Merge pull request #17675 from holiman/eip1234

Eip1234

consensus/ethash/consensus.go

@@ -40,8 +40,22 @@ import (
 var (
 	FrontierBlockReward       = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
 	ByzantiumBlockReward      = big.NewInt(3e+18) // Block reward in wei for successfully mining a block upward from Byzantium
+	ConstantinopleBlockReward = big.NewInt(2e+18) // Block reward in wei for successfully mining a block upward from Constantinople
 	maxUncles                 = 2                 // Maximum number of uncles allowed in a single block
 	allowedFutureBlockTime    = 15 * time.Second  // Max time from current time allowed for blocks, before they're considered future blocks
+
+	// calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople.
+	// It returns the difficulty that a new block should have when created at time given the
+	// parent block's time and difficulty. The calculation uses the Byzantium rules, but with
+	// bomb offset 5M.
+	// Specification EIP-1234: https://eips.ethereum.org/EIPS/eip-1234
+	calcDifficultyConstantinople = makeDifficultyCalculator(big.NewInt(5000000))
+
+	// calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
+	// the difficulty that a new block should have when created at time given the
+	// parent block's time and difficulty. The calculation uses the Byzantium rules.
+	// Specification EIP-649: https://eips.ethereum.org/EIPS/eip-649
+	calcDifficultyByzantium = makeDifficultyCalculator(big.NewInt(3000000))
 )
 
 // Various error messages to mark blocks invalid. These should be private to
@@ -299,6 +313,8 @@ func (ethash *Ethash) CalcDifficulty(chain consensus.ChainReader, time uint64, p
 func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
 	next := new(big.Int).Add(parent.Number, big1)
 	switch {
+	case config.IsConstantinople(next):
+		return calcDifficultyConstantinople(time, parent)
 	case config.IsByzantium(next):
 		return calcDifficultyByzantium(time, parent)
 	case config.IsHomestead(next):
@@ -316,13 +332,16 @@ var (
 	big9          = big.NewInt(9)
 	big10         = big.NewInt(10)
 	bigMinus99    = big.NewInt(-99)
-	big2999999    = big.NewInt(2999999)
 )
 
-// calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
-// the difficulty that a new block should have when created at time given the
-// parent block's time and difficulty. The calculation uses the Byzantium rules.
-func calcDifficultyByzantium(time uint64, parent *types.Header) *big.Int {
+// makeDifficultyCalculator creates a difficultyCalculator with the given bomb-delay.
+// the difficulty is calculated with Byzantium rules, which differs from Homestead in
+// how uncles affect the calculation
+func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *types.Header) *big.Int {
+	// Note, the calculations below looks at the parent number, which is 1 below
+	// the block number. Thus we remove one from the delay given
+	bombDelayFromParent := new(big.Int).Sub(bombDelay, big1)
+	return func(time uint64, parent *types.Header) *big.Int {
 		// https://github.com/ethereum/EIPs/issues/100.
 		// algorithm:
 		// diff = (parent_diff +
@@ -357,12 +376,11 @@ func calcDifficultyByzantium(time uint64, parent *types.Header) *big.Int {
 		if x.Cmp(params.MinimumDifficulty) < 0 {
 			x.Set(params.MinimumDifficulty)
 		}
-	// calculate a fake block number for the ice-age delay:
-	// https://github.com/ethereum/EIPs/pull/669
-	// fake_block_number = max(0, block.number - 3_000_000)
+		// calculate a fake block number for the ice-age delay
+		// Specification: https://eips.ethereum.org/EIPS/eip-1234
 		fakeBlockNumber := new(big.Int)
-	if parent.Number.Cmp(big2999999) >= 0 {
-		fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, big2999999) // Note, parent is 1 less than the actual block number
+		if parent.Number.Cmp(bombDelayFromParent) >= 0 {
+			fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
 		}
 		// for the exponential factor
 		periodCount := fakeBlockNumber
@@ -376,6 +394,7 @@ func calcDifficultyByzantium(time uint64, parent *types.Header) *big.Int {
 			x.Add(x, y)
 		}
 		return x
+	}
 }
 
 // calcDifficultyHomestead is the difficulty adjustment algorithm. It returns
@@ -592,6 +611,9 @@ func accumulateRewards(config *params.ChainConfig, state *state.StateDB, header
 	if config.IsByzantium(header.Number) {
 		blockReward = ByzantiumBlockReward
 	}
+	if config.IsConstantinople(header.Number) {
+		blockReward = ConstantinopleBlockReward
+	}
 	// Accumulate the rewards for the miner and any included uncles
 	reward := new(big.Int).Set(blockReward)
 	r := new(big.Int)