eth/catalyst/api.go

@@ -197,18 +197,19 @@ func (api *ConsensusAPI) ForkchoiceUpdatedV1(update beacon.ForkchoiceStateV1, pa
 	// sealed by the beacon client. The payload will be requested later, and we
 	// might replace it arbitrarily many times in between.
 	if payloadAttributes != nil {
-		log.Info("Creating new payload for sealing")
+		// Create an empty block first which can be used as a fallback
-		start := time.Now()
+		empty, err := api.eth.Miner().GetSealingBlockSync(update.HeadBlockHash, payloadAttributes.Timestamp, payloadAttributes.SuggestedFeeRecipient, payloadAttributes.Random, true)
-
-		data, err := api.assembleBlock(update.HeadBlockHash, payloadAttributes)
 		if err != nil {
-			log.Error("Failed to create sealing payload", "err", err)
+			return valid(nil), err
-			return valid(nil), err // valid setHead, invalid payload
+		}
+		// Send a request to generate a full block in the background.
+		// The result can be obtained via the returned channel.
+		resCh, err := api.eth.Miner().GetSealingBlockAsync(update.HeadBlockHash, payloadAttributes.Timestamp, payloadAttributes.SuggestedFeeRecipient, payloadAttributes.Random, false)
+		if err != nil {
+			return valid(nil), err
 		}
 		id := computePayloadId(update.HeadBlockHash, payloadAttributes)
-		api.localBlocks.put(id, data)
+		api.localBlocks.put(id, &payload{empty: empty, result: resCh})
-
-		log.Info("Created payload for sealing", "id", id, "elapsed", time.Since(start))
 		return valid(&id), nil
 	}
 	return valid(nil), nil
@@ -344,14 +345,3 @@ func (api *ConsensusAPI) invalid(err error) beacon.PayloadStatusV1 {
 	errorMsg := err.Error()
 	return beacon.PayloadStatusV1{Status: beacon.INVALID, LatestValidHash: &currentHash, ValidationError: &errorMsg}
 }
-
-// assembleBlock creates a new block and returns the "execution
-// data" required for beacon clients to process the new block.
-func (api *ConsensusAPI) assembleBlock(parentHash common.Hash, params *beacon.PayloadAttributesV1) (*beacon.ExecutableDataV1, error) {
-	log.Info("Producing block", "parentHash", parentHash)
-	block, err := api.eth.Miner().GetSealingBlock(parentHash, params.Timestamp, params.SuggestedFeeRecipient, params.Random)
-	if err != nil {
-		return nil, err
-	}
-	return beacon.BlockToExecutableData(block), nil
-}

eth/catalyst/api_test.go

@@ -93,7 +93,7 @@ func TestEth2AssembleBlock(t *testing.T) {
 	blockParams := beacon.PayloadAttributesV1{
 		Timestamp: blocks[9].Time() + 5,
 	}
-	execData, err := api.assembleBlock(blocks[9].Hash(), &blockParams)
+	execData, err := assembleBlock(api, blocks[9].Hash(), &blockParams)
 	if err != nil {
 		t.Fatalf("error producing block, err=%v", err)
 	}
@@ -114,7 +114,7 @@ func TestEth2AssembleBlockWithAnotherBlocksTxs(t *testing.T) {
 	blockParams := beacon.PayloadAttributesV1{
 		Timestamp: blocks[8].Time() + 5,
 	}
-	execData, err := api.assembleBlock(blocks[8].Hash(), &blockParams)
+	execData, err := assembleBlock(api, blocks[8].Hash(), &blockParams)
 	if err != nil {
 		t.Fatalf("error producing block, err=%v", err)
 	}
@@ -273,7 +273,7 @@ func TestEth2NewBlock(t *testing.T) {
 		tx, _ := types.SignTx(types.NewContractCreation(nonce, new(big.Int), 1000000, big.NewInt(2*params.InitialBaseFee), logCode), types.LatestSigner(ethservice.BlockChain().Config()), testKey)
 		ethservice.TxPool().AddLocal(tx)
 
