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babe.go
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babe.go
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// Copyright 2021 ChainSafe Systems (ON)
// SPDX-License-Identifier: LGPL-3.0-only
package babe
import (
"bytes"
"context"
"errors"
"fmt"
"sync"
"time"
"github.com/ChainSafe/gossamer/dot/telemetry"
"github.com/ChainSafe/gossamer/dot/types"
"github.com/ChainSafe/gossamer/internal/log"
"github.com/ChainSafe/gossamer/lib/crypto/sr25519"
ethmetrics "github.com/ethereum/go-ethereum/metrics"
)
var logger = log.NewFromGlobal(log.AddContext("pkg", "babe"))
// Service contains the VRF keys for the validator, as well as BABE configuation data
type Service struct {
ctx context.Context
cancel context.CancelFunc
authority bool
dev bool
// lead is used when setting up a new network from genesis.
// the "lead" node is the node that is designated to build block 1, after which the rest of the nodes
// will sync block 1 and determine the first slot of the network based on it
lead bool
constants constants
epochHandler *epochHandler
// Storage interfaces
blockState BlockState
storageState StorageState
transactionState TransactionState
epochState EpochState
blockImportHandler BlockImportHandler
// BABE authority keypair
keypair *sr25519.Keypair // TODO: change to BABE keystore (#1864)
// State variables
sync.RWMutex
pause chan struct{}
telemetry Telemetry
}
// ServiceConfig represents a BABE configuration
type ServiceConfig struct {
LogLvl log.Level
BlockState BlockState
StorageState StorageState
TransactionState TransactionState
EpochState EpochState
BlockImportHandler BlockImportHandler
Keypair *sr25519.Keypair
AuthData []types.Authority
IsDev bool
Authority bool
Lead bool
Telemetry Telemetry
}
// Validate returns error if config does not contain required attributes
func (sc *ServiceConfig) Validate() error {
if sc.Keypair == nil && sc.Authority {
return errNoBABEAuthorityKeyProvided
}
return nil
}
// Builder struct to hold babe builder functions
type Builder struct{}
// NewServiceIFace returns a new Babe Service using the provided VRF keys and runtime
func (Builder) NewServiceIFace(cfg *ServiceConfig) (service *Service, err error) {
if err := cfg.Validate(); err != nil {
return nil, fmt.Errorf("could not verify service config: %w", err)
}
logger.Patch(log.SetLevel(cfg.LogLvl))
slotDuration, err := cfg.EpochState.GetSlotDuration()
if err != nil {
return nil, fmt.Errorf("cannot get slot duration: %w", err)
}
epochLength, err := cfg.EpochState.GetEpochLength()
if err != nil {
return nil, fmt.Errorf("cannot get epoch length: %w", err)
}
ctx, cancel := context.WithCancel(context.Background())
babeService := &Service{
ctx: ctx,
cancel: cancel,
blockState: cfg.BlockState,
storageState: cfg.StorageState,
epochState: cfg.EpochState,
keypair: cfg.Keypair,
transactionState: cfg.TransactionState,
pause: make(chan struct{}),
authority: cfg.Authority,
dev: cfg.IsDev,
blockImportHandler: cfg.BlockImportHandler,
lead: cfg.Lead,
constants: constants{
slotDuration: slotDuration,
epochLength: epochLength,
},
telemetry: cfg.Telemetry,
}
logger.Debugf(
"created service with block producer ID=%v, slot duration %s, epoch length (slots) %d",
cfg.Authority, babeService.constants.slotDuration, babeService.constants.epochLength,
)
if cfg.Lead {
logger.Debug("node designated to build block 1")
}
return babeService, nil
}
// NewService function to create babe service
func NewService(cfg *ServiceConfig) (*Service, error) {
if cfg.Keypair == nil && cfg.Authority {
return nil, errors.New("cannot create BABE service as authority; no keypair provided")
}
logger.Patch(log.SetLevel(cfg.LogLvl))
slotDuration, err := cfg.EpochState.GetSlotDuration()
if err != nil {
return nil, fmt.Errorf("cannot get slot duration: %w", err)
}
epochLength, err := cfg.EpochState.GetEpochLength()
if err != nil {
