wallet: Switch to using output groups instead of coins in coin selection

6 files changed, 175 insertions, 160 deletions

diff --git a/src/bench/coin_selection.cpp b/src/bench/coin_selection.cpp
index f3180809b5..7510d53c88 100644
--- a/src/bench/coin_selection.cpp
+++ b/src/bench/coin_selection.cpp
@@ -8,7 +8,7 @@
 
 #include <set>
 
-static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<COutput>& vCoins)
+static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<OutputGroup>& groups)
 {
     int nInput = 0;
 
@@ -21,7 +21,7 @@ static void addCoin(const CAmount& nValue, const CWallet& wallet, std::vector<CO
 
     int nAge = 6 * 24;
     COutput output(wtx, nInput, nAge, true /* spendable */, true /* solvable */, true /* safe */);
-    vCoins.push_back(output);
+    groups.emplace_back(output.GetInputCoin(), 0, false, 0, 0);
 }
 
 // Simple benchmark for wallet coin selection. Note that it maybe be necessary
@@ -37,11 +37,11 @@ static void CoinSelection(benchmark::State& state)
     LOCK(wallet.cs_wallet);
 
     // Add coins.
-    std::vector<COutput> vCoins;
+    std::vector<OutputGroup> groups;
     for (int i = 0; i < 1000; ++i) {
-        addCoin(1000 * COIN, wallet, vCoins);
+        addCoin(1000 * COIN, wallet, groups);
     }
-    addCoin(3 * COIN, wallet, vCoins);
+    addCoin(3 * COIN, wallet, groups);
 
     const CoinEligibilityFilter filter_standard(1, 6, 0);
     const CoinSelectionParams coin_selection_params(true, 34, 148, CFeeRate(0), 0);
@@ -49,7 +49,7 @@ static void CoinSelection(benchmark::State& state)
         std::set<CInputCoin> setCoinsRet;
         CAmount nValueRet;
         bool bnb_used;
-        bool success = wallet.SelectCoinsMinConf(1003 * COIN, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used);
+        bool success = wallet.SelectCoinsMinConf(1003 * COIN, filter_standard, groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used);
         assert(success);
         assert(nValueRet == 1003 * COIN);
         assert(setCoinsRet.size() == 2);
@@ -57,17 +57,21 @@ static void CoinSelection(benchmark::State& state)
 }
 
 typedef std::set<CInputCoin> CoinSet;
+static const CWallet testWallet("dummy", WalletDatabase::CreateDummy());
+std::vector<std::unique_ptr<CWalletTx>> wtxn;
 
 // Copied from src/wallet/test/coinselector_tests.cpp
-static void add_coin(const CAmount& nValue, int nInput, std::vector<CInputCoin>& set)
+static void add_coin(const CAmount& nValue, int nInput, std::vector<OutputGroup>& set)
 {
     CMutableTransaction tx;
     tx.vout.resize(nInput + 1);
     tx.vout[nInput].nValue = nValue;
-    set.emplace_back(MakeTransactionRef(tx), nInput);
+    std::unique_ptr<CWalletTx> wtx(new CWalletTx(&testWallet, MakeTransactionRef(std::move(tx))));
+    set.emplace_back(COutput(wtx.get(), nInput, 0, true, true, true).GetInputCoin(), 0, true, 0, 0);
+    wtxn.emplace_back(std::move(wtx));
 }
 // Copied from src/wallet/test/coinselector_tests.cpp
-static CAmount make_hard_case(int utxos, std::vector<CInputCoin>& utxo_pool)
+static CAmount make_hard_case(int utxos, std::vector<OutputGroup>& utxo_pool)
 {
     utxo_pool.clear();
     CAmount target = 0;
@@ -82,7 +86,7 @@ static CAmount make_hard_case(int utxos, std::vector<CInputCoin>& utxo_pool)
 static void BnBExhaustion(benchmark::State& state)
 {
     // Setup
-    std::vector<CInputCoin> utxo_pool;
+    std::vector<OutputGroup> utxo_pool;
     CoinSet selection;
     CAmount value_ret = 0;
     CAmount not_input_fees = 0;
diff --git a/src/wallet/coinselection.cpp b/src/wallet/coinselection.cpp
index 8bc4e10b8d..99e0832abf 100644
--- a/src/wallet/coinselection.cpp
+++ b/src/wallet/coinselection.cpp
@@ -8,7 +8,7 @@
 
