cmd, core, params: use gas-per-second block limiting

cmd/geth/main.go

@@ -150,7 +150,7 @@ participating.
 		utils.MiningGPUFlag,
 		utils.AutoDAGFlag,
 		utils.TargetGasLimitFlag,
-		utils.BlockTimeLimitFlag,
+		utils.GasPerSecondFlag,
 		utils.NATFlag,
 		utils.NatspecEnabledFlag,
 		utils.NoDiscoverFlag,

cmd/geth/usage.go

@@ -126,7 +126,7 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.AutoDAGFlag,
 			utils.EtherbaseFlag,
 			utils.TargetGasLimitFlag,
-			utils.BlockTimeLimitFlag,
+			utils.GasPerSecondFlag,
 			utils.GasPriceFlag,
 			utils.ExtraDataFlag,
 		},

cmd/utils/flags.go

@@ -183,10 +183,10 @@ var (
 		Usage: "Sets the artificial target gas floor for the blocks to mine",
 		Value: params.GenesisGasLimit.String(),
 	}
-	BlockTimeLimitFlag = cli.IntFlag{
-		Name:  "blocktimelimit",
-		Usage: "Time limit for processing a block after which to halve the hard gas limit",
-		Value: 5,
+	GasPerSecondFlag = cli.StringFlag{
+		Name:  "gaspersec",
+		Usage: "Gas consumption per second below which to tighten the block limits",
+		Value: params.GasPerSecondThreshold.String(),
 	}
 	AutoDAGFlag = cli.BoolFlag{
 		Name:  "autodag",
@@ -752,7 +752,7 @@ func SetupNetwork(ctx *cli.Context) {
 	}
 	params.TargetGasLimit = common.String2Big(ctx.GlobalString(TargetGasLimitFlag.Name))
 	params.CurrentGasCeil.Set(params.TargetGasLimit)
-	params.BlockTimeLimit = time.Duration(ctx.GlobalInt(BlockTimeLimitFlag.Name)) * time.Second
+	params.GasPerSecondThreshold = common.String2Big(ctx.GlobalString(GasPerSecondFlag.Name))
 }
 
 // MustMakeChainConfig reads the chain configuration from the database in ctx.Datadir.

core/blockchain.go

@@ -980,8 +980,9 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 		stats.processed++
 
 		// Update the current gas limit (mining only) based on import times
+		if gasUsed := chain[i].GasUsed(); gasUsed.Cmp(common.Big0) > 0 {
 			params.CurrentGasCeilLock.Lock()
-		if time.Since(bstart) > params.BlockTimeLimit {
+			if gasPerSecond := gasUsed.Uint64() * uint64(time.Second) / uint64(time.Since(bstart)); gasPerSecond < params.GasPerSecondThreshold.Uint64() {
 				ceil := new(big.Int).Div(params.CurrentGasCeil, params.CurrentGasCeilCutDiv)
 				params.CurrentGasCeil.Set(common.BigMax(ceil, params.MinGasLimit))
 			} else {
@@ -992,6 +993,7 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			glog.V(logger.Debug).Infof("block gas ceiling changed to %v", params.CurrentGasCeil)
 			params.CurrentGasCeilLock.Unlock()
 		}
+	}
 
 	if (stats.queued > 0 || stats.processed > 0 || stats.ignored > 0) && bool(glog.V(logger.Info)) {
 		start, end := chain[0], chain[len(chain)-1]

params/miner_strategy.go

@@ -19,13 +19,12 @@ package params
 import (
 	"math/big"
 	"sync"
-	"time"
 )
 
 var (
 	GenesisGasLimit       = big.NewInt(4712388)               // Gas limit of the Genesis block.
 	TargetGasLimit        = new(big.Int).Set(GenesisGasLimit) // The artificial target
-	BlockTimeLimit  = 5 * time.Second                   // Block processing time limit to reduce gas after
+	GasPerSecondThreshold = big.NewInt(4712388 / 2)           // Threshold below which to start reducing block gas limits
 
 	// Temp hack to get a dynamic gas limit in palace (clean up!!!)
 	CurrentGasCeil       = new(big.Int).Set(GenesisGasLimit)