diff options
Diffstat (limited to 'consensus/ethash/consensus.go')
| -rw-r--r-- | consensus/ethash/consensus.go | 46 |
1 files changed, 24 insertions, 22 deletions
diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go index 2930032e5..d02542224 100644 --- a/consensus/ethash/consensus.go +++ b/consensus/ethash/consensus.go @@ -239,7 +239,7 @@ func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent * return errZeroBlockTime } // Verify the block's difficulty based in it's timestamp and parent's difficulty - expected := CalcDifficulty(chain.Config(), header.Time.Uint64(), parent.Time.Uint64(), parent.Number, parent.Difficulty) + expected := CalcDifficulty(chain.Config(), header.Time.Uint64(), parent) if expected.Cmp(header.Difficulty) != 0 { return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected) } @@ -283,16 +283,19 @@ func (ethash *Ethash) verifyHeader(chain consensus.ChainReader, header, parent * return nil } -// CalcDifficulty 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. +// CalcDifficulty 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. // // TODO (karalabe): Move the chain maker into this package and make this private! -func CalcDifficulty(config *params.ChainConfig, time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int { - if config.IsHomestead(new(big.Int).Add(parentNumber, common.Big1)) { - return calcDifficultyHomestead(time, parentTime, parentNumber, parentDiff) +func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int { + next := new(big.Int).Add(parent.Number, common.Big1) + switch { + case config.IsHomestead(next): + return calcDifficultyHomestead(time, parent) + default: + return calcDifficultyFrontier(time, parent) } - return calcDifficultyFrontier(time, parentTime, parentNumber, parentDiff) } // Some weird constants to avoid constant memory allocs for them. @@ -305,15 +308,15 @@ var ( // calcDifficultyHomestead 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 Homestead rules. -func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int { +func calcDifficultyHomestead(time uint64, parent *types.Header) *big.Int { // https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.mediawiki // algorithm: // diff = (parent_diff + // (parent_diff / 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99)) // ) + 2^(periodCount - 2) - bigTime := new(big.Int).SetUint64(time) - bigParentTime := new(big.Int).SetUint64(parentTime) + bigTime := new(big.Int).Set(parent.Time) + bigParentTime := new(big.Int).Set(parent.Time) // holds intermediate values to make the algo easier to read & audit x := new(big.Int) @@ -329,16 +332,16 @@ func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff * x.Set(bigMinus99) } // (parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99)) - y.Div(parentDiff, params.DifficultyBoundDivisor) + y.Div(parent.Difficulty, params.DifficultyBoundDivisor) x.Mul(y, x) - x.Add(parentDiff, x) + x.Add(parent.Difficulty, x) // minimum difficulty can ever be (before exponential factor) if x.Cmp(params.MinimumDifficulty) < 0 { x.Set(params.MinimumDifficulty) } // for the exponential factor - periodCount := new(big.Int).Add(parentNumber, common.Big1) + periodCount := new(big.Int).Add(parent.Number, common.Big1) periodCount.Div(periodCount, expDiffPeriod) // the exponential factor, commonly referred to as "the bomb" @@ -354,25 +357,25 @@ func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff * // calcDifficultyFrontier 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 Frontier rules. -func calcDifficultyFrontier(time, parentTime uint64, parentNumber, parentDiff *big.Int) *big.Int { +func calcDifficultyFrontier(time uint64, parent *types.Header) *big.Int { diff := new(big.Int) - adjust := new(big.Int).Div(parentDiff, params.DifficultyBoundDivisor) + adjust := new(big.Int).Div(parent.Difficulty, params.DifficultyBoundDivisor) bigTime := new(big.Int) bigParentTime := new(big.Int) bigTime.SetUint64(time) - bigParentTime.SetUint64(parentTime) + bigParentTime.Set(parent.Time) if bigTime.Sub(bigTime, bigParentTime).Cmp(params.DurationLimit) < 0 { - diff.Add(parentDiff, adjust) + diff.Add(parent.Difficulty, adjust) } else { - diff.Sub(parentDiff, adjust) + diff.Sub(parent.Difficulty, adjust) } if diff.Cmp(params.MinimumDifficulty) < 0 { diff.Set(params.MinimumDifficulty) } - periodCount := new(big.Int).Add(parentNumber, common.Big1) + periodCount := new(big.Int).Add(parent.Number, common.Big1) periodCount.Div(periodCount, expDiffPeriod) if periodCount.Cmp(common.Big1) > 0 { // diff = diff + 2^(periodCount - 2) @@ -434,8 +437,7 @@ func (ethash *Ethash) Prepare(chain consensus.ChainReader, header *types.Header) if parent == nil { return consensus.ErrUnknownAncestor } - header.Difficulty = CalcDifficulty(chain.Config(), header.Time.Uint64(), - parent.Time.Uint64(), parent.Number, parent.Difficulty) + header.Difficulty = CalcDifficulty(chain.Config(), header.Time.Uint64(), parent) return nil } |