Optimisation

Signed-off-by: JCW <a1q123456@users.noreply.github.com>

src/libxrpl/beast/utility/beast_Journal.cpp

@@ -131,6 +131,7 @@ Journal::JsonLogContext::reset(
         ThreadIdStringInitializer()
         {
             std::stringstream threadIdStream;
+            threadIdStream.imbue(std::locale::classic());
             threadIdStream << std::this_thread::get_id();
             value = threadIdStream.str();
         }

src/tests/libxrpl/basics/log.cpp

@@ -209,6 +209,41 @@ TEST_CASE("Global attributes inheritable")
     beast::Journal::disableStructuredJournal();
 }
 
+TEST_CASE("Test JsonWriter")
+{
+    {
+        std::ostringstream stream;
+        beast::SimpleJsonWriter writer{stream};
+
+        writer.writeString("\n");
+        CHECK(writer.str() == "\"\\n\"");
+    }
+
+    {
+        std::ostringstream stream;
+        beast::SimpleJsonWriter writer{stream};
+
+        writer.writeString("\t");
+        CHECK(writer.str() == "\"\\t\"");
+    }
+
+    {
+        std::ostringstream stream;
+        beast::SimpleJsonWriter writer{stream};
+
+        writer.writeString(std::string_view{"\0", 1});
+        CHECK(writer.str() == "\"\\u0000\"");
+    }
+
+    {
+        std::ostringstream stream;
+        beast::SimpleJsonWriter writer{stream};
+
+        writer.writeString("\"\\");
+        CHECK(writer.str() == "\"\\\"\\\\\"");
+    }
+}
+
 /**
  * @brief sink for writing all log messages to a stringstream
  */