From 002cd1d5b972005fb074863fc4a621f9ad3ce81f Mon Sep 17 00:00:00 2001
From: Mat Sutcliffe <oktal3700@gmail.com>
Date: Tue, 28 Sep 2021 18:34:25 +0100
Subject: [PATCH] Issue #11 Improve CEventLoop API

---
 src/blackcore/application.cpp              |  9 ++--
 src/blackcore/db/backgrounddataupdater.cpp |  3 +-
 src/blackmisc/eventloop.h                  | 58 ++++++++++------------
 src/blackmisc/network/networkutils.cpp     |  9 ++--
 4 files changed, 38 insertions(+), 41 deletions(-)

diff --git a/src/blackcore/application.cpp b/src/blackcore/application.cpp
index 8a966ba21..9065c75de 100644
--- a/src/blackcore/application.cpp
+++ b/src/blackcore/application.cpp
@@ -426,11 +426,12 @@ namespace BlackCore
     CStatusMessageList CApplication::waitForSetup(int timeoutMs)
     {
         if (!m_setupReader) { return CStatusMessage(this).error(u"No setup reader"); }
-        CEventLoop::processEventsUntil(this, &CApplication::setupHandlingCompleted, timeoutMs, [this]
+        CEventLoop eventLoop;
+        eventLoop.stopWhen(this, &CApplication::setupHandlingCompleted);
+        if (!m_setupReader->isSetupAvailable())
         {
-            // init, if this is true event queue is not started
-            return m_setupReader->isSetupAvailable();
-        });
+            eventLoop.exec(timeoutMs);
+        }
 
         // setup handling completed with success or failure, or we run into time out
         CStatusMessageList msgs;
diff --git a/src/blackcore/db/backgrounddataupdater.cpp b/src/blackcore/db/backgrounddataupdater.cpp
index b11cfdd6d..a9364128a 100644
--- a/src/blackcore/db/backgrounddataupdater.cpp
+++ b/src/blackcore/db/backgrounddataupdater.cpp
@@ -152,7 +152,8 @@ namespace BlackCore::Db
             {
                 // just give the system some time to relax, consolidation is time consuming
                 if (!this->doWorkCheck()) { return; }
-                CEventLoop::processEventsFor(1000);
+                CEventLoop eventLoop;
+                eventLoop.exec(1000);
             }
         }
     }
diff --git a/src/blackmisc/eventloop.h b/src/blackmisc/eventloop.h
index 83209e05f..686d0ec34 100644
--- a/src/blackmisc/eventloop.h
+++ b/src/blackmisc/eventloop.h
@@ -25,47 +25,41 @@ namespace BlackMisc
     class CEventLoop
     {
     public:
-        //! Deleted constructor
-        CEventLoop() = delete;
-
-        //! Wait for the given time, while processing events.
-        static void processEventsFor(int timeoutMs)
-        {
-            QEventLoop eventLoop;
-            QTimer::singleShot(timeoutMs, &eventLoop, &QEventLoop::quit);
-            eventLoop.exec();
-        }
-
-        //! Block, but keep processing events, until sender emits the signal or the timeout expires.
-        //! Return true if the signal was emitted, false if the timeout expired.
+        //! Event loop will stop if the given signal is received.
         template <typename T, typename F>
-        static bool processEventsUntil(const T *sender, F signal, int timeoutMs)
+        void stopWhen(const T *sender, F signal)
         {
-            return processEventsUntil(sender, signal, timeoutMs, [] {});
+            QObject::connect(sender, signal, &m_eventLoop, [this] { m_eventLoop.exit(GotSignal); });
         }
 
-        //! Overloaded version that executes an initial function after connecting the signal.
-        //! If the function's return type is convertible to bool, and it evaluates to true,
-        //! then the waiting will immediately time out and return true.
+        //! Event loop will stop if the given signal is received and condition returns true.
         template <typename T, typename F1, typename F2>
-        static bool processEventsUntil(const T *sender, F1 signal, int timeoutMs, F2 init)
+        void stopWhen(const T *sender, F1 signal, F2 &&condition)
         {
-            QEventLoop eventLoop;
-            bool result = false;
-            QObject::connect(sender, signal, &eventLoop, [ & ]
+            QObject::connect(sender, signal, &m_eventLoop, [this, condition = std::forward<F2>(condition)](auto &&... args)
             {
-                result = true;
-                eventLoop.quit();
+                if (condition(std::forward<decltype(args)>(args)...)) { m_eventLoop.exit(GotSignal); }
             });
-            if constexpr (std::is_void_v<decltype(init())>) { init(); }
-            else if (init()) { return true; }
-            if (timeoutMs > 0)
-            {
-                QTimer::singleShot(timeoutMs, &eventLoop, &QEventLoop::quit);
-            }
-            eventLoop.exec();
-            return result;
         }
+
+        //! Begin processing events until the timeout or stop condition occurs.
+        //! \return True if the signal was received, false if it timed out.
+        bool exec(int timeoutMs)
+        {
+            if (timeoutMs >= 0)
+            {
+                QTimer::singleShot(timeoutMs, &m_eventLoop, [this] { m_eventLoop.exit(TimedOut); });
+            }
+            return m_eventLoop.exec() == GotSignal;
+        }
+
+    private:
+        enum Result
+        {
+            GotSignal = 0,
+            TimedOut,
+        };
+        QEventLoop m_eventLoop;
     };
 } // ns
 
diff --git a/src/blackmisc/network/networkutils.cpp b/src/blackmisc/network/networkutils.cpp
index af0e865c1..1b9a3643f 100644
--- a/src/blackmisc/network/networkutils.cpp
+++ b/src/blackmisc/network/networkutils.cpp
@@ -81,10 +81,11 @@ namespace BlackMisc::Network
         QObject::connect(&socket, &QTcpSocket::connected, &mapper, qOverload<>(&QSignalMapper::map));
         QObject::connect(&socket, qOverload<QAbstractSocket::SocketError>(&QTcpSocket::error), &mapper, qOverload<>(&QSignalMapper::map));
         mapper.setMapping(&socket, 0);
-        const bool timedOut = !CEventLoop::processEventsUntil(&mapper, qOverload<int>(&QSignalMapper::mapped), timeoutMs, [&]
-        {
-            socket.connectToHost(hostAddress, static_cast<quint16>(port));
-        });
+
+        CEventLoop eventLoop;
+        eventLoop.stopWhen(&mapper, qOverload<int>(&QSignalMapper::mapped));
+        socket.connectToHost(hostAddress, static_cast<quint16>(port));
+        const bool timedOut = !eventLoop.exec(timeoutMs);
 
         if (socket.state() != QTcpSocket::ConnectedState)
         {