Merge bitcoin-core/gui#381: refactor: Make BitcoinCore class reusable

8169fc4 qt, refactor: Fix code styling of moved InitExecutor class (Hennadii Stepanov)
c82165a qt, refactor: Move InitExecutor class into its own module (Hennadii Stepanov)
dbcf56b scripted-diff: Rename BitcoinCore class to InitExecutor (Hennadii Stepanov)
19a1d00 qt: Add BitcoinCore::m_thread member (Hennadii Stepanov)

Pull request description:

  This PR makes the `BitcoinCore` class reusable, i.e., it can be used by the widget-based GUI or by the [QML-based](https://github.com/bitcoin-core/gui-qml/tree/main/src/qml) one, and it makes the divergence between these two repos minimal.

  The small benefit to the current branch is more structured code.

  Actually, this PR is ported from bitcoin-core/gui-qml#10.
  The example of the re-using of the `BitcoinCore` class is bitcoin-core/gui-qml#11.

ACKs for top commit:
  laanwj:
    ACK 8169fc4
  ryanofsky:
    Code review ACK 8169fc4. Only change is switching from `m_executor` from pointer to optional type (thanks for update!)

Tree-SHA512: a0552c32d26d9acf42921eb12bcdf68f02d52f7183c688c43257b1a58679f64e45f193ee2d316850c7f0f516561e17abe989fe545bfa05e158ad3f4c66d19bca

Author: laanwj

src/Makefile.qt.include

@@ -58,6 +58,7 @@ QT_MOC_CPP = \
   qt/moc_editaddressdialog.cpp \
   qt/moc_governancelist.cpp \
   qt/moc_guiutil.cpp \
+  qt/moc_initexecutor.cpp \
   qt/moc_intro.cpp \
   qt/moc_macdockiconhandler.cpp \
   qt/moc_macnotificationhandler.cpp \
@@ -133,6 +134,7 @@ BITCOIN_QT_H = \
   qt/governancelist.h \
   qt/guiconstants.h \
   qt/guiutil.h \
+  qt/initexecutor.h \
   qt/intro.h \
   qt/macdockiconhandler.h \
   qt/macnotificationhandler.h \
@@ -222,6 +224,7 @@ BITCOIN_QT_BASE_CPP = \
   qt/clientmodel.cpp \
   qt/csvmodelwriter.cpp \
   qt/guiutil.cpp \
+  qt/initexecutor.cpp \
   qt/intro.cpp \
   qt/modaloverlay.cpp \
   qt/networkstyle.cpp \

src/qt/bitcoin.cpp

@@ -8,41 +8,41 @@
 #endif
 
 #include <qt/bitcoin.h>
-#include <qt/bitcoingui.h>
 
 #include <chainparams.h>
 #include <fs.h>
+#include <init.h>
+#include <interfaces/handler.h>
+#include <interfaces/node.h>
+#include <net.h>
+#include <node/context.h>
+#include <node/ui_interface.h>
+#include <noui.h>
+#include <qt/bitcoingui.h>
 #include <qt/clientmodel.h>
 #include <qt/guiconstants.h>
 #include <qt/guiutil.h>
+#include <qt/initexecutor.h>
 #include <qt/intro.h>
-#include <net.h>
 #include <qt/networkstyle.h>
 #include <qt/optionsmodel.h>
 #include <qt/splashscreen.h>
 #include <qt/utilitydialog.h>
 #include <qt/winshutdownmonitor.h>
+#include <stacktraces.h>
+#include <uint256.h>
 #include <util/string.h>
+#include <util/system.h>
+#include <util/threadnames.h>
+#include <util/translation.h>
+#include <validation.h>
 
 #ifdef ENABLE_WALLET
 #include <qt/paymentserver.h>
 #include <qt/walletcontroller.h>
 #include <qt/walletmodel.h>
 #endif // ENABLE_WALLET
 
-#include <init.h>
-#include <interfaces/handler.h>
-#include <interfaces/node.h>
-#include <node/context.h>
-#include <node/ui_interface.h>
-#include <noui.h>
-#include <stacktraces.h>
-#include <uint256.h>
-#include <util/system.h>
-#include <util/threadnames.h>
-#include <util/translation.h>
-#include <validation.h>
-
 #include <boost/signals2/connection.hpp>
 #include <memory>
 
@@ -52,7 +52,6 @@
 #include <QLibraryInfo>
 #include <QLocale>
 #include <QMessageBox>
-#include <QProcess>
 #include <QSettings>
 #include <QThread>
 #include <QTimer>
@@ -208,72 +207,11 @@ void DebugMessageHandler(QtMsgType type, const QMessageLogContext& context, cons
     }
 }
 
