backport: wallet coin selection prerequisites for #7400

src/Makefile.bench.include

@@ -92,6 +92,7 @@ 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 200 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,
@@ -505,7 +507,7 @@ void SendCoinsDialog::presentPSBT(PartiallySignedTransaction& psbtx)
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
     ssTx << psbtx;
     GUIUtil::setClipboard(EncodeBase64(ssTx.str()).c_str());
-    QMessageBox msgBox;
+    QMessageBox msgBox(this);
     msgBox.setText("Unsigned Transaction");
     msgBox.setInformativeText("The PSBT has been copied to the clipboard. You can also save it.");
     msgBox.setStandardButtons(QMessageBox::Save | QMessageBox::Discard);
@@ -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;