-		execData, err := api.assembleBlock(parent.Hash(), &beacon.PayloadAttributesV1{
+		execData, err := assembleBlock(api, parent.Hash(), &beacon.PayloadAttributesV1{
 			Timestamp: parent.Time() + 5,
 		})
 		if err != nil {
@@ -313,7 +313,7 @@ func TestEth2NewBlock(t *testing.T) {
 	)
 	parent = preMergeBlocks[len(preMergeBlocks)-1]
 	for i := 0; i < 10; i++ {
-		execData, err := api.assembleBlock(parent.Hash(), &beacon.PayloadAttributesV1{
+		execData, err := assembleBlock(api, parent.Hash(), &beacon.PayloadAttributesV1{
 			Timestamp: parent.Time() + 6,
 		})
 		if err != nil {
@@ -530,3 +530,77 @@ func TestExchangeTransitionConfig(t *testing.T) {
 		t.Fatalf("expected no error on valid config, got %v", err)
 	}
 }
+
+func TestEmptyBlocks(t *testing.T) {
+	genesis, preMergeBlocks := generatePreMergeChain(10)
+	n, ethservice := startEthService(t, genesis, preMergeBlocks)
+	ethservice.Merger().ReachTTD()
+	defer n.Close()
+	var (
+		api    = NewConsensusAPI(ethservice)
+		parent = ethservice.BlockChain().CurrentBlock()
+		// This EVM code generates a log when the contract is created.
+		logCode = common.Hex2Bytes("60606040525b7f24ec1d3ff24c2f6ff210738839dbc339cd45a5294d85c79361016243157aae7b60405180905060405180910390a15b600a8060416000396000f360606040526008565b00")
+	)
+	for i := 0; i < 10; i++ {
+		statedb, _ := ethservice.BlockChain().StateAt(parent.Root())
+		nonce := statedb.GetNonce(testAddr)
+		tx, _ := types.SignTx(types.NewContractCreation(nonce, new(big.Int), 1000000, big.NewInt(2*params.InitialBaseFee), logCode), types.LatestSigner(ethservice.BlockChain().Config()), testKey)
+		ethservice.TxPool().AddLocal(tx)
+
+		params := beacon.PayloadAttributesV1{
+			Timestamp:             parent.Time() + 1,
+			Random:                crypto.Keccak256Hash([]byte{byte(i)}),
+			SuggestedFeeRecipient: parent.Coinbase(),
+		}
+
+		fcState := beacon.ForkchoiceStateV1{
+			HeadBlockHash:      parent.Hash(),
+			SafeBlockHash:      common.Hash{},
+			FinalizedBlockHash: common.Hash{},
+		}
+		resp, err := api.ForkchoiceUpdatedV1(fcState, &params)
+		if err != nil {
+			t.Fatalf("error preparing payload, err=%v", err)
+		}
+		if resp.PayloadStatus.Status != beacon.VALID {
+			t.Fatalf("error preparing payload, invalid status: %v", resp.PayloadStatus.Status)
+		}
+		payload, err := api.GetPayloadV1(*resp.PayloadID)
+		if err != nil {
+			t.Fatalf("can't get payload: %v", err)
+		}
+		// TODO(493456442, marius) this test can be flaky since we rely on a 100ms
+		// allowance for block generation internally.
+		if len(payload.Transactions) == 0 {
+			t.Fatalf("payload should not be empty")
+		}
+		execResp, err := api.NewPayloadV1(*payload)
+		if err != nil {
+			t.Fatalf("can't execute payload: %v", err)
+		}
+		if execResp.Status != beacon.VALID {
+			t.Fatalf("invalid status: %v", execResp.Status)
+		}
+		fcState = beacon.ForkchoiceStateV1{
+			HeadBlockHash:      payload.BlockHash,
+			SafeBlockHash:      payload.ParentHash,
+			FinalizedBlockHash: payload.ParentHash,
+		}
+		if _, err := api.ForkchoiceUpdatedV1(fcState, nil); err != nil {
+			t.Fatalf("Failed to insert block: %v", err)
+		}
+		if ethservice.BlockChain().CurrentBlock().NumberU64() != payload.Number {
+			t.Fatalf("Chain head should be updated")
+		}
+		parent = ethservice.BlockChain().CurrentBlock()
+	}
+}
+
+func assembleBlock(api *ConsensusAPI, parentHash common.Hash, params *beacon.PayloadAttributesV1) (*beacon.ExecutableDataV1, error) {
+	block, err := api.eth.Miner().GetSealingBlockSync(parentHash, params.Timestamp, params.SuggestedFeeRecipient, params.Random, false)
+	if err != nil {
+		return nil, err
+	}
+	return beacon.BlockToExecutableData(block), nil
+}

eth/catalyst/queue.go

@@ -18,6 +18,7 @@ package catalyst
 
 import (
 	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/beacon"
@@ -34,11 +35,52 @@ const maxTrackedPayloads = 10
 // latest one; but have a slight wiggle room for non-ideal conditions.
 const maxTrackedHeaders = 10
 
