Merge bitcoin/bitcoin#17331: Use effective values throughout coin selection

51a3ac242c92e69b59df26f8f9e287b31e5c3b0f Have OutputGroup determine the value to use (Andrew Chow)
6d6d2784759878ef0c4ac128d12aac68add1edca Change SelectCoins_test to actually test SelectCoins (Andrew Chow)
9d3bd74ab4430532d6e53eef8cf77ad999044b14 Remove CreateTransaction while loop and some related variables (Andrew Chow)
6f0d5189af4c881fe8b97a0c28ce1ffa33480715 Remove use_bnb and bnb_used (Andrew Chow)
de26eb0e1fa2b6f03c58ba104d00f7a8ffead39c Do both BnB and Knapsack coin selection in SelectCoinsMinConf (Andrew Chow)
01dc8ebda50a382d45d3d169b2c3f3965869dcae Have KnapsackSolver actually use effective values (Andrew Chow)
bf26e018de33216d6f0ed0d6ff822b93536f7cc1 Roll static tx fees into nValueToSelect instead of having it be separate (Andrew Chow)
cc3f14b27c06b7a0da1472f5c7100c3f0b76fd98 Move output reductions for fee to after coin selection (Andrew Chow)
d97d25d95006725e705635530b27643363d6b2a4 Make cost_of_change part of CoinSelectionParams (Andrew Chow)
af5867c89688b06173b295b7c32a42845ea455da Move some calculations to common code in SelectCoinsMinConf (Andrew Chow)
1bf4a62cb61bd4b91d9cd4e379fea2b914786342 scripted-diff: rename some variables (Andrew Chow)

Pull request description:

  Changes `KnapsackSolver` to use effective values instead of just the nominal txout value. Since fees are taken into account during the selection itself, we finally get rid of the `CreateTransaction` loop as well as a few other things that only were only necessary because of that loop.

  This should not change coin selection behavior at all (except maybe remove weird edge cases that were caused by the loop). In order to keep behavior the same, `KnapsackSolver` will select outputs with a negative effective value (as it did before).

ACKs for top commit:
  ryanofsky:
    Code review ACK 51a3ac242c92e69b59df26f8f9e287b31e5c3b0f. Looks good to go!
  instagibbs:
    review ACK https://github.com/bitcoin/bitcoin/pull/17331/commits/51a3ac242c92e69b59df26f8f9e287b31e5c3b0f
  meshcollider:
    re-light-utACK 51a3ac242c92e69b59df26f8f9e287b31e5c3b0f

Tree-SHA512: 372c27e00edcd5dbf85177421ba88f20bfdaf1791b6e3dc022c44876ecc379403e2375ed69e71c512c49e6af87641001ff385c4b25ab93684b3a08a53bf3824e

1 files changed, 67 insertions, 78 deletions

diff --git a/src/wallet/test/coinselector_tests.cpp b/src/wallet/test/coinselector_tests.cpp
index 7bca385deb..14c3578473 100644
--- a/src/wallet/test/coinselector_tests.cpp
+++ b/src/wallet/test/coinselector_tests.cpp
@@ -35,7 +35,7 @@ static CAmount balance = 0;
 CoinEligibilityFilter filter_standard(1, 6, 0);
 CoinEligibilityFilter filter_confirmed(1, 1, 0);
 CoinEligibilityFilter filter_standard_extra(6, 6, 0);
-CoinSelectionParams coin_selection_params(/* use_bnb= */ false, /* change_output_size= */ 0,
+CoinSelectionParams coin_selection_params(/* change_output_size= */ 0,
                                           /* change_spend_size= */ 0, /* effective_feerate= */ CFeeRate(0),
                                           /* long_term_feerate= */ CFeeRate(0), /* discard_feerate= */ CFeeRate(0),
                                           /* tx_no_inputs_size= */ 0, /* avoid_partial= */ false);
@@ -148,14 +148,13 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     CoinSet selection;
     CoinSet actual_selection;
     CAmount value_ret = 0;
-    CAmount not_input_fees = 0;
 
