Activate ASERT difficulty adjustment at block 6500
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SHA256:739BZv8LvIDY2tR7lXLy/IQ6MaGTQtYcG9GNvCjmpVM
4 changed files with 290 additions and 1 deletions
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@ -180,6 +180,8 @@ public:
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consensus.difficultyMinActualTimespan = consensus.difficultyTargetTimespan * 92 / 100;
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consensus.difficultyMaxActualTimespan = consensus.difficultyTargetTimespan * 116 / 100;
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consensus.asertActivationHeight = 6500;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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@ -219,6 +221,8 @@ public:
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consensus.difficultyMinActualTimespan = consensus.difficultyTargetTimespan * 92 / 100;
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consensus.difficultyMaxActualTimespan = consensus.difficultyTargetTimespan * 116 / 100;
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consensus.asertActivationHeight = 6500;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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@ -451,6 +455,8 @@ public:
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consensus.difficultyMinActualTimespan = consensus.difficultyTargetTimespan * 92 / 100;
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consensus.difficultyMaxActualTimespan = consensus.difficultyTargetTimespan * 116 / 100;
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consensus.asertActivationHeight = 6500;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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consensus.BIP65Height = 1351;
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@ -121,6 +121,8 @@ struct Params {
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int64_t difficultyMinActualTimespan;
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int64_t difficultyMaxActualTimespan;
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int asertActivationHeight;
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int64_t asertHalfLife;
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73
src/pow.cpp
73
src/pow.cpp
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@ -22,13 +22,84 @@ unsigned int InitialDifficulty(const Consensus::Params& params)
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return PowLimit(params);
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}
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unsigned int CalculateASERT(const CBlockIndex* pindexLast, const Consensus::Params& params)
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{
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// Anchor ASERT to the last block before activation.
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const int anchorHeight = params.asertActivationHeight - 1;
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const CBlockIndex* pindexAnchor = pindexLast->GetAncestor(anchorHeight);
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if (pindexAnchor == nullptr) {
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return pindexLast->nBits;
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}
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const int64_t heightDiff = pindexLast->nHeight - pindexAnchor->nHeight;
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const int64_t timeDiff = pindexLast->GetBlockTime() - pindexAnchor->pprev->GetBlockTime();
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// ASERT exponent in fixed-point 16.16:
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// exponent = (timeDiff - idealTime) / halfLife
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const int64_t idealTime = (heightDiff + 1) * params.nPowTargetSpacing;
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const int64_t exponent = ((timeDiff - idealTime) * 65536) / params.asertHalfLife;
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int64_t shifts = exponent >> 16;
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const uint16_t frac = static_cast<uint16_t>(exponent);
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// Approximation of 2^(frac/65536), scaled by 65536.
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const uint64_t factor =
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65536ULL +
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((195766423245049ULL * frac +
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971821376ULL * frac * frac +
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5127ULL * frac * frac * frac +
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(1ULL << 47)) >> 48);
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arith_uint256 target;
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target.SetCompact(pindexAnchor->nBits);
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target *= factor;
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// factor is scaled by 2^16.
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shifts -= 16;
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const arith_uint256 powLimit = UintToArith256(params.powLimit);
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if (shifts <= 0) {
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if (-shifts >= 256) {
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target = 1;
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} else {
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target >>= -shifts;
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}
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} else {
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if (shifts >= 256 || target > (powLimit >> shifts)) {
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target = powLimit;
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} else {
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target <<= shifts;
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}
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}
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if (target == 0) {
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target = 1;
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}
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if (target > powLimit) {
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target = powLimit;
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}
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return target.GetCompact();
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}
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unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params& params)
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{
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// Vexta is SHA256D-only. Use one global averaging window.
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// Vexta is SHA256D-only.
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if (pindexLast == nullptr) {
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return InitialDifficulty(params);
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}
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// ASERT activates for the block at asertActivationHeight.
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// pindexLast is the previous block, so activation starts when
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// the next block height reaches the configured activation height.
