backport: wallet coin selection prerequisites for #7400

src/Makefile.bench.include

@@ -91,6 +91,7 @@ if ENABLE_WALLET
 bench_bench_dash_SOURCES += bench/coin_selection.cpp
 bench_bench_dash_SOURCES += bench/wallet_balance.cpp
 bench_bench_dash_SOURCES += bench/wallet_create.cpp
+bench_bench_dash_SOURCES += bench/wallet_create_tx.cpp
 bench_bench_dash_SOURCES += bench/wallet_loading.cpp
 bench_bench_dash_LDADD += $(BDB_LIBS) $(SQLITE_LIBS)
 endif

src/bench/wallet_create_tx.cpp

@@ -0,0 +1,142 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#include <bench/bench.h>
+#include <chainparams.h>
+#include <wallet/coincontrol.h>
+#include <consensus/merkle.h>
+#include <kernel/chain.h>
+#include <node/context.h>
+#include <test/util/setup_common.h>
+#include <test/util/wallet.h>
+#include <validation.h>
+#include <wallet/spend.h>
+#include <wallet/wallet.h>
+
+using wallet::CWallet;
+using wallet::CreateMockWalletDatabase;
+using wallet::DBErrors;
+using wallet::WALLET_FLAG_DESCRIPTORS;
+
+struct TipBlock
+{
+    uint256 prev_block_hash;
+    int64_t prev_block_time;
+    int tip_height;
+};
+
+TipBlock getTip(const CChainParams& params, const node::NodeContext& context)
+{
+    auto tip = WITH_LOCK(::cs_main, return context.chainman->ActiveTip());
+    return (tip) ? TipBlock{tip->GetBlockHash(), tip->GetBlockTime(), tip->nHeight} :
+           TipBlock{params.GenesisBlock().GetHash(), params.GenesisBlock().GetBlockTime(), 0};
+}
+
+void generateFakeBlock(const CChainParams& params,
+                       const node::NodeContext& context,
+                       CWallet& wallet,
+                       const CScript& coinbase_out_script)
+{
+    TipBlock tip{getTip(params, context)};
+
+    // Create block
+    CBlock block;
+    CMutableTransaction coinbase_tx;
+    coinbase_tx.vin.resize(1);
+    coinbase_tx.vin[0].prevout.SetNull();
+    coinbase_tx.vout.resize(2);
+    coinbase_tx.vout[0].scriptPubKey = coinbase_out_script;
+    coinbase_tx.vout[0].nValue = 49 * COIN;
+    coinbase_tx.vin[0].scriptSig = CScript() << ++tip.tip_height << OP_0;
+    coinbase_tx.vout[1].scriptPubKey = coinbase_out_script; // extra output
+    coinbase_tx.vout[1].nValue = 1 * COIN;
+    block.vtx = {MakeTransactionRef(std::move(coinbase_tx))};
+
+    block.nVersion = VERSIONBITS_LAST_OLD_BLOCK_VERSION;
+    block.hashPrevBlock = tip.prev_block_hash;
+    block.hashMerkleRoot = BlockMerkleRoot(block);
+    block.nTime = ++tip.prev_block_time;
+    block.nBits = params.GenesisBlock().nBits;
+    block.nNonce = 0;
+
+    {
+        LOCK(::cs_main);
+        // Add it to the index
+        CBlockIndex* pindex{context.chainman->m_blockman.AddToBlockIndex(block, block.GetHash(), context.chainman->m_best_header)};
+        // add it to the chain
+        context.chainman->ActiveChain().SetTip(*pindex);
+    }
+
+    // notify wallet
+    const auto& pindex = WITH_LOCK(::cs_main, return context.chainman->ActiveChain().Tip());
+    wallet.blockConnected(kernel::MakeBlockInfo(pindex, &block));
+}
+
+struct PreSelectInputs {
+    // How many coins from the wallet the process should select
+    int num_of_internal_inputs;
+    // future: this could have external inputs as well.
+};
+
+static void WalletCreateTx(benchmark::Bench& bench, bool allow_other_inputs, std::optional<PreSelectInputs> preset_inputs)
+{
+    const auto test_setup = MakeNoLogFileContext<const TestingSetup>();
+
+    CWallet wallet{test_setup->m_node.chain.get(), test_setup->m_node.coinjoin_loader.get(), "", gArgs, CreateMockWalletDatabase()};
+    {
+        LOCK(wallet.cs_wallet);
+        wallet.SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
+        wallet.SetupDescriptorScriptPubKeyMans("", "");
+        if (wallet.LoadWallet() != DBErrors::LOAD_OK) assert(false);
+    }
+
+    // Generate destinations
+    CScript dest = GetScriptForDestination(getNewDestination(wallet));
+
+    // Generate chain; each coinbase will have two outputs to fill-up the wallet
+    const auto& params = Params();
+    unsigned int chain_size = 5000; // 5k blocks means 10k UTXO for the wallet (minus 100 due COINBASE_MATURITY)
+    for (unsigned int i = 0; i < chain_size; ++i) {
+        generateFakeBlock(params, test_setup->m_node, wallet, dest);
+    }
+
+    // Check available balance
+    auto bal = WITH_LOCK(wallet.cs_wallet, return wallet::AvailableCoins(wallet).total_amount); // Cache
+    assert(bal == 50 * COIN * (chain_size - COINBASE_MATURITY));
+
+    wallet::CCoinControl coin_control;
+    coin_control.m_allow_other_inputs = allow_other_inputs;
+
+    CAmount target = 0;
+    if (preset_inputs) {
+        // Select inputs, each has 49 DASH
+        const auto& res = WITH_LOCK(wallet.cs_wallet,
+                                    return wallet::AvailableCoins(wallet, nullptr, std::nullopt, 1, MAX_MONEY,
+                                                                  MAX_MONEY, preset_inputs->num_of_internal_inputs));
+        for (int i = 0; i < preset_inputs->num_of_internal_inputs; i++) {
+            const auto& coin{res.legacy[i]};
+            target += coin.txout.nValue;
+            coin_control.Select(coin.outpoint);
+        }
+    }
+
+    // If automatic coin selection is enabled, add the value of another UTXO to the target
+    if (coin_control.m_allow_other_inputs) target += 50 * COIN;
+    std::vector<wallet::CRecipient> recipients = {{dest, target, true}};
+
+    bench.epochIterations(5).run([&] {
+        LOCK(wallet.cs_wallet);
+        const auto& tx_res = CreateTransaction(wallet, recipients, wallet::RANDOM_CHANGE_POSITION, coin_control);
+        assert(tx_res);
+    });
+}
+
+static void WalletCreateTxUseOnlyPresetInputs(benchmark::Bench& bench) { WalletCreateTx(bench, /*allow_other_inputs=*/false,
+                                                                                        {{/*num_of_internal_inputs=*/4}}); }
+
+static void WalletCreateTxUsePresetInputsAndCoinSelection(benchmark::Bench& bench) { WalletCreateTx(bench, /*allow_other_inputs=*/true,
+                                                                                                    {{/*num_of_internal_inputs=*/4}}); }
+
+BENCHMARK(WalletCreateTxUseOnlyPresetInputs, benchmark::PriorityLevel::LOW)
+BENCHMARK(WalletCreateTxUsePresetInputsAndCoinSelection, benchmark::PriorityLevel::LOW)

