Use early exit/continue to simplify code and reduce indentation, move increase/decrease query count into functions

Library/OSRM_impl.cpp

@@ -100,12 +100,49 @@ void OSRM_impl::RegisterPlugin(BasePlugin *plugin)
 
 int OSRM_impl::RunQuery(RouteParameters &route_parameters, JSON::Object &json_result)
 {
-    const PluginMap::const_iterator &iter = plugin_map.find(route_parameters.service);
+    const auto &plugin_iterator = plugin_map.find(route_parameters.service);
 
-    if (plugin_map.end() != iter)
+    if (plugin_map.end() == plugin_iterator)
     {
-        if (barrier)
+        return 400;
+    }
+
+    increase_concurrent_query_count();
+    plugin_iterator->second->HandleRequest(route_parameters, json_result);
+    decrease_concurrent_query_count();
+    return 200;
+}
+
+// decrease number of concurrent queries
+void OSRM_impl::decrease_concurrent_query_count()
 {
+    if (!barrier)
+    {
+        return;
+    }
+    // lock query
+    boost::interprocess::scoped_lock<boost::interprocess::named_mutex> query_lock(
+        barrier->query_mutex);
+
+    // decrement query count
+    --(barrier->number_of_queries);
+    BOOST_ASSERT_MSG(0 <= barrier->number_of_queries, "invalid number of queries");
+
+    // notify all processes that were waiting for this condition
+    if (0 == barrier->number_of_queries)
+    {
+        barrier->no_running_queries_condition.notify_all();
+    }
+}
+
+// increase number of concurrent queries
+void OSRM_impl::increase_concurrent_query_count()
+{
+    if (!barrier)
+    {
+        return;
+    }
+
     // lock update pending
     boost::interprocess::scoped_lock<boost::interprocess::named_mutex> pending_lock(
         barrier->pending_update_mutex);
@@ -124,30 +161,7 @@ int OSRM_impl::RunQuery(RouteParameters &route_parameters, JSON::Object &json_re
         ->CheckAndReloadFacade();
 }
 
-        iter->second->HandleRequest(route_parameters, json_result);
-        if (barrier)
-        {
-            // lock query
-            boost::interprocess::scoped_lock<boost::interprocess::named_mutex> query_lock(
-                barrier->query_mutex);
-
-            // decrement query count
-            --(barrier->number_of_queries);
-            BOOST_ASSERT_MSG(0 <= barrier->number_of_queries, "invalid number of queries");
-
-            // notify all processes that were waiting for this condition
-            if (0 == barrier->number_of_queries)
-            {
-                barrier->no_running_queries_condition.notify_all();
-            }
-        }
-        return 200;
-    }
-    return 400;
-}
-
 // proxy code for compilation firewall
-
 OSRM::OSRM(libosrm_config &lib_config)
     : OSRM_pimpl_(osrm::make_unique<OSRM_impl>(lib_config))
 {

Library/OSRM_impl.h

@@ -62,6 +62,11 @@ class OSRM_impl
     std::unique_ptr<SharedBarriers> barrier;
     // base class pointer to the objects
     BaseDataFacade<QueryEdge::EdgeData> *query_data_facade;
+
+    // decrease number of concurrent queries
+    void decrease_concurrent_query_count();
+    // increase number of concurrent queries
+    void increase_concurrent_query_count();
 };
 
 #endif // OSRM_IMPL_H