     /////////////////////////
     // Known Outcome tests //
     /////////////////////////
 
     // Empty utxo pool
-    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(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));
     selection.clear();
 
     // Add utxos
@@ -166,7 +165,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
 
     // Select 1 Cent
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(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));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     BOOST_CHECK_EQUAL(value_ret, 1 * CENT);
     actual_selection.clear();
@@ -174,7 +173,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
 
     // Select 2 Cent
     add_coin(2 * CENT, 2, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(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));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     BOOST_CHECK_EQUAL(value_ret, 2 * CENT);
     actual_selection.clear();
@@ -183,27 +182,27 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     // Select 5 Cent
     add_coin(4 * CENT, 4, actual_selection);
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(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));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     BOOST_CHECK_EQUAL(value_ret, 5 * CENT);
     actual_selection.clear();
     selection.clear();
 
     // Select 11 Cent, not possible
-    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(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));
     actual_selection.clear();
     selection.clear();
 
     // Cost of change is greater than the difference between target value and utxo sum
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0.5 * CENT, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0.5 * CENT, selection, value_ret));
     BOOST_CHECK_EQUAL(value_ret, 1 * CENT);
     BOOST_CHECK(equal_sets(selection, actual_selection));
     actual_selection.clear();
     selection.clear();
 
     // Cost of change is less than the difference between target value and utxo sum
-    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0, selection, value_ret, not_input_fees));
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), 0.9 * CENT, 0, selection, value_ret));
     actual_selection.clear();
     selection.clear();
 
@@ -212,7 +211,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     add_coin(5 * CENT, 5, actual_selection);
     add_coin(4 * CENT, 4, actual_selection);
     add_coin(1 * CENT, 1, actual_selection);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(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));
     BOOST_CHECK(equal_sets(selection, actual_selection));
     BOOST_CHECK_EQUAL(value_ret, 10 * CENT);
     actual_selection.clear();
@@ -223,21 +222,21 @@ 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(GroupCoins(utxo_pool), 10 * CENT, 5000, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 10 * CENT, 5000, selection, value_ret));
     BOOST_CHECK_EQUAL(value_ret, 10 * CENT);
     // FIXME: this test is redundant with the above, because 1 Cent is selected, not "too small"
     // BOOST_CHECK(equal_sets(selection, actual_selection));
 
     // Select 0.25 Cent, not possible
-    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(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));
     actual_selection.clear();
     selection.clear();
 
     // Iteration exhaustion test
     CAmount target = make_hard_case(17, utxo_pool);
-    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret, not_input_fees)); // Should exhaust
+    BOOST_CHECK(!SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret)); // Should exhaust
     target = make_hard_case(14, utxo_pool);
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret, not_input_fees)); // Should not exhaust
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), target, 0, selection, value_ret)); // Should not exhaust
 
     // Test same value early bailout optimization
     utxo_pool.clear();
@@ -254,7 +253,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
     for (int i = 0; i < 50000; ++i) {
         add_coin(5 * CENT, 7, utxo_pool);
     }
-    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 30 * CENT, 5000, selection, value_ret, not_input_fees));
+    BOOST_CHECK(SelectCoinsBnB(GroupCoins(utxo_pool), 30 * CENT, 5000, selection, value_ret));
     BOOST_CHECK_EQUAL(value_ret, 30 * CENT);
     BOOST_CHECK(equal_sets(selection, actual_selection));
 
@@ -268,29 +267,27 @@ 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(GroupCoins(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));
     }
 
     // Make sure that effective value is working in SelectCoinsMinConf when BnB is used
-    CoinSelectionParams coin_selection_params_bnb(/* use_bnb= */ true, /* change_output_size= */ 0,
+    CoinSelectionParams coin_selection_params_bnb(/* change_output_size= */ 0,
                                                   /* change_spend_size= */ 0, /* effective_feerate= */ CFeeRate(3000),
                                                   /* long_term_feerate= */ CFeeRate(1000), /* discard_feerate= */ CFeeRate(1000),
                                                   /* tx_no_inputs_size= */ 0, /* avoid_partial= */ false);
     CoinSet setCoinsRet;
     CAmount nValueRet;
-    bool bnb_used;
     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, vCoins, setCoinsRet, nValueRet, coin_selection_params_bnb));
 
