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ethash: documentation + cleanup

This commit is contained in:
Martin Holst Swende 2018-09-17 11:49:39 +02:00
parent 3df7df0386
commit 7efb12d29b
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1 changed files with 13 additions and 8 deletions
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21
consensus/ethash/consensus.go
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@ -46,13 +46,16 @@ var (
// calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople. // calcDifficultyConstantinople is the difficulty adjustment algorithm for Constantinople.
// It returns the difficulty that a new block should have when created at time given the // 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. // parent block's time and difficulty. The calculation uses the Byzantium rules, but with
calcDifficultyConstantinople = makeDifficultyCalculator(big.NewInt(4999999)) // 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 // calcDifficultyByzantium is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time given the // 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. // parent block's time and difficulty. The calculation uses the Byzantium rules.
calcDifficultyByzantium = makeDifficultyCalculator(big.NewInt(2999999)) // 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 // Various error messages to mark blocks invalid. These should be private to
@ -335,6 +338,9 @@ var (
// the difficulty is calculated with Byzantium rules, which differs from Homestead in // the difficulty is calculated with Byzantium rules, which differs from Homestead in
// how uncles affect the calculation // how uncles affect the calculation
func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *types.Header) *big.Int { 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 { return func(time uint64, parent *types.Header) *big.Int {
// https://github.com/ethereum/EIPs/issues/100. // https://github.com/ethereum/EIPs/issues/100.
// algorithm: // algorithm:
@ -370,12 +376,11 @@ func makeDifficultyCalculator(bombDelay *big.Int) func(time uint64, parent *type
if x.Cmp(params.MinimumDifficulty) < 0 { if x.Cmp(params.MinimumDifficulty) < 0 {
x.Set(params.MinimumDifficulty) x.Set(params.MinimumDifficulty)
} }
// calculate a fake block number for the ice-age delay: // calculate a fake block number for the ice-age delay
// https://github.com/ethereum/EIPs/pull/669 // Specification: https://eips.ethereum.org/EIPS/eip-1234
// fake_block_number = max(0, block.number - 3_000_000)
fakeBlockNumber := new(big.Int) fakeBlockNumber := new(big.Int)
if parent.Number.Cmp(bombDelay) >= 0 { if parent.Number.Cmp(bombDelayFromParent) >= 0 {
fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelay) // Note, parent is 1 less than the actual block number fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, bombDelayFromParent)
} }
// for the exponential factor // for the exponential factor
periodCount := fakeBlockNumber periodCount := fakeBlockNumber