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consensus/ethash: refactor remote sealer (ethereum#20335)
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The original idea behind this change was to remove a use of the
deprecated CancelRequest method. Simply removing it would've been an
option, but I couldn't resist and did a bit of a refactoring instead.

All remote sealing code was contained in a single giant function. Remote
sealing is now extracted into its own object, remoteSealer.
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@fjl @enriquefynn
fjl authored and enriquefynn committed Feb 15, 2021
1 parent dbcf0b0 commit 7e12363
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Showing 5 changed files with 294 additions and 304 deletions.
2 changes: 1 addition & 1 deletion consensus/ethash/algorithm_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -729,7 +729,7 @@ func TestConcurrentDiskCacheGeneration(t *testing.T) {

go func(idx int) {
defer pend.Done()
ethash := New(Config{cachedir, 0, 1, "", 0, 0, ModeNormal}, nil, false)
ethash := New(Config{cachedir, 0, 1, "", 0, 0, ModeNormal, nil}, nil, false)
defer ethash.Close()
if err := ethash.VerifySeal(nil, block.Header()); err != nil {
t.Errorf("proc %d: block verification failed: %v", idx, err)
Expand Down
26 changes: 10 additions & 16 deletions consensus/ethash/api.go
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ var errEthashStopped = errors.New("ethash stopped")

// API exposes ethash related methods for the RPC interface.
type API struct {
ethash *Ethash // Make sure the mode of ethash is normal.
ethash *Ethash
}

// GetWork returns a work package for external miner.
Expand All @@ -39,21 +39,19 @@ type API struct {
// result[2] - 32 bytes hex encoded boundary condition ("target"), 2^256/difficulty
// result[3] - hex encoded block number
func (api *API) GetWork() ([4]string, error) {
if api.ethash.config.PowMode != ModeNormal && api.ethash.config.PowMode != ModeTest {
if api.ethash.remote == nil {
return [4]string{}, errors.New("not supported")
}

var (
workCh = make(chan [4]string, 1)
errc = make(chan error, 1)
)

select {
case api.ethash.fetchWorkCh <- &sealWork{errc: errc, res: workCh}:
case <-api.ethash.exitCh:
case api.ethash.remote.fetchWorkCh <- &sealWork{errc: errc, res: workCh}:
case <-api.ethash.remote.exitCh:
return [4]string{}, errEthashStopped
}

select {
case work := <-workCh:
return work, nil
Expand All @@ -66,23 +64,21 @@ func (api *API) GetWork() ([4]string, error) {
// It returns an indication if the work was accepted.
// Note either an invalid solution, a stale work a non-existent work will return false.
func (api *API) SubmitWork(nonce types.BlockNonce, hash, digest common.Hash) bool {
if api.ethash.config.PowMode != ModeNormal && api.ethash.config.PowMode != ModeTest {
if api.ethash.remote == nil {
return false
}

var errc = make(chan error, 1)

select {
case api.ethash.submitWorkCh <- &mineResult{
case api.ethash.remote.submitWorkCh <- &mineResult{
nonce: nonce,
mixDigest: digest,
hash: hash,
errc: errc,
}:
case <-api.ethash.exitCh:
case <-api.ethash.remote.exitCh:
return false
}

err := <-errc
return err == nil
}
Expand All @@ -94,21 +90,19 @@ func (api *API) SubmitWork(nonce types.BlockNonce, hash, digest common.Hash) boo
// It accepts the miner hash rate and an identifier which must be unique
// between nodes.
func (api *API) SubmitHashRate(rate hexutil.Uint64, id common.Hash) bool {
if api.ethash.config.PowMode != ModeNormal && api.ethash.config.PowMode != ModeTest {
if api.ethash.remote == nil {
return false
}

var done = make(chan struct{}, 1)

select {
case api.ethash.submitRateCh <- &hashrate{done: done, rate: uint64(rate), id: id}:
case <-api.ethash.exitCh:
case api.ethash.remote.submitRateCh <- &hashrate{done: done, rate: uint64(rate), id: id}:
case <-api.ethash.remote.exitCh:
return false
}

