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, 14 insertions, 11 deletions

diff --git a/src/qt/walletmodel.cpp b/src/qt/walletmodel.cpp
index 61f26107af..37d82ec063 100644
--- a/src/qt/walletmodel.cpp
+++ b/src/qt/walletmodel.cpp
@@ -98,18 +98,21 @@ void WalletModel::updateStatus()
 
 void WalletModel::pollBalanceChanged()
 {
-    bool heightChanged = false;
-    {
-        LOCK(cs_main);
-        if(chainActive.Height() != cachedNumBlocks)
-        {
-            // Balance and number of transactions might have changed
-            cachedNumBlocks = chainActive.Height();
-            heightChanged = true;
-        }
-    }
-    if(heightChanged)
+    // Get required locks 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;
+    TRY_LOCK(wallet->cs_wallet, lockWallet);
+    if(!lockWallet)
+        return;
+
+    if(chainActive.Height() != cachedNumBlocks)
     {
+        // Balance and number of transactions might have changed
+        cachedNumBlocks = chainActive.Height();
+
         checkBalanceChanged();
         if(transactionTableModel)
             transactionTableModel->updateConfirmations();