 // Descending order comparator
 struct {
-    bool operator()(const CInputCoin& a, const CInputCoin& b) const
+    bool operator()(const OutputGroup& a, const OutputGroup& b) const
     {
         return a.effective_value > b.effective_value;
     }
@@ -59,7 +59,7 @@ struct {
 
 static const size_t TOTAL_TRIES = 100000;
 
-bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees)
+bool SelectCoinsBnB(std::vector<OutputGroup>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees)
 {
     out_set.clear();
     CAmount curr_value = 0;
@@ -70,7 +70,7 @@ bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_va
 
     // Calculate curr_available_value
     CAmount curr_available_value = 0;
-    for (const CInputCoin& utxo : utxo_pool) {
+    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(utxo.effective_value > 0);
         curr_available_value += utxo.effective_value;
@@ -123,11 +123,11 @@ bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_va
 
             // Output was included on previous iterations, try excluding now.
             curr_selection.back() = false;
-            CInputCoin& utxo = utxo_pool.at(curr_selection.size() - 1);
+            OutputGroup& utxo = utxo_pool.at(curr_selection.size() - 1);
             curr_value -= utxo.effective_value;
             curr_waste -= utxo.fee - utxo.long_term_fee;
         } else { // Moving forwards, continuing down this branch
-            CInputCoin& utxo = utxo_pool.at(curr_selection.size());
+            OutputGroup& utxo = utxo_pool.at(curr_selection.size());
 
             // Remove this utxo from the curr_available_value utxo amount
             curr_available_value -= utxo.effective_value;
@@ -156,32 +156,32 @@ bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_va
     value_ret = 0;
     for (size_t i = 0; i < best_selection.size(); ++i) {
         if (best_selection.at(i)) {
-            out_set.insert(utxo_pool.at(i));
-            value_ret += utxo_pool.at(i).txout.nValue;
+            util::insert(out_set, utxo_pool.at(i).m_outputs);
+            value_ret += utxo_pool.at(i).m_value;
         }
     }
 
     return true;
 }
 
-static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const CAmount& nTotalLower, const CAmount& nTargetValue,
+static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const CAmount& nTotalLower, const CAmount& nTargetValue,
                                   std::vector<char>& vfBest, CAmount& nBest, int iterations = 1000)
 {
     std::vector<char> vfIncluded;
 
-    vfBest.assign(vValue.size(), true);
+    vfBest.assign(groups.size(), true);
     nBest = nTotalLower;
 
     FastRandomContext insecure_rand;
 
     for (int nRep = 0; nRep < iterations && nBest != nTargetValue; nRep++)
     {
-        vfIncluded.assign(vValue.size(), false);
+        vfIncluded.assign(groups.size(), false);
         CAmount nTotal = 0;
         bool fReachedTarget = false;
         for (int nPass = 0; nPass < 2 && !fReachedTarget; nPass++)
         {
-            for (unsigned int i = 0; i < vValue.size(); i++)
+            for (unsigned int i = 0; i < groups.size(); i++)
             {
                 //The solver here uses a randomized algorithm,
                 //the randomness serves no real security purpose but is just
@@ -191,7 +191,7 @@ static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const C
                 //the selection random.
                 if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
                 {
-                    nTotal += vValue[i].txout.nValue;
+                    nTotal += groups[i].m_value;
                     vfIncluded[i] = true;
                     if (nTotal >= nTargetValue)
                     {
@@ -201,7 +201,7 @@ static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const C
                             nBest = nTotal;
                             vfBest = vfIncluded;
                         }
-                        nTotal -= vValue[i].txout.nValue;
+                        nTotal -= groups[i].m_value;
                         vfIncluded[i] = false;
                     }
                 }
@@ -210,86 +210,75 @@ static void ApproximateBestSubset(const std::vector<CInputCoin>& vValue, const C
     }
 }
 
-bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet)
+bool KnapsackSolver(const CAmount& nTargetValue, std::vector<OutputGroup>& groups, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet)
 {
     setCoinsRet.clear();
     nValueRet = 0;
 
     // List of values less than target
-    boost::optional<CInputCoin> coinLowestLarger;
-    std::vector<CInputCoin> vValue;
+    boost::optional<OutputGroup> lowest_larger;
+    std::vector<OutputGroup> applicable_groups;
     CAmount nTotalLower = 0;
 
