transformerServer.js

const cluster = require("cluster");
const http = require("http");
const numCPUs = require("os").cpus().length;
var url = require("url");
var jsonQ = require("jsonq");

function start(port, route) {
  if (cluster.isMaster) {
    console.log(`Master ${process.pid} is running`);

    // Fork workers.
    for (let i = 0; i < numCPUs; i++) {
      cluster.fork();
    }

    cluster.on("exit", (worker, code, signal) => {
      console.log(`worker ${worker.process.pid} died`);
    });
  } else {
    // Main server body
    http
      .createServer(function(request, response) {
        var pathname = url.parse(request.url).pathname;

        // Adding logic for a call that will invalidate cache
        // for particular module in order that next require call for
        // that module will reload the same
        if (request.method == "POST" && pathname != "/reload") {
          var body = "";
          var respBody = "";

          request.on("data", function(data) {
            body += data;

            // Too much POST data, kill the connection!
            // 1e6 === 1 * Math.pow(10, 6) === 1 * 1000000 ~~~ 1MB
            if (body.length > 1e8) request.connection.destroy();
          });

          request.on("end", async function() {
            try {
              // need to send 400 error for malformed JSON
              // respJson = await route(pathname, request, response, body);
              // var respList = "[" + respJson + "]"; //caller expects list
              var respList;
              respList = route(pathname, request, response, body)
                .then(function(result) {
                  console.log("result", result);
                  console.log("string", String(result));

                  respList = "[" + String(result) + "]";
                  console.log(respList);
                  response.statusCode = 200;
                  response.end(respList);
                })
                .catch(function(error) {
                  response.statusCode = 500; // 500 for other errors
                  response.statusMessage = error.message;
                  response.end('[{"error":"Invalid Input"}]');
                });
            } catch (se) {
              switch (se.constructor.name) {
                case "RangeError":
                  response.statusCode = 400; // 400 for unexpected value as well
                  response.statusMessage = se.message;
                  break;
                case "SyntaxError":
                  console.log(se.message);
                  response.statusCode = 400; // 400 for JSON syntax error
                  response.statusMessage =
                    "Malformed JSON payload " + se.message;
                  break;
                default:
                  response.statusCode = 500; // 500 for other errors
                  response.statusMessage = se.message;
                  console.log(se.stack);
              }
              response.end();
            }
          });
          // logic for module cache invalidation
        } else if (pathname == "/reload") {
          var query = url.parse(request.url, true).query;
          delete require.cache[
            require.resolve("./" + query.version + "/" + query.name + ".js")
          ];
          response.statusCode = 200;
          response.end();
        }
      })
      .listen(port);
    console.log(`Worker ${process.pid} started`);
  }
  console.log("transformerServer: started");
}

exports.start = start;