+// payload wraps the miner's block production channel, allowing the mined block
+// to be retrieved later upon the GetPayload engine API call.
+type payload struct {
+	lock   sync.Mutex
+	done   bool
+	empty  *types.Block
+	block  *types.Block
+	result chan *types.Block
+}
+
+// resolve extracts the generated full block from the given channel if possible
+// or fallback to empty block as an alternative.
+func (req *payload) resolve() *beacon.ExecutableDataV1 {
+	// this function can be called concurrently, prevent any
+	// concurrency issue in the first place.
+	req.lock.Lock()
+	defer req.lock.Unlock()
+
+	// Try to resolve the full block first if it's not obtained
+	// yet. The returned block can be nil if the generation fails.
+
+	if !req.done {
+		timeout := time.NewTimer(500 * time.Millisecond)
+		defer timeout.Stop()
+
+		select {
+		case req.block = <-req.result:
+			req.done = true
+		case <-timeout.C:
+			// TODO(rjl49345642, Marius), should we keep this
+			// 100ms timeout allowance? Why not just use the
+			// default and then fallback to empty directly?
+		}
+	}
+
+	if req.block != nil {
+		return beacon.BlockToExecutableData(req.block)
+	}
+	return beacon.BlockToExecutableData(req.empty)
+}
+
 // payloadQueueItem represents an id->payload tuple to store until it's retrieved
 // or evicted.
 type payloadQueueItem struct {
-	id      beacon.PayloadID
+	id   beacon.PayloadID
-	payload *beacon.ExecutableDataV1
+	data *payload
 }
 
 // payloadQueue tracks the latest handful of constructed payloads to be retrieved
@@ -57,14 +99,14 @@ func newPayloadQueue() *payloadQueue {
 }
 
 // put inserts a new payload into the queue at the given id.
-func (q *payloadQueue) put(id beacon.PayloadID, data *beacon.ExecutableDataV1) {
+func (q *payloadQueue) put(id beacon.PayloadID, data *payload) {
 	q.lock.Lock()
 	defer q.lock.Unlock()
 
 	copy(q.payloads[1:], q.payloads)
 	q.payloads[0] = &payloadQueueItem{
-		id:      id,
+		id:   id,
-		payload: data,
+		data: data,
 	}
 }
 
@@ -78,7 +120,7 @@ func (q *payloadQueue) get(id beacon.PayloadID) *beacon.ExecutableDataV1 {
 			return nil // no more items
 		}
 		if item.id == id {
-			return item.payload
+			return item.data.resolve()
 		}
 	}
 	return nil

miner/miner.go

@@ -235,14 +235,32 @@ func (miner *Miner) DisablePreseal() {
 	miner.worker.disablePreseal()
 }
 
-// GetSealingBlock retrieves a sealing block based on the given parameters.
-// The returned block is not sealed but all other fields should be filled.
-func (miner *Miner) GetSealingBlock(parent common.Hash, timestamp uint64, coinbase common.Address, random common.Hash) (*types.Block, error) {
-	return miner.worker.getSealingBlock(parent, timestamp, coinbase, random)
-}
-
 // SubscribePendingLogs starts delivering logs from pending transactions
 // to the given channel.
 func (miner *Miner) SubscribePendingLogs(ch chan<- []*types.Log) event.Subscription {
 	return miner.worker.pendingLogsFeed.Subscribe(ch)
 }
+
+// GetSealingBlockAsync requests to generate a sealing block according to the
+// given parameters. Regardless of whether the generation is successful or not,
+// there is always a result that will be returned through the result channel.
+// The difference is that if the execution fails, the returned result is nil
+// and the concrete error is dropped silently.
+func (miner *Miner) GetSealingBlockAsync(parent common.Hash, timestamp uint64, coinbase common.Address, random common.Hash, noTxs bool) (chan *types.Block, error) {
+	resCh, _, err := miner.worker.getSealingBlock(parent, timestamp, coinbase, random, noTxs)
+	if err != nil {
+		return nil, err
+	}
+	return resCh, nil
+}
+
+// GetSealingBlockSync creates a sealing block according to the given parameters.
+// If the generation is failed or the underlying work is already closed, an error
+// will be returned.
+func (miner *Miner) GetSealingBlockSync(parent common.Hash, timestamp uint64, coinbase common.Address, random common.Hash, noTxs bool) (*types.Block, error) {
+	resCh, errCh, err := miner.worker.getSealingBlock(parent, timestamp, coinbase, random, noTxs)
+	if err != nil {
+		return nil, err
+	}
+	return <-resCh, <-errCh
+}

miner/worker.go

@@ -170,8 +170,8 @@ type newWorkReq struct {
 // getWorkReq represents a request for getting a new sealing work with provided parameters.
 type getWorkReq struct {
 	params *generateParams
-	err    error
+	result chan *types.Block // non-blocking channel
-	result chan *types.Block
+	err    chan error
 }
 
