Start housekeeper before services

The housekeeper needs to be initialized before services are started.

server/core/gateway.cc

@@ -2142,6 +2142,15 @@ int main(int argc, char **argv)
         goto return_main;
     }
 
+    // Start the housekeeper thread
+    if (!hkinit())
+    {
+        const char* logerr = "Failed to start housekeeper thread.";
+        print_log_n_stderr(true, true, logerr, logerr, 0);
+        rc = MAXSCALE_INTERNALERROR;
+        goto return_main;
+    }
+
     /** Start all monitors */
     monitorStartAll();
 
@@ -2176,17 +2185,6 @@ int main(int argc, char **argv)
         goto return_main;
     }
 
-    /*
-     * Start the housekeeper thread
-     */
-    if (!hkinit())
-    {
-        const char* logerr = "Failed to start housekeeper thread.";
-        print_log_n_stderr(true, true, logerr, logerr, 0);
-        rc = MAXSCALE_INTERNALERROR;
-        goto return_main;
-    }
-
     /*<
      * Start the routing workers running in their own thread.
      */

server/core/housekeeper.cc

@@ -256,12 +256,14 @@ json_t* Housekeeper::tasks_json(const char* host)
 
 void hktask_add(const char *name, TASKFN func, void *data, int frequency)
 {
+    ss_dassert(hk);
     Task task(name, func, data, frequency);
     hk->add(task);
 }
 
 void hktask_remove(const char *name)
 {
+    ss_dassert(hk);
     hk->remove(name);
 }
 
@@ -293,6 +295,7 @@ bool hkinit()
 
 void hkshutdown()
 {
+    ss_dassert(hk);
     hk->stop();
 }
 
@@ -306,10 +309,12 @@ void hkfinish()
 
 void hkshow_tasks(DCB *pDcb)
 {
+    ss_dassert(hk);
     hk->print_tasks(pDcb);
 }
 
 json_t* hk_tasks_json(const char* host)
 {
+    ss_dassert(hk);
     return hk->tasks_json(host);
 }