GasLimit adjustment logic updated and network specific gas ceil is used

Previously the gas adjustment was being done using arbitrary code which I
couldn't track from Geth. And the variables were being used in a wrong way.

PROBLEM: To be specific, genesis gas limit was set to the min gas limit and
Parent gas limit was given as an input to the CalcGasLimit function. This meant
that the gas limit would never adjust and it will always stay the same as the
genesis gas limit set in the genesis block.

SOLUTION: Gas limit should adjust based on the usage, and by default a spike in
the gas limit shouldn't be allowed This Commit does exactly that.

CalcGasLimit takes parent gas limit and the desired gas limit and returns the
gas limit after adjustment, either adding/subtracting a fixed proportion of the parent gas
limit to the parent gas limit.

If the percentage of gas used is less than 80 percent adjust downwards to
default GasFloor and otherwise adjust upwards to the GasCeil

Since this is not consensus, a Node operator can change this default behavior
if he chooses to do so, he can increase or decrease within the allowable range.

cmd/utils/flags.go

@@ -609,7 +609,6 @@ var (
 		Usage: "Enable colorized logging",
 	}
 
-
 	LogToStdOutFlag = cli.BoolFlag{
 		Name:  "logtostdout",
 		Usage: "Write log messages to stdout",
@@ -932,6 +931,27 @@ func setSubUrls(ctx *cli.Context, cfg *ethconfig.Config) {
 	}
 }
 
+// setGasLimitCeil sets the gas limit ceils based on the network that is
+// running
+func setGasLimitCeil(ctx *cli.Context, cfg *ethconfig.Config) {
+	switch {
+	case ctx.GlobalBool(ColosseumFlag.Name):
+		cfg.Miner.GasCeil = params.ColosseumGasCeil
+	case ctx.GlobalBool(GardenFlag.Name):
+		cfg.Miner.GasCeil = params.GardenGasCeil
+	case ctx.GlobalBool(OrchardFlag.Name):
+		cfg.Miner.GasCeil = params.OrchardGasCeil
+	case ctx.GlobalBool(GalenaFlag.Name):
+		cfg.Miner.GasCeil = params.GalenaGasCeil
+	case ctx.GlobalBool(LocalFlag.Name):
+		cfg.Miner.GasCeil = params.LocalGasCeil
+	case ctx.GlobalBool(DeveloperFlag.Name):
+		cfg.Miner.GasCeil = params.LocalGasCeil
+	default:
+		cfg.Miner.GasCeil = params.ColosseumGasCeil
+	}
+}
+
 // makeSubUrls returns the subordinate chain urls
 func makeSubUrls(ctx *cli.Context) []string {
 	return strings.Split(ctx.GlobalString(SubUrls.Name), ",")
@@ -1352,6 +1372,9 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
 	// set the subordinate chain websocket urls
 	setSubUrls(ctx, cfg)
 
+	// set the gas limit ceil
+	setGasLimitCeil(ctx, cfg)
+
 	// set the slices that the node is running
 	setSlicesRunning(ctx, cfg)
 

core/genesis.go

@@ -319,8 +319,8 @@ func DefaultColosseumGenesisBlock() *Genesis {
 	return &Genesis{
 		Config:     params.ColosseumChainConfig,
 		Nonce:      66,
-		ExtraData:  hexutil.MustDecode("0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa"),
-		GasLimit:   50000000,
+		ExtraData:  hexutil.MustDecode("0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fb"),
+		GasLimit:   5000000,
 		Difficulty: big.NewInt(1000),
 	}
 }
@@ -330,8 +330,8 @@ func DefaultGardenGenesisBlock() *Genesis {
 	return &Genesis{
 		Config:     params.GardenChainConfig,
 		Nonce:      0,
-		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353535"),
-		GasLimit:   17000000,
+		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353539"),
+		GasLimit:   5000000,
 		Difficulty: big.NewInt(1000),
 	}
 }
@@ -341,8 +341,8 @@ func DefaultOrchardGenesisBlock() *Genesis {
 	return &Genesis{
 		Config:     params.OrchardChainConfig,
 		Nonce:      0,
-		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353535"),
-		GasLimit:   50000000,
+		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353536"),
+		GasLimit:   5000000,
 		Difficulty: big.NewInt(1000),
 	}
 }
@@ -352,8 +352,8 @@ func DefaultGalenaGenesisBlock() *Genesis {
 	return &Genesis{
 		Config:     params.GalenaChainConfig,
 		Nonce:      0,
-		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353535"),
-		GasLimit:   160000000,
+		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353537"),
+		GasLimit:   5000000,
 		Difficulty: big.NewInt(1000),
 	}
 }
@@ -364,7 +364,7 @@ func DefaultLocalGenesisBlock() *Genesis {
 		Config:     params.LocalChainConfig,
 		Nonce:      0,
 		ExtraData:  hexutil.MustDecode("0x3535353535353535353535353535353535353535353535353535353535353535"),
-		GasLimit:   160000000,
+		GasLimit:   5000000,
 		Difficulty: big.NewInt(1000),
 	}
 }

core/worker.go

@@ -57,15 +57,13 @@ type environment struct {
 	gasPool   *GasPool       // available gas used to pack transactions
 	coinbase  common.Address
 
