qt: get required locks upfront in polling functions

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.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/qt/clientmodel.cpp b/src/qt/clientmodel.cpp
index 287296644c..3c0564c208 100644
--- a/src/qt/clientmodel.cpp
+++ b/src/qt/clientmodel.cpp
@@ -92,6 +92,12 @@ double ClientModel::getVerificationProgress() const
 
 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();