add comments

.github/workflows/osrm-backend.yml

@@ -715,6 +715,7 @@ jobs:
         pushd ${OSRM_BUILD_DIR}
         make --jobs=${JOBS} benchmarks
         ./src/benchmarks/alias-bench 
+        ./src/benchmarks/json-render-bench
         ./src/benchmarks/match-bench ../test/data/ch/monaco.osrm
         ./src/benchmarks/packedvector-bench
         ./src/benchmarks/rtree-bench ../test/data/monaco.osrm.ramIndex ../test/data/monaco.osrm.fileIndex ../test/data/monaco.osrm.nbg_nodes

include/util/json_renderer.hpp

@@ -34,10 +34,11 @@ template <typename Out> struct Renderer
     void operator()(const String &string)
     {
         write('"');
+        // here we assume that vast majority of strings don't need to be escaped,
+        // so we check it first and escape only if needed
         auto size = SizeOfEscapedJSONString(string.value);
         if (size == string.value.size())
         {
-            // we don't need to escape anything
             write(string.value);
         }
         else

src/benchmarks/json_render.cpp

@@ -106,7 +106,8 @@ int main(int, char **)
     TIMER_STOP(vector);
     std::cout << "Vector: " << TIMER_MSEC(vector) << "ms" << std::endl;
 
-    if (std::string{out_vec.begin(), out_vec.end()} != out_str || out_str != out_ss_str) {
+    if (std::string{out_vec.begin(), out_vec.end()} != out_str || out_str != out_ss_str)
+    {
         throw std::logic_error("Vector/stringstream/string results are not equal");
     }
     return EXIT_SUCCESS;