-	header              *types.Header
-	txs                 []*types.Transaction
-	etxs                []*types.Transaction
-	subManifest         types.BlockManifest
-	receipts            []*types.Receipt
-	uncleMu             sync.RWMutex
-	uncles              map[common.Hash]*types.Header
-	externalGasUsed     uint64
-	externalBlockLength int
+	header      *types.Header
+	txs         []*types.Transaction
+	etxs        []*types.Transaction
+	subManifest types.BlockManifest
+	receipts    []*types.Receipt
+	uncleMu     sync.RWMutex
+	uncles      map[common.Hash]*types.Header
 }
 
 // copy creates a deep copy of environment.
@@ -244,6 +242,8 @@ func newWorker(config *Config, chainConfig *params.ChainConfig, db ethdb.Databas
 		resubmitIntervalCh: make(chan time.Duration),
 		resubmitAdjustCh:   make(chan *intervalAdjust, resubmitAdjustChanSize),
 	}
+	// Set the GasFloor of the worker to the minGasLimit
+	worker.config.GasFloor = params.MinGasLimit
 
 	phBodyCache, _ := lru.New(pendingBlockBodyLimit)
 	worker.pendingBlockBody = phBodyCache
@@ -531,14 +531,13 @@ func (w *worker) makeEnv(parent *types.Block, header *types.Header, coinbase com
 
 	// Note the passed coinbase may be different with header.Coinbase.
 	env := &environment{
-		signer:          types.MakeSigner(w.chainConfig, header.Number()),
-		state:           state,
-		coinbase:        coinbase,
-		ancestors:       mapset.NewSet(),
-		family:          mapset.NewSet(),
-		header:          header,
-		uncles:          make(map[common.Hash]*types.Header),
-		externalGasUsed: uint64(0),
+		signer:    types.MakeSigner(w.chainConfig, header.Number()),
+		state:     state,
+		coinbase:  coinbase,
+		ancestors: mapset.NewSet(),
+		family:    mapset.NewSet(),
+		header:    header,
+		uncles:    make(map[common.Hash]*types.Header),
 	}
 	// when 08 is processed ancestors contain 07 (quick block)
 	for _, ancestor := range w.hc.GetBlocksFromHash(parent.Hash(), 7) {
@@ -841,10 +840,12 @@ func (w *worker) fillTransactions(interrupt *int32, env *environment, block *typ
 // into the given sealing block. The transaction selection and ordering strategy can
 // be customized with the plugin in the future.
 func (w *worker) adjustGasLimit(interrupt *int32, env *environment, parent *types.Block) {
-
-	gasUsed := (parent.GasUsed() + env.externalGasUsed) / uint64(env.externalBlockLength+1)
-
-	env.header.SetGasLimit(CalcGasLimit(parent.GasLimit(), gasUsed))
+	percentGasUsed := parent.GasUsed() * 100 / parent.GasLimit()
+	if percentGasUsed > params.PercentGasUsedThreshold {
+		env.header.SetGasLimit(CalcGasLimit(parent.GasLimit(), w.config.GasCeil))
+	} else {
+		env.header.SetGasLimit(CalcGasLimit(parent.GasLimit(), w.config.GasFloor))
+	}
 }
 
 func (w *worker) FinalizeAssemble(chain consensus.ChainHeaderReader, header *types.Header, parent *types.Block, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, etxs []*types.Transaction, subManifest types.BlockManifest, receipts []*types.Receipt) (*types.Block, error) {

eth/ethconfig/config.go

@@ -67,7 +67,7 @@ var Defaults = Config{
 	TrieTimeout:             60 * time.Minute,
 	SnapshotCache:           102,
 	Miner: core.Config{
-		GasCeil:  8000000,
+		GasCeil:  18000000,
 		GasPrice: big.NewInt(params.GWei),
 		Recommit: 3 * time.Second,
 	},