-    random_shuffle(vCoins.begin(), vCoins.end(), GetRandInt);
+    random_shuffle(groups.begin(), groups.end(), GetRandInt);
 
-    for (const CInputCoin &coin : vCoins)
-    {
-        if (coin.txout.nValue == nTargetValue)
-        {
-            setCoinsRet.insert(coin);
-            nValueRet += coin.txout.nValue;
+    for (const OutputGroup& group : groups) {
+        if (group.m_value == nTargetValue) {
+            util::insert(setCoinsRet, group.m_outputs);
+            nValueRet += group.m_value;
             return true;
-        }
-        else if (coin.txout.nValue < nTargetValue + MIN_CHANGE)
-        {
-            vValue.push_back(coin);
-            nTotalLower += coin.txout.nValue;
-        }
-        else if (!coinLowestLarger || coin.txout.nValue < coinLowestLarger->txout.nValue)
-        {
-            coinLowestLarger = coin;
+        } else if (group.m_value < nTargetValue + MIN_CHANGE) {
+            applicable_groups.push_back(group);
+            nTotalLower += group.m_value;
+        } else if (!lowest_larger || group.m_value < lowest_larger->m_value) {
+            lowest_larger = group;
         }
     }
 
-    if (nTotalLower == nTargetValue)
-    {
-        for (const auto& input : vValue)
-        {
-            setCoinsRet.insert(input);
-            nValueRet += input.txout.nValue;
+    if (nTotalLower == nTargetValue) {
+        for (const auto& group : applicable_groups) {
+            util::insert(setCoinsRet, group.m_outputs);
+            nValueRet += group.m_value;
         }
         return true;
     }
 
-    if (nTotalLower < nTargetValue)
-    {
-        if (!coinLowestLarger)
-            return false;
-        setCoinsRet.insert(coinLowestLarger.get());
-        nValueRet += coinLowestLarger->txout.nValue;
+    if (nTotalLower < nTargetValue) {
+        if (!lowest_larger) return false;
+        util::insert(setCoinsRet, lowest_larger->m_outputs);
+        nValueRet += lowest_larger->m_value;
         return true;
     }
 
     // Solve subset sum by stochastic approximation
-    std::sort(vValue.begin(), vValue.end(), descending);
+    std::sort(applicable_groups.begin(), applicable_groups.end(), descending);
     std::vector<char> vfBest;
     CAmount nBest;
 
-    ApproximateBestSubset(vValue, nTotalLower, nTargetValue, vfBest, nBest);
-    if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE)
-        ApproximateBestSubset(vValue, nTotalLower, nTargetValue + MIN_CHANGE, vfBest, nBest);
+    ApproximateBestSubset(applicable_groups, nTotalLower, nTargetValue, vfBest, nBest);
+    if (nBest != nTargetValue && nTotalLower >= nTargetValue + MIN_CHANGE) {
+        ApproximateBestSubset(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,
     //                                   or the next bigger coin is closer), return the bigger coin
-    if (coinLowestLarger &&
-        ((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || coinLowestLarger->txout.nValue <= nBest))
-    {
-        setCoinsRet.insert(coinLowestLarger.get());
-        nValueRet += coinLowestLarger->txout.nValue;
-    }
-    else {
-        for (unsigned int i = 0; i < vValue.size(); i++)
-            if (vfBest[i])
-            {
-                setCoinsRet.insert(vValue[i]);
-                nValueRet += vValue[i].txout.nValue;
+    if (lowest_larger &&
+        ((nBest != nTargetValue && nBest < nTargetValue + MIN_CHANGE) || lowest_larger->m_value <= nBest)) {
+        util::insert(setCoinsRet, lowest_larger->m_outputs);
+        nValueRet += lowest_larger->m_value;
+    } else {
+        for (unsigned int i = 0; i < applicable_groups.size(); i++) {
+            if (vfBest[i]) {
+                util::insert(setCoinsRet, applicable_groups[i].m_outputs);
+                nValueRet += applicable_groups[i].m_value;
             }
+        }
 
