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Slightly optimize ApproximateBestSubset and its usage for PS txes #3184

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Merged
UdjinM6 merged 3 commits into from
Nov 4, 2019
Merged

Slightly optimize ApproximateBestSubset and its usage for PS txes #3184

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ae2f68d
From 2 best sets with the same `nTotal` in ApproximateBestSubset pref…
UdjinM6 Oct 31, 2019
5d89b84
There is no reason to run ApproximateBestSubset again if nMinChange is 0
UdjinM6 Oct 31, 2019
e06f5a6
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UdjinM6 Nov 4, 2019
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9 changes: 7 additions & 2 deletions src/wallet/wallet.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2863,13 +2863,15 @@ static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const C

vfBest.assign(vValue.size(), true);
nBest = nTotalLower;
int nBestInputCount = 0;

FastRandomContext insecure_rand;

for (int nRep = 0; nRep < iterations && nBest != nTargetValue; nRep++)
{
vfIncluded.assign(vValue.size(), false);
CAmount nTotal = 0;
int nTotalInputCount = 0;
bool fReachedTarget = false;
for (int nPass = 0; nPass < 2 && !fReachedTarget; nPass++)
{
Expand All @@ -2884,16 +2886,19 @@ static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const C
if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
{
nTotal += vValue[i].txout.nValue;
++nTotalInputCount;
vfIncluded[i] = true;
if (nTotal >= nTargetValue)
{
fReachedTarget = true;
if (nTotal < nBest)
if (nTotal < nBest || (nTotal == nBest && nTotalInputCount < nBestInputCount))
{
nBest = nTotal;
nBestInputCount = nTotalInputCount;
vfBest = vfIncluded;
}
nTotal -= vValue[i].txout.nValue;
--nTotalInputCount;
vfIncluded[i] = false;
}
}
Expand Down Expand Up @@ -3047,7 +3052,7 @@ bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const int nConfMin
CAmount nBest;

ApproximateBestSubset(vValue, nTotalLower, nTargetValue, vfBest, nBest);
if (nBest != nTargetValue && nTotalLower >= nTargetValue + nMinChange)
if (nBest != nTargetValue && nMinChange != 0 && nTotalLower >= nTargetValue + nMinChange)
ApproximateBestSubset(vValue, nTotalLower, nTargetValue + nMinChange, vfBest, nBest);

// If we have a bigger coin and (either the stochastic approximation didn't find a good solution,
Expand Down