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doc: Revise comments and whitespace to clarify

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Ben Woosley 2022-02-28 12:10:16 +00:00
parent def43a4d88
commit 9d2005285c
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1 changed files with 8 additions and 8 deletions
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16
src/wallet/coinselection.cpp
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@ -71,7 +71,8 @@ std::optional<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_poo
// Calculate curr_available_value
CAmount curr_available_value = 0;
for (const OutputGroup& utxo : utxo_pool) {
// Assert that this utxo is not negative. It should never be negative, effective value calculation should have removed it
// Assert that this utxo is not negative. It should never be negative,
// effective value calculation should have removed it
assert(utxo.GetSelectionAmount() > 0);
curr_available_value += utxo.GetSelectionAmount();
}
@ -90,8 +91,8 @@ std::optional<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_poo
for (size_t curr_try = 0, utxo_pool_index = 0; curr_try < TOTAL_TRIES; ++curr_try, ++utxo_pool_index) {
// Conditions for starting a backtrack
bool backtrack = false;
if (curr_value + curr_available_value < selection_target || // Cannot possibly reach target with the amount remaining in the curr_available_value.
curr_value > selection_target + cost_of_change || // Selected value is out of range, go back and try other branch
if (curr_value + curr_available_value < selection_target || // Cannot possibly reach target with the amount remaining in the curr_available_value.
curr_value > selection_target + cost_of_change || // Selected value is out of range, go back and try other branch
(curr_waste > best_waste && (utxo_pool.at(0).fee - utxo_pool.at(0).long_term_fee) > 0)) { // Don't select things which we know will be more wasteful if the waste is increasing
backtrack = true;
} else if (curr_value >= selection_target) { // Selected value is within range
@ -111,13 +112,12 @@ std::optional<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_poo
backtrack = true;
}
// Backtracking, moving backwards
if (backtrack) {
if (backtrack) { // Backtracking, moving backwards
if (curr_selection.empty()) { // We have walked back to the first utxo and no branch is untraversed. All solutions searched
break;
}
// Walk backwards to find the last included UTXO that still needs to have its omission branch traversed.
// Add omitted UTXOs back to lookahead before traversing the omission branch of last included UTXO.
for (--utxo_pool_index; utxo_pool_index > curr_selection.back(); --utxo_pool_index) {
curr_available_value += utxo_pool.at(utxo_pool_index).GetSelectionAmount();
}
@ -134,11 +134,11 @@ std::optional<SelectionResult> SelectCoinsBnB(std::vector<OutputGroup>& utxo_poo
// Remove this utxo from the curr_available_value utxo amount
curr_available_value -= utxo.GetSelectionAmount();
// Avoid searching a branch if the previous UTXO has the same value and same waste and was excluded. Since the ratio of fee to
// long term fee is the same, we only need to check if one of those values match in order to know that the waste is the same.
if (curr_selection.empty() ||
// The previous index is included and therefore not relevant for exclusion shortcut
(utxo_pool_index - 1) == curr_selection.back() ||
// Avoid searching a branch if the previous UTXO has the same value and same waste and was excluded.
// Since the ratio of fee to long term fee is the same, we only need to check if one of those values match in order to know that the waste is the same.
utxo.GetSelectionAmount() != utxo_pool.at(utxo_pool_index - 1).GetSelectionAmount() ||
utxo.fee != utxo_pool.at(utxo_pool_index - 1).fee)
{