beacon_chain/extras,
../beacon_chain/ssz/[merkleization, ssz_serialization],
./simutils
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type Timers = enum
tBlock = "Process non-epoch slot with block"
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tEpoch = "Process epoch slot with block"
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tHashBlock = "Tree-hash block"
tShuffle = "Retrieve committee once using get_beacon_committee"
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tAttest = "Combine committee attestations"
proc jsonName(prefix, slot: auto): string =
fmt"{prefix:04}-{shortLog(slot):08}.json"
proc writeJson*(fn, v: auto) =
var f: File
defer: close(f)
Json.saveFile(fn, v, pretty = true)
cli do(slots = SLOTS_PER_EPOCH * 6,
validators = SLOTS_PER_EPOCH * 100, # One per shard is minimum
json_interval = SLOTS_PER_EPOCH,
write_last_json = false,
prefix: int = 0,
attesterRatio {.desc: "ratio of validators that attest in each round"} = 0.73,
validate = true):
let
flags = if validate: {} else: {skipBlsValidation}
state = loadGenesis(validators, validate)
genesisBlock = get_initial_beacon_block(state.data)
echo "Starting simulation..."
var
attestations = initTable[Slot, seq[Attestation]]()
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latest_block_root = hash_tree_root(genesisBlock.message)
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timers: array[Timers, RunningStat]
attesters: RunningStat
r = initRand(1)
signedBlock: SignedBeaconBlock
cache = StateCache()
proc maybeWrite(last: bool) =
if write_last_json:
if state[].data.slot mod json_interval.uint64 == 0:
write(stdout, ":")
else:
write(stdout, ".")
if last:
writeJson("state.json", state[])
else:
if state[].data.slot mod json_interval.uint64 == 0:
writeJson(jsonName(prefix, state[].data.slot), state[].data)
write(stdout, ":")
else:
write(stdout, ".")
# TODO doAssert against this up-front
# indexed attestation: validator index beyond max validators per committee
# len(indices) <= MAX_VALIDATORS_PER_COMMITTEE
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for i in 0..<slots:
maybeWrite(false)
verifyConsensus(state[].data, attesterRatio)
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let
attestations_idx = state[].data.slot
blockAttestations = attestations.getOrDefault(attestations_idx)
attestations.del attestations_idx
doAssert attestations.lenu64 <=
SLOTS_PER_EPOCH + MIN_ATTESTATION_INCLUSION_DELAY
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let t =
if (state[].data.slot > GENESIS_SLOT and
(state[].data.slot + 1).isEpoch): tEpoch
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else: tBlock
withTimer(timers[t]):
signedBlock = addTestBlock(
state[], latest_block_root, cache, attestations = blockAttestations,
flags = flags)
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latest_block_root = withTimerRet(timers[tHashBlock]):
hash_tree_root(signedBlock.message)
signedBlock.root = latest_block_root
if attesterRatio > 0.0:
# attesterRatio is the fraction of attesters that actually do their
# work for every slot - we'll randomize it deterministically to give
# some variation
let
target_slot = state[].data.slot + MIN_ATTESTATION_INCLUSION_DELAY - 1
committees_per_slot =
get_committee_count_per_slot(state[].data, target_slot.epoch, cache)
let
scass = withTimerRet(timers[tShuffle]):
mapIt(
0 ..< committees_per_slot.int,
get_beacon_committee(state[].data, target_slot, it.CommitteeIndex, cache))
for i, scas in scass:
var
attestation: Attestation
first = true
attesters.push scas.len()
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withTimer(timers[tAttest]):
for v in scas:
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if (rand(r, high(int)).float * attesterRatio).int <= high(int):
if first:
attestation =
makeAttestation(state[].data, latest_block_root, scas, target_slot,
i.uint64, v, cache, flags)
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first = false
else:
attestation.combine(
makeAttestation(state[].data, latest_block_root, scas, target_slot,
i.uint64, v, cache, flags),
flags)
if not first:
# add the attestation if any of the validators attested, as given
# by the randomness. We have to delay when the attestation is
# actually added to the block per the attestation delay rule!
let target_slot =
attestation.data.slot + MIN_ATTESTATION_INCLUSION_DELAY - 1
doAssert target_slot > attestations_idx
var target_slot_attestations =
getOrDefault(attestations, target_slot)
target_slot_attestations.add attestation
attestations[target_slot] = target_slot_attestations
flushFile(stdout)
if (state[].data.slot).isEpoch:
echo &" slot: {shortLog(state[].data.slot)} ",
&"epoch: {shortLog(state[].data.get_current_epoch())}"
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maybeWrite(true) # catch that last state as well..
echo "Done!"
printTimers(state[].data, attesters, validate, timers)