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Eip1234 #17675

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merged 3 commits into from
Sep 17, 2018
Merged

Eip1234 #17675

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0732617
consensus: implement Constantinople EIP 1234
Sep 12, 2018
3df7df0
ethash: less copy-paste for EIP 1234
holiman Sep 15, 2018
7efb12d
ethash: documentation + cleanup
holiman Sep 17, 2018
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142 changes: 82 additions & 60 deletions consensus/ethash/consensus.go
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Original file line number Diff line number Diff line change
Expand Up @@ -38,10 +38,24 @@ import (

// Ethash proof-of-work protocol constants.
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
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
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
Expand Down Expand Up @@ -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):
Expand All @@ -316,66 +332,69 @@ 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 {
// https://github.com/ethereum/EIPs/issues/100.
// algorithm:
// diff = (parent_diff +
// (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
// ) + 2^(periodCount - 2)

bigTime := new(big.Int).SetUint64(time)
bigParentTime := new(big.Int).Set(parent.Time)

// holds intermediate values to make the algo easier to read & audit
x := new(big.Int)
y := new(big.Int)

// (2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9
x.Sub(bigTime, bigParentTime)
x.Div(x, big9)
if parent.UncleHash == types.EmptyUncleHash {
x.Sub(big1, x)
} else {
x.Sub(big2, x)
}
// max((2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9, -99)
if x.Cmp(bigMinus99) < 0 {
x.Set(bigMinus99)
}
// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
x.Mul(y, x)
x.Add(parent.Difficulty, x)

// minimum difficulty can ever be (before exponential factor)
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)
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
}
// for the exponential factor
periodCount := fakeBlockNumber
periodCount.Div(periodCount, expDiffPeriod)
// 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 +
// (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
// ) + 2^(periodCount - 2)

bigTime := new(big.Int).SetUint64(time)
bigParentTime := new(big.Int).Set(parent.Time)

// holds intermediate values to make the algo easier to read & audit
x := new(big.Int)
y := new(big.Int)

// (2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9
x.Sub(bigTime, bigParentTime)
x.Div(x, big9)
if parent.UncleHash == types.EmptyUncleHash {
x.Sub(big1, x)
} else {
x.Sub(big2, x)
}
// max((2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9, -99)
if x.Cmp(bigMinus99) < 0 {
x.Set(bigMinus99)
}
// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
x.Mul(y, x)
x.Add(parent.Difficulty, x)

// minimum difficulty can ever be (before exponential factor)
if x.Cmp(params.MinimumDifficulty) < 0 {
x.Set(params.MinimumDifficulty)
}
// 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(bombDelayFromParent) >= 0 {
fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
}
// for the exponential factor
periodCount := fakeBlockNumber
periodCount.Div(periodCount, expDiffPeriod)

// the exponential factor, commonly referred to as "the bomb"
// diff = diff + 2^(periodCount - 2)
if periodCount.Cmp(big1) > 0 {
y.Sub(periodCount, big2)
y.Exp(big2, y, nil)
x.Add(x, y)
// the exponential factor, commonly referred to as "the bomb"
// diff = diff + 2^(periodCount - 2)
if periodCount.Cmp(big1) > 0 {
y.Sub(periodCount, big2)
y.Exp(big2, y, nil)
x.Add(x, y)
}
return x
}
return x
}

// calcDifficultyHomestead is the difficulty adjustment algorithm. It returns
Expand Down Expand Up @@ -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)
Expand Down