configurable gas limit (#1448)

Add the ability to configure/change the gasLimit at different block heights using transitions.

```
"transitions": [{ 
  "miner.gasLimit": 10000
}]
```

Fixes #1434

Co-authored-by: Antony Denyer <git@antonydenyer.co.uk>

cmd/puppeth/genesis.go

@@ -138,7 +138,7 @@ func newAlethGenesisSpec(network string, genesis *core.Genesis) (*alethGenesisSp
 	spec.Params.NetworkID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())
 	spec.Params.ChainID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())
 	spec.Params.MaximumExtraDataSize = (hexutil.Uint64)(params.MaximumExtraDataSize)
-	spec.Params.MinGasLimit = (hexutil.Uint64)(params.MinGasLimit)
+	spec.Params.MinGasLimit = (hexutil.Uint64)(params.DefaultMinGasLimit)
 	spec.Params.MaxGasLimit = (hexutil.Uint64)(math.MaxInt64)
 	spec.Params.MinimumDifficulty = (*hexutil.Big)(params.MinimumDifficulty)
 	spec.Params.DifficultyBoundDivisor = (*math2.HexOrDecimal256)(params.DifficultyBoundDivisor)
@@ -413,7 +413,7 @@ func newParityChainSpec(network string, genesis *core.Genesis, bootnodes []strin
 		spec.setIstanbul(num)
 	}
 	spec.Params.MaximumExtraDataSize = (hexutil.Uint64)(params.MaximumExtraDataSize)
-	spec.Params.MinGasLimit = (hexutil.Uint64)(params.MinGasLimit)
+	spec.Params.MinGasLimit = (hexutil.Uint64)(params.DefaultMinGasLimit)
 	spec.Params.GasLimitBoundDivisor = (math2.HexOrDecimal64)(params.GasLimitBoundDivisor)
 	spec.Params.NetworkID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())
 	spec.Params.ChainID = (hexutil.Uint64)(genesis.Config.ChainID.Uint64())

consensus/istanbul/backend/engine_test.go

@@ -98,7 +98,7 @@ func makeHeader(parent *types.Block, config *istanbul.Config) *types.Header {
 	header := &types.Header{
 		ParentHash: parent.Hash(),
 		Number:     blockNumber,
-		GasLimit:   core.CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit()),
+		GasLimit:   core.CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit(), parent.GasLimit()),
 		GasUsed:    0,
 		Time:       parent.Time() + config.GetConfig(blockNumber).BlockPeriod,
 		Difficulty: istanbulcommon.DefaultDifficulty,

core/bench_test.go

@@ -113,7 +113,7 @@ func genTxRing(naccounts int) func(int, *BlockGen) {
 	from := 0
 	return func(i int, gen *BlockGen) {
 		block := gen.PrevBlock(i - 1)
-		gas := CalcGasLimit(block, block.GasLimit(), block.GasLimit())
+		gas := CalcGasLimit(block, block.GasLimit(), block.GasLimit(), block.GasLimit())
 		for {
 			gas -= params.TxGas
 			if gas < params.TxGas {

core/block_validator.go

@@ -108,7 +108,7 @@ func (v *BlockValidator) ValidateState(block *types.Block, statedb *state.StateD
 // to keep the baseline gas above the provided floor, and increase it towards the
 // ceil if the blocks are full. If the ceil is exceeded, it will always decrease
 // the gas allowance.
-func CalcGasLimit(parent *types.Block, gasFloor, gasCeil uint64) uint64 {
+func CalcGasLimit(parent *types.Block, minGasLimit, gasFloor, gasCeil uint64) uint64 {
 	// contrib = (parentGasUsed * 3 / 2) / 4096
 	contrib := (parent.GasUsed() + parent.GasUsed()/2) / params.GasLimitBoundDivisor
 