src/qt/sendcoinsdialog.cpp

@@ -324,7 +324,9 @@ bool SendCoinsDialog::send(const QList<SendCoinsRecipient>& recipients, QString&
 
     updateCoinControlState();
 
-    prepareStatus = model->prepareTransaction(*m_current_transaction, *m_coin_control);
+    CCoinControl coin_control = *m_coin_control;
+    coin_control.m_allow_other_inputs = !coin_control.HasSelected(); // future, could introduce a checkbox to customize this value.
+    prepareStatus = model->prepareTransaction(*m_current_transaction, coin_control);
 
     // process prepareStatus and on error generate message shown to user
     processSendCoinsReturn(prepareStatus,
@@ -895,8 +897,13 @@ void SendCoinsDialog::useAvailableBalance(SendCoinsEntry* entry)
     // Include watch-only for wallets without private key
     m_coin_control->fAllowWatchOnly = model->wallet().privateKeysDisabled() && !model->wallet().hasExternalSigner();
 
+    // Same behavior as send: if we have selected coins, only obtain their available balance.
+    // Copy to avoid modifying the member's data.
+    CCoinControl coin_control = *m_coin_control;
+    coin_control.m_allow_other_inputs = !coin_control.HasSelected();
+
     // Calculate available amount to send.
-    CAmount amount = model->wallet().getAvailableBalance(*m_coin_control);
+    CAmount amount = model->wallet().getAvailableBalance(coin_control);
     for (int i = 0; i < ui->entries->count(); ++i) {
         SendCoinsEntry* e = qobject_cast<SendCoinsEntry*>(ui->entries->itemAt(i)->widget());
         if (e && !e->isHidden() && e != entry) {

src/qt/sendcoinsdialog.h

@@ -50,6 +50,9 @@ class SendCoinsDialog : public QDialog
     void pasteEntry(const SendCoinsRecipient &rv);
     bool handlePaymentRequest(const SendCoinsRecipient &recipient);
 
+    // Only used for testing-purposes
+    wallet::CCoinControl* getCoinControl() { return m_coin_control.get(); }
+
 public Q_SLOTS:
     void clear();
     void reject() override;

src/qt/test/wallettests.cpp

@@ -20,6 +20,7 @@
 #include <key_io.h>
 #include <test/util/setup_common.h>
 #include <validation.h>
+#include <wallet/coincontrol.h>
 #include <wallet/wallet.h>
 #include <qt/overviewpage.h>
 #include <qt/receivecoinsdialog.h>
@@ -99,6 +100,42 @@ QModelIndex FindTx(const QAbstractItemModel& model, const uint256& txid)
     return {};
 }
 
