3c76dd7070
Rewrites the LWMA difficulty algorithm to match the C++ daemon exactly: - Uses N=60 window with linear weighting (position 1..n) - Clamps solve times to [-6T, 6T] - Excludes genesis block from the difficulty window - Selects target based on hardfork: 120s pre-HF2, 240s post-HF2 On testnet, HF2 activates at height 10 (active from height 11), doubling the target from 120s to 240s. The previous fixed 120s target produced exactly half the expected difficulty from height 11 onward. Integration test verifies all 2576 testnet blocks match the daemon. Co-Authored-By: Charon <charon@lethean.io>
78 lines
2.1 KiB
Go
78 lines
2.1 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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"testing"
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"forge.lthn.ai/core/go-blockchain/config"
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"forge.lthn.ai/core/go-blockchain/types"
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store "forge.lthn.ai/core/go-store"
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"github.com/stretchr/testify/require"
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)
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// preHF2Forks is a fork schedule where HF2 never activates,
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// so the target stays at 120s.
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var preHF2Forks = []config.HardFork{
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{Version: config.HF0Initial, Height: 0},
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}
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func TestNextDifficulty_Genesis(t *testing.T) {
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s, err := store.New(":memory:")
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require.NoError(t, err)
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defer s.Close()
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c := New(s)
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diff, err := c.NextDifficulty(0, preHF2Forks)
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require.NoError(t, err)
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require.Equal(t, uint64(1), diff)
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}
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func TestNextDifficulty_FewBlocks(t *testing.T) {
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s, err := store.New(":memory:")
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require.NoError(t, err)
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defer s.Close()
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c := New(s)
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// Store genesis + 4 blocks with constant 120s intervals and difficulty 1000.
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// Genesis at height 0 is excluded from the LWMA window.
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baseDiff := uint64(1000)
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for i := uint64(0); i < 5; i++ {
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err := c.PutBlock(&types.Block{}, &BlockMeta{
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Hash: types.Hash{byte(i + 1)},
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Height: i,
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Timestamp: i * 120,
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Difficulty: baseDiff,
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CumulativeDiff: baseDiff * (i + 1),
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})
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require.NoError(t, err)
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}
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// Next difficulty for height 5 uses blocks 1-4 (n=3 intervals).
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// LWMA formula with constant D and T gives D/n = 1000/3 ≈ 333.
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diff, err := c.NextDifficulty(5, preHF2Forks)
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require.NoError(t, err)
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require.Greater(t, diff, uint64(0))
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// LWMA gives total_work * T * (n+1) / (2 * weighted_solvetimes * n).
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// For constant intervals: D/n = 1000/3 = 333.
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expected := uint64(333)
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require.Equal(t, expected, diff)
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}
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func TestNextDifficulty_EmptyChain(t *testing.T) {
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s, err := store.New(":memory:")
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require.NoError(t, err)
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defer s.Close()
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c := New(s)
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// Height 1 with no blocks stored — should return starter difficulty.
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diff, err := c.NextDifficulty(1, preHF2Forks)
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require.NoError(t, err)
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require.Equal(t, uint64(1), diff)
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}
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