@@ -123,8 +123,8 @@ func CalcGasLimit(parent *types.Block, gasFloor, gasCeil uint64) uint64 {
 		from parentGasLimit * (2/3) parentGasUsed is.
 	*/
 	limit := parent.GasLimit() - decay + contrib
-	if limit < params.MinGasLimit {
-		limit = params.MinGasLimit
+	if limit < minGasLimit {
+		limit = minGasLimit
 	}
 	// If we're outside our allowed gas range, we try to hone towards them
 	if limit < gasFloor {

core/chain_makers.go

@@ -280,7 +280,7 @@ func makeHeader(chain consensus.ChainReader, parent *types.Block, state *state.S
 			Difficulty: parent.Difficulty(),
 			UncleHash:  parent.UncleHash(),
 		}),
-		GasLimit: CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit()),
+		GasLimit: CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit(), parent.GasLimit()),
 		Number:   new(big.Int).Add(parent.Number(), common.Big1),
 		Time:     time,
 	}

core/state_processor_test.go

@@ -131,7 +131,7 @@ func GenerateBadBlock(parent *types.Block, engine consensus.Engine, txs types.Tr
 			Difficulty: parent.Difficulty(),
 			UncleHash:  parent.UncleHash(),
 		}),
-		GasLimit:  CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit()),
+		GasLimit:  CalcGasLimit(parent, parent.GasLimit(), parent.GasLimit(), parent.GasLimit()),
 		Number:    new(big.Int).Add(parent.Number(), common.Big1),
 		Time:      parent.Time() + 10,
 		UncleHash: types.EmptyUncleHash,

eth/backend.go

@@ -833,7 +833,11 @@ func (s *Ethereum) Stop() error {
 }
 
 func (s *Ethereum) CalcGasLimit(block *types.Block) uint64 {
-	return core.CalcGasLimit(block, s.config.Miner.GasFloor, s.config.Miner.GasCeil)
+	minGasLimit := params.DefaultMinGasLimit
+	if s != nil && s.config != nil && s.config.Genesis != nil {
+		minGasLimit = s.config.Genesis.Config.GetMinerMinGasLimit(block.Number(), params.DefaultMinGasLimit)
+	}
+	return core.CalcGasLimit(block, minGasLimit, s.config.Miner.GasFloor, s.config.Miner.GasCeil)
 }
 
 // (Quorum)

eth/ethconfig/config.go

@@ -81,7 +81,7 @@ var Defaults = Config{
 	TrieTimeout:             60 * time.Minute,
 	SnapshotCache:           102,
 	Miner: miner.Config{
-		GasFloor: params.MinGasLimit,
+		GasFloor: params.DefaultMinGasLimit,
 		GasCeil:  params.GenesisGasLimit,
 		GasPrice: big.NewInt(params.GWei),
 		Recommit: 3 * time.Second,

miner/worker.go

@@ -997,11 +997,12 @@ func (w *worker) commitNewWork(interrupt *int32, noempty bool, timestamp int64)
 	if parent.Time() >= uint64(timestamp) {
 		timestamp = int64(parent.Time() + 1)
 	}
+	minGasLimit := w.chainConfig.GetMinerMinGasLimit(parent.Number(), params.DefaultMinGasLimit)
 	num := parent.Number()
 	header := &types.Header{
 		ParentHash: parent.Hash(),
 		Number:     num.Add(num, common.Big1),
-		GasLimit:   core.CalcGasLimit(parent, w.config.GasFloor, w.config.GasCeil),
+		GasLimit:   core.CalcGasLimit(parent, minGasLimit, w.config.GasFloor, w.config.GasCeil),
 		Extra:      w.extra,
 		Time:       uint64(timestamp),
 	}

params/config.go

@@ -443,8 +443,9 @@ type Transition struct {
 	ValidatorContractAddress     common.Address `json:"validatorcontractaddress"`               // Smart contract address for list of validators
 	ValidatorSelectionMode       string         `json:"validatorselectionmode"`                 // Validator selection mode to switch to
 	EnhancedPermissioningEnabled bool           `json:"enhancedPermissioningEnabled,omitempty"` // aka QIP714Block
-	PrivacyEnhancementsEnabled   bool           `json:"privacyEnhancementsEnabled,omitempty"`
-	PrivacyPrecompileEnalbed     bool           `json:"privacyPrecompileEnalbed,omitempty"`
+	PrivacyEnhancementsEnabled   bool           `json:"privacyEnhancementsEnabled,omitempty"`   // privacy enhancements (mandatory party, private state validation)
+	PrivacyPrecompileEnalbed     bool           `json:"privacyPrecompileEnabled,omitempty"`     // enable marker transactions support
+	MinerGasLimit                uint64         `json:"miner.gaslimit"`                         // Gas Limit
 }
 
