var countWords = function()

in aws-blog-lambda-map-reduce-streaming/wordcount.js [25:86]
57 lines of code
6 McCabe index (conditional complexity)

  var countWords = function(srcKey, cb){
    try {      
      var lineCount = 0;
      var totalWords = 0;
      var finished = false;
      var warning = '';

      // Create our processor that splits lines/words
      var lineSplitter = es.split();
      lineSplitter.on('data', function(line){
        lineCount++;
        totalWords += line.split(/\W/).length;
        // Check our execution time
        var timeDiff = process.hrtime(startTime);
        if (timeDiff[0] >= MAX_EXEC_TIME){
          var msg = 'Hit max execution time of ' + MAX_EXEC_TIME +
            ' seconds, sending incomplete results.';
          console.error(msg);
          warning = msg;
          this.end();
        }
      })
      .on('error', function(err){
        console.error('Error in lineSplitter: ' + err);
      })
      .on('end', function(err){
        if (finished) return;
        if (err){
          console.error(err);
          cb(err, null);
          return;
        }
        console.log('Finished ' + srcKey + ' with ' +
          totalWords + ' in ' + lineCount + ' lines');
        cb(null, [srcKey, totalWords, lineCount, warning]);
        finished = true;
      });

      console.log('Downloading key ' + srcKey);
      // Create our pipeline
      if (srcKey.match(/\.gz/)){
        s3.getObject({
          Bucket: srcBucket,
          Key: srcKey
        })
          .createReadStream()
          .pipe(zlib.createGunzip())
          .pipe(lineSplitter);
      }
      else {
        s3.getObject({
          Bucket: srcBucket,
          Key: srcKey
        })
          .createReadStream()
          .pipe(lineSplitter);
      }
    } catch (e) {
      console.error(e);
      cb(e, null);
    }
  };