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Merge bitcoin/bitcoin#24560: wallet: Use single FastRandomContext when creating a wallet tx

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fa7deaa046 wallet: Pass FastRandomContext& to coin selection (MarcoFalke)
77773b061c wallet: Pass FastRandomContext& to DiscourageFeeSniping (MarcoFalke)

Pull request description:

  Passing around a single randomness context shouldn't come with any downsides, but documents better where randomness is used and allows the unit test to be deterministic, if they wish to be so.

ACKs for top commit:
  achow101:
    ACK fa7deaa046
  promag:
    Code review ACK fa7deaa046.
  glozow:
    light code review ACK fa7deaa046

Tree-SHA512: c16287708cc82ce58311710595d0127af42fb156c93fbcaa5bde634ce323d325f4d8c99a74af24423ab22b5ad58163dd771e8b1a0e7d6bff39c9fb2a1cb21bc7
This commit is contained in:
Andrew Chow
2022-03-23 13:41:16 -04:00
parent f9ed0aec1b fa7deaa046
commit 3ab96f2945
5 changed files with 86 additions and 52 deletions
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16
src/wallet/coinselection.cpp
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@@ -165,14 +165,14 @@ std::optional<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_poo
return result;
}
std::optional<SelectionResult> SelectCoinsSRD(const std::vector<OutputGroup>& utxo_pool, CAmount target_value)
std::optional<SelectionResult> SelectCoinsSRD(const std::vector<OutputGroup>& utxo_pool, CAmount target_value, FastRandomContext& rng)
{
SelectionResult result(target_value);
std::vector<size_t> indexes;
indexes.resize(utxo_pool.size());
std::iota(indexes.begin(), indexes.end(), 0);
Shuffle(indexes.begin(), indexes.end(), FastRandomContext());
Shuffle(indexes.begin(), indexes.end(), rng);
CAmount selected_eff_value = 0;
for (const size_t i : indexes) {
@@ -187,7 +187,7 @@ std::optional<SelectionResult> SelectCoinsSRD(const std::vector<OutputGroup>& ut
return std::nullopt;
}
static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const CAmount& nTotalLower, const CAmount& nTargetValue,
static void ApproximateBestSubset(FastRandomContext& insecure_rand, const std::vector<OutputGroup>& groups, const CAmount& nTotalLower, const CAmount& nTargetValue,
std::vector<char>& vfBest, CAmount& nBest, int iterations = 1000)
{
std::vector<char> vfIncluded;
@@ -195,8 +195,6 @@ static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const
vfBest.assign(groups.size(), true);
nBest = nTotalLower;
FastRandomContext insecure_rand;
for (int nRep = 0; nRep < iterations && nBest != nTargetValue; nRep++)
{
vfIncluded.assign(groups.size(), false);
@@ -233,7 +231,7 @@ static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const
}
}
std::optional<SelectionResult> KnapsackSolver(std::vector<OutputGroup>& groups, const CAmount& nTargetValue)
std::optional<SelectionResult> KnapsackSolver(std::vector<OutputGroup>& groups, const CAmount& nTargetValue, FastRandomContext& rng)
{
SelectionResult result(nTargetValue);
@@ -242,7 +240,7 @@ std::optional<SelectionResult> KnapsackSolver(std::vector<OutputGroup>& groups,
std::vector<OutputGroup> applicable_groups;
CAmount nTotalLower = 0;
Shuffle(groups.begin(), groups.end(), FastRandomContext());
Shuffle(groups.begin(), groups.end(), rng);
for (const OutputGroup& group : groups) {
if (group.GetSelectionAmount() == nTargetValue) {
@@ -274,9 +272,9 @@ std::optional<SelectionResult> KnapsackSolver(std::vector<OutputGroup>& groups,
std::vector<char> vfBest;
CAmount nBest;
ApproximateBestSubset(applicable_groups, nTotalLower, nTargetValue, vfBest, nBest);
ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue, vfBest, nBest);
if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE) {
ApproximateBestSubset(applicable_groups, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
ApproximateBestSubset(rng, applicable_groups, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
}
// If we have a bigger coin and (either the stochastic approximation didn't find a good solution,