Remove NumBlocksOfPeers

Generally useless information. Only updates on connect time, not after
that. Peers can easily lie and the median filter is not effective in
preventing that.

In the past it was used for progress display in the GUI but
`CheckPoints::guessVerificationProgress` provides a better way that is now used.
It was too easy to mislead it. Peers do lie about it in practice, see issue #4065.

From the RPC, `getpeerinfo` gives the peer raw values, which are more
useful.

9 files changed, 19 insertions, 75 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 40c713ce93..46183bf431 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -54,8 +54,6 @@ int64_t CTransaction::nMinTxFee = 10000;  // Override with -mintxfee
 /** Fees smaller than this (in satoshi) are considered zero fee (for relaying and mining) */
 int64_t CTransaction::nMinRelayTxFee = 1000;
 
-static CMedianFilter<int> cPeerBlockCounts(8, 0); // Amount of blocks that other nodes claim to have
-
 struct COrphanBlock {
     uint256 hashBlock;
     uint256 hashPrev;
@@ -1303,12 +1301,6 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
     return true;
 }
 
-// Return maximum amount of blocks that other nodes claim to have
-int GetNumBlocksOfPeers()
-{
-    return std::max(cPeerBlockCounts.median(), Checkpoints::GetTotalBlocksEstimate());
-}
-
 bool IsInitialBlockDownload()
 {
     LOCK(cs_main);
@@ -3484,9 +3476,6 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         LogPrintf("receive version message: %s: version %d, blocks=%d, us=%s, them=%s, peer=%s\n", pfrom->cleanSubVer, pfrom->nVersion, pfrom->nStartingHeight, addrMe.ToString(), addrFrom.ToString(), pfrom->addr.ToString());
 
         AddTimeData(pfrom->addr, nTime);
-
-        LOCK(cs_main);
-        cPeerBlockCounts.input(pfrom->nStartingHeight);
     }
 
 
diff --git a/src/main.h b/src/main.h
index 825e577d1e..e459772e88 100644
--- a/src/main.h
+++ b/src/main.h
@@ -160,8 +160,6 @@ void ThreadScriptCheck();
 bool CheckProofOfWork(uint256 hash, unsigned int nBits);
 /** Calculate the minimum amount of work a received block needs, without knowing its direct parent */
 unsigned int ComputeMinWork(unsigned int nBase, int64_t nTime);
-/** Get the number of active peers */
-int GetNumBlocksOfPeers();
 /** Check whether we are doing an initial block download (synchronizing from disk or network) */
 bool IsInitialBlockDownload();
 /** Format a string that describes several potential problems detected by the core */
diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index da7762282a..e6190aec13 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -403,8 +403,8 @@ void BitcoinGUI::setClientModel(ClientModel *clientModel)
         setNumConnections(clientModel->getNumConnections());
         connect(clientModel, SIGNAL(numConnectionsChanged(int)), this, SLOT(setNumConnections(int)));
 
-        setNumBlocks(clientModel->getNumBlocks(), clientModel->getNumBlocksOfPeers());
-        connect(clientModel, SIGNAL(numBlocksChanged(int,int)), this, SLOT(setNumBlocks(int,int)));
+        setNumBlocks(clientModel->getNumBlocks());
+        connect(clientModel, SIGNAL(numBlocksChanged(int)), this, SLOT(setNumBlocks(int)));
 
         // Receive and report messages from client model
         connect(clientModel, SIGNAL(message(QString,QString,unsigned int)), this, SLOT(message(QString,QString,unsigned int)));
@@ -617,7 +617,7 @@ void BitcoinGUI::setNumConnections(int count)
     labelConnectionsIcon->setToolTip(tr("%n active connection(s) to Bitcoin network", "", count));
 }
 
-void BitcoinGUI::setNumBlocks(int count, int nTotalBlocks)
+void BitcoinGUI::setNumBlocks(int count)
 {
     // Prevent orphan statusbar messages (e.g. hover Quit in main menu, wait until chain-sync starts -> garbelled text)
     statusBar()->clearMessage();
@@ -646,17 +646,10 @@ void BitcoinGUI::setNumBlocks(int count, int nTotalBlocks)
     QDateTime currentDate = QDateTime::currentDateTime();
     int secs = lastBlockDate.secsTo(currentDate);
 
-    if(count < nTotalBlocks)
-    {
-        tooltip = tr("Processed %1 of %2 (estimated) blocks of transaction history.").arg(count).arg(nTotalBlocks);
-    }
-    else
-    {
-        tooltip = tr("Processed %1 blocks of transaction history.").arg(count);
-    }
+    tooltip = tr("Processed %1 blocks of transaction history.").arg(count);
 