 // String implements the fmt.Stringer interface.
@@ -614,6 +615,21 @@ func (c *ChainConfig) getTransitionValue(num *big.Int, callback func(transition
 	}
 }
 
+// Quorum
+//
+// GetMinerMinGasLimit returns the miners minGasLimit for the given block number
+func (c *ChainConfig) GetMinerMinGasLimit(num *big.Int, defaultValue uint64) uint64 {
+	minGasLimit := defaultValue
+	if c != nil && num != nil && len(c.Transitions) > 0 {
+		for i := 0; i < len(c.Transitions) && c.Transitions[i].Block.Cmp(num) <= 0; i++ {
+			if c.Transitions[i].MinerGasLimit != 0 {
+				minGasLimit = c.Transitions[i].MinerGasLimit
+			}
+		}
+	}
+	return minGasLimit
+}
+
 // Quorum
 //
 // validates the maxCodeSizeConfig data passed in config
@@ -806,6 +822,9 @@ func isTransitionsConfigCompatible(c1, c2 *ChainConfig, head *big.Int) (error, *
 		if isSameBlock || c1.Transitions[i].ValidatorSelectionMode != c2.Transitions[i].ValidatorSelectionMode {
 			return ErrTransitionIncompatible("ValidatorSelectionMode"), head, head
 		}
+		if isSameBlock || c1.Transitions[i].MinerGasLimit != c2.Transitions[i].MinerGasLimit {
+			return ErrTransitionIncompatible("Miner GasLimit"), head, head
+		}
 	}
 
 	return nil, big.NewInt(0), big.NewInt(0)

params/config_test.go

@@ -330,10 +330,10 @@ func TestCheckTransitionsData(t *testing.T) {
 		wantErr error
 	}
 	var ibftTransitionsConfig, qbftTransitionsConfig, invalidTransition, invalidBlockOrder []Transition
-	tranI0 := Transition{big.NewInt(0), IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false}
-	tranQ5 := Transition{big.NewInt(5), QBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false}
-	tranI10 := Transition{big.NewInt(10), IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false}
-	tranQ8 := Transition{big.NewInt(8), QBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false}
+	tranI0 := Transition{big.NewInt(0), IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false, 0}
+	tranQ5 := Transition{big.NewInt(5), QBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false, 1}
+	tranI10 := Transition{big.NewInt(10), IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false, 0}
+	tranQ8 := Transition{big.NewInt(8), QBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false, 2}
 
 	ibftTransitionsConfig = append(ibftTransitionsConfig, tranI0, tranI10)
 	qbftTransitionsConfig = append(qbftTransitionsConfig, tranQ5, tranQ8)
@@ -393,7 +393,7 @@ func TestCheckTransitionsData(t *testing.T) {
 			wantErr: ErrBlockOrder,
 		},
 		{
-			stored:  &ChainConfig{Transitions: []Transition{{nil, IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false}}},
+			stored:  &ChainConfig{Transitions: []Transition{{nil, IBFT, 30000, 5, 10, 50, common.Address{}, "", false, false, false, 0}}},
 			wantErr: ErrBlockNumberMissing,
 		},
 		{

params/protocol_params.go

@@ -25,7 +25,7 @@ const (
 
 	// modified values for Quorum
 	GasLimitBoundDivisor uint64 = 4096      // The bound divisor of the gas limit, used in update calculations.
-	MinGasLimit          uint64 = 700000000 // Minimum the gas limit may ever be.
+	DefaultMinGasLimit   uint64 = 700000000 // Minimum the gas limit may ever be.
 	GenesisGasLimit      uint64 = 800000000 // Gas limit of the Genesis block.
 
 	MaximumExtraDataSize  uint64 = 32    // Maximum size extra data may be after Genesis.

params/protocol_params_test.go

@@ -14,7 +14,7 @@ func TestQuorumParams(t *testing.T) {
 	}
 	var testData = map[string]data{
 		"GasLimitBoundDivisor":       {GasLimitBoundDivisor, 4096},
-		"MinGasLimit":                {MinGasLimit, 700000000},
+		"MinGasLimit":                {DefaultMinGasLimit, 700000000},
 		"GenesisGasLimit":            {GenesisGasLimit, 800000000},
 		"QuorumMaximumExtraDataSize": {QuorumMaximumExtraDataSize, 65},
 		"QuorumMaxPayloadBufferSize": {QuorumMaxPayloadBufferSize, 128},