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Reinstate previous testnet adjustment behaviour

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When the difficulty adjustment algorithm was altered, the special testnet
min-difficulty case was maintained, but the difficulty adjustment for the
following block then adjusted from min-difficulty instead of from the last
non-min-difficulty block. This caused the difficulty on the testnet to sawtooth
instead of stabilising. The intended behaviour is restored here.
This commit is contained in:
Jack Grigg
2016-07-21 20:50:05 +12:00
parent cebeabb2f4
commit e99731b4a4
2 changed files with 17 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
src/pow.cpp
View File

@@ -24,14 +24,20 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
if (pindexLast == NULL) if (pindexLast == NULL)
return nProofOfWorkLimit; return nProofOfWorkLimit;
const CBlockIndex* pindexBits = pindexLast;
{ {
if (params.fPowAllowMinDifficultyBlocks) if (params.fPowAllowMinDifficultyBlocks)
{ {
// Special difficulty rule for testnet: // Special difficulty rule for testnet:
// If the new block's timestamp is more than 2* 10 minutes // If the new block's timestamp is more than 2* 2.5 minutes
// then allow mining of a min-difficulty block. // then allow mining of a min-difficulty block.
if (pblock->GetBlockTime() > pindexLast->GetBlockTime() + params.nPowTargetSpacing*2) if (pblock->GetBlockTime() > pindexLast->GetBlockTime() + params.nPowTargetSpacing*2)
return nProofOfWorkLimit; return nProofOfWorkLimit;
else {
// Get the last non-min-difficulty (or at worst the genesis difficulty)
while (pindexBits->pprev && pindexBits->nBits == nProofOfWorkLimit)
pindexBits = pindexBits->pprev;
}
} }
} }
@@ -45,14 +51,19 @@ unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHead
if (pindexFirst == NULL) if (pindexFirst == NULL)
return nProofOfWorkLimit; return nProofOfWorkLimit;
return CalculateNextWorkRequired(pindexLast, pindexFirst->GetMedianTimePast(), params); return CalculateNextWorkRequired(pindexBits->nBits, pindexLast->GetMedianTimePast(), pindexFirst->GetMedianTimePast(), params);
} }
unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params) unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params& params)
{
return CalculateNextWorkRequired(pindexLast->nBits, pindexLast->GetMedianTimePast(), nFirstBlockTime, params);
}
unsigned int CalculateNextWorkRequired(uint32_t nBits, int64_t nLastBlockTime, int64_t nFirstBlockTime, const Consensus::Params& params)
{ {
// Limit adjustment step // Limit adjustment step
// Use medians to prevent time-warp attacks // Use medians to prevent time-warp attacks
int64_t nActualTimespan = pindexLast->GetMedianTimePast() - nFirstBlockTime; int64_t nActualTimespan = nLastBlockTime - nFirstBlockTime;
LogPrint("pow", " nActualTimespan = %d before dampening\n", nActualTimespan); LogPrint("pow", " nActualTimespan = %d before dampening\n", nActualTimespan);
nActualTimespan = params.AveragingWindowTimespan() + (nActualTimespan - params.AveragingWindowTimespan())/4; nActualTimespan = params.AveragingWindowTimespan() + (nActualTimespan - params.AveragingWindowTimespan())/4;
LogPrint("pow", " nActualTimespan = %d before bounds\n", nActualTimespan); LogPrint("pow", " nActualTimespan = %d before bounds\n", nActualTimespan);
@@ -66,7 +77,7 @@ unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nF
const arith_uint256 bnPowLimit = UintToArith256(params.powLimit); const arith_uint256 bnPowLimit = UintToArith256(params.powLimit);
arith_uint256 bnNew; arith_uint256 bnNew;
arith_uint256 bnOld; arith_uint256 bnOld;
bnNew.SetCompact(pindexLast->nBits); bnNew.SetCompact(nBits);
bnOld = bnNew; bnOld = bnNew;
bnNew /= params.AveragingWindowTimespan(); bnNew /= params.AveragingWindowTimespan();
bnNew *= nActualTimespan; bnNew *= nActualTimespan;
@@ -77,7 +88,7 @@ unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nF
/// debug print /// debug print
LogPrint("pow", "GetNextWorkRequired RETARGET\n"); LogPrint("pow", "GetNextWorkRequired RETARGET\n");
LogPrint("pow", "params.AveragingWindowTimespan() = %d nActualTimespan = %d\n", params.AveragingWindowTimespan(), nActualTimespan); LogPrint("pow", "params.AveragingWindowTimespan() = %d nActualTimespan = %d\n", params.AveragingWindowTimespan(), nActualTimespan);
LogPrint("pow", "Before: %08x %s\n", pindexLast->nBits, bnOld.ToString()); LogPrint("pow", "Before: %08x %s\n", nBits, bnOld.ToString());
LogPrint("pow", "After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString()); LogPrint("pow", "After: %08x %s\n", bnNew.GetCompact(), bnNew.ToString());
return bnNew.GetCompact(); return bnNew.GetCompact();

1
src/pow.h
View File

@@ -18,6 +18,7 @@ class arith_uint256;
unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params&); unsigned int GetNextWorkRequired(const CBlockIndex* pindexLast, const CBlockHeader *pblock, const Consensus::Params&);
unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params&); unsigned int CalculateNextWorkRequired(const CBlockIndex* pindexLast, int64_t nFirstBlockTime, const Consensus::Params&);
unsigned int CalculateNextWorkRequired(uint32_t nBits, int64_t nLastBlockTime, int64_t nFirstBlockTime, const Consensus::Params&);
/** Check whether the Equihash solution in a block header is valid */ /** Check whether the Equihash solution in a block header is valid */
bool CheckEquihashSolution(const CBlockHeader *pblock, const CChainParams&); bool CheckEquihashSolution(const CBlockHeader *pblock, const CChainParams&);