prysm-pulse/beacon-chain/core/state/state.go
2021-04-08 19:33:54 +00:00

274 lines
9.0 KiB
Go

// Package state implements the whole state transition
// function which consists of per slot, per-epoch transitions, and
// bootstrapping the genesis state according to the eth2 spec.
package state
import (
"context"
"fmt"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
b "github.com/prysmaticlabs/prysm/beacon-chain/core/blocks"
iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
"github.com/prysmaticlabs/prysm/beacon-chain/state/stateV0"
pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
"github.com/prysmaticlabs/prysm/shared/params"
"github.com/prysmaticlabs/prysm/shared/trieutil"
)
// GenesisBeaconState gets called when MinGenesisActiveValidatorCount count of
// full deposits were made to the deposit contract and the ChainStart log gets emitted.
//
// Spec pseudocode definition:
// def initialize_beacon_state_from_eth1(eth1_block_hash: Bytes32,
// eth1_timestamp: uint64,
// deposits: Sequence[Deposit]) -> BeaconState:
// fork = Fork(
// previous_version=GENESIS_FORK_VERSION,
// current_version=GENESIS_FORK_VERSION,
// epoch=GENESIS_EPOCH,
// )
// state = BeaconState(
// genesis_time=eth1_timestamp + GENESIS_DELAY,
// fork=fork,
// eth1_data=Eth1Data(block_hash=eth1_block_hash, deposit_count=uint64(len(deposits))),
// latest_block_header=BeaconBlockHeader(body_root=hash_tree_root(BeaconBlockBody())),
// randao_mixes=[eth1_block_hash] * EPOCHS_PER_HISTORICAL_VECTOR, # Seed RANDAO with Eth1 entropy
// )
//
// # Process deposits
// leaves = list(map(lambda deposit: deposit.data, deposits))
// for index, deposit in enumerate(deposits):
// deposit_data_list = List[DepositData, 2**DEPOSIT_CONTRACT_TREE_DEPTH](*leaves[:index + 1])
// state.eth1_data.deposit_root = hash_tree_root(deposit_data_list)
// process_deposit(state, deposit)
//
// # Process activations
// for index, validator in enumerate(state.validators):
// balance = state.balances[index]
// validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
// if validator.effective_balance == MAX_EFFECTIVE_BALANCE:
// validator.activation_eligibility_epoch = GENESIS_EPOCH
// validator.activation_epoch = GENESIS_EPOCH
//
// # Set genesis validators root for domain separation and chain versioning
// state.genesis_validators_root = hash_tree_root(state.validators)
//
// return state
// This method differs from the spec so as to process deposits beforehand instead of the end of the function.
func GenesisBeaconState(ctx context.Context, deposits []*ethpb.Deposit, genesisTime uint64, eth1Data *ethpb.Eth1Data) (iface.BeaconState, error) {
state, err := EmptyGenesisState()
if err != nil {
return nil, err
}
// Process initial deposits.
state, err = updateGenesisEth1Data(state, deposits, eth1Data)
if err != nil {
return nil, err
}
state, err = b.ProcessPreGenesisDeposits(ctx, state, deposits)
if err != nil {
return nil, errors.Wrap(err, "could not process validator deposits")
}
return OptimizedGenesisBeaconState(genesisTime, state, state.Eth1Data())
}
// OptimizedGenesisBeaconState is used to create a state that has already processed deposits. This is to efficiently
// create a mainnet state at chainstart.
func OptimizedGenesisBeaconState(genesisTime uint64, preState iface.BeaconState, eth1Data *ethpb.Eth1Data) (iface.BeaconState, error) {
if eth1Data == nil {
return nil, errors.New("no eth1data provided for genesis state")
}
randaoMixes := make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector)
for i := 0; i < len(randaoMixes); i++ {
h := make([]byte, 32)
copy(h, eth1Data.BlockHash)
randaoMixes[i] = h
}
zeroHash := params.BeaconConfig().ZeroHash[:]
activeIndexRoots := make([][]byte, params.BeaconConfig().EpochsPerHistoricalVector)
for i := 0; i < len(activeIndexRoots); i++ {
activeIndexRoots[i] = zeroHash
}
blockRoots := make([][]byte, params.BeaconConfig().SlotsPerHistoricalRoot)
for i := 0; i < len(blockRoots); i++ {
blockRoots[i] = zeroHash
}
stateRoots := make([][]byte, params.BeaconConfig().SlotsPerHistoricalRoot)
for i := 0; i < len(stateRoots); i++ {
stateRoots[i] = zeroHash
}
slashings := make([]uint64, params.BeaconConfig().EpochsPerSlashingsVector)
genesisValidatorsRoot, err := stateV0.ValidatorRegistryRoot(preState.Validators())
if err != nil {
return nil, errors.Wrapf(err, "could not hash tree root genesis validators %v", err)
}
state := &pb.BeaconState{
// Misc fields.
