Resubmit block build job periodically (#22)

Author: Ruteri

builder/builder.go

@@ -3,6 +3,7 @@ package builder
 import (
 	"errors"
 	_ "os"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/beacon"
@@ -41,6 +42,7 @@ type Builder struct {
 	beaconClient IBeaconClient
 	relay        IRelay
 	eth          IEthereumService
+	resubmitter  Resubmitter
 
 	builderSecretKey     *bls.SecretKey
 	builderPublicKey     boostTypes.PublicKey
@@ -56,6 +58,7 @@ func NewBuilder(sk *bls.SecretKey, bc IBeaconClient, relay IRelay, builderSignin
 		beaconClient:     bc,
 		relay:            relay,
 		eth:              eth,
+		resubmitter:      Resubmitter{},
 		builderSecretKey: sk,
 		builderPublicKey: pk,
 
@@ -140,13 +143,23 @@ func (b *Builder) OnPayloadAttribute(attrs *BuilderPayloadAttributes) error {
 		return errors.New("parent block not found in blocktree")
 	}
 
-	executableData, block := b.eth.BuildBlock(attrs)
-	if executableData == nil || block == nil {
-		log.Error("did not receive the payload")
-		return errors.New("could not build block")
-	}
+	firstBlockResult := b.resubmitter.newTask(12*time.Second, time.Second, func() error {
+		executableData, block := b.eth.BuildBlock(attrs)
+		if executableData == nil || block == nil {
+			log.Error("did not receive the payload")
+			return errors.New("did not receive the payload")
+		}
+
+		err := b.onSealedBlock(executableData, block, proposerPubkey, vd.FeeRecipient, attrs.Slot)
+		if err != nil {
+			log.Error("could not run block hook", "err", err)
+			return err
+		}
+
+		return nil
+	})
 
-	return b.onSealedBlock(executableData, block, proposerPubkey, vd.FeeRecipient, attrs.Slot)
+	return firstBlockResult
 }
 
 func executableDataToExecutionPayload(data *beacon.ExecutableDataV1) (*boostTypes.ExecutionPayload, error) {

builder/builder_test.go

@@ -3,6 +3,7 @@ package builder
 import (
 	"math/big"
 	"testing"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -120,4 +121,10 @@ func TestOnPayloadAttributes(t *testing.T) {
 	require.Equal(t, expectedSignature, testRelay.submittedMsg.Signature)
 
 	require.Equal(t, uint64(25), testRelay.requestedSlot)
+
+	// Clear the submitted message and check that the job will be ran again and a new message will be submitted
+	testRelay.submittedMsg = nil
+	time.Sleep(2 * time.Second)
+	require.NotNil(t, testRelay.submittedMsg)
+	require.Equal(t, expectedMessage, *testRelay.submittedMsg.Message)
 }

builder/resubmitter.go

@@ -0,0 +1,42 @@
+package builder
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+type Resubmitter struct {
+	mu     sync.Mutex
+	cancel context.CancelFunc
+}
+
+func (r *Resubmitter) newTask(repeatFor time.Duration, interval time.Duration, fn func() error) error {
+	repeatUntilCh := time.After(repeatFor)
+
+	r.mu.Lock()
+	if r.cancel != nil {
+		r.cancel()
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	r.cancel = cancel
+	r.mu.Unlock()
+
+	firstRunErr := fn()
+
+	go func() {
+		for ctx.Err() == nil {
+			select {
+			case <-ctx.Done():
+				return
+			case <-repeatUntilCh:
+				cancel()
+				return
+			case <-time.After(interval):
+				fn()
+			}
+		}
+	}()
+
+	return firstRunErr
+}

builder/resubmitter_test.go

@@ -0,0 +1,56 @@
+package builder
+
+import (
+	"errors"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestResubmitter(t *testing.T) {
+
+	resubmitter := Resubmitter{}
+
+	pingCh := make(chan error)
+	go func() {
+		res := resubmitter.newTask(time.Second, 100*time.Millisecond, func() error {
+			return <-pingCh
+		})
+		require.ErrorContains(t, res, "xx")
+	}()
+
+	select {
+	case pingCh <- errors.New("xx"):
+	case <-time.After(time.Second):
+		t.Error("timeout waiting for the function")
+	}
+
+	select {
+	case pingCh <- nil:
+		t.Error("function restarted too soon")
+	default:
+	}
+
+	time.Sleep(200 * time.Millisecond)
+
+	select {
+	case pingCh <- nil:
+	default:
+		t.Error("function restarted too late")
+	}
+
+	time.Sleep(800 * time.Millisecond)
+
+	select {
+	case pingCh <- nil:
+	default:
+		t.Error("function restarted too late")
+	}
+
+	select {
+	case pingCh <- nil:
+		t.Error("function restarted after deadline")
+	case <-time.After(200 * time.Millisecond):
+	}
+}