Feat/fakepow delaysealer

consensus/ethash/consensus.go

@@ -463,7 +463,7 @@ func (ethash *Ethash) VerifySeal(chain consensus.ChainHeaderReader, header *type
 // to make remote mining fast.
 func (ethash *Ethash) verifySeal(chain consensus.ChainHeaderReader, header *types.Header, fulldag bool) error {
 	// If we're running a fake PoW, accept any seal as valid
-	if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModeFullFake {
+	if ethash.config.PowMode == ModeFake || ethash.config.PowMode == ModePoissonFake || ethash.config.PowMode == ModeFullFake {
 		time.Sleep(ethash.fakeDelay)
 		if ethash.fakeFail == header.Number.Uint64() {
 			return errInvalidPoW

consensus/ethash/ethash.go

@@ -499,9 +499,28 @@ const (
 	ModeShared
 	ModeTest
 	ModeFake
+	ModePoissonFake
 	ModeFullFake
 )
 
+func (m Mode) String() string {
+	switch m {
+	case ModeNormal:
+		return "Normal"
+	case ModeShared:
+		return "Shared"
+	case ModeTest:
+		return "Test"
+	case ModeFake:
+		return "Fake"
+	case ModePoissonFake:
+		return "PoissonFake"
+	case ModeFullFake:
+		return "FullFake"
+	}
+	return "unknown"
+}
+
 // Config are the configuration parameters of the ethash.
 type Config struct {
 	CacheDir         string

consensus/ethash/sealer.go

@@ -34,6 +34,8 @@ import (
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/consensus"
 	"github.com/ethereum/go-ethereum/core/types"
+	exprand "golang.org/x/exp/rand"
+	"gonum.org/v1/gonum/stat/distuv"
 )
 
 const (
@@ -46,6 +48,21 @@ var (
 	errInvalidSealResult = errors.New("invalid or stale proof-of-work solution")
 )
 
+// makePoissonFakeDelay uses the ethash.threads value as a mean time (lambda)
+// for a Poisson distribution, returning a random value from
+// that discrete function. I think a Poisson distribution probably
+// fairly accurately models real world block times.
+// Note that this is a hacky way to use ethash.threads since
+// lower values will yield faster blocks, but it saves having
+// to add or modify any more code than necessary.
+func (ethash *Ethash) makePoissonFakeDelay() float64 {
+	p := distuv.Poisson{
+		Lambda: float64(ethash.Threads()),
+		Src:    exprand.NewSource(uint64(time.Now().UnixNano())),
+	}
+	return p.Rand()
+}
+
 // Seal implements consensus.Engine, attempting to find a nonce that satisfies
 // the block's difficulty requirements.
 func (ethash *Ethash) Seal(chain consensus.ChainHeaderReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
@@ -59,6 +76,35 @@ func (ethash *Ethash) Seal(chain consensus.ChainHeaderReader, block *types.Block
 			ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
 		}
 		return nil
+	} else if ethash.config.PowMode == ModePoissonFake {
+		go func(header *types.Header) {
+			// Assign random (but non-zero) values to header nonce and mix.
+			header.Nonce = types.EncodeNonce(uint64(rand.Int63n(math.MaxInt64)))
+			b, _ := header.Nonce.MarshalText()
+			header.MixDigest = common.BytesToHash(b)
+
+			// Wait some amount of time.
+			timeout := time.NewTimer(time.Duration(ethash.makePoissonFakeDelay()) * time.Second)
+			defer timeout.Stop()
+
+			select {
+			case <-stop:
+				return
+			case <-ethash.update:
+				timeout.Stop()
+				if err := ethash.Seal(chain, block, results, stop); err != nil {
+					ethash.config.Log.Error("Failed to restart sealing after update", "err", err)
+				}
+			case <-timeout.C:
+				// Send the results when the timeout expires.
+				select {
+				case results <- block.WithSeal(header):
+				default:
+					ethash.config.Log.Warn("Sealing result is not read by miner", "mode", "fake", "sealhash", ethash.SealHash(block.Header()))
+				}
+			}
+		}(block.Header())
+		return nil
 	}
 	// If we're running a shared PoW, delegate sealing to it
 	if ethash.shared != nil {

consensus/ethash/sealer_test.go

@@ -22,6 +22,7 @@ import (
 	"math/big"
 	"net/http"
 	"net/http/httptest"
+	"sort"
 	"testing"
 	"time"
 