         if (LogAcceptCategory(BCLog::SELECTCOINS)) {
             LogPrint(BCLog::SELECTCOINS, "SelectCoins() best subset: "); /* Continued */
-            for (unsigned int i = 0; i < vValue.size(); i++) {
+            for (unsigned int i = 0; i < applicable_groups.size(); i++) {
                 if (vfBest[i]) {
-                    LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(vValue[i].txout.nValue)); /* Continued */
+                    LogPrint(BCLog::SELECTCOINS, "%s ", FormatMoney(applicable_groups[i].m_value)); /* Continued */
                 }
             }
             LogPrint(BCLog::SELECTCOINS, "total %s\n", FormatMoney(nBest));
diff --git a/src/wallet/coinselection.h b/src/wallet/coinselection.h
index 0211851750..01fd6d17c8 100644
--- a/src/wallet/coinselection.h
+++ b/src/wallet/coinselection.h
@@ -95,9 +95,9 @@ struct OutputGroup
     bool EligibleForSpending(const CoinEligibilityFilter& eligibility_filter) const;
 };
 
-bool SelectCoinsBnB(std::vector<CInputCoin>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees);
+bool SelectCoinsBnB(std::vector<OutputGroup>& utxo_pool, const CAmount& target_value, const CAmount& cost_of_change, std::set<CInputCoin>& out_set, CAmount& value_ret, CAmount not_input_fees);
 
 // Original coin selection algorithm as a fallback
-bool KnapsackSolver(const CAmount& nTargetValue, std::vector<CInputCoin>& vCoins, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet);
+bool KnapsackSolver(const CAmount& nTargetValue, std::vector<OutputGroup>& groups, std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet);
 
 #endif // BITCOIN_WALLET_COINSELECTION_H
diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
index d90be33000..1561760577 100644
--- a/src/wallet/test/coinselector_tests.cpp
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -102,6 +102,22 @@ static CAmount make_hard_case(int utxos, std::vector<CInputCoin>& utxo_pool)
     return target;
 }
 
+inline std::vector<OutputGroup>& GroupCoins(const std::vector<CInputCoin>& coins)
+{
+    static std::vector<OutputGroup> static_groups;
+    static_groups.clear();
+    for (auto& coin : coins) static_groups.emplace_back(coin, 0, true, 0, 0);
+    return static_groups;
+}
+
+inline std::vector<OutputGroup>& GroupCoins(const std::vector<COutput>& coins)
+{
+    static std::vector<OutputGroup> static_groups;
+    static_groups.clear();
+    for (auto& coin : coins) static_groups.emplace_back(coin.GetInputCoin(), coin.nDepth, coin.tx->fDebitCached && coin.tx->nDebitCached == 1 /* HACK: we can't figure out the is_me flag so we use the conditions defined above; perhaps set safe to false for !fIsFromMe in add_coin() */, 0, 0);
+    return static_groups;
+}
+
 // Branch and bound coin selection tests
 BOOST_AUTO_TEST_CASE(bnb_search_test)
 {
@@ -121,7 +137,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     BOOST_TEST_MESSAGE("Testing known outcomes");
 
     // Empty utxo pool
-    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     selection.clear();
 
     // Add utxos
@@ -132,14 +148,14 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
 
     // Select 1 Cent
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 1 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     actual_selection.clear();
     selection.clear();
 
     // Select 2 Cent
     add_coin(2 * CENT, 2, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 2 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 2 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     actual_selection.clear();
     selection.clear();
@@ -147,13 +163,13 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     // Select 5 Cent
     add_coin(3 * CENT, 3, actual_selection);
     add_coin(2 * CENT, 2, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 5 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 5 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     actual_selection.clear();
     selection.clear();
 
     // Select 11 Cent, not possible
-    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 11 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 11 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     actual_selection.clear();
     selection.clear();
 
@@ -163,7 +179,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     add_coin(3 * CENT, 3, actual_selection);
     add_coin(2 * CENT, 2, actual_selection);
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 10 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 10 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     actual_selection.clear();
     selection.clear();
@@ -173,18 +189,18 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     add_coin(5 * CENT, 5, actual_selection);
     add_coin(3 * CENT, 3, actual_selection);
     add_coin(2 * CENT, 2, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 10 * CENT, 5000, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 10 * CENT, 5000, selection, value_ret, not_input_fees));
 
     // Select 0.25 Cent, not possible
-    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 0.25 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 0.25 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
     actual_selection.clear();
     selection.clear();
 