     // Set icon state: spinning if catching up, tick otherwise
-    if(secs < 90*60 && count >= nTotalBlocks)
+    if(secs < 90*60)
     {
         tooltip = tr("Up to date") + QString(".<br>") + tooltip;
         labelBlocksIcon->setPixmap(QIcon(":/icons/synced").pixmap(STATUSBAR_ICONSIZE, STATUSBAR_ICONSIZE));
diff --git a/src/qt/bitcoingui.h b/src/qt/bitcoingui.h
index 0cc1ebc502..b4675b95ac 100644
--- a/src/qt/bitcoingui.h
+++ b/src/qt/bitcoingui.h
@@ -130,7 +130,7 @@ public slots:
     /** Set number of connections shown in the UI */
     void setNumConnections(int count);
     /** Set number of blocks shown in the UI */
-    void setNumBlocks(int count, int nTotalBlocks);
+    void setNumBlocks(int count);
 
     /** Notify the user of an event from the core network or transaction handling code.
        @param[in] title     the message box / notification title
diff --git a/src/qt/clientmodel.cpp b/src/qt/clientmodel.cpp
index 3c0564c208..d1f68ebd22 100644
--- a/src/qt/clientmodel.cpp
+++ b/src/qt/clientmodel.cpp
@@ -23,7 +23,7 @@ static const int64_t nClientStartupTime = GetTime();
 
 ClientModel::ClientModel(OptionsModel *optionsModel, QObject *parent) :
     QObject(parent), optionsModel(optionsModel),
-    cachedNumBlocks(0), cachedNumBlocksOfPeers(0),
+    cachedNumBlocks(0),
     cachedReindexing(0), cachedImporting(0),
     numBlocksAtStartup(-1), pollTimer(0)
 {
@@ -101,19 +101,16 @@ void ClientModel::updateTimer()
     // Some quantities (such as number of blocks) change so fast that we don't want to be notified for each change.
     // Periodically check and update with a timer.
     int newNumBlocks = getNumBlocks();
-    int newNumBlocksOfPeers = getNumBlocksOfPeers();
 
     // check for changed number of blocks we have, number of blocks peers claim to have, reindexing state and importing state
-    if (cachedNumBlocks != newNumBlocks || cachedNumBlocksOfPeers != newNumBlocksOfPeers ||
+    if (cachedNumBlocks != newNumBlocks ||
         cachedReindexing != fReindex || cachedImporting != fImporting)
     {
         cachedNumBlocks = newNumBlocks;
-        cachedNumBlocksOfPeers = newNumBlocksOfPeers;
         cachedReindexing = fReindex;
         cachedImporting = fImporting;
 
-        // ensure we return the maximum of newNumBlocksOfPeers and newNumBlocks to not create weird displays in the GUI
-        emit numBlocksChanged(newNumBlocks, std::max(newNumBlocksOfPeers, newNumBlocks));
+        emit numBlocksChanged(newNumBlocks);
     }
 
     emit bytesChanged(getTotalBytesRecv(), getTotalBytesSent());
@@ -166,11 +163,6 @@ enum BlockSource ClientModel::getBlockSource() const
     return BLOCK_SOURCE_NONE;
 }
 
-int ClientModel::getNumBlocksOfPeers() const
-{
-    return GetNumBlocksOfPeers();
-}
-
 QString ClientModel::getStatusBarWarnings() const
 {
     return QString::fromStdString(GetWarnings("statusbar"));
diff --git a/src/qt/clientmodel.h b/src/qt/clientmodel.h
index f29b695ea1..cab853d92d 100644
--- a/src/qt/clientmodel.h
+++ b/src/qt/clientmodel.h
@@ -60,8 +60,6 @@ public:
     bool inInitialBlockDownload() const;
     //! Return true if core is importing blocks
     enum BlockSource getBlockSource() const;
-    //! Return conservative estimate of total number of blocks, or 0 if unknown
-    int getNumBlocksOfPeers() const;
     //! Return warnings to be displayed in status bar
     QString getStatusBarWarnings() const;
 
@@ -75,7 +73,6 @@ private:
     OptionsModel *optionsModel;
 
     int cachedNumBlocks;
-    int cachedNumBlocksOfPeers;
     bool cachedReindexing;
     bool cachedImporting;
 
