multiprocess: Delay wallet client construction

Delay wallet client construction until after logging, thread and other
init for two reasons:

- More responsive multiprocess GUI startup. When bitcoin-gui is started
  this moves the call from bitcoin-gui to bitcoin-node that spawns
  bitcoin-wallet off of the GUI event thread and onto the background GUI
  init executor thread.

- Avoids feature_logging.py test failures with bitcoin-node by making
  bitcoin-wallet logging start after bitcoin-node logging starts,
  because the tests are not written to handle the bitcoin-wallet logging
  init code running first.

This partially reverts commit b266b3e0bf,
moving wallet client creation back to the place it was located before.

src/init.cpp

@@ -1065,11 +1065,6 @@ bool AppInitLockDataDirectory()
 bool AppInitInterfaces(NodeContext& node)
 {
     node.chain = node.init->makeChain();
-    // Create client interfaces for wallets that are supposed to be loaded
-    // according to -wallet and -disablewallet options. This only constructs
-    // the interfaces, it doesn't load wallet data. Wallets actually get loaded
-    // when load() and start() interface methods are called below.
-    g_wallet_init_interface.Construct(node);
     return true;
 }
 
@@ -1133,6 +1128,13 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
 
     GetMainSignals().RegisterBackgroundSignalScheduler(*node.scheduler);
 
+    // Create client interfaces for wallets that are supposed to be loaded
+    // according to -wallet and -disablewallet options. This only constructs
+    // the interfaces, it doesn't load wallet data. Wallets actually get loaded
+    // when load() and start() interface methods are called below.
+    g_wallet_init_interface.Construct(node);
+    uiInterface.InitWallet();
+
     /* Register RPC commands regardless of -server setting so they will be
      * available in the GUI RPC console even if external calls are disabled.
      */

src/interfaces/node.h

@@ -197,6 +197,10 @@ public:
     using ShowProgressFn = std::function<void(const std::string& title, int progress, bool resume_possible)>;
     virtual std::unique_ptr<Handler> handleShowProgress(ShowProgressFn fn) = 0;
 
+    //! Register handler for wallet client constructed messages.
+    using InitWalletFn = std::function<void()>;
+    virtual std::unique_ptr<Handler> handleInitWallet(InitWalletFn fn) = 0;
+
     //! Register handler for number of connections changed messages.
     using NotifyNumConnectionsChangedFn = std::function<void(int new_num_connections)>;
     virtual std::unique_ptr<Handler> handleNotifyNumConnectionsChanged(NotifyNumConnectionsChangedFn fn) = 0;

src/node/interfaces.cpp

@@ -281,6 +281,10 @@ public:
     {
         return MakeHandler(::uiInterface.ShowProgress_connect(fn));
     }
+    std::unique_ptr<Handler> handleInitWallet(InitWalletFn fn) override
+    {
+        return MakeHandler(::uiInterface.InitWallet_connect(fn));
+    }
     std::unique_ptr<Handler> handleNotifyNumConnectionsChanged(NotifyNumConnectionsChangedFn fn) override
     {
         return MakeHandler(::uiInterface.NotifyNumConnectionsChanged_connect(fn));

