cmd, miner: add noempty-precommit flag

cmd/geth/main.go

@@ -129,6 +129,7 @@ var (
 		utils.MinerLegacyExtraDataFlag,
 		utils.MinerRecommitIntervalFlag,
 		utils.MinerNoVerfiyFlag,
+		utils.MinerNoEmptyPrecommitFlag,
 		utils.NATFlag,
 		utils.NoDiscoverFlag,
 		utils.DiscoveryV5Flag,

cmd/geth/usage.go

@@ -210,6 +210,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.MinerExtraDataFlag,
 			utils.MinerRecommitIntervalFlag,
 			utils.MinerNoVerfiyFlag,
+			utils.MinerNoEmptyPrecommitFlag,
 		},
 	},
 	{

cmd/utils/flags.go

@@ -483,6 +483,10 @@ var (
 		Name:  "miner.noverify",
 		Usage: "Disable remote sealing verification",
 	}
+	MinerNoEmptyPrecommitFlag = cli.BoolFlag{
+		Name:  "miner.noempty-precommit",
+		Usage: "Disable empty mining solution precommit",
+	}
 	// Account settings
 	UnlockedAccountFlag = cli.StringFlag{
 		Name:  "unlock",
@@ -1359,6 +1363,9 @@ func setMiner(ctx *cli.Context, cfg *miner.Config) {
 	if ctx.GlobalIsSet(MinerNoVerfiyFlag.Name) {
 		cfg.Noverify = ctx.Bool(MinerNoVerfiyFlag.Name)
 	}
+	if ctx.GlobalIsSet(MinerNoEmptyPrecommitFlag.Name) {
+		cfg.NoEmptyPrecommit = ctx.Bool(MinerNoEmptyPrecommitFlag.Name)
+	}
 }
 
 func setWhitelist(ctx *cli.Context, cfg *eth.Config) {

miner/miner.go

@@ -51,6 +51,7 @@ type Config struct {
 	GasPrice         *big.Int       // Minimum gas price for mining a transaction
 	Recommit         time.Duration  // The time interval for miner to re-create mining work.
 	Noverify         bool           // Disable remote mining solution verification(only useful in ethash).
+	NoEmptyPrecommit bool           // Disable pre-commit empty mining solution
 }
 
 // Miner creates blocks and searches for proof-of-work values.

miner/worker.go

@@ -305,6 +305,10 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 		if interrupt != nil {
 			atomic.StoreInt32(interrupt, s)
 		}
+		// Disable empty mining solution precommit if required.
+		if !noempty && w.config.NoEmptyPrecommit {
+			noempty = true
+		}
 		interrupt = new(int32)
 		w.newWorkCh <- &newWorkReq{interrupt: interrupt, noempty: noempty, timestamp: timestamp}
 		timer.Reset(recommit)
@@ -922,8 +926,10 @@ func (w *worker) commitNewWork(interrupt *int32, noempty bool, timestamp int64)
 		log.Error("Failed to fetch pending transactions", "err", err)
 		return
 	}
-	// Short circuit if there is no available pending transactions
-	if len(pending) == 0 {
+	// Short circuit if there is no available pending transactions.
+	// But if we disable empty precommit already, ignore it. Since
+	// empty block is necessary to keep the liveness of the network.
+	if len(pending) == 0 && !w.config.NoEmptyPrecommit {
 		w.updateSnapshot()
 		return
 	}