refactor: return const set reference from CWallet::ListLockedCoins()

Avoid a pointless set→vector copy: return `const std::set<COutPoint>&`
directly from the wallet layer, and `std::set<COutPoint>` through the
interface (copied under lock).

In buttonLockAllClicked, fetch the locked set once instead of calling
isLockedCoin() per visible UTXO (1 lock acquisition instead of N).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: UdjinM6

src/interfaces/wallet.h

@@ -21,6 +21,7 @@
 #include <map>
 #include <memory>
 #include <psbt.h>
+#include <set>
 #include <string>
 #include <tuple>
 #include <type_traits>
@@ -170,7 +171,7 @@ class Wallet
     virtual bool isLockedCoin(const COutPoint& output) = 0;
 
     //! List locked coins.
-    virtual std::vector<COutPoint> listLockedCoins() = 0;
+    virtual std::set<COutPoint> listLockedCoins() = 0;
 
     //! Lock the provided coins in a single batch.
     virtual bool lockCoins(const std::vector<COutPoint>& outputs) = 0;

src/qt/coincontroldialog.cpp

@@ -189,6 +189,9 @@ void CoinControlDialog::buttonSelectAllClicked()
 // (un)lock all
 void CoinControlDialog::buttonLockAllClicked()
 {
+    // Fetch the wallet-wide locked set once (single cs_wallet acquisition)
+    const std::set<COutPoint> lockedSet{model->wallet().listLockedCoins()};
+
     // Collect all visible UTXOs; track locked ones separately for the unlock path
     // (works in both tree and list modes)
     std::vector<COutPoint> outputs;
@@ -200,15 +203,15 @@ void CoinControlDialog::buttonLockAllClicked()
             const COutPoint outpt(uint256S(item->data(COLUMN_ADDRESS, TxHashRole).toString().toStdString()),
                                   item->data(COLUMN_ADDRESS, VOutRole).toUInt());
             outputs.emplace_back(outpt);
-            if (model->wallet().isLockedCoin(outpt)) lockedOutputs.emplace_back(outpt);
+            if (lockedSet.contains(outpt)) lockedOutputs.emplace_back(outpt);
         } else {
             // Tree mode: top-level item is an address group; collect children
             for (int j = 0; j < item->childCount(); j++) {
                 QTreeWidgetItem* child = item->child(j);
                 const COutPoint outpt(uint256S(child->data(COLUMN_ADDRESS, TxHashRole).toString().toStdString()),
                                       child->data(COLUMN_ADDRESS, VOutRole).toUInt());
                 outputs.emplace_back(outpt);
-                if (model->wallet().isLockedCoin(outpt)) lockedOutputs.emplace_back(outpt);
+                if (lockedSet.contains(outpt)) lockedOutputs.emplace_back(outpt);
             }
         }
     }

src/wallet/interfaces.cpp

@@ -321,7 +321,7 @@ class WalletImpl : public Wallet
         LOCK(m_wallet->cs_wallet);
         return m_wallet->IsLockedCoin(output);
     }
-    std::vector<COutPoint> listLockedCoins() override
+    std::set<COutPoint> listLockedCoins() override
     {
         LOCK(m_wallet->cs_wallet);
         return m_wallet->ListLockedCoins();

src/wallet/wallet.cpp

@@ -2742,10 +2742,10 @@ bool CWallet::IsLockedCoin(const COutPoint& output) const
     return setLockedCoins.count(output) > 0;
 }
 
-std::vector<COutPoint> CWallet::ListLockedCoins() const
+const std::set<COutPoint>& CWallet::ListLockedCoins() const
 {
     AssertLockHeld(cs_wallet);
-    return std::vector<COutPoint>(setLockedCoins.begin(), setLockedCoins.end());
+    return setLockedCoins;
 }
 
 std::vector<COutPoint> CWallet::ListProTxCoins() const { return ListProTxCoins(setWalletUTXO); }

src/wallet/wallet.h

@@ -582,7 +582,7 @@ class CWallet final : public WalletStorage, public interfaces::Chain::Notificati
     bool LockCoin(const COutPoint& output, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool UnlockCoin(const COutPoint& output, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool UnlockAllCoins() EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
-    std::vector<COutPoint> ListLockedCoins() const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    const std::set<COutPoint>& ListLockedCoins() const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::vector<COutPoint> ListProTxCoins() const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     std::vector<COutPoint> ListProTxCoins(const std::set<COutPoint>& utxos) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     void LockProTxCoins(const std::set<COutPoint>& utxos, WalletBatch* batch = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);