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if (!params.fPowNoRetargeting &&
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!params.fEasyPow &&
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pindexLast->nHeight + 1 >= params.asertActivationHeight) {
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return CalculateASERT(pindexLast, params);
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}
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const CBlockIndex* pindexFirst = pindexLast;
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for (int i = 0; pindexFirst && i < params.difficultyAveragingWindow; i++) {
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pindexFirst = pindexFirst->pprev;
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@ -141,4 +141,214 @@ BOOST_AUTO_TEST_CASE(ChainParams_SIGNET_sanity)
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sanity_check_chainparams(*m_node.args, CBaseChainParams::SIGNET);
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}
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BOOST_AUTO_TEST_CASE(ASERT_behavior_test)
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{
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const auto chainParams = CreateChainParams(*m_node.args, CBaseChainParams::MAIN);
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const auto consensus = chainParams->GetConsensus();
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std::vector<CBlockIndex> blocks(6501);
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arith_uint256 anchorTargetValue = UintToArith256(consensus.powLimit);
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anchorTargetValue >>= 8;
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const unsigned int anchorBits = anchorTargetValue.GetCompact();
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const int64_t startTime = 1800000000;
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for (int i = 0; i <= 6500; ++i) {
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blocks[i].pprev = i ? &blocks[i - 1] : nullptr;
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blocks[i].nHeight = i;
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blocks[i].nTime = startTime + i * consensus.nPowTargetSpacing;
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blocks[i].nBits = anchorBits;
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}
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// Block 6499 is still governed by the legacy DAA.
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const unsigned int preActivationBits =
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GetNextWorkRequired(&blocks[6498], nullptr, consensus);
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BOOST_CHECK_EQUAL(preActivationBits, anchorBits);
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// Block 6500 is the first ASERT block. Ideal 10-minute spacing
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// must preserve the anchor target.
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const unsigned int idealBits =
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GetNextWorkRequired(&blocks[6499], nullptr, consensus);
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BOOST_CHECK_EQUAL(idealBits, anchorBits);
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// Block 6501 after a very fast previous block: target must decrease
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// (difficulty increases).
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blocks[6500].nTime =
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blocks[6499].nTime + consensus.nPowTargetSpacing / 10;
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const unsigned int fastBits =
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GetNextWorkRequired(&blocks[6500], nullptr, consensus);
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arith_uint256 fastTarget;
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fastTarget.SetCompact(fastBits);
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arith_uint256 anchorTarget;
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anchorTarget.SetCompact(anchorBits);
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BOOST_CHECK(fastTarget < anchorTarget);
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// Block 6501 after a slow previous block: target must increase
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// (difficulty decreases).
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blocks[6500].nTime =
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blocks[6499].nTime + consensus.nPowTargetSpacing * 3;
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const unsigned int slowBits =
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GetNextWorkRequired(&blocks[6500], nullptr, consensus);
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arith_uint256 slowTarget;
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slowTarget.SetCompact(slowBits);
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BOOST_CHECK(slowTarget > anchorTarget);
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// Extreme delay must never produce a target above powLimit.
