Fix the issues with QTimer start/stop in different thread

Author: wonder-sk

src/core/qgsconnectionpool.h

@@ -43,6 +43,9 @@
  * - being derived from QObject
  * - calling initTimer( this ) in constructor
  * - having handleConnectionExpired() slot that calls onConnectionExpired()
+ * - having startExpirationTimer(), stopExpirationTimer() slots to start/stop the expiration timer
+ *
+ * For an example on how to use the template class, have a look at the implementation in postgres/spatialite providers.
  */
 template <typename T>
 class QgsConnectionPoolGroup
@@ -88,10 +91,8 @@ class QgsConnectionPoolGroup
           // no need to run if nothing can expire
           if ( conns.isEmpty() )
           {
-            if ( QThread::currentThread() == qApp->thread() )
-              expirationTimer->stop();
-            else
-              QgsDebugMsg( "expirationTimer not stopped from thread" );  // TODO use signals in that case?
+            // will call the slot directly or queue the call (if the object lives in a different thread)
+            QMetaObject::invokeMethod( expirationTimer->parent(), "stopExpirationTimer" );
           }
 
           return i.c;
@@ -120,10 +121,8 @@ class QgsConnectionPoolGroup
 
       if ( !expirationTimer->isActive() )
       {
-        if ( QThread::currentThread() == qApp->thread() )
-          expirationTimer->start();
-        else
-          QgsDebugMsg( "expirationTimer not started from thread" );  // TODO use signals in that case?
+        // will call the slot directly or queue the call (if the object lives in a different thread)
+        QMetaObject::invokeMethod( expirationTimer->parent(), "startExpirationTimer" );
       }
 
       connMutex.unlock();

src/providers/postgres/qgspostgresconnpool.h

@@ -46,6 +46,8 @@ class QgsPostgresConnPoolGroup : public QObject, public QgsConnectionPoolGroup<Q
 
   protected slots:
     void handleConnectionExpired() { onConnectionExpired(); }
+    void startExpirationTimer() { expirationTimer->start(); }
+    void stopExpirationTimer() { expirationTimer->stop(); }
 
   protected:
     Q_DISABLE_COPY( QgsPostgresConnPoolGroup )

src/providers/spatialite/qgsspatialiteconnpool.h

@@ -45,6 +45,8 @@ class QgsSpatiaLiteConnPoolGroup : public QObject, public QgsConnectionPoolGroup
 
   protected slots:
     void handleConnectionExpired() { onConnectionExpired(); }
+    void startExpirationTimer() { expirationTimer->start(); }
+    void stopExpirationTimer() { expirationTimer->stop(); }
 
   protected:
     Q_DISABLE_COPY( QgsSpatiaLiteConnPoolGroup )