     // Test fees subtracted from output:
     empty_wallet();
     add_coin(1 * CENT);
     vCoins.at(0).nInputBytes = 40;
-    BOOST_CHECK(!testWallet.SelectCoinsMinConf( 1 * CENT, filter_standard, vCoins, setCoinsRet, nValueRet, coin_selection_params_bnb, bnb_used));
     coin_selection_params_bnb.m_subtract_fee_outputs = true;
-    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, vCoins, setCoinsRet, nValueRet, coin_selection_params_bnb));
     BOOST_CHECK_EQUAL(nValueRet, 1 * CENT);
 
     // Make sure that can use BnB when there are preset inputs
@@ -307,9 +304,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
         coin_control.fAllowOtherInputs = true;
         coin_control.Select(COutPoint(vCoins.at(0).tx->GetHash(), vCoins.at(0).i));
         coin_selection_params_bnb.m_effective_feerate = CFeeRate(0);
-        BOOST_CHECK(wallet->SelectCoins(vCoins, 10 * CENT, setCoinsRet, nValueRet, coin_control, coin_selection_params_bnb, bnb_used));
-        BOOST_CHECK(bnb_used);
-        BOOST_CHECK(coin_selection_params_bnb.use_bnb);
+        BOOST_CHECK(wallet->SelectCoins(vCoins, 10 * CENT, setCoinsRet, nValueRet, coin_control, coin_selection_params_bnb));
     }
 }
 
@@ -317,7 +312,6 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
 {
     CoinSet setCoinsRet, setCoinsRet2;
     CAmount nValueRet;
-    bool bnb_used;
 
     LOCK(testWallet.cs_wallet);
     testWallet.SetupLegacyScriptPubKeyMan();
@@ -328,24 +322,24 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
 
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
 
         // 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
 
         // 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 3 * CENT);
 
         add_coin(5*CENT);           // add a mature 5 cent coin,
@@ -355,33 +349,33 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         // 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         // 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 10 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -395,30 +389,30 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
+        BOOST_CHECK(!testWallet.SelectCoinsMinConf(72 * CENT, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params));
 
         // 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 11 * CENT);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -427,11 +421,11 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 2 * COIN);  // we should get 2 BTC in 1 coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -446,14 +440,14 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // if we add more small coins:
@@ -461,7 +455,7 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 1 * MIN_CHANGE); // we should get the exact amount
 
         // run the 'mtgox' test (see https://blockexplorer.com/tx/29a3efd3ef04f9153d47a990bd7b048a4b2d213daaa5fb8ed670fb85f13bdbcf)
@@ -470,7 +464,7 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 500000 * COIN); // we should get the exact amount
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 10U); // in ten coins
 
@@ -483,7 +477,7 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 1111 * MIN_CHANGE); // we get the bigger coin
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 1U);
 
@@ -493,7 +487,7 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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
 
@@ -504,12 +498,12 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
         BOOST_CHECK_EQUAL(nValueRet, 101 * MIN_CHANGE);
         BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
       }
@@ -523,7 +517,7 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
 
            // We only create the wallet once to save time, but we still run the coin selection RUN_TESTS times.
            for (int i = 0; i < RUN_TESTS; i++) {
-             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params, bnb_used));
+             BOOST_CHECK(testWallet.SelectCoinsMinConf(2000, filter_confirmed, vCoins, setCoinsRet, nValueRet, coin_selection_params));
 
              if (amt - 2000 < MIN_CHANGE) {
                  // needs more than one input:
@@ -549,17 +543,19 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
           for (int i = 0; i < RUN_TESTS; i++) {
             // 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(KnapsackSolver(50 * COIN, GroupCoins(vCoins), setCoinsRet, nValueRet));
+            BOOST_CHECK(KnapsackSolver(50 * COIN, GroupCoins(vCoins), setCoinsRet2, nValueRet));
             BOOST_CHECK(!equal_sets(setCoinsRet, setCoinsRet2));
 