@@ -31,6 +32,24 @@ import (
 	"github.com/ethereum/go-ethereum/log"
 )
 
+func TestSealFakePoisson(t *testing.T) {
+	cases := []int{
+		3, 10, 19, 33,
+	}
+	for _, c := range cases {
+		e := &Ethash{threads: c} // "threads" is actually the desired MEAN (lambda) of the Poisson distribution
+		got := []float64{}
+		for i := 0; i < 20; i++ {
+			d := e.makePoissonFakeDelay()
+			got = append(got, d)
+		}
+		sort.Slice(got, func(i, j int) bool {
+			return got[i] < got[j]
+		})
+		t.Logf("ethash.threads,lamda=%2d %v", c, got)
+	}
+}
+
 // Tests whether remote HTTP servers are correctly notified of new work.
 func TestRemoteNotify(t *testing.T) {
 	// Start a simple web server to capture notifications.

go.mod

@@ -18,7 +18,6 @@ require (
 	github.com/dlclark/regexp2 v1.2.0 // indirect
 	github.com/docker/docker v1.4.2-0.20180625184442-8e610b2b55bf
 	github.com/dop251/goja v0.0.0-20200721192441-a695b0cdd498
-	github.com/dvyukov/go-fuzz v0.0.0-20200318091601-be3528f3a813 // indirect
 	github.com/edsrzf/mmap-go v0.0.0-20160512033002-935e0e8a636c
 	github.com/fatih/color v1.7.0
 	github.com/fjl/memsize v0.0.0-20180418122429-ca190fb6ffbc
@@ -29,8 +28,8 @@ require (
 	github.com/go-test/deep v1.0.5
 	github.com/golang/protobuf v1.4.2
 	github.com/golang/snappy v0.0.2-0.20200707131729-196ae77b8a26
-	github.com/gorilla/websocket v1.4.2
 	github.com/google/gofuzz v1.1.1-0.20200604201612-c04b05f3adfa
+	github.com/gorilla/websocket v1.4.2
 	github.com/graph-gophers/graphql-go v0.0.0-20191115155744-f33e81362277
 	github.com/hashicorp/golang-lru v0.5.4
 	github.com/holiman/uint256 v1.1.1
@@ -66,15 +65,15 @@ require (
 	github.com/tyler-smith/go-bip39 v1.0.1-0.20181017060643-dbb3b84ba2ef
 	github.com/wsddn/go-ecdh v0.0.0-20161211032359-48726bab9208
 	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
-	golang.org/x/mobile v0.0.0-20200801112145-973feb4309de // indirect
+	golang.org/x/exp v0.0.0-20191030013958-a1ab85dbe136
 	golang.org/x/net v0.0.0-20200822124328-c89045814202 // indirect
-	golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e
 	golang.org/x/sys v0.0.0-20200824131525-c12d262b63d8
 	golang.org/x/text v0.3.3
 	golang.org/x/time v0.0.0-20190308202827-9d24e82272b4
+	gonum.org/v1/gonum v0.8.1
 	gonum.org/v1/plot v0.8.0
 	gopkg.in/natefinch/npipe.v2 v2.0.0-20160621034901-c1b8fa8bdcce
 	gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6
 	gopkg.in/urfave/cli.v1 v1.20.0
-	gotest.tools v2.2.0+incompatible
+	gotest.tools v2.2.0+incompatible // indirect
 )