Upon destruction, sigslot signals now wait for the signal_manager's signal...

Upon destruction, sigslot signals now wait for the signal_manager's signal queue to be flushed. This avoids crashed due to the signal_manager processing dangling signals, which have been deleted while being in the queue.

ext/sigslot/sigslot.cpp

@@ -98,6 +98,36 @@ namespace sigslot {
         _handlingMode = mode;
     }
 
+    void signal_manager::waitForSignalQueueFlushed() {
+        // nothing to wait for if current thread is signal_manager's thread.
+        if (isCurrentThreadSignalManagerThread())
+            return;
+
+        // nothing to wait for if the signal queue is already empty.
+        if (_signalQueue.empty())
+            return;
+
+        class SIGSLOT_API flushed_signal : public _signal_handle_base {
+        public:
+            flushed_signal(bool* ptr)
+                : _ptr(ptr)
+            {}
+
+            ~flushed_signal() {}
+
+            virtual void processSignal() const {
+                *_ptr = true;
+            }
+
+        private:
+            bool* _ptr;
+        };
+
+        bool signalVariable = false;
+        this->queueSignalImpl(new flushed_signal(&signalVariable));
+        while (! signalVariable)
+            std::this_thread::yield(); // so we do some busy waiting here - hopefully not too long...
+    }
 
     const std::string signal_manager::loggerCat_;
 

ext/sigslot/sigslot.h

@@ -346,6 +346,13 @@ namespace sigslot {
         /// \see Runnable:run
         virtual void run();
 
+
+        /**
+         * Halts the calling thread until the current signal queue has been flushed.
+         * Flushing means that all signals currently in the signal queue have been fully handled.
+         */
+        void waitForSignalQueueFlushed();
+
     private:
         /// Private constructor only for singleton
         signal_manager();
@@ -444,6 +451,11 @@ namespace sigslot {
     class SIGSLOT_API _signal_base
     {
     public:
+        ~_signal_base() {
+            if (signal_manager::isInited())
+                signal_manager::getRef().waitForSignalQueueFlushed();
+        }
+
         virtual void slot_disconnect(has_slots* pslot) = 0;
         virtual void slot_duplicate(has_slots const* poldslot, has_slots* pnewslot) = 0;