             int fails = 0;
             for (int j = 0; j < RANDOM_REPEATS; j++)
             {
-                // 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));
+                // Test that the KnapsackSolver selects randomly from equivalent coins (same value and same input size).
+                // When choosing 1 from 100 identical coins, 1% of the time, this test will choose the same coin twice
+                // which will cause it to fail.
+                // To avoid that issue, run the test RANDOM_REPEATS times and only complain if all of them fail
+                BOOST_CHECK(KnapsackSolver(COIN, GroupCoins(vCoins), setCoinsRet, nValueRet));
+                BOOST_CHECK(KnapsackSolver(COIN, GroupCoins(vCoins), setCoinsRet2, nValueRet));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -579,10 +575,8 @@ BOOST_AUTO_TEST_CASE(knapsack_solver_test)
             int fails = 0;
             for (int j = 0; j < RANDOM_REPEATS; j++)
             {
-                // 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(KnapsackSolver(90*CENT, GroupCoins(vCoins), setCoinsRet, nValueRet));
+                BOOST_CHECK(KnapsackSolver(90*CENT, GroupCoins(vCoins), setCoinsRet2, nValueRet));
                 if (equal_sets(setCoinsRet, setCoinsRet2))
                     fails++;
             }
@@ -597,7 +591,6 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
 {
     CoinSet setCoinsRet;
     CAmount nValueRet;
-    bool bnb_used;
 
     LOCK(testWallet.cs_wallet);
     testWallet.SetupLegacyScriptPubKeyMan();
@@ -609,7 +602,7 @@ 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, vCoins, setCoinsRet, nValueRet, coin_selection_params));
     BOOST_CHECK_EQUAL(nValueRet, 1003 * COIN);
     BOOST_CHECK_EQUAL(setCoinsRet.size(), 2U);
 
@@ -619,6 +612,7 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
 // Tests that with the ideal conditions, the coin selector will always be able to find a solution that can pay the target value
 BOOST_AUTO_TEST_CASE(SelectCoins_test)
 {
+    LOCK(testWallet.cs_wallet);
     testWallet.SetupLegacyScriptPubKeyMan();
 
     // Random generator stuff
@@ -644,19 +638,14 @@ BOOST_AUTO_TEST_CASE(SelectCoins_test)
         CAmount target = rand.randrange(balance - 1000) + 1000;
 
         // Perform selection
-        CoinSelectionParams coin_selection_params_knapsack(/* use_bnb= */ false, /* change_output_size= */ 34,
-                                                           /* change_spend_size= */ 148, /* effective_feerate= */ CFeeRate(0),
-                                                           /* long_term_feerate= */ CFeeRate(0), /* discard_feerate= */ CFeeRate(0),
-                                                           /* tx_no_inputs_size= */ 0, /* avoid_partial= */ false);
-        CoinSelectionParams coin_selection_params_bnb(/* use_bnb= */ true, /* change_output_size= */ 34,
-                                                      /* change_spend_size= */ 148, /* effective_feerate= */ CFeeRate(0),
-                                                      /* long_term_feerate= */ CFeeRate(0), /* discard_feerate= */ CFeeRate(0),
-                                                      /* tx_no_inputs_size= */ 0, /* avoid_partial= */ false);
+        CoinSelectionParams cs_params(/* change_output_size= */ 34,
+                                      /* change_spend_size= */ 148, /* effective_feerate= */ CFeeRate(0),
+                                      /* long_term_feerate= */ CFeeRate(0), /* discard_feerate= */ CFeeRate(0),
+                                      /* tx_no_inputs_size= */ 0, /* avoid_partial= */ false);
         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));
+        CCoinControl cc;
+        BOOST_CHECK(testWallet.SelectCoins(vCoins, target, out_set, out_value, cc, cs_params));
         BOOST_CHECK_GE(out_value, target);
     }
 }