return nil, fmt.Errorf("cannot get epoch length: %w", err)
}
ctx, cancel := context.WithCancel(context.Background())
babeService := &Service{
ctx: ctx,
cancel: cancel,
blockState: cfg.BlockState,
storageState: cfg.StorageState,
epochState: cfg.EpochState,
keypair: cfg.Keypair,
transactionState: cfg.TransactionState,
pause: make(chan struct{}),
authority: cfg.Authority,
dev: cfg.IsDev,
blockImportHandler: cfg.BlockImportHandler,
lead: cfg.Lead,
constants: constants{
slotDuration: slotDuration,
epochLength: epochLength,
},
telemetry: cfg.Telemetry,
}
logger.Debugf(
"created service with block producer ID=%v, slot duration %s, epoch length (slots) %d",
cfg.Authority, babeService.constants.slotDuration, babeService.constants.epochLength,
)
if cfg.Lead {
logger.Debug("node designated to build block 1")
}
return babeService, nil
}
// Start starts BABE block authoring
func (b *Service) Start() error {
if !b.authority {
return nil
}
// if we aren't leading node, wait for first block
if !b.lead {
if err := b.waitForFirstBlock(); err != nil {
return err
}
}
go b.initiate()
return nil
}
func (b *Service) waitForFirstBlock() error {
head, err := b.blockState.BestBlockHeader()
if err != nil {
return fmt.Errorf("cannot get best block header: %w", err)
}
if head.Number > 0 {
return nil
}
ch := b.blockState.GetImportedBlockNotifierChannel()
defer b.blockState.FreeImportedBlockNotifierChannel(ch)
const firstBlockTimeout = time.Minute * 5
timer := time.NewTimer(firstBlockTimeout)
// loop until block 1
for {
select {
case block, ok := <-ch:
if !ok {
timer.Stop()
return errChannelClosed
}
if ok && block.Header.Number > 0 {
timer.Stop()
return nil
}
case <-timer.C:
return errFirstBlockTimeout
case <-b.ctx.Done():
timer.Stop()
return b.ctx.Err()
}
}
}
// SlotDuration returns the current service slot duration in milliseconds
func (b *Service) SlotDuration() uint64 {
return uint64(b.constants.slotDuration.Milliseconds())
}
// EpochLength returns the current service epoch duration
func (b *Service) EpochLength() uint64 {
return b.constants.epochLength
}
// Pause pauses the service ie. halts block production
func (b *Service) Pause() error {
b.Lock()
defer b.Unlock()
if b.IsPaused() {
return nil
}
close(b.pause)
return nil
}
// Resume resumes the service ie. resumes block production
func (b *Service) Resume() error {
b.Lock()
defer b.Unlock()
if !b.IsPaused() {
return nil
}
b.pause = make(chan struct{})
go b.initiate()
logger.Debug("service resumed")
return nil
}
// IsPaused returns if the service is paused or not (ie. producing blocks)
func (b *Service) IsPaused() bool {
select {
case <-b.pause:
return true
default:
return false
}
}
// Stop stops the service. If stop is called, it cannot be resumed.
func (b *Service) Stop() error {
if !b.authority {
return nil
}
b.Lock()
defer b.Unlock()
if b.ctx.Err() != nil {
return errors.New("service already stopped")
}
ethmetrics.Unregister(buildBlockTimer)
ethmetrics.Unregister(buildBlockErrors)
b.cancel()
return nil
}
// Authorities returns the current BABE authorities
func (b *Service) Authorities() []types.Authority {
auths := make([]types.Authority, len(b.epochHandler.epochData.authorities))
for i, auth := range b.epochHandler.epochData.authorities {
auths[i] = *auth.DeepCopy()
}
return auths
}
// IsStopped returns true if the service is stopped (ie not producing blocks)
func (b *Service) IsStopped() bool {
return b.ctx.Err() != nil
}
func (b *Service) getAuthorityIndex(Authorities []types.Authority) (uint32, error) {
if !b.authority {
return 0, ErrNotAuthority
}
pub := b.keypair.Public()
for i, auth := range Authorities {
if bytes.Equal(pub.Encode(), auth.Key.Encode()) {
return uint32(i), nil
}
}
return 0, fmt.Errorf("key not in BABE authority data")
}
func (b *Service) initiate() {
// we should consider better error handling for this - we should
// retry to run the engine at some point (maybe the next epoch) if
// there's an error.