@@ -88,7 +85,7 @@ private:
 
 signals:
     void numConnectionsChanged(int count);
-    void numBlocksChanged(int count, int countOfPeers);
+    void numBlocksChanged(int count);
     void alertsChanged(const QString &warnings);
     void bytesChanged(quint64 totalBytesIn, quint64 totalBytesOut);
 
diff --git a/src/qt/forms/rpcconsole.ui b/src/qt/forms/rpcconsole.ui
index 31d61ec468..fcb6bb60bb 100644
--- a/src/qt/forms/rpcconsole.ui
+++ b/src/qt/forms/rpcconsole.ui
@@ -254,36 +254,13 @@
         </widget>
        </item>
        <item row="11" column="0">
-        <widget class="QLabel" name="label_4">
-         <property name="text">
-          <string>Estimated total blocks</string>
-         </property>
-        </widget>
-       </item>
-       <item row="11" column="1">
-        <widget class="QLabel" name="totalBlocks">
-         <property name="cursor">
-          <cursorShape>IBeamCursor</cursorShape>
-         </property>
-         <property name="text">
-          <string>N/A</string>
-         </property>
-         <property name="textFormat">
-          <enum>Qt::PlainText</enum>
-         </property>
-         <property name="textInteractionFlags">
-          <set>Qt::LinksAccessibleByMouse|Qt::TextSelectableByKeyboard|Qt::TextSelectableByMouse</set>
-         </property>
-        </widget>
-       </item>
-       <item row="12" column="0">
         <widget class="QLabel" name="label_2">
          <property name="text">
           <string>Last block time</string>
          </property>
         </widget>
        </item>
-       <item row="12" column="1">
+       <item row="11" column="1">
         <widget class="QLabel" name="lastBlockTime">
          <property name="cursor">
           <cursorShape>IBeamCursor</cursorShape>
@@ -299,7 +276,7 @@
          </property>
         </widget>
        </item>
-       <item row="13" column="0">
+       <item row="12" column="0">
         <spacer name="verticalSpacer_2">
          <property name="orientation">
           <enum>Qt::Vertical</enum>
@@ -312,7 +289,7 @@
          </property>
         </spacer>
        </item>
-       <item row="14" column="0">
+       <item row="13" column="0">
         <widget class="QLabel" name="labelDebugLogfile">
          <property name="font">
           <font>
@@ -325,7 +302,7 @@
          </property>
         </widget>
        </item>
-       <item row="15" column="0">
+       <item row="14" column="0">
         <widget class="QPushButton" name="openDebugLogfileButton">
          <property name="toolTip">
           <string>Open the Bitcoin debug log file from the current data directory. This can take a few seconds for large log files.</string>
@@ -338,7 +315,7 @@
          </property>
         </widget>
        </item>
-       <item row="16" column="0">
+       <item row="15" column="0">
         <spacer name="verticalSpacer">
          <property name="orientation">
           <enum>Qt::Vertical</enum>
diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
index ba5871ae2b..0a46a722e4 100644
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -271,8 +271,8 @@ void RPCConsole::setClientModel(ClientModel *model)
         setNumConnections(model->getNumConnections());
         connect(model, SIGNAL(numConnectionsChanged(int)), this, SLOT(setNumConnections(int)));
 
-        setNumBlocks(model->getNumBlocks(), model->getNumBlocksOfPeers());
-        connect(model, SIGNAL(numBlocksChanged(int,int)), this, SLOT(setNumBlocks(int,int)));
+        setNumBlocks(model->getNumBlocks());
+        connect(model, SIGNAL(numBlocksChanged(int)), this, SLOT(setNumBlocks(int)));
 
         updateTrafficStats(model->getTotalBytesRecv(), model->getTotalBytesSent());
         connect(model, SIGNAL(bytesChanged(quint64,quint64)), this, SLOT(updateTrafficStats(quint64, quint64)));
@@ -366,11 +366,9 @@ void RPCConsole::setNumConnections(int count)
     ui->numberOfConnections->setText(connections);
 }
 
-void RPCConsole::setNumBlocks(int count, int countOfPeers)
+void RPCConsole::setNumBlocks(int count)
 {
     ui->numberOfBlocks->setText(QString::number(count));
-    // If there is no current countOfPeers available display N/A instead of 0, which can't ever be true
-    ui->totalBlocks->setText(countOfPeers == 0 ? tr("N/A") : QString::number(countOfPeers));
     if(clientModel)
         ui->lastBlockTime->setText(clientModel->getLastBlockDate().toString());
 }
diff --git a/src/qt/rpcconsole.h b/src/qt/rpcconsole.h
index f7a7772050..091a6d294f 100644
--- a/src/qt/rpcconsole.h
+++ b/src/qt/rpcconsole.h
@@ -52,7 +52,7 @@ public slots:
     /** Set number of connections shown in the UI */
     void setNumConnections(int count);
     /** Set number of blocks shown in the UI */
-    void setNumBlocks(int count, int countOfPeers);
+    void setNumBlocks(int count);
     /** Go forward or back in history */
     void browseHistory(int offset);
     /** Scroll console view to end */