-BitcoinCore::BitcoinCore(interfaces::Node& node) :
-    QObject(), m_node(node)
-{
-}
-
-void BitcoinCore::handleRunawayException(const std::exception_ptr e)
-{
-    PrintExceptionContinue(e, "Runaway exception");
-    Q_EMIT runawayException(QString::fromStdString(m_node.getWarnings().translated));
-}
-
-void BitcoinCore::initialize()
-{
-    try
-    {
-        util::ThreadRename("qt-init");
-        qDebug() << __func__ << ": Running initialization in thread";
-        interfaces::BlockAndHeaderTipInfo tip_info;
-        bool rv = m_node.appInitMain(&tip_info);
-        Q_EMIT initializeResult(rv, tip_info);
-    } catch (...) {
-        handleRunawayException(std::current_exception());
-    }
-}
-
-void BitcoinCore::restart(QStringList args)
-{
-    static bool executing_restart{false};
-
-    if(!executing_restart) { // Only restart 1x, no matter how often a user clicks on a restart-button
-        executing_restart = true;
-        try
-        {
-            qDebug() << __func__ << ": Running Restart in thread";
-            m_node.appPrepareShutdown();
-            qDebug() << __func__ << ": Shutdown finished";
-            Q_EMIT shutdownResult();
-            CExplicitNetCleanup::callCleanup();
-            QProcess::startDetached(QApplication::applicationFilePath(), args);
-            qDebug() << __func__ << ": Restart initiated...";
-            QApplication::quit();
-        } catch (...) {
-            handleRunawayException(std::current_exception());
-        }
-    }
-}
-
-void BitcoinCore::shutdown()
-{
-    try
-    {
-        qDebug() << __func__ << ": Running Shutdown in thread";
-        m_node.appShutdown();
-        qDebug() << __func__ << ": Shutdown finished";
-        Q_EMIT shutdownResult();
-    } catch (...) {
-        handleRunawayException(std::current_exception());
-    }
-}
-
 static int qt_argc = 1;
 static const char* qt_argv = "dash-qt";
 
 BitcoinApplication::BitcoinApplication():
     QApplication(qt_argc, const_cast<char **>(&qt_argv)),
-    coreThread(nullptr),
     optionsModel(nullptr),
     clientModel(nullptr),
     window(nullptr),
@@ -287,13 +225,7 @@ BitcoinApplication::BitcoinApplication():
 
 BitcoinApplication::~BitcoinApplication()
 {
-    if(coreThread)
-    {
-        qDebug() << __func__ << ": Stopping thread";
-        coreThread->quit();
-        coreThread->wait();
-        qDebug() << __func__ << ": Stopped thread";
-    }
+    m_executor.reset();
 
     delete window;
     window = nullptr;
@@ -350,23 +282,16 @@ bool BitcoinApplication::baseInitialize()
 
 void BitcoinApplication::startThread()
 {
-    if(coreThread)
-        return;
-    coreThread = new QThread(this);
-    BitcoinCore *executor = new BitcoinCore(node());
-    executor->moveToThread(coreThread);
+    assert(!m_executor);
+    m_executor.emplace(node());
 
     /*  communication to and from thread */
-    connect(executor, &BitcoinCore::initializeResult, this, &BitcoinApplication::initializeResult);
-    connect(executor, &BitcoinCore::shutdownResult, this, &BitcoinApplication::shutdownResult);
-    connect(executor, &BitcoinCore::runawayException, this, &BitcoinApplication::handleRunawayException);
-    connect(this, &BitcoinApplication::requestedInitialize, executor, &BitcoinCore::initialize);
-    connect(this, &BitcoinApplication::requestedShutdown, executor, &BitcoinCore::shutdown);
-    connect(window, &BitcoinGUI::requestedRestart, executor, &BitcoinCore::restart);
-    /*  make sure executor object is deleted in its own thread */
-    connect(coreThread, &QThread::finished, executor, &QObject::deleteLater);
-
-    coreThread->start();
+    connect(&m_executor.value(), &InitExecutor::initializeResult, this, &BitcoinApplication::initializeResult);
+    connect(&m_executor.value(), &InitExecutor::shutdownResult, this, &BitcoinApplication::shutdownResult);
+    connect(&m_executor.value(), &InitExecutor::runawayException, this, &BitcoinApplication::handleRunawayException);
+    connect(this, &BitcoinApplication::requestedInitialize, &m_executor.value(), &InitExecutor::initialize);
+    connect(this, &BitcoinApplication::requestedShutdown, &m_executor.value(), &InitExecutor::shutdown);
+    connect(window, &BitcoinGUI::requestedRestart, &m_executor.value(), &InitExecutor::restart);
 }
 
 void BitcoinApplication::parameterSetup()
@@ -399,7 +324,6 @@ void BitcoinApplication::requestShutdown()
     shutdownWindow.reset(ShutdownWindow::showShutdownWindow(window));
 
     qDebug() << __func__ << ": Requesting shutdown";
-    startThread();
     window->hide();
     // Must disconnect node signals otherwise current thread can deadlock since
     // no event loop is running.

