Merge bitcoin#10600: Make feebumper class stateless

aed1d90 [wallet] Change feebumper from class to functions (Russell Yanofsky)
37bdcca [refactor] Make feebumper namespace (Russell Yanofsky)
7c4f009 [trivial] Rename feebumper variables according to project code style (Russell Yanofsky)

Pull request description:

  Make feebumper methods static and remove stored state in the class.

  Having the results of feebumper calls persist in an object makes process
  separation between Qt and wallet awkward, because it means the feebumper object
  either has to be serialized back and forth between Qt and wallet processes
  between fee bump calls, or that the feebumper object needs to stay alive in the
  wallet process with an object reference passed back to Qt. It's simpler just to
  have fee bumper calls return their results immediately instead of storing them
  in an object with an extended lifetime.

  In addition to making feebumper methods static, also:

  - Move LOCK calls from Qt code to feebumper
  - Move TransactionCanBeBumped implementation from Qt code to feebumper
  - Rename CFeeBumper class to FeeBumper (every CFeeBumper reference had to be
    updated in this PR anyway so this doesn't increase the size of the diff)

  This change was originally part of bitcoin#10244

Tree-SHA512: bf75e0c741b4e9c8912e66cc1dedf0ff715f77ea65fc33f7020d97d9099b0f6448f5852236dac63eea649de7d6fc03b0b21492e2c5140fb7560a39cf085506fd

src/qt/walletmodel.cpp

@@ -659,45 +659,39 @@ bool WalletModel::abandonTransaction(uint256 hash) const
 
 bool WalletModel::transactionCanBeBumped(uint256 hash) const
 {
-    LOCK2(cs_main, wallet->cs_wallet);
-    const CWalletTx *wtx = wallet->GetWalletTx(hash);
-    return wtx && SignalsOptInRBF(*(wtx->tx)) && !wtx->mapValue.count("replaced_by_txid");
+    return feebumper::TransactionCanBeBumped(wallet, hash);
 }
 
 bool WalletModel::bumpFee(uint256 hash)
 {
-    std::unique_ptr<CFeeBumper> feeBump;
-    {
-        CCoinControl coin_control;
-        coin_control.signalRbf = true;
-        LOCK2(cs_main, wallet->cs_wallet);
-        feeBump.reset(new CFeeBumper(wallet, hash, coin_control, 0));
-    }
-    if (feeBump->getResult() != BumpFeeResult::OK)
-    {
+    CCoinControl coin_control;
+    coin_control.signalRbf = true;
+    std::vector<std::string> errors;
+    CAmount old_fee;
+    CAmount new_fee;
+    CMutableTransaction mtx;
+    if (feebumper::CreateTransaction(wallet, hash, coin_control, 0 /* totalFee */, errors, old_fee, new_fee, mtx) != feebumper::Result::OK) {
         QMessageBox::critical(0, tr("Fee bump error"), tr("Increasing transaction fee failed") + "<br />(" +
-            (feeBump->getErrors().size() ? QString::fromStdString(feeBump->getErrors()[0]) : "") +")");
+            (errors.size() ? QString::fromStdString(errors[0]) : "") +")");
          return false;
     }
 
     // allow a user based fee verification
     QString questionString = tr("Do you want to increase the fee?");
     questionString.append("<br />");
-    CAmount oldFee = feeBump->getOldFee();
-    CAmount newFee = feeBump->getNewFee();
     questionString.append("<table style=\"text-align: left;\">");
     questionString.append("<tr><td>");
     questionString.append(tr("Current fee:"));
     questionString.append("</td><td>");
-    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), oldFee));
+    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), old_fee));
     questionString.append("</td></tr><tr><td>");
     questionString.append(tr("Increase:"));
     questionString.append("</td><td>");
-    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), newFee - oldFee));
+    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), new_fee - old_fee));
     questionString.append("</td></tr><tr><td>");
     questionString.append(tr("New fee:"));
     questionString.append("</td><td>");
-    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), newFee));
+    questionString.append(BitcoinUnits::formatHtmlWithUnit(getOptionsModel()->getDisplayUnit(), new_fee));
     questionString.append("</td></tr></table>");
     SendConfirmationDialog confirmationDialog(tr("Confirm fee bump"), questionString);
     confirmationDialog.exec();
@@ -715,23 +709,15 @@ bool WalletModel::bumpFee(uint256 hash)
     }
 
     // sign bumped transaction
-    bool res = false;
-    {
-        LOCK2(cs_main, wallet->cs_wallet);
-        res = feeBump->signTransaction(wallet);
-    }
-    if (!res) {
+    if (!feebumper::SignTransaction(wallet, mtx)) {
         QMessageBox::critical(0, tr("Fee bump error"), tr("Can't sign transaction."));
         return false;
     }
     // commit the bumped transaction
-    {
-        LOCK2(cs_main, wallet->cs_wallet);
-        res = feeBump->commit(wallet);
-    }
-    if(!res) {
+    uint256 txid;
+    if (feebumper::CommitTransaction(wallet, hash, std::move(mtx), errors, txid) != feebumper::Result::OK) {
         QMessageBox::critical(0, tr("Fee bump error"), tr("Could not commit transaction") + "<br />(" +
-            QString::fromStdString(feeBump->getErrors()[0])+")");
+            QString::fromStdString(errors[0])+")");
          return false;
     }
     return true;