createForwarder.js

var createForwarder = function(path) {
  var forwardToGolangProcess = function(event, context, metricName)
  {
    if (!golangProcess) {
      ensureGoLangBinary(function() {
        golangProcess = child_process.spawn(SPARTA_BINARY_PATH, ['execute', '--signal', process.pid], {});

        golangProcess.stdout.on('data', function(buf) {
          buf.toString('utf-8').split('\n').forEach(function (eachLine) {
            sparta_utils.log(eachLine);
          });
        });
        golangProcess.stderr.on('data', function(buf) {
          buf.toString('utf-8').split('\n').forEach(function (eachLine) {
            sparta_utils.log(eachLine);
          });
        });

        var terminationHandler = function(eventName) {
          return function(value) {
            var onPosted = function() {
              console.error(util.format('Sparta %s: %s\n', eventName.toUpperCase(), JSON.stringify(value)));
              failCount += 1;
              if (failCount > MAXIMUM_RESPAWN_COUNT) {
                process.exit(1);
              }
              golangProcess = null;
              forwardToGolangProcess(null, null, METRIC_NAMES.TERMINATED);
            };
            postMetricCounter(METRIC_NAMES.TERMINATED, onPosted);
          };
        };
        golangProcess.on('error', terminationHandler('error'));
        golangProcess.on('exit', terminationHandler('exit'));
        process.on('exit', function() {
          if (golangProcess) {
            golangProcess.kill();
          }
        });
        var golangProcessReadyHandler = function() {
          process.removeListener('SIGUSR2', golangProcessReadyHandler);
          forwardToGolangProcess(event, context, METRIC_NAMES.CREATED);
        };
        process.on('SIGUSR2', golangProcessReadyHandler);
      });
    }
    else if (event && context)
    {
      postMetricCounter(metricName || METRIC_NAMES.REUSED);
      makeRequest(path, event, context);
    }
  };
  return forwardToGolangProcess;
};