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Use SelectionResult for waste calculation

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This commit is contained in:
Andrew Chow 2021-05-21 18:15:55 -04:00
parent e8f7ae5eb3
commit bb50850a44
2 changed files with 10 additions and 12 deletions
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2
src/wallet/coinselection.h
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@ -187,6 +187,8 @@ struct OutputGroup
* where excess = selected_effective_value - target
* change_cost = effective_feerate * change_output_size + long_term_feerate * change_spend_size
*
* Note this function is separate from SelectionResult for the tests.
*
* @param[in] inputs The selected inputs
* @param[in] change_cost The cost of creating change and spending it in the future.
* Only used if there is change, in which case it must be positive.

20
src/wallet/spend.cpp
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@ -378,16 +378,14 @@ bool AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const
{
setCoinsRet.clear();
nValueRet = 0;
// Vector of results for use with waste calculation
// In order: calculated waste, selected inputs, selected input value (sum of input values)
// TODO: Use a struct representing the selection result
std::vector<std::tuple<CAmount, std::set<CInputCoin>, CAmount>> results;
// Vector of results. We will choose the best one based on waste.
std::vector<SelectionResult> results;
// Note that unlike KnapsackSolver, we do not include the fee for creating a change output as BnB will not create a change output.
std::vector<OutputGroup> positive_groups = GroupOutputs(wallet, coins, coin_selection_params, eligibility_filter, true /* positive_only */);
if (auto bnb_result{SelectCoinsBnB(positive_groups, nTargetValue, coin_selection_params.m_cost_of_change)}) {
bnb_result->ComputeAndSetWaste(CAmount(0));
results.emplace_back(std::make_tuple(bnb_result->GetWaste(), bnb_result->GetInputSet(), bnb_result->GetSelectedValue()));
results.push_back(*bnb_result);
}
// The knapsack solver has some legacy behavior where it will spend dust outputs. We retain this behavior, so don't filter for positive only here.
@ -396,7 +394,7 @@ bool AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const
// So we need to include that for KnapsackSolver as well, as we are expecting to create a change output.
if (auto knapsack_result{KnapsackSolver(all_groups, nTargetValue + coin_selection_params.m_change_fee)}) {
knapsack_result->ComputeAndSetWaste(coin_selection_params.m_cost_of_change);
results.emplace_back(std::make_tuple(knapsack_result->GetWaste(), knapsack_result->GetInputSet(), knapsack_result->GetSelectedValue()));
results.push_back(*knapsack_result);
}
// We include the minimum final change for SRD as we do want to avoid making really small change.
@ -404,7 +402,7 @@ bool AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const
const CAmount srd_target = nTargetValue + coin_selection_params.m_change_fee + MIN_FINAL_CHANGE;
if (auto srd_result{SelectCoinsSRD(positive_groups, srd_target)}) {
srd_result->ComputeAndSetWaste(coin_selection_params.m_cost_of_change);
results.emplace_back(std::make_tuple(srd_result->GetWaste(), srd_result->GetInputSet(), srd_result->GetSelectedValue()));
results.push_back(*srd_result);
}
if (results.size() == 0) {
@ -414,11 +412,9 @@ bool AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const
// Choose the result with the least waste
// If the waste is the same, choose the one which spends more inputs.
const auto& best_result = std::min_element(results.begin(), results.end(), [](const auto& a, const auto& b) {
return std::get<0>(a) < std::get<0>(b) || (std::get<0>(a) == std::get<0>(b) && std::get<1>(a).size() > std::get<1>(b).size());
});
setCoinsRet = std::get<1>(*best_result);
nValueRet = std::get<2>(*best_result);
auto& best_result = *std::min_element(results.begin(), results.end());
setCoinsRet = best_result.GetInputSet();
nValueRet = best_result.GetSelectedValue();
return true;
}