Stop MainWorker after RoutingWorkers

This allows normal operation during the shutdown. This fixes the problem
where mxs_clock would not get updated after the shutdown was initiated.

include/maxscale/mainworker.hh

@@ -140,6 +140,9 @@ private:
     bool balance_workers_dc(Worker::Call::action_t action);
     void order_balancing_dc();
 
+    // Waits until all RoutingWorkers have stopped and then stops the MainWorker
+    bool wait_for_shutdown(Worker::Call::action_t action);
+
     std::map<std::string, Task> m_tasks_by_name;
     IndexedStorage              m_storage;
     uint32_t                    m_rebalancing_dc {0};

include/maxscale/routingworker.hh

@@ -262,6 +262,11 @@ public:
      */
     static void join_workers();
 
+    /**
+     * Check if all workers have finished shutting down
+     */
+    static bool shutdown_complete();
+
     /**
      * Posts a task to all workers for execution.
      *

server/core/mainworker.cc

@@ -312,12 +312,26 @@ void MainWorker::start_shutdown()
             // will exit the event loop.
             mxs::RoutingWorker::start_shutdown();
 
-            // Stop the MainWorker now that shutdown has been started
-            MainWorker::get()->shutdown();
+            // Wait until RoutingWorkers have stopped before proceeding with MainWorker shudown
+            auto self = MainWorker::get();
+            self->delayed_call(100, &MainWorker::wait_for_shutdown, self);
         };
 
     MainWorker::get()->execute(func, EXECUTE_QUEUED);
 }
+
+bool MainWorker::wait_for_shutdown(Call::action_t action)
+{
+    if (action == Call::EXECUTE)
+    {
+        if (RoutingWorker::shutdown_complete())
+        {
+            shutdown();
+        }
+    }
+
+    return true;
+}
 }
 
 extern "C"

server/core/routingworker.cc

@@ -407,6 +407,25 @@ void RoutingWorker::join_workers()
     this_unit.running = false;
 }
 
+// static
+bool RoutingWorker::shutdown_complete()
+{
+    bool rval = true;
+
+    for (int i = this_unit.id_min_worker; i <= this_unit.id_max_worker; i++)
+    {
+        RoutingWorker* pWorker = this_unit.ppWorkers[i];
+        mxb_assert(pWorker);
+
+        if (pWorker->state() != Worker::FINISHED && pWorker->state() != Worker::STOPPED)
+        {
+            rval = false;
+        }
+    }
+
+    return rval;
+}
+
 RoutingWorker::SessionsById& RoutingWorker::session_registry()
 {
     return m_sessions;