src/node/ui_interface.cpp

@@ -15,6 +15,7 @@ struct UISignals {
     boost::signals2::signal<CClientUIInterface::ThreadSafeMessageBoxSig, boost::signals2::optional_last_value<bool>> ThreadSafeMessageBox;
     boost::signals2::signal<CClientUIInterface::ThreadSafeQuestionSig, boost::signals2::optional_last_value<bool>> ThreadSafeQuestion;
     boost::signals2::signal<CClientUIInterface::InitMessageSig> InitMessage;
+    boost::signals2::signal<CClientUIInterface::InitWalletSig> InitWallet;
     boost::signals2::signal<CClientUIInterface::NotifyNumConnectionsChangedSig> NotifyNumConnectionsChanged;
     boost::signals2::signal<CClientUIInterface::NotifyNetworkActiveChangedSig> NotifyNetworkActiveChanged;
     boost::signals2::signal<CClientUIInterface::NotifyAlertChangedSig> NotifyAlertChanged;
@@ -34,6 +35,7 @@ static UISignals g_ui_signals;
 ADD_SIGNALS_IMPL_WRAPPER(ThreadSafeMessageBox);
 ADD_SIGNALS_IMPL_WRAPPER(ThreadSafeQuestion);
 ADD_SIGNALS_IMPL_WRAPPER(InitMessage);
+ADD_SIGNALS_IMPL_WRAPPER(InitWallet);
 ADD_SIGNALS_IMPL_WRAPPER(NotifyNumConnectionsChanged);
 ADD_SIGNALS_IMPL_WRAPPER(NotifyNetworkActiveChanged);
 ADD_SIGNALS_IMPL_WRAPPER(NotifyAlertChanged);
@@ -45,6 +47,7 @@ ADD_SIGNALS_IMPL_WRAPPER(BannedListChanged);
 bool CClientUIInterface::ThreadSafeMessageBox(const bilingual_str& message, const std::string& caption, unsigned int style) { return g_ui_signals.ThreadSafeMessageBox(message, caption, style).value_or(false);}
 bool CClientUIInterface::ThreadSafeQuestion(const bilingual_str& message, const std::string& non_interactive_message, const std::string& caption, unsigned int style) { return g_ui_signals.ThreadSafeQuestion(message, non_interactive_message, caption, style).value_or(false);}
 void CClientUIInterface::InitMessage(const std::string& message) { return g_ui_signals.InitMessage(message); }
+void CClientUIInterface::InitWallet() { return g_ui_signals.InitWallet(); }
 void CClientUIInterface::NotifyNumConnectionsChanged(int newNumConnections) { return g_ui_signals.NotifyNumConnectionsChanged(newNumConnections); }
 void CClientUIInterface::NotifyNetworkActiveChanged(bool networkActive) { return g_ui_signals.NotifyNetworkActiveChanged(networkActive); }
 void CClientUIInterface::NotifyAlertChanged() { return g_ui_signals.NotifyAlertChanged(); }

src/node/ui_interface.h

@@ -82,6 +82,9 @@ public:
     /** Progress message during initialization. */
     ADD_SIGNALS_DECL_WRAPPER(InitMessage, void, const std::string& message);
 
+    /** Wallet client created. */
+    ADD_SIGNALS_DECL_WRAPPER(InitWallet, void, );
+
     /** Number of network connections changed. */
     ADD_SIGNALS_DECL_WRAPPER(NotifyNumConnectionsChanged, void, int newNumConnections);
 

src/qt/bitcoin.cpp

@@ -271,7 +271,6 @@ void BitcoinApplication::createSplashScreen(const NetworkStyle *networkStyle)
     // We don't hold a direct pointer to the splash screen after creation, but the splash
     // screen will take care of deleting itself when finish() happens.
     m_splash->show();
-    connect(this, &BitcoinApplication::requestedInitialize, m_splash, &SplashScreen::handleLoadWallet);
     connect(this, &BitcoinApplication::splashFinished, m_splash, &SplashScreen::finish);
     connect(this, &BitcoinApplication::requestedShutdown, m_splash, &QWidget::close);
 }

src/qt/splashscreen.cpp

@@ -194,6 +194,7 @@ void SplashScreen::subscribeToCoreSignals()
     // Connect signals to client
     m_handler_init_message = m_node->handleInitMessage(std::bind(InitMessage, this, std::placeholders::_1));
     m_handler_show_progress = m_node->handleShowProgress(std::bind(ShowProgress, this, std::placeholders::_1, std::placeholders::_2, std::placeholders::_3));
+    m_handler_init_wallet = m_node->handleInitWallet([this]() { handleLoadWallet(); });
 }
 
 void SplashScreen::handleLoadWallet()

src/qt/splashscreen.h

@@ -66,6 +66,7 @@ private:
     bool m_shutdown = false;
     std::unique_ptr<interfaces::Handler> m_handler_init_message;
     std::unique_ptr<interfaces::Handler> m_handler_show_progress;
+    std::unique_ptr<interfaces::Handler> m_handler_init_wallet;
     std::unique_ptr<interfaces::Handler> m_handler_load_wallet;
     std::list<std::unique_ptr<interfaces::Wallet>> m_connected_wallets;
     std::list<std::unique_ptr<interfaces::Handler>> m_connected_wallet_handlers;