     // Iteration exhaustion test
     CAmount target = make_hard_case(17, utxo_pool);
-    BOOST_CHECK(!SelectCoinsBnB(utxo_pool, target, 0, selection, value_ret, not_input_fees)); // Should exhaust
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret, not_input_fees)); // Should exhaust
     target = make_hard_case(14, utxo_pool);
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, target, 0, selection, value_ret, not_input_fees)); // Should not exhaust
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret, not_input_fees)); // Should not exhaust
 
     // Test same value early bailout optimization
     add_coin(7 * CENT, 7, actual_selection);
@@ -200,7 +216,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     for (int i = 0; i < 50000; ++i) {
         add_coin(5 * CENT, 7, utxo_pool);
     }
-    BOOST_CHECK(SelectCoinsBnB(utxo_pool, 30 * CENT, 5000, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 30 * CENT, 5000, selection, value_ret, not_input_fees));
 
     ////////////////////
     // Behavior tests //
@@ -212,7 +228,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     }
     // Run 100 times, to make sure it is never finding a solution
     for (int i = 0; i < 100; ++i) {
-        BOOST_CHECK(!SelectCoinsBnB(utxo_pool, 1 * CENT, 2 * CENT, selection, value_ret, not_input_fees));
+        BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 1 * CENT, 2 * CENT, selection, value_ret, not_input_fees));
     }
 
     // Make sure that effective value is working in SelectCoinsMinConf when BnB is used
@@ -223,7 +239,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     empty_wallet();
     add_coin(1);
     vCoins.at(0).nInputBytes = 40; // Make sure that it has a negative effective value. The next check should assert if this somehow got through. Otherwise it will fail
-    BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params_bnb, bnb_used));
+    BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params_bnb, bnb_used));
 
     // Make sure that we aren't using BnB when there are preset inputs
     empty_wallet();
@@ -252,24 +268,24 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         empty_wallet();
 
         // with an empty wallet we can't even pay one cent
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
         add_coin(1*CENT, 4);        // add a new 1 cent coin
 
         // with a new 1 cent coin, we still can't find a mature 1 cent
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
         // but we can find a new 1 cent
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 1 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 1 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
 
         add_coin(2*CENT);           // add a mature 2 cent coin
 
         // we can't make 3 cents of mature coins
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 3 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf( 3 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
         // we can make 3 cents of new coins
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 3 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 3 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
 
         add_coin(5*CENT);           // add a mature 5 cent coin,
@@ -279,33 +295,33 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         // now we have new: 1+10=11 (of which 10 was self-sent), and mature: 2+5+20=27.  total = 38
 
         // we can't make 38 cents only if we disallow new coins:
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         // we can't even make 37 cents if we don't allow new coins even if they're from us
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard_extra, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(38 * CENT, filter_standard_extra, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         // but we can make 37 cents if we accept new coins from ourself
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(37 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(37 * CENT, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 37 * CENT);
         // and we can make 38 cents if we accept all new coins
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(38 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(38 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 38 * CENT);
 
         // try making 34 cents from 1,2,5,10,20 - we can't do it exactly
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(34 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(34 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 35 * CENT);       // but 35 cents is closest
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);     // the best should be 20+10+5.  it's incredibly unlikely the 1 or 2 got included (but possible)
 
         // when we try making 7 cents, the smaller coins (1,2,5) are enough.  We should see just 2+5
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 7 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 7 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 7 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
         // when we try making 8 cents, the smaller coins (1,2,5) are exactly enough.
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 8 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 8 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK(nValueRet == 8 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         // when we try making 9 cents, no subset of smaller coins is enough, and we get the next bigger coin (10)
-        BOOST_CHECK( testWallet.SelectCoinsMinConf( 9 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf( 9 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -319,30 +335,30 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin(30*CENT); // now we have 6+7+8+20+30 = 71 cents total
 
         // check that we have 71 and not 72
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(71 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
-        BOOST_CHECK(!testWallet.SelectCoinsMinConf(72 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(71 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(72 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
         // now try making 16 cents.  the best smaller coins can do is 6+7+8 = 21; not as good at the next biggest coin, 20
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 20 * CENT); // we should get 20 in one coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
         add_coin( 5*CENT); // now we have 5+6+7+8+20+30 = 75 cents total
 
         // now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, better than the next biggest coin, 20
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 18 * CENT); // we should get 18 in 3 coins
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         add_coin( 18*CENT); // now we have 5+6+7+8+18+20+30
 
