18ceb7fa26
The 240s PoW target was incorrectly gated on HF2 (block 10,080), matching the Zano upstream where HF2 coincides with the difficulty target change. Lethean mainnet uses 120s blocks between HF2 and HF6 (999,999,999), so the gate is corrected to HF6. Also adds NextPoSDifficulty with the same HF6 gate using the PoS target constants (DifficultyPosTarget / DifficultyPosTargetHF6). Both public methods delegate to a shared nextDifficultyWith helper to avoid duplicating the LWMA window logic. Co-Authored-By: Charon <charon@lethean.io>
87 lines
3.1 KiB
Go
87 lines
3.1 KiB
Go
// Copyright (c) 2017-2026 Lethean (https://lt.hn)
|
|
//
|
|
// Licensed under the European Union Public Licence (EUPL) version 1.2.
|
|
// SPDX-License-Identifier: EUPL-1.2
|
|
|
|
package chain
|
|
|
|
import (
|
|
"math/big"
|
|
|
|
"forge.lthn.ai/core/go-blockchain/config"
|
|
"forge.lthn.ai/core/go-blockchain/difficulty"
|
|
)
|
|
|
|
// nextDifficultyWith computes the expected difficulty for the block at the
|
|
// given height using the LWMA algorithm, parameterised by pre/post-HF6 targets.
|
|
//
|
|
// The genesis block (height 0) is excluded from the difficulty window,
|
|
// matching the C++ daemon's load_targetdata_cache which skips index 0.
|
|
//
|
|
// The target block time depends on the hardfork schedule:
|
|
// - Pre-HF6: baseTarget (120s for both PoW and PoS on Lethean)
|
|
// - Post-HF6: hf6Target (240s -- halves block rate, halves emission)
|
|
//
|
|
// NOTE: This was originally gated on HF2, matching the Zano upstream where
|
|
// HF2 coincides with the difficulty target change. Lethean mainnet keeps 120s
|
|
// blocks between HF2 (height 10,080) and HF6 (height 999,999,999), so the
|
|
// gate was corrected to HF6 in March 2026.
|
|
func (c *Chain) nextDifficultyWith(height uint64, forks []config.HardFork, baseTarget, hf6Target uint64) (uint64, error) {
|
|
if height == 0 {
|
|
return 1, nil
|
|
}
|
|
|
|
// LWMA needs N+1 entries (N solve-time intervals).
|
|
// Start from height 1 -- genesis is excluded from the difficulty window.
|
|
maxLookback := difficulty.LWMAWindow + 1
|
|
lookback := min(height, maxLookback) // height excludes genesis since we start from 1
|
|
|
|
// Start from max(1, height - lookback) to exclude genesis.
|
|
startHeight := height - lookback
|
|
if startHeight == 0 {
|
|
startHeight = 1
|
|
lookback = height - 1
|
|
}
|
|
|
|
if lookback == 0 {
|
|
return 1, nil
|
|
}
|
|
|
|
count := int(lookback)
|
|
timestamps := make([]uint64, count)
|
|
cumulDiffs := make([]*big.Int, count)
|
|
|
|
for i := range count {
|
|
meta, err := c.getBlockMeta(startHeight + uint64(i))
|
|
if err != nil {
|
|
// Fewer blocks than expected -- use what we have.
|
|
timestamps = timestamps[:i]
|
|
cumulDiffs = cumulDiffs[:i]
|
|
break
|
|
}
|
|
timestamps[i] = meta.Timestamp
|
|
cumulDiffs[i] = new(big.Int).SetUint64(meta.CumulativeDiff)
|
|
}
|
|
|
|
// Determine the target block time based on hardfork status.
|
|
// HF6 doubles the target from 120s to 240s (corrected from HF2 gate).
|
|
target := baseTarget
|
|
if config.IsHardForkActive(forks, config.HF6, height) {
|
|
target = hf6Target
|
|
}
|
|
|
|
result := difficulty.NextDifficulty(timestamps, cumulDiffs, target)
|
|
return result.Uint64(), nil
|
|
}
|
|
|
|
// NextDifficulty computes the expected PoW difficulty for the block at the
|
|
// given height. Pre-HF6 the target is 120s; post-HF6 it doubles to 240s.
|
|
func (c *Chain) NextDifficulty(height uint64, forks []config.HardFork) (uint64, error) {
|
|
return c.nextDifficultyWith(height, forks, config.DifficultyPowTarget, config.DifficultyPowTargetHF6)
|
|
}
|
|
|
|
// NextPoSDifficulty computes the expected PoS difficulty for the block at the
|
|
// given height. Pre-HF6 the target is 120s; post-HF6 it doubles to 240s.
|
|
func (c *Chain) NextPoSDifficulty(height uint64, forks []config.HardFork) (uint64, error) {
|
|
return c.nextDifficultyWith(height, forks, config.DifficultyPosTarget, config.DifficultyPosTargetHF6)
|
|
}
|