if err := b.runEngine(); err != nil {
logger.Criticalf("failed to run block production engine: %s", err)
}
}
func (b *Service) initiateAndGetEpochHandler(epoch uint64) (*epochHandler, error) {
epochData, err := b.initiateEpoch(epoch)
if err != nil {
return nil, fmt.Errorf("failed to initiate epoch: %w", err)
}
logger.Debugf("initiated epoch with threshold %s, randomness 0x%x and authorities %v",
epochData.threshold, epochData.randomness[:], epochData.authorities)
epochStartSlot, err := b.epochState.GetStartSlotForEpoch(epoch)
if err != nil {
return nil, fmt.Errorf("failed to get start slot for current epoch %d: %w", epoch, err)
}
return newEpochHandler(epoch,
epochStartSlot,
epochData,
b.constants,
b.handleSlot,
b.keypair,
)
}
func (b *Service) runEngine() error {
epoch, err := b.epochState.GetCurrentEpoch()
if err != nil {
return fmt.Errorf("failed to get current epoch: %s", err)
}
for {
next, err := b.handleEpoch(epoch)
if errors.Is(err, errServicePaused) || errors.Is(err, context.Canceled) {
return nil
} else if err != nil {
return fmt.Errorf("cannot handle epoch: %w", err)
}
epoch = next
}
}
func (b *Service) handleEpoch(epoch uint64) (next uint64, err error) {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
b.epochHandler, err = b.initiateAndGetEpochHandler(epoch)
if err != nil {
return 0, fmt.Errorf("cannot initiate and get epoch handler: %w", err)
}
// get start slot for current epoch
nextEpochStart, err := b.epochState.GetStartSlotForEpoch(epoch + 1)
if err != nil {
return 0, fmt.Errorf("failed to get start slot for next epoch %d: %w", epoch+1, err)
}
nextEpochStartTime := getSlotStartTime(nextEpochStart, b.constants.slotDuration)
epochTimer := time.NewTimer(time.Until(nextEpochStartTime))
errCh := make(chan error)
go b.epochHandler.run(ctx, errCh)
select {
case <-b.ctx.Done():
epochTimer.Stop()
return 0, b.ctx.Err()
case <-b.pause:
epochTimer.Stop()
return 0, errServicePaused
case <-epochTimer.C:
// stop current epoch handler
cancel()
case err := <-errCh:
// TODO: errEpochPast is sent on this channel, but it doesnot get logged here
epochTimer.Stop()
logger.Errorf("error from epochHandler: %s", err)
}
// setup next epoch, re-invoke block authoring
next, err = b.incrementEpoch()
if err != nil {
return 0, fmt.Errorf("failed to increment epoch: %w", err)
}
logger.Infof("epoch %d complete, upcoming epoch: %d", epoch, next)
return next, nil
}
func (b *Service) getParentForBlockAuthoring(slotNum uint64) (*types.Header, error) {
parentHeader, err := b.blockState.BestBlockHeader()
if err != nil {
return nil, fmt.Errorf("could not get best block header: %w", err)
}
if parentHeader == nil {
return nil, errNilParentHeader
}
atGenesisBlock := b.blockState.GenesisHash() == parentHeader.Hash()
if !atGenesisBlock {
bestBlockSlotNum, err := b.blockState.GetSlotForBlock(parentHeader.Hash())
if err != nil {
return nil, fmt.Errorf("could not get slot for block: %w", err)
}
if bestBlockSlotNum > slotNum {
return nil, fmt.Errorf("%w: best block slot number is %d and got slot number %d",
errLaggingSlot, bestBlockSlotNum, slotNum)
}
if bestBlockSlotNum == slotNum {
// pick parent of best block instead to handle slot
newParentHeader, err := b.blockState.GetHeader(parentHeader.ParentHash)
if err != nil {
return nil, fmt.Errorf("could not get header: %w", err)
}
if newParentHeader == nil {
return nil, fmt.Errorf("%w: for block hash %s", errNilParentHeader, parentHeader.ParentHash)
}
parentHeader = newParentHeader
}
}
// there is a chance that the best block header may change in the course of building the block,
// so let's copy it first.
parent, err := parentHeader.DeepCopy()
if err != nil {
return nil, fmt.Errorf("could not create deep copy of parent header: %w", err)
}
return parent, nil
}
func (b *Service) handleSlot(epoch, slotNum uint64,
authorityIndex uint32,
preRuntimeDigest *types.PreRuntimeDigest,
) error {
currentSlot := Slot{
start: time.Now(),
duration: b.constants.slotDuration,
number: slotNum,
}
parent, err := b.getParentForBlockAuthoring(slotNum)
if err != nil {
return fmt.Errorf("could not get parent for claiming slot %d: %w", slotNum, err)
}
b.storageState.Lock()
defer b.storageState.Unlock()
// set runtime trie before building block
// if block building is successful, store the resulting trie in the storage state
ts, err := b.storageState.TrieState(&parent.StateRoot)
if err != nil || ts == nil {
logger.Errorf("failed to get parent trie with parent state root %s: %s", parent.StateRoot, err)
return err
}
rt, err := b.blockState.GetRuntime(parent.Hash())
if err != nil {
return err
}
rt.SetContextStorage(ts)
block, err := b.buildBlock(parent, currentSlot, rt, authorityIndex, preRuntimeDigest)
if err != nil {
return err
}
logger.Infof(
"built block %d with hash %s, state root %s, epoch %d and slot %d",
block.Header.Number, block.Header.Hash(), block.Header.StateRoot, epoch, slotNum)
logger.Tracef(
"built block with parent hash %s, header %s and body %s",
parent.Hash(), block.Header.String(), block.Body)
b.telemetry.SendMessage(
telemetry.NewPreparedBlockForProposing(
block.Header.Hash(),
fmt.Sprint(block.Header.Number),
),
)
if err := b.blockImportHandler.HandleBlockProduced(block, ts); err != nil {
logger.Warnf("failed to import built block: %s", err)
return err
}
return nil
}
func getCurrentSlot(slotDuration time.Duration) uint64 {
return uint64(time.Now().UnixNano()) / uint64(slotDuration.Nanoseconds())
}
func getSlotStartTime(slot uint64, slotDuration time.Duration) time.Time {
return time.Unix(0, int64(slot)*slotDuration.Nanoseconds())
}