Use fee/priority estimates in wallet CreateTransaction

The wallet now uses the mempool fee estimator with a new
command-line option: -txconfirmtarget (default: 1) instead
of using hard-coded fees or priorities.

A new bitcoind that hasn't seen enough transactions to estimate
will fall back to the old hard-coded minimum priority or
transaction fee.

-paytxfee option overrides -txconfirmtarget.

Relaying and mining code isn't changed.

For Qt, the coin control dialog now uses priority estimates to
label transaction priority (instead of hard-coded constants);
unspent outputs were consistently labeled with a much higher
priority than is justified by the free transactions actually
being accepted into blocks.

I did not implement any GUI for setting -txconfirmtarget; I would
suggest getting rid of the "Pay transaction fee" GUI and replace
it with either "target number of confirmations" or maybe
a "faster confirmation <--> lower fee" slider or select box.

2 files changed, 30 insertions, 21 deletions

diff --git a/src/qt/coincontroldialog.cpp b/src/qt/coincontroldialog.cpp
index c6a6150392..73494f52ea 100644
--- a/src/qt/coincontroldialog.cpp
+++ b/src/qt/coincontroldialog.cpp
@@ -16,6 +16,8 @@
 #include "main.h"
 #include "wallet.h"
 
+#include <boost/assign/list_of.hpp> // for 'map_list_of()'
+
 #include <QApplication>
 #include <QCheckBox>
 #include <QCursor>
@@ -400,23 +402,24 @@ void CoinControlDialog::viewItemChanged(QTreeWidgetItem* item, int column)
 }
 
 // return human readable label for priority number
-QString CoinControlDialog::getPriorityLabel(double dPriority)
+QString CoinControlDialog::getPriorityLabel(const CTxMemPool& pool, double dPriority)
 {
-    if (AllowFree(dPriority)) // at least medium
+    // confirmations -> textual description
+    typedef std::map<unsigned int, QString> PriorityDescription;
+    static PriorityDescription priorityDescriptions = boost::assign::map_list_of
+        (1, tr("highest"))(2, tr("higher"))(3, tr("high"))
+        (5, tr("medium-high"))(6, tr("medium"))
+        (10, tr("low-medium"))(15, tr("low"))
+        (20, tr("lower"));
+
+    BOOST_FOREACH(const PriorityDescription::value_type& i, priorityDescriptions)
     {
-        if      (AllowFree(dPriority / 1000000))  return tr("highest");
-        else if (AllowFree(dPriority / 100000))   return tr("higher");
-        else if (AllowFree(dPriority / 10000))    return tr("high");
-        else if (AllowFree(dPriority / 1000))     return tr("medium-high");
-        else                                      return tr("medium");
-    }
-    else
-    {
-        if      (AllowFree(dPriority * 10))   return tr("low-medium");
-        else if (AllowFree(dPriority * 100))  return tr("low");
-        else if (AllowFree(dPriority * 1000)) return tr("lower");
-        else                                  return tr("lowest");
+        double p = mempool.estimatePriority(i.first);
+        if (p > 0 && dPriority >= p) return i.second;
     }
+    // Note: if mempool hasn't accumulated enough history (estimatePriority
+    // returns -1) we're conservative and classify as "lowest"
+    return tr("lowest");
 }
 
 // shows count of locked unspent outputs
@@ -518,15 +521,20 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
 
         // Priority
         dPriority = dPriorityInputs / (nBytes - nBytesInputs + (nQuantityUncompressed * 29)); // 29 = 180 - 151 (uncompressed public keys are over the limit. max 151 bytes of the input are ignored for priority)
-        sPriorityLabel = CoinControlDialog::getPriorityLabel(dPriority);
+        sPriorityLabel = CoinControlDialog::getPriorityLabel(mempool, dPriority);
 
         // Fee
         int64_t nFee = payTxFee.GetFee(max((unsigned int)1000, nBytes));
 
         // Min Fee
-        int64_t nMinFee = GetMinFee(txDummy, nBytes, AllowFree(dPriority), GMF_SEND);
+        nPayFee = CWallet::GetMinimumFee(nBytes, nTxConfirmTarget, mempool);
+
+        double dPriorityNeeded = mempool.estimatePriority(nTxConfirmTarget);
+        if (dPriorityNeeded <= 0) // Not enough mempool history: never send free
+            dPriorityNeeded = std::numeric_limits<double>::max();
 
-        nPayFee = max(nFee, nMinFee);
+        if (nBytes <= MAX_FREE_TRANSACTION_CREATE_SIZE && dPriority >= dPriorityNeeded)
+            nPayFee = 0;
 
         if (nPayAmount > 0)
         {
@@ -591,7 +599,7 @@ void CoinControlDialog::updateLabels(WalletModel *model, QDialog* dialog)
     }
 
     // turn labels "red"
-    l5->setStyleSheet((nBytes >= 1000) ? "color:red;" : "");                            // Bytes >= 1000
+    l5->setStyleSheet((nBytes >= MAX_FREE_TRANSACTION_CREATE_SIZE) ? "color:red;" : "");// Bytes >= 1000
     l6->setStyleSheet((dPriority > 0 && !AllowFree(dPriority)) ? "color:red;" : "");    // Priority < "medium"
     l7->setStyleSheet((fDust) ? "color:red;" : "");                                     // Dust = "yes"
 
@@ -732,7 +740,7 @@ void CoinControlDialog::updateView()
 
             // priority
             double dPriority = ((double)out.tx->vout[out.i].nValue  / (nInputSize + 78)) * (out.nDepth+1); // 78 = 2 * 34 + 10
-            itemOutput->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(dPriority));
+            itemOutput->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(mempool, dPriority));
             itemOutput->setText(COLUMN_PRIORITY_INT64, strPad(QString::number((int64_t)dPriority), 20, " "));
             dPrioritySum += (double)out.tx->vout[out.i].nValue  * (out.nDepth+1);
             nInputSum    += nInputSize;
@@ -765,7 +773,7 @@ void CoinControlDialog::updateView()
             itemWalletAddress->setText(COLUMN_CHECKBOX, "(" + QString::number(nChildren) + ")");
             itemWalletAddress->setText(COLUMN_AMOUNT, BitcoinUnits::format(nDisplayUnit, nSum));
             itemWalletAddress->setText(COLUMN_AMOUNT_INT64, strPad(QString::number(nSum), 15, " "));
-            itemWalletAddress->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(dPrioritySum));
+            itemWalletAddress->setText(COLUMN_PRIORITY, CoinControlDialog::getPriorityLabel(mempool, dPrioritySum));
             itemWalletAddress->setText(COLUMN_PRIORITY_INT64, strPad(QString::number((int64_t)dPrioritySum), 20, " "));
         }
     }
diff --git a/src/qt/coincontroldialog.h b/src/qt/coincontroldialog.h
index 465e2a009d..4f7422642f 100644
--- a/src/qt/coincontroldialog.h
+++ b/src/qt/coincontroldialog.h
@@ -19,6 +19,7 @@ namespace Ui {
 }
 class WalletModel;
 class CCoinControl;
+class CTxMemPool;
 
 class CoinControlDialog : public QDialog
 {
@@ -32,7 +33,7 @@ public:
 
     // static because also called from sendcoinsdialog
     static void updateLabels(WalletModel*, QDialog*);
-    static QString getPriorityLabel(double);
+    static QString getPriorityLabel(const CTxMemPool& pool, double);
 
     static QList<qint64> payAmounts;
     static CCoinControl *coinControl;