         // and now if we try making 16 cents again, the smaller coins can make 5+6+7 = 18 cents, the same as the next biggest coin, 18
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(16 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 18 * CENT);  // we should get 18 in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U); // because in the event of a tie, the biggest coin wins
 
         // now try making 11 cents.  we should get 5+6
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(11 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(11 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -351,11 +367,11 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin( 2*COIN);
         add_coin( 3*COIN);
         add_coin( 4*COIN); // now we have 5+6+7+8+18+20+30+100+200+300+400 = 1094 cents
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(95 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(95 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 1 * COIN);  // we should get 1 BTC in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(195 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(195 * CENT, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -370,14 +386,14 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
 
         // try making 1 * MIN_CHANGE from the 1.5 * MIN_CHANGE
         // we'll get change smaller than MIN_CHANGE whatever happens, so can expect MIN_CHANGE exactly
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);
 
         // but if we add a bigger coin, small change is avoided
         add_coin(1111*MIN_CHANGE);
 
         // try making 1 from 0.1 + 0.2 + 0.3 + 0.4 + 0.5 + 1111 = 1112.5
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // if we add more small coins:
@@ -385,7 +401,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin(MIN_CHANGE * 7 / 10);
 
         // and try again to make 1.0 * MIN_CHANGE
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // run the 'mtgox' test (see http://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
@@ -394,7 +410,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         for (int j = 0; j < 20; j++)
             add_coin(50000 * COIN);
 
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(500000 * COIN, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(500000 * COIN, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
 
@@ -407,7 +423,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin(MIN_CHANGE * 6 / 10);
         add_coin(MIN_CHANGE * 7 / 10);
         add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(1 * MIN_CHANGE, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -417,7 +433,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin(MIN_CHANGE * 6 / 10);
         add_coin(MIN_CHANGE * 8 / 10);
         add_coin(1111 * MIN_CHANGE);
-        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK( testWallet.SelectCoinsMinConf(MIN_CHANGE, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE);   // we should get the exact amount
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U); // in two coins 0.4+0.6
 
@@ -428,12 +444,12 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
         add_coin(MIN_CHANGE * 100);
 
         // trying to make 100.01 from these three coins
-        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 10001 / 100, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, MIN_CHANGE * 10105 / 100); // we should get all coins
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 3U);
 
         // but if we try to make 99.9, we should take the bigger of the two small coins to avoid small change
-        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(MIN_CHANGE * 9990 / 100, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
         BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -443,7 +459,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
              // Create 676 inputs (=  (old MAX_STANDARD_TX_SIZE == 100000)  / 148 bytes per input)
              for (uint16_t j = 0; j < 676; j++)
                  add_coin(amt);
-             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, filter_confirmed, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
              if (amt - 2000 < MIN_CHANGE) {
                  // needs more than one input:
                  uint16_t returnSize = std::ceil((2000.0 + MIN_CHANGE)/amt);
@@ -465,8 +481,8 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
 
             // picking 50 from 100 coins doesn't depend on the shuffle,
             // but does depend on randomness in the stochastic approximation code
-            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
-            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, GroupCoins(vCoins), setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+            BOOST_CHECK(testWallet.SelectCoinsMinConf(50 * COIN, filter_standard, GroupCoins(vCoins), setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
             BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
 
             int fails = 0;
@@ -474,8 +490,8 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
             {
                 // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                 // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, GroupCoins(vCoins), setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(COIN, filter_standard, GroupCoins(vCoins), setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -495,8 +511,8 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
             {
                 // selecting 1 from 100 identical coins depends on the shuffle; this test will fail 1% of the time
                 // run the test RANDOM_REPEATS times and only complain if all of them fail
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, vCoins, setCoinsRet , nValueRet, coin_selection_params, bnb_used));
-                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, vCoins, setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, GroupCoins(vCoins), setCoinsRet , nValueRet, coin_selection_params, bnb_used));
+                BOOST_CHECK(testWallet.SelectCoinsMinConf(90*CENT, filter_standard, GroupCoins(vCoins), setCoinsRet2, nValueRet, coin_selection_params, bnb_used));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -521,7 +537,7 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
         add_coin(1000 * COIN);
     add_coin(3 * COIN);
 
