Merge bitcoin-core/gui#434: Keep InitExecutor in main gui thread

03a5fe06bd qt: Keep InitExecutor in main gui thread (João Barbosa)

Pull request description:

  The `InitExecutor` constructor moves the instance to a dedicated thread. This PR changes that by using `GUIUtil::ObjectInvoke` to run the relevant code in that thread.

  A possible follow-up is to ditch the dedicated thread and use `QThreadPool` or even `QtConcurrent::run` (if we want to enable that).

ACKs for top commit:
  hebasto:
    ACK 03a5fe06bd, tested on Linux Mint 20.2 (Qt 5.12.8).
  jarolrod:
    ACK 03a5fe06bd

Tree-SHA512: 8b40300371d4c04efb9913600a06ba4899af0b5f50fdb26ea23ec751df6d3bd52f8bd693a5e8f6a94ebf3790583dc96c6070e6878d247dece62347aa9bd99031

src/qt/initexecutor.cpp

@@ -5,6 +5,7 @@
 #include <qt/initexecutor.h>
 
 #include <interfaces/node.h>
+#include <qt/guiutil.h>
 #include <util/system.h>
 #include <util/threadnames.h>
 
@@ -18,7 +19,7 @@
 InitExecutor::InitExecutor(interfaces::Node& node)
     : QObject(), m_node(node)
 {
-    this->moveToThread(&m_thread);
+    m_context.moveToThread(&m_thread);
     m_thread.start();
 }
 
@@ -38,9 +39,10 @@ void InitExecutor::handleRunawayException(const std::exception* e)
 
 void InitExecutor::initialize()
 {
+    GUIUtil::ObjectInvoke(&m_context, [this] {
         try {
             util::ThreadRename("qt-init");
-        qDebug() << __func__ << ": Running initialization in thread";
+            qDebug() << "Running initialization in thread";
             interfaces::BlockAndHeaderTipInfo tip_info;
             bool rv = m_node.appInitMain(&tip_info);
             Q_EMIT initializeResult(rv, tip_info);
@@ -49,18 +51,21 @@ void InitExecutor::initialize()
         } catch (...) {
             handleRunawayException(nullptr);
         }
+    });
 }
 
 void InitExecutor::shutdown()
 {
+    GUIUtil::ObjectInvoke(&m_context, [this] {
         try {
-        qDebug() << __func__ << ": Running Shutdown in thread";
+            qDebug() << "Running Shutdown in thread";
             m_node.appShutdown();
-        qDebug() << __func__ << ": Shutdown finished";
+            qDebug() << "Shutdown finished";
             Q_EMIT shutdownResult();
         } catch (const std::exception& e) {
             handleRunawayException(&e);
         } catch (...) {
             handleRunawayException(nullptr);
         }
+    });
 }

src/qt/initexecutor.h

@@ -40,6 +40,7 @@ private:
     void handleRunawayException(const std::exception* e);
 
     interfaces::Node& m_node;
+    QObject m_context;
     QThread m_thread;
 };
 

src/qt/test/test_main.cpp

@@ -9,7 +9,6 @@
 #include <interfaces/init.h>
 #include <interfaces/node.h>
 #include <qt/bitcoin.h>
-#include <qt/initexecutor.h>
 #include <qt/test/apptests.h>
 #include <qt/test/rpcnestedtests.h>
 #include <qt/test/uritests.h>