// Block until hash rate submitted successfully.
<-done

return true
}

Expand Down
112 changes: 34 additions & 78 deletions consensus/ethash/ethash.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,9 +34,7 @@ import (
"unsafe"

mmap "github.com/edsrzf/mmap-go"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/consensus"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/metrics"
"github.com/ethereum/go-ethereum/rpc"
Expand All @@ -50,7 +48,7 @@ var (
two256 = new(big.Int).Exp(big.NewInt(2), big.NewInt(256), big.NewInt(0))

// sharedEthash is a full instance that can be shared between multiple users.
sharedEthash = New(Config{"", 3, 0, "", 1, 0, ModeNormal}, nil, false)
sharedEthash = New(Config{"", 3, 0, "", 1, 0, ModeNormal, nil}, nil, false)

// algorithmRevision is the data structure version used for file naming.
algorithmRevision = 23
Expand Down Expand Up @@ -403,36 +401,8 @@ type Config struct {
DatasetsInMem int
DatasetsOnDisk int
PowMode Mode
}

// sealTask wraps a seal block with relative result channel for remote sealer thread.
type sealTask struct {
block *types.Block
results chan<- *types.Block
}

// mineResult wraps the pow solution parameters for the specified block.
type mineResult struct {
nonce types.BlockNonce
mixDigest common.Hash
hash common.Hash

errc chan error
}

// hashrate wraps the hash rate submitted by the remote sealer.
type hashrate struct {
id common.Hash
ping time.Time
rate uint64

done chan struct{}
}

// sealWork wraps a seal work package for remote sealer.
type sealWork struct {
errc chan error
res chan [4]string
Log log.Logger `toml:"-"`
}

// Ethash is a consensus engine based on proof-of-work implementing the ethash
Expand All @@ -448,72 +418,56 @@ type Ethash struct {
threads int // Number of threads to mine on if mining
update chan struct{} // Notification channel to update mining parameters
hashrate metrics.Meter // Meter tracking the average hashrate

// Remote sealer related fields
workCh chan *sealTask // Notification channel to push new work and relative result channel to remote sealer
fetchWorkCh chan *sealWork // Channel used for remote sealer to fetch mining work
submitWorkCh chan *mineResult // Channel used for remote sealer to submit their mining result
fetchRateCh chan chan uint64 // Channel used to gather submitted hash rate for local or remote sealer.
submitRateCh chan *hashrate // Channel used for remote sealer to submit their mining hashrate
remote *remoteSealer

// The fields below are hooks for testing
shared *Ethash // Shared PoW verifier to avoid cache regeneration
fakeFail uint64 // Block number which fails PoW check even in fake mode
fakeDelay time.Duration // Time delay to sleep for before returning from verify

lock sync.Mutex // Ensures thread safety for the in-memory caches and mining fields
closeOnce sync.Once // Ensures exit channel will not be closed twice.
exitCh chan chan error // Notification channel to exiting backend threads
lock sync.Mutex // Ensures thread safety for the in-memory caches and mining fields
closeOnce sync.Once // Ensures exit channel will not be closed twice.
}