-    BOOST_CHECK(testWallet.SelectCoinsMinConf(1003 * COIN, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+    BOOST_CHECK(testWallet.SelectCoinsMinConf(1003 * COIN, filter_standard, GroupCoins(vCoins), setCoinsRet, nValueRet, coin_selection_params, bnb_used));
     BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
     BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -559,8 +575,8 @@ BOOST_AUTO_TEST_CASE(SelectCoins_test)
         CoinSet out_set;
         CAmount out_value = 0;
         bool bnb_used = false;
-        BOOST_CHECK(testWallet.SelectCoinsMinConf(target, filter_standard, vCoins, out_set, out_value, coin_selection_params_bnb, bnb_used) ||
-                    testWallet.SelectCoinsMinConf(target, filter_standard, vCoins, out_set, out_value, coin_selection_params_knapsack, bnb_used));
+        BOOST_CHECK(testWallet.SelectCoinsMinConf(target, filter_standard, GroupCoins(vCoins), out_set, out_value, coin_selection_params_bnb, bnb_used) ||
+                    testWallet.SelectCoinsMinConf(target, filter_standard, GroupCoins(vCoins), out_set, out_value, coin_selection_params_knapsack, bnb_used));
         BOOST_CHECK_GE(out_value, target);
     }
 }
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 03c829357b..3c7e3302fb 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2431,15 +2431,14 @@ bool CWallet::OutputEligibleForSpending(const COutput& output, const CoinEligibi
     return true;
 }
 
-bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<COutput> vCoins,
+bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<OutputGroup> groups,
                                  std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CoinSelectionParams& coin_selection_params, bool& bnb_used) const
 {
     setCoinsRet.clear();
     nValueRet = 0;
 
-    std::vector<CInputCoin> utxo_pool;
+    std::vector<OutputGroup> utxo_pool;
     if (coin_selection_params.use_bnb) {
-
         // Get long term estimate
         FeeCalculation feeCalc;
         CCoinControl temp;
@@ -2450,19 +2449,26 @@ bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibil
         CAmount cost_of_change = GetDiscardRate(*this, ::feeEstimator).GetFee(coin_selection_params.change_spend_size) + coin_selection_params.effective_fee.GetFee(coin_selection_params.change_output_size);
 
         // Filter by the min conf specs and add to utxo_pool and calculate effective value
-        for (const COutput &output : vCoins)
-        {
-            if (!OutputEligibleForSpending(output, eligibility_filter))
-                continue;
-
-            CInputCoin coin(output.tx->tx, output.i);
-            coin.effective_value = coin.txout.nValue - (output.nInputBytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(output.nInputBytes));
-            // Only include outputs that are positive effective value (i.e. not dust)
-            if (coin.effective_value > 0) {
-                coin.fee = output.nInputBytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(output.nInputBytes);
-                coin.long_term_fee = output.nInputBytes < 0 ? 0 : long_term_feerate.GetFee(output.nInputBytes);
-                utxo_pool.push_back(coin);
+        for (OutputGroup& group : groups) {
+            if (!group.EligibleForSpending(eligibility_filter)) continue;
+
+            group.fee = 0;
+            group.long_term_fee = 0;
+            group.effective_value = 0;
+            for (auto it = group.m_outputs.begin(); it != group.m_outputs.end(); ) {
+                const CInputCoin& coin = *it;
+                CAmount effective_value = coin.txout.nValue - (coin.m_input_bytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(coin.m_input_bytes));
+                // Only include outputs that are positive effective value (i.e. not dust)
+                if (effective_value > 0) {
+                    group.fee += coin.m_input_bytes < 0 ? 0 : coin_selection_params.effective_fee.GetFee(coin.m_input_bytes);
+                    group.long_term_fee += coin.m_input_bytes < 0 ? 0 : long_term_feerate.GetFee(coin.m_input_bytes);
+                    group.effective_value += effective_value;
+                    ++it;
+                } else {
+                    it = group.Discard(coin);
+                }
             }
+            if (group.effective_value > 0) utxo_pool.push_back(group);
         }
         // Calculate the fees for things that aren't inputs
         CAmount not_input_fees = coin_selection_params.effective_fee.GetFee(coin_selection_params.tx_noinputs_size);
@@ -2470,13 +2476,9 @@ bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibil
         return SelectCoinsBnB(utxo_pool, nTargetValue, cost_of_change, setCoinsRet, nValueRet, not_input_fees);
     } else {
         // Filter by the min conf specs and add to utxo_pool
-        for (const COutput &output : vCoins)
-        {
-            if (!OutputEligibleForSpending(output, eligibility_filter))
-                continue;
-
-            CInputCoin coin = CInputCoin(output.tx->tx, output.i);
-            utxo_pool.push_back(coin);
+        for (const OutputGroup& group : groups) {
+            if (!group.EligibleForSpending(eligibility_filter)) continue;
+            utxo_pool.push_back(group);
         }
         bnb_used = false;
         return KnapsackSolver(nTargetValue, utxo_pool, setCoinsRet, nValueRet);
@@ -2498,7 +2500,7 @@ bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAm
             if (!out.fSpendable)
                  continue;
             nValueRet += out.tx->tx->vout[out.i].nValue;
-            setCoinsRet.insert(CInputCoin(out.tx->tx, out.i));
+            setCoinsRet.insert(out.GetInputCoin());
         }
         return (nValueRet >= nTargetValue);
     }
@@ -2532,27 +2534,31 @@ bool CWallet::SelectCoins(const std::vector<COutput>& vAvailableCoins, const CAm
     // remove preset inputs from vCoins
     for (std::vector<COutput>::iterator it = vCoins.begin(); it != vCoins.end() && coin_control.HasSelected();)
     {
-        if (setPresetCoins.count(CInputCoin(it->tx->tx, it->i)))
+        if (setPresetCoins.count(it->GetInputCoin()))
             it = vCoins.erase(it);
         else
             ++it;
     }
 
