Add option to node bindings to return result as a pre-generated JSON string (this avoids a lot of overhead, and moves JSON string rendering out of the main event loop).

src/nodejs/node_osrm.cpp

@@ -9,12 +9,15 @@
 #include "osrm/trip_parameters.hpp"
 
 #include <exception>
+#include <sstream>
 #include <type_traits>
 #include <utility>
 
 #include "nodejs/node_osrm.hpp"
 #include "nodejs/node_osrm_support.hpp"
 
+#include "util/json_renderer.hpp"
+
 namespace node_osrm
 {
 
@@ -122,6 +125,8 @@ inline void async(const Nan::FunctionCallbackInfo<v8::Value> &info,
     if (!params)
         return;
 
+    auto pluginParams = argumentsToPluginParameters(info);
+
     BOOST_ASSERT(params->IsValid());
 
     if (!info[info.Length() - 1]->IsFunction())
@@ -137,9 +142,89 @@ inline void async(const Nan::FunctionCallbackInfo<v8::Value> &info,
         Worker(std::shared_ptr<osrm::OSRM> osrm_,
                ParamPtr params_,
                ServiceMemFn service,
-               Nan::Callback *callback)
+               Nan::Callback *callback,
+               PluginParameters pluginParams_)
             : Base(callback), osrm{std::move(osrm_)}, service{std::move(service)},
-              params{std::move(params_)}
+              params{std::move(params_)}, pluginParams{std::move(pluginParams_)}
+        {
+        }
+
+        void Execute() override try
+        {
+            osrm::json::Object r;
+            const auto status = ((*osrm).*(service))(*params, r);
+            ParseResult(status, r);
+            if (pluginParams.renderJSONToBuffer)
+            {
+                std::ostringstream buf;
+                osrm::util::json::render(buf, r);
+                result = buf.str();
+            }
+            else
+            {
+                result = r;
+            }
+        }
+        catch (const std::exception &e)
+        {
+            SetErrorMessage(e.what());
+        }
+
+        void HandleOKCallback() override
+        {
+            Nan::HandleScope scope;
+
+            const constexpr auto argc = 2u;
+            v8::Local<v8::Value> argv[argc] = {Nan::Null(), render(result)};
+
+            callback->Call(argc, argv);
+        }
+
+        // Keeps the OSRM object alive even after shutdown until we're done with callback
+        std::shared_ptr<osrm::OSRM> osrm;
+        ServiceMemFn service;
+        const ParamPtr params;
+        const PluginParameters pluginParams;
+
+        ObjectOrString result;
+    };
+
+    auto *callback = new Nan::Callback{info[info.Length() - 1].As<v8::Function>()};
+    Nan::AsyncQueueWorker(
+        new Worker{self->this_, std::move(params), service, callback, std::move(pluginParams)});
+}
+
+template <typename ParameterParser, typename ServiceMemFn>
+inline void asyncForTiles(const Nan::FunctionCallbackInfo<v8::Value> &info,
+                          ParameterParser argsToParams,
+                          ServiceMemFn service,
+                          bool requires_multiple_coordinates)
+{
+    auto params = argsToParams(info, requires_multiple_coordinates);
+    if (!params)
+        return;
+
+    auto pluginParams = argumentsToPluginParameters(info);
+
+    BOOST_ASSERT(params->IsValid());
+
+    if (!info[info.Length() - 1]->IsFunction())
+        return Nan::ThrowTypeError("last argument must be a callback function");
+
+    auto *const self = Nan::ObjectWrap::Unwrap<Engine>(info.Holder());
+    using ParamPtr = decltype(params);
+
+    struct Worker final : Nan::AsyncWorker
+    {
+        using Base = Nan::AsyncWorker;
+
+        Worker(std::shared_ptr<osrm::OSRM> osrm_,
+               ParamPtr params_,
+               ServiceMemFn service,
+               Nan::Callback *callback,
+               PluginParameters pluginParams_)
+            : Base(callback), osrm{std::move(osrm_)}, service{std::move(service)},
+              params{std::move(params_)}, pluginParams{std::move(pluginParams_)}
         {
         }
 
@@ -167,18 +252,14 @@ inline void async(const Nan::FunctionCallbackInfo<v8::Value> &info,
         std::shared_ptr<osrm::OSRM> osrm;
         ServiceMemFn service;
         const ParamPtr params;
+        const PluginParameters pluginParams;
 
-        // All services return json::Object .. except for Tile!
-        using ObjectOrString =
-            typename std::conditional<std::is_same<ParamPtr, tile_parameters_ptr>::value,
-                                      std::string,
-                                      osrm::json::Object>::type;
-
-        ObjectOrString result;
+        std::string result;
     };
 
     auto *callback = new Nan::Callback{info[info.Length() - 1].As<v8::Function>()};
-    Nan::AsyncQueueWorker(new Worker{self->this_, std::move(params), service, callback});
+    Nan::AsyncQueueWorker(
+        new Worker{self->this_, std::move(params), service, callback, std::move(pluginParams)});
 }
 
 // clang-format off
@@ -341,7 +422,7 @@ NAN_METHOD(Engine::table) //
 // clang-format on
 NAN_METHOD(Engine::tile)
 {
-    async(info, &argumentsToTileParameters, &osrm::OSRM::Tile, {/*unused*/});
+    asyncForTiles(info, &argumentsToTileParameters, &osrm::OSRM::Tile, {/*unused*/});
 }
 
 // clang-format off