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blocks[6500].nTime =
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blocks[6499].nTime + consensus.asertHalfLife * 16;
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const unsigned int extremeSlowBits =
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GetNextWorkRequired(&blocks[6500], nullptr, consensus);
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BOOST_CHECK_EQUAL(
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extremeSlowBits,
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UintToArith256(consensus.powLimit).GetCompact());
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}
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BOOST_AUTO_TEST_CASE(ASERT_reference_vector_run04_test)
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{
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auto chainParams = CreateChainParams(*m_node.args, CBaseChainParams::MAIN);
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auto consensus = chainParams->GetConsensus();
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consensus.asertActivationHeight = 2;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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std::vector<CBlockIndex> blocks(3);
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blocks[0].pprev = nullptr;
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blocks[0].nHeight = 0;
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blocks[0].nTime = 0;
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blocks[0].nBits = 0x01010000;
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blocks[1].pprev = &blocks[0];
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blocks[1].nHeight = 1;
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blocks[1].nTime = 600;
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blocks[1].nBits = 0x01010000;
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// BCHN official ASERT run04 vector:
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// anchor height = 1
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// anchor ancestor time = 0
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// evaluation height = 2
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// evaluation time = 174000
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// expected next target = 0x01020000
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blocks[2].pprev = &blocks[1];
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blocks[2].nHeight = 2;
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blocks[2].nTime = 174000;
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blocks[2].nBits = 0x01010000;
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const unsigned int result =
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GetNextWorkRequired(&blocks[2], nullptr, consensus);
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BOOST_CHECK_EQUAL(result, 0x01020000U);
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}
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BOOST_AUTO_TEST_CASE(ASERT_reference_vector_run05_test)
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{
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auto chainParams = CreateChainParams(*m_node.args, CBaseChainParams::MAIN);
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auto consensus = chainParams->GetConsensus();
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consensus.asertActivationHeight = 2;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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std::vector<CBlockIndex> blocks(291);
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blocks[0].pprev = nullptr;
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blocks[0].nHeight = 0;
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blocks[0].nTime = 0;
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blocks[0].nBits = 0x1d00ffff;
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blocks[1].pprev = &blocks[0];
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blocks[1].nHeight = 1;
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blocks[1].nTime = 600;
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blocks[1].nBits = 0x1d00ffff;
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// BCHN official ASERT run05 vector, iteration 1:
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blocks[2].pprev = &blocks[1];
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blocks[2].nHeight = 2;
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blocks[2].nTime = 0;
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blocks[2].nBits = 0x1d00ffff;
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BOOST_CHECK_EQUAL(
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GetNextWorkRequired(&blocks[2], nullptr, consensus),
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0x1d00fec5U);
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// BCHN official ASERT run05 vector, iteration 2:
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// evaluation height = 290, time = 0
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for (int h = 3; h <= 290; ++h) {
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blocks[h].pprev = &blocks[h - 1];
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blocks[h].nHeight = h;
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blocks[h].nTime = 0;
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blocks[h].nBits = 0x1d00ffff;
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}
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BOOST_CHECK_EQUAL(
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GetNextWorkRequired(&blocks[290], nullptr, consensus),
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0x1c7f62c0U);
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}
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BOOST_AUTO_TEST_CASE(ASERT_reference_vector_run06_test)
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{
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auto chainParams = CreateChainParams(*m_node.args, CBaseChainParams::MAIN);
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auto consensus = chainParams->GetConsensus();
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consensus.asertActivationHeight = 2;
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consensus.asertHalfLife = 2 * 24 * 60 * 60;
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std::vector<CBlockIndex> blocks(13);
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blocks[0].pprev = nullptr;
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blocks[0].nHeight = 0;
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blocks[0].nTime = 0;
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blocks[0].nBits = 0x1802aee8;
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blocks[1].pprev = &blocks[0];
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blocks[1].nHeight = 1;
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blocks[1].nTime = 600;
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blocks[1].nBits = 0x1802aee8;
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const int64_t times[] = {
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0, 600,
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1200, 1310, 1327, 1739, 2219, 2604,
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2746, 7099, 7099, 7657, 8626
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};
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const unsigned int expected[] = {
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0,
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0,
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0x1802aee8U,
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0x1802ad91U,
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0x1802abf8U,
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0x1802ab73U,
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0x1802ab20U,
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0x1802aa89U,
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0x1802a94bU,
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0x1802b39cU,
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0x1802b1f2U,
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0x1802b1d4U,
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0x1802b2dbU
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};
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for (int h = 2; h <= 12; ++h) {
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blocks[h].pprev = &blocks[h - 1];
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blocks[h].nHeight = h;
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blocks[h].nTime = times[h];
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blocks[h].nBits = 0x1802aee8;
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BOOST_CHECK_EQUAL(
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GetNextWorkRequired(&blocks[h], nullptr, consensus),
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expected[h]);
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}
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}
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BOOST_AUTO_TEST_SUITE_END()
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