+    // form groups from remaining coins; note that preset coins will not
+    // automatically have their associated (same address) coins included
+    std::vector<OutputGroup> groups = GroupOutputs(vCoins, !coin_control.m_avoid_partial_spends);
+
     size_t max_ancestors = (size_t)std::max<int64_t>(1, gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT));
     size_t max_descendants = (size_t)std::max<int64_t>(1, gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT));
     bool fRejectLongChains = gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS);
 
     bool res = nTargetValue <= nValueFromPresetInputs ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 6, 0), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
-        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 1, 0), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
-        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, 2), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
-        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::min((size_t)4, max_ancestors/3), std::min((size_t)4, max_descendants/3)), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
-        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, max_ancestors/2, max_descendants/2), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
-        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, max_ancestors-1, max_descendants-1), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
-        (m_spend_zero_conf_change && !fRejectLongChains && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max()), vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 6, 0), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
+        SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(1, 1, 0), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used) ||
+        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, 2), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::min((size_t)4, max_ancestors/3), std::min((size_t)4, max_descendants/3)), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, max_ancestors/2, max_descendants/2), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (m_spend_zero_conf_change && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, max_ancestors-1, max_descendants-1), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used)) ||
+        (m_spend_zero_conf_change && !fRejectLongChains && SelectCoinsMinConf(nTargetValue - nValueFromPresetInputs, CoinEligibilityFilter(0, 1, std::numeric_limits<uint64_t>::max()), groups, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
 
     // because SelectCoinsMinConf clears the setCoinsRet, we now add the possible inputs to the coinset
-    setCoinsRet.insert(setPresetCoins.begin(), setPresetCoins.end());
+    util::insert(setCoinsRet, setPresetCoins);
 
     // add preset inputs to the total value selected
     nValueRet += nValueFromPresetInputs;
@@ -2666,7 +2672,7 @@ OutputType CWallet::TransactionChangeType(OutputType change_type, const std::vec
 }
 
 bool CWallet::CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CReserveKey& reservekey, CAmount& nFeeRet,
-                                int& nChangePosInOut, std::string& strFailReason, const CCoinControl& coin_control, bool sign)
+                         int& nChangePosInOut, std::string& strFailReason, const CCoinControl& coin_control, bool sign)
 {
     CAmount nValue = 0;
     int nChangePosRequest = nChangePosInOut;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index f3e3a78f83..6c8063c47c 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -857,7 +857,7 @@ public:
      * completion the coin set and corresponding actual target value is
      * assembled
      */
-    bool SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<COutput> vCoins,
+    bool SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibilityFilter& eligibility_filter, std::vector<OutputGroup> groups,
         std::set<CInputCoin>& setCoinsRet, CAmount& nValueRet, const CoinSelectionParams& coin_selection_params, bool& bnb_used) const;
 
     bool IsSpent(const uint256& hash, unsigned int n) const;