gui: Avoid Wallet::GetBalance in WalletModel::pollBalanceChanged

src/interfaces/wallet.cpp

@@ -380,16 +380,17 @@ public:
         }
         return result;
     }
-    bool tryGetBalances(WalletBalances& balances, int& num_blocks) override
+    bool tryGetBalances(WalletBalances& balances, int& num_blocks, bool force, int cached_num_blocks) override
     {
         auto locked_chain = m_wallet->chain().lock(true /* try_lock */);
         if (!locked_chain) return false;
+        num_blocks = locked_chain->getHeight().get_value_or(-1);
+        if (!force && num_blocks == cached_num_blocks) return false;
         TRY_LOCK(m_wallet->cs_wallet, locked_wallet);
         if (!locked_wallet) {
             return false;
         }
         balances = getBalances();
-        num_blocks = locked_chain->getHeight().get_value_or(-1);
         return true;
     }
     CAmount getBalance() override { return m_wallet->GetBalance().m_mine_trusted; }

src/interfaces/wallet.h

@@ -201,8 +201,11 @@ public:
     //! Get balances.
     virtual WalletBalances getBalances() = 0;
 
-    //! Get balances if possible without blocking.
-    virtual bool tryGetBalances(WalletBalances& balances, int& num_blocks) = 0;
+    //! Get balances if possible without waiting for chain and wallet locks.
+    virtual bool tryGetBalances(WalletBalances& balances,
+        int& num_blocks,
+        bool force,
+        int cached_num_blocks) = 0;
 
     //! Get balance.
     virtual CAmount getBalance() = 0;

src/qt/walletmodel.cpp

@@ -78,21 +78,18 @@ void WalletModel::pollBalanceChanged()
     // rescan.
     interfaces::WalletBalances new_balances;
     int numBlocks = -1;
-    if (!m_wallet->tryGetBalances(new_balances, numBlocks)) {
+    if (!m_wallet->tryGetBalances(new_balances, numBlocks, fForceCheckBalanceChanged, cachedNumBlocks)) {
         return;
     }
 
-    if(fForceCheckBalanceChanged || numBlocks != cachedNumBlocks)
-    {
-        fForceCheckBalanceChanged = false;
+    fForceCheckBalanceChanged = false;
 
-        // Balance and number of transactions might have changed
-        cachedNumBlocks = numBlocks;
+    // Balance and number of transactions might have changed
+    cachedNumBlocks = numBlocks;
 
-        checkBalanceChanged(new_balances);
-        if(transactionTableModel)
-            transactionTableModel->updateConfirmations();
-    }
+    checkBalanceChanged(new_balances);
+    if(transactionTableModel)
+        transactionTableModel->updateConfirmations();
 }
 
 void WalletModel::checkBalanceChanged(const interfaces::WalletBalances& new_balances)