wallet: single output groups filtering and grouping process

Optimizes coin selection by performing the "group outputs"
procedure only once, outside the "attempt selection" process.

Avoiding the repeated execution of the 'GroupOutputs' operation
that occurs on each coin eligibility filters (up to 8 of them);
then for every coin vector type plus one for all the coins together.

This also let us not perform coin selection over coin eligibility
filtered groups that don't add new elements.
(because, if the previous round failed, and the subsequent one has
the same coins, then this new round will fail again).

1 files changed, 9 insertions, 6 deletions

diff --git a/src/wallet/spend.h b/src/wallet/spend.h
index 315f8a7fe9..b8bc82db7a 100644
--- a/src/wallet/spend.h
+++ b/src/wallet/spend.h
@@ -106,13 +106,18 @@ const CTxOut& FindNonChangeParentOutput(const CWallet& wallet, const COutPoint&
  */
 std::map<CTxDestination, std::vector<COutput>> ListCoins(const CWallet& wallet) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet);
 
+struct SelectionFilter {
+    CoinEligibilityFilter filter;
+    bool allow_mixed_output_types{true};
+};
+
 /**
 * Group coins by the provided filters.
 */
-OutputGroupTypeMap GroupOutputs(const CWallet& wallet,
+FilteredOutputGroups GroupOutputs(const CWallet& wallet,
                           const CoinsResult& coins,
                           const CoinSelectionParams& coin_sel_params,
-                          const CoinEligibilityFilter& filter);
+                          const std::vector<SelectionFilter>& filters);
 
 /**
  * Attempt to find a valid input set that preserves privacy by not mixing OutputTypes.
@@ -120,10 +125,8 @@ OutputGroupTypeMap GroupOutputs(const CWallet& wallet,
  * the solution (according to the waste metric) will be chosen. If a valid input cannot be found from any
  * single OutputType, fallback to running `ChooseSelectionResult()` over all available coins.
  *
- * param@[in]  wallet                    The wallet which provides solving data for the coins
  * param@[in]  nTargetValue              The target value
- * param@[in]  eligilibity_filter        A filter containing rules for which coins are allowed to be included in this selection
- * param@[in]  available_coins           The struct of coins, organized by OutputType, available for selection prior to filtering
+ * param@[in]  groups                    The grouped outputs mapped by coin eligibility filters
  * param@[in]  coin_selection_params     Parameters for the coin selection
  * param@[in]  allow_mixed_output_types  Relax restriction that SelectionResults must be of the same OutputType
  * returns                               If successful, a SelectionResult containing the input set
@@ -131,7 +134,7 @@ OutputGroupTypeMap GroupOutputs(const CWallet& wallet,
  *                                                  or (2) an specific error message if there was something particularly wrong (e.g. a selection
  *                                                  result that surpassed the tx max weight size).
  */
-util::Result<SelectionResult> AttemptSelection(const CWallet& wallet, const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, const CoinsResult& available_coins,
+util::Result<SelectionResult> AttemptSelection(const CAmount& nTargetValue, OutputGroupTypeMap& groups,
                         const CoinSelectionParams& coin_selection_params, bool allow_mixed_output_types);
 
 /**