Type-safe CFeeRate class

Use CFeeRate instead of an int64_t for quantities that are
fee-per-size.

Helps prevent unit-conversion mismatches between the wallet,
relaying, and mining code.

6 files changed, 23 insertions, 41 deletions

diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index dc9d2afe27..e27f1bff97 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -453,7 +453,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
 
             CTxOut txout(amount, (CScript)vector<unsigned char>(24, 0));
             txDummy.vout.push_back(txout);
-            if (txout.IsDust(CTransaction::nMinRelayTxFee))
+            if (txout.IsDust(CTransaction::minRelayTxFee))
                fDust = true;
         }
     }
@@ -525,7 +525,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
         sPriorityLabel = CoinControlDialog::getPriorityLabel(dPriority);
 
         // Fee
-        int64_t nFee = nTransactionFee * (1 + (int64_t)nBytes / 1000);
+        int64_t nFee = payTxFee.GetFee(nBytes);
 
         // Min Fee
         int64_t nMinFee = GetMinFee(txDummy, nBytes, AllowFree(dPriority), GMF_SEND);
@@ -536,26 +536,11 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
         {
             nChange = nAmount - nPayFee - nPayAmount;
 
-            // if sub-cent change is required, the fee must be raised to at least CTransaction::nMinTxFee
-            if (nPayFee < CTransaction::nMinTxFee && nChange > 0 && nChange < CENT)
-            {
-                if (nChange < CTransaction::nMinTxFee) // change < 0.0001 => simply move all change to fees
-                {
-                    nPayFee += nChange;
-                    nChange = 0;
-                }
-                else
-                {
-                    nChange = nChange + nPayFee - CTransaction::nMinTxFee;
-                    nPayFee = CTransaction::nMinTxFee;
-                }
-            }
-
             // Never create dust outputs; if we would, just add the dust to the fee.
             if (nChange > 0 && nChange < CENT)
             {
                 CTxOut txout(nChange, (CScript)vector<unsigned char>(24, 0));
-                if (txout.IsDust(CTransaction::nMinRelayTxFee))
+                if (txout.IsDust(CTransaction::minRelayTxFee))
                 {
                     nPayFee += nChange;
                     nChange = 0;
@@ -610,19 +595,19 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
 
     // tool tips
     QString toolTip1 = tr("This label turns red, if the transaction size is greater than 1000 bytes.") + "<br /><br />";
-    toolTip1 += tr("This means a fee of at least %1 per kB is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::nMinTxFee)) + "<br /><br />";
+    toolTip1 += tr("This means a fee of at least %1 per kB is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::minTxFee.GetFeePerK())) + "<br /><br />";
     toolTip1 += tr("Can vary +/- 1 byte per input.");
 
     QString toolTip2 = tr("Transactions with higher priority are more likely to get included into a block.") + "<br /><br />";
     toolTip2 += tr("This label turns red, if the priority is smaller than \"medium\".") + "<br /><br />";
-    toolTip2 += tr("This means a fee of at least %1 per kB is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::nMinTxFee));
+    toolTip2 += tr("This means a fee of at least %1 per kB is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::minTxFee.GetFeePerK()));
 
     QString toolTip3 = tr("This label turns red, if any recipient receives an amount smaller than %1.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CENT)) + "<br /><br />";
-    toolTip3 += tr("This means a fee of at least %1 is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::nMinTxFee)) + "<br /><br />";
+    toolTip3 += tr("This means a fee of at least %1 is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::minTxFee.GetFeePerK())) + "<br /><br />";
     toolTip3 += tr("Amounts below 0.546 times the minimum relay fee are shown as dust.");
 
     QString toolTip4 = tr("This label turns red, if the change is smaller than %1.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CENT)) + "<br /><br />";
-    toolTip4 += tr("This means a fee of at least %1 is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::nMinTxFee));
+    toolTip4 += tr("This means a fee of at least %1 is required.").arg(BitcoinUnits::formatWithUnit(nDisplayUnit, CTransaction::minTxFee.GetFeePerK()));
 
     l5->setToolTip(toolTip1);
     l6->setToolTip(toolTip2);
diff --git a/src/qt/guiutil.cpp b/src/qt/guiutil.cpp
index 1922d228c5..4fe98251d9 100644
--- a/src/qt/guiutil.cpp
+++ b/src/qt/guiutil.cpp
@@ -210,7 +210,7 @@ bool isDust(const QString& address, qint64 amount)
     CTxDestination dest = CBitcoinAddress(address.toStdString()).Get();
     CScript script; script.SetDestination(dest);
     CTxOut txOut(amount, script);
-    return txOut.IsDust(CTransaction::nMinRelayTxFee);
+    return txOut.IsDust(CTransaction::minRelayTxFee);
 }
 
 QString HtmlEscape(const QString& str, bool fMultiLine)
diff --git a/src/qt/optionsdialog.cpp b/src/qt/optionsdialog.cpp
index 96464d2cc0..1cbf5f8810 100644
--- a/src/qt/optionsdialog.cpp
+++ b/src/qt/optionsdialog.cpp
@@ -14,7 +14,7 @@
 #include "monitoreddatamapper.h"
 #include "optionsmodel.h"
 
