caf83faf39
Migrate types/asset.go from fmt.Errorf to coreerr.E() for consistency with the rest of the types package. Add usage-example comments (AX-2) to all key exported functions in consensus/, chain/, and types/ so agents can see concrete calling patterns without reading implementation details. Co-Authored-By: Virgil <virgil@lethean.io>
91 lines
3.2 KiB
Go
91 lines
3.2 KiB
Go
// Copyright (c) 2017-2026 Lethean (https://lt.hn)
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//
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// Licensed under the European Union Public Licence (EUPL) version 1.2.
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// SPDX-License-Identifier: EUPL-1.2
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package chain
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import (
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"math/big"
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"dappco.re/go/core/blockchain/config"
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"dappco.re/go/core/blockchain/difficulty"
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)
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// nextDifficultyWith computes the expected difficulty for the block at the
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// given height using the LWMA algorithm, parameterised by pre/post-HF6 targets.
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//
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// The genesis block (height 0) is excluded from the difficulty window,
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// matching the C++ daemon's load_targetdata_cache which skips index 0.
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//
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// The target block time depends on the hardfork schedule:
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// - Pre-HF6: baseTarget (120s for both PoW and PoS on Lethean)
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// - Post-HF6: hf6Target (240s -- halves block rate, halves emission)
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//
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// NOTE: This was originally gated on HF2, matching the Zano upstream where
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// HF2 coincides with the difficulty target change. Lethean mainnet keeps 120s
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// blocks between HF2 (height 10,080) and HF6 (height 999,999,999), so the
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// gate was corrected to HF6 in March 2026.
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func (c *Chain) nextDifficultyWith(height uint64, forks []config.HardFork, baseTarget, hf6Target uint64) (uint64, error) {
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if height == 0 {
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return 1, nil
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}
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// LWMA needs N+1 entries (N solve-time intervals).
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// Start from height 1 -- genesis is excluded from the difficulty window.
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maxLookback := difficulty.LWMAWindow + 1
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lookback := min(height, maxLookback) // height excludes genesis since we start from 1
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// Start from max(1, height - lookback) to exclude genesis.
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startHeight := height - lookback
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if startHeight == 0 {
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startHeight = 1
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lookback = height - 1
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}
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if lookback == 0 {
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return 1, nil
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}
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count := int(lookback)
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timestamps := make([]uint64, count)
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cumulDiffs := make([]*big.Int, count)
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for i := range count {
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meta, err := c.getBlockMeta(startHeight + uint64(i))
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if err != nil {
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// Fewer blocks than expected -- use what we have.
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timestamps = timestamps[:i]
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cumulDiffs = cumulDiffs[:i]
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break
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}
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timestamps[i] = meta.Timestamp
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cumulDiffs[i] = new(big.Int).SetUint64(meta.CumulativeDiff)
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}
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// Determine the target block time based on hardfork status.
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// HF6 doubles the target from 120s to 240s (corrected from HF2 gate).
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target := baseTarget
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if config.IsHardForkActive(forks, config.HF6, height) {
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target = hf6Target
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}
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result := difficulty.NextDifficulty(timestamps, cumulDiffs, target)
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return result.Uint64(), nil
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}
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// NextDifficulty computes the expected PoW difficulty for the block at the
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// given height. Pre-HF6 the target is 120s; post-HF6 it doubles to 240s.
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//
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// diff, err := blockchain.NextDifficulty(nextHeight, config.MainnetForks)
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func (c *Chain) NextDifficulty(height uint64, forks []config.HardFork) (uint64, error) {
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return c.nextDifficultyWith(height, forks, config.DifficultyPowTarget, config.DifficultyPowTargetHF6)
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}
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// NextPoSDifficulty computes the expected PoS difficulty for the block at the
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// given height. Pre-HF6 the target is 120s; post-HF6 it doubles to 240s.
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//
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// diff, err := blockchain.NextPoSDifficulty(nextHeight, config.MainnetForks)
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func (c *Chain) NextPoSDifficulty(height uint64, forks []config.HardFork) (uint64, error) {
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return c.nextDifficultyWith(height, forks, config.DifficultyPosTarget, config.DifficultyPosTargetHF6)
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}
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