GODT-1554 / 1555: Implement gRPC go service and Qt 5 frontend C++ app.

WIP: updates

WIP: cache on disk and autostart.

WIP: mail, keychain and more.

WIP: updated grpc version in go mod file.

WIP: user list.

WIP: RPC service placeholder

WIP: test C++ RPC client skeleton.

Other: missing license script update.

WIP: use Qt test framework.

WIP: test for app and login calls.

WIP: test for update & cache on disk calls.

WIP: tests for mail settings calls.

WIP: all client tests.

WIP: linter fixes.

WIP: fix missing license link.

WIP: update dependency_license script for gRPC and protobuf.

WIP: removed unused file.

WIP: app & login event streaming tests.

WIP: update event stream tests.

WIP: completed event streaming tests.

GODT-1554: qt C++ frontend skeleton.

WIP: C++ backend declaration.

wip: started drafting user model.

WIP: users. not functional.

WIP: invokable methods

WIP: Exception class + backend 'injection' into QML.

WIP: switch to VCPKG to ease multi-arch compilation,  C++ RPC client skeleton.

WIP: Renaming and reorganisation

WIP:introduced new 'grpc' go frontend.

WIP: Worker & Oveerseer for thread management.

WIP: added log to C++ app.

WIP: event stream architecture on Go side.

WIP: event parsing and streamer stopping.

WIP: Moved grpc to frontend subfolder + use vcpkg for gRPC and protobuf.

WIP: windows building ok

WIP: wired a few messages

WIP: more wiring.

WIP: Fixed imports after rebase on top of devel.

WIP: wired some bool and string properties.

WIP: more properties.

WIP: wired cache on disk stuff

WIP: connect event watcher.

WIP: login

WIP: fix showSplashScreen

WIP: Wired login calls.

WIP: user list.

WIP: Refactored main().

WIP: User retrieval .

WIP: no shared pointer in user model.

WIP: fixed user count.

WIP: cached goos.

WIP: Wired autostart

WIP: beta channel toggle wired.

WIP: User removal

WIP: wired theme

WIP: implemented configure apple mail.

WIP: split mode.

WIP: fixed user updates.

WIP: fixed Quit from tray icon

WIP: wired CurrentEmailClient

WIP: wired UseSSLForSMTP

WIP: wired change ports .

WIP: wired DoH. .

WIP: wired keychain calls.

WIP: wired autoupdate option.

WIP: QML Backend clean-up.

WIP: cleanup.

WIP: moved user related files in subfolder. .

WIP: User are managed using smart pointers.

WIP: cleanup.

WIP: more cleanup.

WIP: mail events forwarding

WIP: code inspection tweaks from CLion.

WIP: moved QML, cleanup, and missing copyright notices.

WIP: Backend is not QMLBackend.

Other: fixed issues reported by Leander. [skip ci]

internal/frontend/qt6/Worker/Overseer.cpp

@@ -0,0 +1,103 @@
+// Copyright (c) 2022 Proton AG
+//
+// This file is part of Proton Mail Bridge.
+//
+// Proton Mail Bridge is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Proton Mail Bridge is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Proton Mail Bridge. If not, see <https://www.gnu.org/licenses/>.
+
+
+#include "Pch.h"
+#include "Overseer.h"
+#include "Exception.h"
+
+
+//****************************************************************************************************************************************************
+/// \param[in] worker The worker.
+/// \param[in] parent The parent object of the worker.
+//****************************************************************************************************************************************************
+Overseer::Overseer(Worker *worker, QObject *parent)
+    : QObject(parent)
+    , thread_(new QThread(parent))
+    , worker_(worker)
+{
+    if (!worker_)
+        throw Exception("Overseer cannot accept a nil worker.");
+}
+
+
+//****************************************************************************************************************************************************
+//
+//****************************************************************************************************************************************************
+Overseer::~Overseer()
+{
+    this->release();
+}
+
+
+//****************************************************************************************************************************************************
+/// \param[in] autorelease Should the overseer automatically release the worker and thread when done.
+//****************************************************************************************************************************************************
+void Overseer::startWorker(bool autorelease) const
+{
+    if (!worker_)
+        throw Exception("Cannot start overseer with null worker.");
+    if (!thread_)
+        throw Exception("Cannot start overseer with null thread.");
+
+    worker_->moveToThread(thread_);
+    connect(thread_, &QThread::started, worker_, &Worker::run);
+    connect(worker_, &Worker::finished, thread_, &QThread::quit);
+    connect(worker_, &Worker::error, thread_, &QThread::quit);
+    if (autorelease)
+    {
+        connect(worker_, &Worker::error, this, &Overseer::release);
+        connect(worker_, &Worker::finished, this, &Overseer::release);
+    }
+    thread_->start();
+}
+
+
+//****************************************************************************************************************************************************
+//
+//****************************************************************************************************************************************************
+void Overseer::release()
+{
+    if (worker_)
+    {
+        worker_->deleteLater();
+        worker_ = nullptr;
+    }
+
+    if (thread_)
+    {
+        if (!thread_->isFinished())
+        {
+            thread_->quit();
+            thread_->wait();
+        }
+        thread_->deleteLater();
+        thread_ = nullptr;
+    }
+}
+
+
+//****************************************************************************************************************************************************
+/// \return true iff the worker is finished, release
+//****************************************************************************************************************************************************
+bool Overseer::isFinished() const
+{
+    if ((!worker_) || (!worker_->thread()))
+        return true;
+
+    return worker_->thread()->isFinished();
+}