 // intervalAdjust represents a resubmitting interval adjustment.
@@ -536,12 +536,12 @@ func (w *worker) mainLoop() {
 		case req := <-w.getWorkCh:
 			block, err := w.generateWork(req.params)
 			if err != nil {
-				req.err = err
+				req.err <- err
 				req.result <- nil
 			} else {
+				req.err <- nil
 				req.result <- block
 			}
-
 		case ev := <-w.chainSideCh:
 			// Short circuit for duplicate side blocks
 			if _, exist := w.localUncles[ev.Block.Hash()]; exist {
@@ -969,6 +969,7 @@ type generateParams struct {
 	random     common.Hash    // The randomness generated by beacon chain, empty before the merge
 	noUncle    bool           // Flag whether the uncle block inclusion is allowed
 	noExtra    bool           // Flag whether the extra field assignment is allowed
+	noTxs      bool           // Flag whether an empty block without any transaction is expected
 }
 
 // prepareWork constructs the sealing task according to the given parameters,
@@ -1090,8 +1091,9 @@ func (w *worker) generateWork(params *generateParams) (*types.Block, error) {
 	}
 	defer work.discard()
 
-	w.fillTransactions(nil, work)
+	if !params.noTxs {
-
+		w.fillTransactions(nil, work)
+	}
 	return w.engine.FinalizeAndAssemble(w.chain, work.header, work.state, work.txs, work.unclelist(), work.receipts)
 }
 
@@ -1128,7 +1130,6 @@ func (w *worker) commitWork(interrupt *int32, noempty bool, timestamp int64) {
 		work.discard()
 		return
 	}
-
 	w.commit(work.copy(), w.fullTaskHook, true, start)
 
 	// Swap out the old work with the new one, terminating any leftover
@@ -1177,7 +1178,13 @@ func (w *worker) commit(env *environment, interval func(), update bool, start ti
 }
 
 // getSealingBlock generates the sealing block based on the given parameters.
-func (w *worker) getSealingBlock(parent common.Hash, timestamp uint64, coinbase common.Address, random common.Hash) (*types.Block, error) {
+// The generation result will be passed back via the given channel no matter
+// the generation itself succeeds or not.
+func (w *worker) getSealingBlock(parent common.Hash, timestamp uint64, coinbase common.Address, random common.Hash, noTxs bool) (chan *types.Block, chan error, error) {
+	var (
+		resCh = make(chan *types.Block, 1)
+		errCh = make(chan error, 1)
+	)
 	req := &getWorkReq{
 		params: &generateParams{
 			timestamp:  timestamp,
@@ -1187,18 +1194,16 @@ func (w *worker) getSealingBlock(parent common.Hash, timestamp uint64, coinbase
 			random:     random,
 			noUncle:    true,
 			noExtra:    true,
+			noTxs:      noTxs,
 		},
-		result: make(chan *types.Block, 1),
+		result: resCh,
+		err:    errCh,
 	}
 	select {
 	case w.getWorkCh <- req:
-		block := <-req.result
+		return resCh, errCh, nil
-		if block == nil {
-			return nil, req.err
-		}
-		return block, nil
 	case <-w.exitCh:
-		return nil, errors.New("miner closed")
+		return nil, nil, errors.New("miner closed")
 	}
 }
 

miner/worker_test.go

@@ -638,7 +638,9 @@ func testGetSealingWork(t *testing.T, chainConfig *params.ChainConfig, engine co
 
 	// This API should work even when the automatic sealing is not enabled
 	for _, c := range cases {
-		block, err := w.getSealingBlock(c.parent, timestamp, c.coinbase, c.random)
+		resChan, errChan, _ := w.getSealingBlock(c.parent, timestamp, c.coinbase, c.random, false)
+		block := <-resChan
+		err := <-errChan
 		if c.expectErr {
 			if err == nil {
 				t.Error("Expect error but get nil")
@@ -654,7 +656,9 @@ func testGetSealingWork(t *testing.T, chainConfig *params.ChainConfig, engine co
 	// This API should work even when the automatic sealing is enabled
 	w.start()
 	for _, c := range cases {
-		block, err := w.getSealingBlock(c.parent, timestamp, c.coinbase, c.random)
+		resChan, errChan, _ := w.getSealingBlock(c.parent, timestamp, c.coinbase, c.random, false)
+		block := <-resChan
+		err := <-errChan
 		if c.expectErr {
 			if err == nil {
 				t.Error("Expect error but get nil")