src/qt/bitcoin.h

@@ -9,11 +9,14 @@
 #include <config/bitcoin-config.h>
 #endif
 
-#include <QApplication>
+#include <interfaces/node.h>
+#include <qt/initexecutor.h>
+
 #include <assert.h>
 #include <memory>
+#include <optional>
 
-#include <interfaces/node.h>
+#include <QApplication>
 
 class BitcoinGUI;
 class ClientModel;
@@ -25,32 +28,6 @@ class WalletController;
 class WalletModel;
 
 
-/** Class encapsulating Bitcoin Core startup and shutdown.
- * Allows running startup and shutdown in a different thread from the UI thread.
- */
-class BitcoinCore: public QObject
-{
-    Q_OBJECT
-public:
-    explicit BitcoinCore(interfaces::Node& node);
-
-public Q_SLOTS:
-    void initialize();
-    void shutdown();
-    void restart(QStringList args);
-
-Q_SIGNALS:
-    void initializeResult(bool success, interfaces::BlockAndHeaderTipInfo tip_info);
-    void shutdownResult();
-    void runawayException(const QString &message);
-
-private:
-    /// Pass fatal exception message to UI thread
-    void handleRunawayException(const std::exception_ptr e);
-
-    interfaces::Node& m_node;
-};
-
 /** Main Bitcoin application object */
 class BitcoinApplication: public QApplication
 {
@@ -113,7 +90,7 @@ public Q_SLOTS:
     bool event(QEvent* e) override;
 
 private:
-    QThread *coreThread;
+    std::optional<InitExecutor> m_executor;
     OptionsModel *optionsModel;
     ClientModel *clientModel;
     BitcoinGUI *window;

src/qt/initexecutor.cpp

@@ -0,0 +1,85 @@
+// Copyright (c) 2014-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <qt/initexecutor.h>
+
+#include <interfaces/node.h>
+#include <util/system.h>
+#include <util/threadnames.h>
+
+#include <exception>
+
+#include <QApplication>
+#include <QDebug>
+#include <QObject>
+#include <QProcess>
+#include <QString>
+#include <QThread>
+
+InitExecutor::InitExecutor(interfaces::Node& node)
+    : QObject(), m_node(node)
+{
+    this->moveToThread(&m_thread);
+    m_thread.start();
+}
+
+InitExecutor::~InitExecutor()
+{
+    qDebug() << __func__ << ": Stopping thread";
+    m_thread.quit();
+    m_thread.wait();
+    qDebug() << __func__ << ": Stopped thread";
+}
+
+void InitExecutor::handleRunawayException(const std::exception_ptr e)
+{
+    PrintExceptionContinue(e, "Runaway exception");
+    Q_EMIT runawayException(QString::fromStdString(m_node.getWarnings().translated));
+}
+
+void InitExecutor::initialize()
+{
+    try {
+        util::ThreadRename("qt-init");
+        qDebug() << __func__ << ": Running initialization in thread";
+        interfaces::BlockAndHeaderTipInfo tip_info;
+        bool rv = m_node.appInitMain(&tip_info);
+        Q_EMIT initializeResult(rv, tip_info);
+    } catch (...) {
+        handleRunawayException(std::current_exception());
+    }
+}
+
+void InitExecutor::restart(QStringList args)
+{
+    static bool executing_restart{false};
+
+    if(!executing_restart) { // Only restart 1x, no matter how often a user clicks on a restart-button
+        executing_restart = true;
+        try {
+            qDebug() << __func__ << ": Running Restart in thread";
+            m_node.appPrepareShutdown();
+            qDebug() << __func__ << ": Shutdown finished";
+            Q_EMIT shutdownResult();
+            CExplicitNetCleanup::callCleanup();
+            QProcess::startDetached(QApplication::applicationFilePath(), args);
+            qDebug() << __func__ << ": Restart initiated...";
+            QApplication::quit();
+        } catch (...) {
+            handleRunawayException(std::current_exception());
+        }
+    }
+}
+
+void InitExecutor::shutdown()
+{
+    try {
+        qDebug() << __func__ << ": Running Shutdown in thread";
+        m_node.appShutdown();
+        qDebug() << __func__ << ": Shutdown finished";
+        Q_EMIT shutdownResult();
+    } catch (...) {
+        handleRunawayException(std::current_exception());
+    }
+}