1 files changed, 12 insertions, 11 deletions
diff --git a/src/qt/clientmodel.cpp b/src/qt/clientmodel.cpp
index cb832fdd4..d1f68ebd2 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)
 {
@@ -55,6 +55,7 @@ int ClientModel::getNumConnections(unsigned int flags) const
 
 int ClientModel::getNumBlocks() const
 {
+    LOCK(cs_main);
     return chainActive.Height();
 }
 
@@ -76,6 +77,7 @@ quint64 ClientModel::getTotalBytesSent() const
 
 QDateTime ClientModel::getLastBlockDate() const
 {
+    LOCK(cs_main);
     if (chainActive.Tip())
         return QDateTime::fromTime_t(chainActive.Tip()->GetBlockTime());
     else
@@ -84,27 +86,31 @@ QDateTime ClientModel::getLastBlockDate() const
 
 double ClientModel::getVerificationProgress() const
 {
+    LOCK(cs_main);
     return Checkpoints::GuessVerificationProgress(chainActive.Tip());
 }
 
 void ClientModel::updateTimer()
 {
+    // Get required lock upfront. This avoids the GUI from getting stuck on
+    // 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)
+        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();
-    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());
@@ -157,11 +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"));