// New creates a full sized ethash PoW scheme and starts a background thread for
// remote mining, also optionally notifying a batch of remote services of new work
// packages.
func New(config Config, notify []string, noverify bool) *Ethash {
if config.Log == nil {
config.Log = log.Root()
}
if config.CachesInMem <= 0 {
log.Warn("One ethash cache must always be in memory", "requested", config.CachesInMem)
config.Log.Warn("One ethash cache must always be in memory", "requested", config.CachesInMem)
config.CachesInMem = 1
}
if config.CacheDir != "" && config.CachesOnDisk > 0 {
log.Info("Disk storage enabled for ethash caches", "dir", config.CacheDir, "count", config.CachesOnDisk)
config.Log.Info("Disk storage enabled for ethash caches", "dir", config.CacheDir, "count", config.CachesOnDisk)
}
if config.DatasetDir != "" && config.DatasetsOnDisk > 0 {
log.Info("Disk storage enabled for ethash DAGs", "dir", config.DatasetDir, "count", config.DatasetsOnDisk)
config.Log.Info("Disk storage enabled for ethash DAGs", "dir", config.DatasetDir, "count", config.DatasetsOnDisk)
}
ethash := &Ethash{
config: config,
caches: newlru("cache", config.CachesInMem, newCache),
datasets: newlru("dataset", config.DatasetsInMem, newDataset),
update: make(chan struct{}),
hashrate: metrics.NewMeterForced(),
workCh: make(chan *sealTask),
fetchWorkCh: make(chan *sealWork),
submitWorkCh: make(chan *mineResult),
fetchRateCh: make(chan chan uint64),
submitRateCh: make(chan *hashrate),
exitCh: make(chan chan error),
}
go ethash.remote(notify, noverify)
config: config,
caches: newlru("cache", config.CachesInMem, newCache),
datasets: newlru("dataset", config.DatasetsInMem, newDataset),
update: make(chan struct{}),
hashrate: metrics.NewMeterForced(),
}
ethash.remote = startRemoteSealer(ethash, notify, noverify)
return ethash
}

// NewTester creates a small sized ethash PoW scheme useful only for testing
// purposes.
func NewTester(notify []string, noverify bool) *Ethash {
ethash := &Ethash{
config: Config{PowMode: ModeTest},
caches: newlru("cache", 1, newCache),
datasets: newlru("dataset", 1, newDataset),
update: make(chan struct{}),
hashrate: metrics.NewMeterForced(),
workCh: make(chan *sealTask),
fetchWorkCh: make(chan *sealWork),
submitWorkCh: make(chan *mineResult),
fetchRateCh: make(chan chan uint64),
submitRateCh: make(chan *hashrate),
exitCh: make(chan chan error),
}
go ethash.remote(notify, noverify)
config: Config{PowMode: ModeTest, Log: log.Root()},
caches: newlru("cache", 1, newCache),
datasets: newlru("dataset", 1, newDataset),
update: make(chan struct{}),
hashrate: metrics.NewMeterForced(),
}
ethash.remote = startRemoteSealer(ethash, notify, noverify)
return ethash
}

Expand All @@ -524,6 +478,7 @@ func NewFaker() *Ethash {
return &Ethash{
config: Config{
PowMode: ModeFake,
Log: log.Root(),
},
}
}
Expand All @@ -535,6 +490,7 @@ func NewFakeFailer(fail uint64) *Ethash {
return &Ethash{
config: Config{
PowMode: ModeFake,
Log: log.Root(),
},
fakeFail: fail,
}
Expand All @@ -547,6 +503,7 @@ func NewFakeDelayer(delay time.Duration) *Ethash {
return &Ethash{
config: Config{
PowMode: ModeFake,
Log: log.Root(),
},
fakeDelay: delay,
}
Expand All @@ -558,6 +515,7 @@ func NewFullFaker() *Ethash {
return &Ethash{
config: Config{
PowMode: ModeFullFake,
Log: log.Root(),
},
}
}
Expand All @@ -573,13 +531,11 @@ func (ethash *Ethash) Close() error {
var err error
ethash.closeOnce.Do(func() {
// Short circuit if the exit channel is not allocated.
if ethash.exitCh == nil {
if ethash.remote == nil {
return
}
errc := make(chan error)
ethash.exitCh <- errc
err = <-errc
close(ethash.exitCh)
close(ethash.remote.requestExit)
<-ethash.remote.exitCh
})
return err
}
Expand Down Expand Up @@ -680,8 +636,8 @@ func (ethash *Ethash) Hashrate() float64 {
var res = make(chan uint64, 1)

select {
case ethash.fetchRateCh <- res:
case <-ethash.exitCh:
case ethash.remote.fetchRateCh <- res:
case <-ethash.remote.exitCh:
// Return local hashrate only if ethash is stopped.
return ethash.hashrate.Rate1()
}
Expand Down
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