-#include "main.h" // for CTransaction::nMinTxFee and MAX_SCRIPTCHECK_THREADS
+#include "main.h" // for CTransaction::minTxFee and MAX_SCRIPTCHECK_THREADS
 #include "netbase.h"
 #include "txdb.h" // for -dbcache defaults
 
@@ -101,7 +101,7 @@ OptionsDialog::OptionsDialog(QWidget *parent) :
 #endif
 
     ui->unit->setModel(new BitcoinUnits(this));
-    ui->transactionFee->setSingleStep(CTransaction::nMinTxFee);
+    ui->transactionFee->setSingleStep(CTransaction::minTxFee.GetFeePerK());
 
     /* Widget-to-option mapper */
     mapper = new MonitoredDataMapper(this);
diff --git a/src/qt/optionsmodel.cpp b/src/qt/optionsmodel.cpp
index 051098315d..f3a5f37bb3 100644
--- a/src/qt/optionsmodel.cpp
+++ b/src/qt/optionsmodel.cpp
@@ -94,7 +94,7 @@ void OptionsModel::Init()
 #ifdef ENABLE_WALLET
     if (!settings.contains("nTransactionFee"))
         settings.setValue("nTransactionFee", (qint64)DEFAULT_TRANSACTION_FEE);
-    nTransactionFee = settings.value("nTransactionFee").toLongLong(); // if -paytxfee is set, this will be overridden later in init.cpp
+    payTxFee = CFeeRate(settings.value("nTransactionFee").toLongLong()); // if -paytxfee is set, this will be overridden later in init.cpp
     if (mapArgs.count("-paytxfee"))
         addOverriddenOption("-paytxfee");
 
@@ -187,15 +187,16 @@ QVariant OptionsModel::data(const QModelIndex & index, int role) const
             return settings.value("nSocksVersion", 5);
 
 #ifdef ENABLE_WALLET
-        case Fee:
-            // Attention: Init() is called before nTransactionFee is set in AppInit2()!
+        case Fee: {
+            // Attention: Init() is called before payTxFee is set in AppInit2()!
             // To ensure we can change the fee on-the-fly update our QSetting when
             // opening OptionsDialog, which queries Fee via the mapper.
-            if (nTransactionFee != settings.value("nTransactionFee").toLongLong())
-                settings.setValue("nTransactionFee", (qint64)nTransactionFee);
-            // Todo: Consider to revert back to use just nTransactionFee here, if we don't want
+            if (!(payTxFee == CFeeRate(settings.value("nTransactionFee").toLongLong(), 1000)))
+                settings.setValue("nTransactionFee", (qint64)payTxFee.GetFeePerK());
+            // Todo: Consider to revert back to use just payTxFee here, if we don't want
             // -paytxfee to update our QSettings!
             return settings.value("nTransactionFee");
+        }
         case SpendZeroConfChange:
             return settings.value("bSpendZeroConfChange");
 #endif
@@ -284,12 +285,14 @@ bool OptionsModel::setData(const QModelIndex & index, const QVariant & value, in
         }
         break;
 #ifdef ENABLE_WALLET
-        case Fee: // core option - can be changed on-the-fly
+        case Fee: { // core option - can be changed on-the-fly
             // Todo: Add is valid check  and warn via message, if not
-            nTransactionFee = value.toLongLong();
-            settings.setValue("nTransactionFee", (qint64)nTransactionFee);
+            qint64 nTransactionFee = value.toLongLong();
+            payTxFee = CFeeRate(nTransactionFee, 1000);
+            settings.setValue("nTransactionFee", nTransactionFee);
             emit transactionFeeChanged(nTransactionFee);
             break;
+        }
         case SpendZeroConfChange:
             if (settings.value("bSpendZeroConfChange") != value) {
                 settings.setValue("bSpendZeroConfChange", value);
diff --git a/src/qt/paymentserver.cpp b/src/qt/paymentserver.cpp
index 4c45585685..6165731d22 100644
--- a/src/qt/paymentserver.cpp
+++ b/src/qt/paymentserver.cpp
@@ -551,7 +551,7 @@ bool PaymentServer::processPaymentRequest(PaymentRequestPlus& request, SendCoins
 
         // Extract and check amounts
         CTxOut txOut(sendingTo.second, sendingTo.first);
-        if (txOut.IsDust(CTransaction::nMinRelayTxFee)) {
+        if (txOut.IsDust(CTransaction::minRelayTxFee)) {
             emit message(tr("Payment request error"), tr("Requested payment amount of %1 is too small (considered dust).")
                 .arg(BitcoinUnits::formatWithUnit(optionsModel->getDisplayUnit(), sendingTo.second)),
                 CClientUIInterface::MSG_ERROR);
diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index 37d82ec063..87ff3db584 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -231,12 +231,6 @@ WalletModel::SendCoinsReturn WalletModel::prepareTransaction(WalletModelTransact
         return AmountExceedsBalance;
     }
 
-    if((total + nTransactionFee) > nBalance)
-    {
-        transaction.setTransactionFee(nTransactionFee);
-        return SendCoinsReturn(AmountWithFeeExceedsBalance);
-    }
-
     {
         LOCK2(cs_main, wallet->cs_wallet);