+// Verify the 'useAvailableBalance' functionality. With and without manually selected coins.
+// Case 1: No coin control selected coins.
+// 'useAvailableBalance' should fill the amount edit box with the total available balance
+// Case 2: With coin control selected coins.
+// 'useAvailableBalance' should fill the amount edit box with the sum of the selected coins values.
+void VerifyUseAvailableBalance(SendCoinsDialog& sendCoinsDialog, const WalletModel& walletModel)
+{
+    // Verify first entry amount and "useAvailableBalance" button
+    QVBoxLayout* entries = sendCoinsDialog.findChild<QVBoxLayout*>("entries");
+    QVERIFY(entries->count() == 1); // only one entry
+    SendCoinsEntry* send_entry = qobject_cast<SendCoinsEntry*>(entries->itemAt(0)->widget());
+    QVERIFY(send_entry->getValue().amount == 0);
+    // Now click "useAvailableBalance", check updated balance (the entire wallet balance should be set)
+    Q_EMIT send_entry->useAvailableBalance(send_entry);
+    QVERIFY(send_entry->getValue().amount == walletModel.wallet().getBalance());
+
+    // Now manually select two coins and click on "useAvailableBalance". Then check updated balance
+    // (only the sum of the selected coins should be set).
+    int COINS_TO_SELECT = 2;
+    auto coins = walletModel.wallet().listCoins();
+    CAmount sum_selected_coins = 0;
+    int selected = 0;
+    QVERIFY(coins.size() == 1); // context check, coins received only on one destination
+    for (const auto& [outpoint, tx_out] : coins.begin()->second) {
+        sendCoinsDialog.getCoinControl()->Select(outpoint);
+        sum_selected_coins += tx_out.txout.nValue;
+        if (++selected == COINS_TO_SELECT) break;
+    }
+    QVERIFY(selected == COINS_TO_SELECT);
+
+    // Now that we have 2 coins selected, "useAvailableBalance" should update the balance label only with
+    // the sum of them.
+    Q_EMIT send_entry->useAvailableBalance(send_entry);
+    QVERIFY(send_entry->getValue().amount == sum_selected_coins);
+}
+
 //! Simple qt wallet tests.
 //
 // Test widgets can be debugged interactively calling show() on them and
@@ -171,6 +208,9 @@ void TestGUI(interfaces::Node& node)
         QCOMPARE(balanceText, balanceComparison);
     }
 
+    // Check 'UseAvailableBalance' functionality
+    VerifyUseAvailableBalance(sendCoinsDialog, walletModel);
+
     // Send two transactions, and verify they are added to transaction list.
     TransactionTableModel* transactionTableModel = walletModel.getTransactionTableModel();
     QCOMPARE(transactionTableModel->rowCount({}), 105);

src/rpc/evo.cpp

@@ -366,6 +366,8 @@ static void FundSpecialTx(CWallet& wallet, CMutableTransaction& tx, const Specia
 
     CCoinControl coinControl;
     coinControl.destChange = fundDest;
+    // Fund from the given address only, spending no more of its coins than necessary.
+    coinControl.m_allow_other_inputs = false;
     coinControl.fRequireAllInputs = false;
 
     for (const auto& out : AvailableCoinsListUnspent(wallet).all()) {

src/test/util/wallet.cpp

@@ -25,7 +25,12 @@ const std::string ADDRESS_BCRT1_UNSPENDABLE = "bcrt1qqqqqqqqqqqqqqqqqqqqqqqqqqqq
 #ifdef ENABLE_WALLET
 std::string getnewaddress(CWallet& w)
 {
-    return EncodeDestination(*Assert(w.GetNewDestination("")));
+    return EncodeDestination(getNewDestination(w));
+}
+
+CTxDestination getNewDestination(CWallet& w)
+{
+    return *Assert(w.GetNewDestination(""));
 }
 
 // void importaddress(CWallet& wallet, const std::string& address)

src/test/util/wallet.h

@@ -5,6 +5,8 @@
 #ifndef BITCOIN_TEST_UTIL_WALLET_H
 #define BITCOIN_TEST_UTIL_WALLET_H
 
+#include <script/standard.h>
+
 #include <string>
 
 namespace wallet {
@@ -20,8 +22,10 @@ extern const std::string ADDRESS_BCRT1_UNSPENDABLE;
 
 /** Import the address to the wallet */
 void importaddress(wallet::CWallet& wallet, const std::string& address);
-/** Returns a new address from the wallet */
+/** Returns a new encoded destination from the wallet */
 std::string getnewaddress(wallet::CWallet& w);
+/** Returns a new destination from the wallet. Dash only supports OutputType::LEGACY. */
+CTxDestination getNewDestination(wallet::CWallet& w);
 
 
 #endif // BITCOIN_TEST_UTIL_WALLET_H

src/wallet/coincontrol.h

@@ -48,7 +48,7 @@ class CCoinControl
     bool m_include_unsafe_inputs = false;
     //! If true, the selection process can add extra unselected inputs from the wallet
     //! while requires all selected inputs be used
-    bool m_allow_other_inputs = false;
+    bool m_allow_other_inputs = true;
     //! If false, only include as many inputs as necessary to fulfill a coin selection request. Only usable together with m_allow_other_inputs
     bool fRequireAllInputs = true;
     //! Includes watch only addresses which are solvable