[lbry] blockchain: change the difficulty adjustment algorithm.
adjusted := target + (actual - target) / 8 max := target + (target / 2) min := target - (target / 8) if adjusted > max { adjusted = max } else if adj < min { adjusted = min } diffculty := lastDifficulty * adjusted / target
This commit is contained in:
parent
c8abd8fe93
commit
8591f960e2
2 changed files with 28 additions and 33 deletions
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@ -1736,7 +1736,6 @@ func New(config *Config) (*BlockChain, error) {
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params := config.ChainParams
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targetTimespan := int64(params.TargetTimespan / time.Second)
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targetTimePerBlock := int64(params.TargetTimePerBlock / time.Second)
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adjustmentFactor := params.RetargetAdjustmentFactor
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b := BlockChain{
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checkpoints: config.Checkpoints,
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checkpointsByHeight: checkpointsByHeight,
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@ -1745,8 +1744,8 @@ func New(config *Config) (*BlockChain, error) {
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timeSource: config.TimeSource,
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sigCache: config.SigCache,
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indexManager: config.IndexManager,
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minRetargetTimespan: targetTimespan / adjustmentFactor,
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maxRetargetTimespan: targetTimespan * adjustmentFactor,
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minRetargetTimespan: targetTimespan - (targetTimespan / 8),
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maxRetargetTimespan: targetTimespan + (targetTimespan / 2),
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blocksPerRetarget: int32(targetTimespan / targetTimePerBlock),
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index: newBlockIndex(config.DB, params),
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hashCache: config.HashCache,
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@ -159,7 +159,6 @@ func CalcWork(bits uint32) *big.Int {
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func (b *BlockChain) calcEasiestDifficulty(bits uint32, duration time.Duration) uint32 {
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// Convert types used in the calculations below.
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durationVal := int64(duration / time.Second)
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adjustmentFactor := big.NewInt(b.chainParams.RetargetAdjustmentFactor)
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// The test network rules allow minimum difficulty blocks after more
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// than twice the desired amount of time needed to generate a block has
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@ -178,7 +177,8 @@ func (b *BlockChain) calcEasiestDifficulty(bits uint32, duration time.Duration)
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// multiplied by the max adjustment factor.
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newTarget := CompactToBig(bits)
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for durationVal > 0 && newTarget.Cmp(b.chainParams.PowLimit) < 0 {
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newTarget.Mul(newTarget, adjustmentFactor)
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adj := new(big.Int).Div(newTarget, big.NewInt(2))
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newTarget.Add(newTarget, adj)
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durationVal -= b.maxRetargetTimespan
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}
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@ -224,47 +224,44 @@ func (b *BlockChain) calcNextRequiredDifficulty(lastNode *blockNode, newBlockTim
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return b.chainParams.PowLimitBits, nil
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}
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// Return the previous block's difficulty requirements if this block
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// is not at a difficulty retarget interval.
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if (lastNode.height+1)%b.blocksPerRetarget != 0 {
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// For networks that support it, allow special reduction of the
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// required difficulty once too much time has elapsed without
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// mining a block.
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if b.chainParams.ReduceMinDifficulty {
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// Return minimum difficulty when more than the desired
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// amount of time has elapsed without mining a block.
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reductionTime := int64(b.chainParams.MinDiffReductionTime /
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time.Second)
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allowMinTime := lastNode.timestamp + reductionTime
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if newBlockTime.Unix() > allowMinTime {
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return b.chainParams.PowLimitBits, nil
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}
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// The block was mined within the desired timeframe, so
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// return the difficulty for the last block which did
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// not have the special minimum difficulty rule applied.
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return b.findPrevTestNetDifficulty(lastNode), nil
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// For networks that support it, allow special reduction of the
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// required difficulty once too much time has elapsed without
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// mining a block.
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if b.chainParams.ReduceMinDifficulty {
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// Return minimum difficulty when more than the desired
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// amount of time has elapsed without mining a block.
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reductionTime := int64(b.chainParams.MinDiffReductionTime /
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time.Second)
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allowMinTime := lastNode.timestamp + reductionTime
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if newBlockTime.Unix() > allowMinTime {
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return b.chainParams.PowLimitBits, nil
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}
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// For the main network (or any unrecognized networks), simply
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// return the previous block's difficulty requirements.
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return lastNode.bits, nil
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// The block was mined within the desired timeframe, so
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// return the difficulty for the last block which did
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// not have the special minimum difficulty rule applied.
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return b.findPrevTestNetDifficulty(lastNode), nil
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}
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// Get the block node at the previous retarget (targetTimespan days
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// worth of blocks).
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firstNode := lastNode.RelativeAncestor(b.blocksPerRetarget - 1)
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firstNode := lastNode.RelativeAncestor(b.blocksPerRetarget)
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if lastNode.height == 0 {
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firstNode = lastNode
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}
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if firstNode == nil {
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return 0, AssertError("unable to obtain previous retarget block")
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}
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targetTimeSpan := int64(b.chainParams.TargetTimespan / time.Second)
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// Limit the amount of adjustment that can occur to the previous
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// difficulty.
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actualTimespan := lastNode.timestamp - firstNode.timestamp
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adjustedTimespan := actualTimespan
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if actualTimespan < b.minRetargetTimespan {
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adjustedTimespan := targetTimeSpan + (actualTimespan-targetTimeSpan)/8
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if adjustedTimespan < b.minRetargetTimespan {
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adjustedTimespan = b.minRetargetTimespan
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} else if actualTimespan > b.maxRetargetTimespan {
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} else if adjustedTimespan > b.maxRetargetTimespan {
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adjustedTimespan = b.maxRetargetTimespan
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}
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@ -275,7 +272,6 @@ func (b *BlockChain) calcNextRequiredDifficulty(lastNode *blockNode, newBlockTim
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// result.
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oldTarget := CompactToBig(lastNode.bits)
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newTarget := new(big.Int).Mul(oldTarget, big.NewInt(adjustedTimespan))
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targetTimeSpan := int64(b.chainParams.TargetTimespan / time.Second)
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newTarget.Div(newTarget, big.NewInt(targetTimeSpan))
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// Limit new value to the proof of work limit.
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