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https://github.com/kaspanet/kaspad.git
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f7f44995d6
* [NOD-215] Implement difficulty adjustment algorithm * [NOD-215] Handle blocks with genesis parent, and fix adjustment factor calculation * [NOD-215] Fix tests * [NOD-215] fix calcNextRequiredDifficulty * [NOD-215] Add TestDifficulty * [NOD-215] Fix delay to be positive, and add tests for delayed blocks * [NOD-215] Split calcBlockWindowMinMaxAndMedianTimestamps to two functions * [NOD-215] Make explicit loop for padding blue block window with genesis * [NOD-215] Name return values * [NOD-215] Fix delay != 0 error messages * [NOD-215] Fix comments * [NOD-215] Fix blueBlockWindow * [NOD-215] Add TestBlueBlockWindow * [NOD-215] Rename PowLimit -> PowMax * [NOD-215] Fix delay != 0 error messages * [NOD-215] Move PowMaxBits to BlockDAG * [NOD-215] Make blockWindow type * [NOD-215] Make blueBlockWindow always pad with genesis * [NOD-215] Remove redundant line in checkWindowIDs * [NOD-215] Make medianTimestamp return error for empty window
53 lines
2.0 KiB
Go
53 lines
2.0 KiB
Go
// Copyright (c) 2013-2017 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package blockdag
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import (
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"math/big"
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"time"
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"github.com/daglabs/btcd/util"
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)
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// requiredDifficulty calculates the required difficulty for a
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// block given its bluest parent.
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func (dag *BlockDAG) requiredDifficulty(bluestParent *blockNode, newBlockTime time.Time) uint32 {
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// Genesis block.
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if bluestParent == nil || bluestParent.blueScore < dag.difficultyAdjustmentWindowSize+1 {
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return dag.powMaxBits
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}
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// Fetch window of dag.difficultyAdjustmentWindowSize + 1 so we can have dag.difficultyAdjustmentWindowSize block intervals
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timestampsWindow := blueBlockWindow(bluestParent, dag.difficultyAdjustmentWindowSize+1)
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windowMinTimestamp, windowMaxTimeStamp := timestampsWindow.minMaxTimestamps()
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// Remove the last block from the window so to calculate the average target of dag.difficultyAdjustmentWindowSize blocks
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targetsWindow := timestampsWindow[:dag.difficultyAdjustmentWindowSize]
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// Calculate new target difficulty as:
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// averageWindowTarget * (windowMinTimestamp / (targetTimePerBlock * windowSize))
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// The result uses integer division which means it will be slightly
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// rounded down.
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newTarget := targetsWindow.averageTarget()
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newTarget.
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Mul(newTarget, big.NewInt(windowMaxTimeStamp-windowMinTimestamp)).
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Div(newTarget, big.NewInt(dag.targetTimePerBlock)).
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Div(newTarget, big.NewInt(int64(dag.difficultyAdjustmentWindowSize)))
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if newTarget.Cmp(dag.dagParams.PowMax) > 0 {
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return dag.powMaxBits
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}
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newTargetBits := util.BigToCompact(newTarget)
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return newTargetBits
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}
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// NextRequiredDifficulty calculates the required difficulty for a block that will
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// be built on top of the current tips.
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//
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// This function is safe for concurrent access.
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func (dag *BlockDAG) NextRequiredDifficulty(timestamp time.Time) uint32 {
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difficulty := dag.requiredDifficulty(dag.virtual.parents.bluest(), timestamp)
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return difficulty
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}
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