Slot: 0,
GenesisTime: genesisTime,
GenesisValidatorsRoot: genesisValidatorsRoot[:],
Fork: &pb.Fork{
PreviousVersion: params.BeaconConfig().GenesisForkVersion,
CurrentVersion: params.BeaconConfig().GenesisForkVersion,
Epoch: 0,
},
// Validator registry fields.
Validators: preState.Validators(),
Balances: preState.Balances(),
// Randomness and committees.
RandaoMixes: randaoMixes,
// Finality.
PreviousJustifiedCheckpoint: &ethpb.Checkpoint{
Epoch: 0,
Root: params.BeaconConfig().ZeroHash[:],
},
CurrentJustifiedCheckpoint: &ethpb.Checkpoint{
Epoch: 0,
Root: params.BeaconConfig().ZeroHash[:],
},
JustificationBits: []byte{0},
FinalizedCheckpoint: &ethpb.Checkpoint{
Epoch: 0,
Root: params.BeaconConfig().ZeroHash[:],
},
HistoricalRoots: [][]byte{},
BlockRoots: blockRoots,
StateRoots: stateRoots,
Slashings: slashings,
CurrentEpochAttestations: []*pb.PendingAttestation{},
PreviousEpochAttestations: []*pb.PendingAttestation{},
// Eth1 data.
Eth1Data: eth1Data,
Eth1DataVotes: []*ethpb.Eth1Data{},
Eth1DepositIndex: preState.Eth1DepositIndex(),
}
bodyRoot, err := (&ethpb.BeaconBlockBody{
RandaoReveal: make([]byte, 96),
Eth1Data: &ethpb.Eth1Data{
DepositRoot: make([]byte, 32),
BlockHash: make([]byte, 32),
},
Graffiti: make([]byte, 32),
}).HashTreeRoot()
if err != nil {
return nil, errors.Wrap(err, "could not hash tree root empty block body")
}
state.LatestBlockHeader = &ethpb.BeaconBlockHeader{
ParentRoot: zeroHash,
StateRoot: zeroHash,
BodyRoot: bodyRoot[:],
}
return stateV0.InitializeFromProto(state)
}
// EmptyGenesisState returns an empty beacon state object.
func EmptyGenesisState() (iface.BeaconState, error) {
state := &pb.BeaconState{
// Misc fields.
Slot: 0,
Fork: &pb.Fork{
PreviousVersion: params.BeaconConfig().GenesisForkVersion,
CurrentVersion: params.BeaconConfig().GenesisForkVersion,
Epoch: 0,
},
// Validator registry fields.
Validators: []*ethpb.Validator{},
Balances: []uint64{},
JustificationBits: []byte{0},
HistoricalRoots: [][]byte{},
CurrentEpochAttestations: []*pb.PendingAttestation{},
PreviousEpochAttestations: []*pb.PendingAttestation{},
// Eth1 data.
Eth1Data: &ethpb.Eth1Data{},
Eth1DataVotes: []*ethpb.Eth1Data{},
Eth1DepositIndex: 0,
}
return stateV0.InitializeFromProto(state)
}
// IsValidGenesisState gets called whenever there's a deposit event,
// it checks whether there's enough effective balance to trigger and
// if the minimum genesis time arrived already.
//
// Spec pseudocode definition:
// def is_valid_genesis_state(state: BeaconState) -> bool:
// if state.genesis_time < MIN_GENESIS_TIME:
// return False
// if len(get_active_validator_indices(state, GENESIS_EPOCH)) < MIN_GENESIS_ACTIVE_VALIDATOR_COUNT:
// return False
// return True
// This method has been modified from the spec to allow whole states not to be saved
// but instead only cache the relevant information.
func IsValidGenesisState(chainStartDepositCount, currentTime uint64) bool {
if currentTime < params.BeaconConfig().MinGenesisTime {
return false
}
if chainStartDepositCount < params.BeaconConfig().MinGenesisActiveValidatorCount {
return false
}
return true
}
func updateGenesisEth1Data(state iface.BeaconState, deposits []*ethpb.Deposit, eth1Data *ethpb.Eth1Data) (iface.BeaconState, error) {
if eth1Data == nil {
return nil, errors.New("no eth1data provided for genesis state")
}
var leaves [][]byte
for _, deposit := range deposits {
if deposit == nil || deposit.Data == nil {
return nil, fmt.Errorf("nil deposit or deposit with nil data cannot be processed: %v", deposit)
}
hash, err := deposit.Data.HashTreeRoot()
if err != nil {
return nil, err
}
leaves = append(leaves, hash[:])
}
var trie *trieutil.SparseMerkleTrie
var err error
if len(leaves) > 0 {
trie, err = trieutil.GenerateTrieFromItems(leaves, params.BeaconConfig().DepositContractTreeDepth)
if err != nil {
return nil, err
}
} else {
trie, err = trieutil.NewTrie(params.BeaconConfig().DepositContractTreeDepth)
if err != nil {
return nil, err
}
}
depositRoot := trie.Root()
eth1Data.DepositRoot = depositRoot[:]
err = state.SetEth1Data(eth1Data)
if err != nil {
return nil, err
}
return state, nil
}