params/config.go

@@ -25,11 +25,11 @@ import (
 
 // Genesis hashes to enforce below configs on.
 var (
-	ColosseumGenesisHash = common.HexToHash("0xff5907242c1dd76d1965e811bb65080788ead1f83863743d07302861ad8645c5")
-	GardenGenesisHash    = common.HexToHash("0xc4bba72ab2bc665b30fff8a2d4a40867b501f861d55ffa84559dd1cf896833c7")
-	OrchardGenesisHash   = common.HexToHash("0xfae78a649e29c4c3fffe9b2a7475e164ac25ccb324063504e8e6d0818d95806f")
-	LocalGenesisHash     = common.HexToHash("0xa39b3d005d2541da2509e032289236a625d0d413cc14824ef31b0beef0c6bb85")
-	GalenaGenesisHash    = common.HexToHash("0xa39b3d005d2541da2509e032289236a625d0d413cc14824ef31b0beef0c6bb85")
+	ColosseumGenesisHash = common.HexToHash("0x937e935af7be23cee3a138dcc0e1a0ba1ccf2c9d085d144d4fb2e6fbd54fdd67")
+	GardenGenesisHash    = common.HexToHash("0x8975f8760d317524559986d595058d4d66c05d62e0eda1d740cdee56a25788a5")
+	OrchardGenesisHash   = common.HexToHash("0x17cf57642df199efff2d6bbf34d99a842d0545980df30e40707ed54663b42baa")
+	LocalGenesisHash     = common.HexToHash("0x9e7149a4f5ff07675e0e7881f004cd0dc1f5a28bb9ba8c4de86794ba6fe80b60")
+	GalenaGenesisHash    = common.HexToHash("0xe0a395a3fcd7ecbb28dd66eeceab2fb40db01a2bfbf9e5fbc5b93269104df19a")
 )
 
 var (

params/protocol_params.go

@@ -19,9 +19,10 @@ package params
 import "math/big"
 
 const (
-	GasLimitBoundDivisor uint64 = 1024      // The bound divisor of the gas limit, used in update calculations.
-	MinGasLimit          uint64 = 17000000  // Minimum the gas limit may ever be.
-	GenesisGasLimit      uint64 = 471238800 // Gas limit of the Genesis block.
+	GasLimitBoundDivisor    uint64 = 1024    // The bound divisor of the gas limit, used in update calculations.
+	PercentGasUsedThreshold uint64 = 95      // Percent Gas used threshold at which the gas limit adjusts
+	MinGasLimit             uint64 = 5000000 // Minimum the gas limit may ever be.
+	GenesisGasLimit         uint64 = 5000000 // Gas limit of the Genesis block.
 
 	MaximumExtraDataSize  uint64 = 32    // Maximum size extra data may be after Genesis.
 	ExpByteGas            uint64 = 10    // Times ceil(log256(exponent)) for the EXP instruction.
@@ -129,14 +130,19 @@ const (
 )
 
 var (
-	DifficultyBoundDivisor = big.NewInt(2048)  // The bound divisor of the difficulty, used in the update calculations.
-	ZoneMinDifficulty      = big.NewInt(1000)  // The minimum difficulty in a zone. Prime & regions should be multiples of this value
-	MinimumDifficulty      = ZoneMinDifficulty // The minimum that the difficulty may ever be.
-	GenesisDifficulty      = ZoneMinDifficulty // Difficulty of the Genesis block.
-	DurationLimit          = big.NewInt(10)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
-	GardenDurationLimit    = big.NewInt(3)     // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
-	OrchardDurationLimit   = big.NewInt(12)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
-	GalenaDurationLimit    = big.NewInt(12)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
-	LocalDurationLimit     = big.NewInt(2)     // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
-	TimeFactor             = big.NewInt(7)
+	ColosseumGasCeil       uint64 = 50000000
+	GardenGasCeil          uint64 = 17000000
+	OrchardGasCeil         uint64 = 50000000
+	GalenaGasCeil          uint64 = 160000000
+	LocalGasCeil           uint64 = 20000000
+	DifficultyBoundDivisor        = big.NewInt(2048)  // The bound divisor of the difficulty, used in the update calculations.
+	ZoneMinDifficulty             = big.NewInt(1000)  // The minimum difficulty in a zone. Prime & regions should be multiples of this value
+	MinimumDifficulty             = ZoneMinDifficulty // The minimum that the difficulty may ever be.
+	GenesisDifficulty             = ZoneMinDifficulty // Difficulty of the Genesis block.
+	DurationLimit                 = big.NewInt(10)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
+	GardenDurationLimit           = big.NewInt(3)     // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
+	OrchardDurationLimit          = big.NewInt(12)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
+	GalenaDurationLimit           = big.NewInt(12)    // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
+	LocalDurationLimit            = big.NewInt(2)     // The decision boundary on the blocktime duration used to determine whether difficulty should go up or not.
+	TimeFactor                    = big.NewInt(7)
 )