[Qt] rework setNumBlocks to have blockDate as parameter

- reduces some functional overhead and simplifies the code

src/qt/clientmodel.cpp

@@ -18,7 +18,6 @@
 
 #include <stdint.h>
 
-#include <QDateTime>
 #include <QDebug>
 #include <QTimer>
 
@@ -29,6 +28,7 @@ ClientModel::ClientModel(OptionsModel *optionsModel, QObject *parent) :
     optionsModel(optionsModel),
     peerTableModel(0),
     cachedNumBlocks(0),
+    cachedBlockDate(QDateTime()),
     cachedReindexing(0),
     cachedImporting(0),
     pollTimer(0)
@@ -79,10 +79,11 @@ quint64 ClientModel::getTotalBytesSent() const
 QDateTime ClientModel::getLastBlockDate() const
 {
     LOCK(cs_main);
+
     if (chainActive.Tip())
         return QDateTime::fromTime_t(chainActive.Tip()->GetBlockTime());
-    else
-        return QDateTime::fromTime_t(Params().GenesisBlock().GetBlockTime()); // Genesis block's time of current network
+
+    return QDateTime::fromTime_t(Params().GenesisBlock().GetBlockTime()); // Genesis block's time of current network
 }
 
 double ClientModel::getVerificationProgress() const
@@ -97,21 +98,26 @@ void ClientModel::updateTimer()
     // periodical polls if the core is holding the locks for a longer time -
     // for example, during a wallet rescan.
     TRY_LOCK(cs_main, lockMain);
-    if(!lockMain)
+    if (!lockMain)
         return;
+
     // 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();
+    QDateTime newBlockDate = getLastBlockDate();
 
     // check for changed number of blocks we have, number of blocks peers claim to have, reindexing state and importing state
     if (cachedNumBlocks != newNumBlocks ||
-        cachedReindexing != fReindex || cachedImporting != fImporting)
+        cachedBlockDate != newBlockDate ||
+        cachedReindexing != fReindex ||
+        cachedImporting != fImporting)
     {
         cachedNumBlocks = newNumBlocks;
+        cachedBlockDate = newBlockDate;
         cachedReindexing = fReindex;
         cachedImporting = fImporting;
 
-        emit numBlocksChanged(newNumBlocks);
+        emit numBlocksChanged(newNumBlocks, newBlockDate);
     }
 
     emit bytesChanged(getTotalBytesRecv(), getTotalBytesSent());