refactor: removed async module usage

[vijay-qlogic]

Fixes #2883 (it's a good idea to open an issue first for discussion)

• Tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

[romlogic]

line 24. the link is not working, and please add a full stop (period) for all the comments with complete sentences as some of them have full stops (line 33), and others don't.

[vijay-qlogic]

Done!
comments from line-21 to line-23 is single sentence, so not added full stop (period) there, elsewhere it's added.
link update to https://cloud.google.com/docs/authentication/getting-started, this page speaks as per the comments.

bb6ccac

[AVaksman]

Same comment here, I think you can just return Promise.all(taskss);
and line 83 make into
Index.prototype.lookup = async words => {

[vijay-qlogic]

Done! bb6ccac

[AVaksman]

I think you can just return Promise.all(tasks); here
and on line 60 make it into an async function
Index.prototype.add = async (filename, document) => {

[vijay-qlogic]

Done !
bb6ccac

[AVaksman]

for getTextFromFiles() function:
refactor to

async function getTextFromFiles(index, inputFiles) {
  // Make a call to the Vision API to detect text
  const requests = inputFiles.map(filename => {
    return {
      image: {content: fs.readFileSync(filename).toString('base64')},
      features: [{type: 'TEXT_DETECTION'}],
    };
  });
  const [results] = await client.batchAnnotateImages({requests: requests});
  const detections = results[0].responses;
  const textResponse = {};
  const tasks = inputFiles.map((filename, i) => {
    const response = detections[i];
    if (response.error) {
      console.log('API Error for ' + filename, response.error);
      return;
    } else if (Array.isArray(response)) {
      textResponse[filename] = 1;
    } else {
      textResponse[filename] = 0;
    }
    return cb => extractDescriptions(filename, index, response, cb);
  });
  return Promise.all(tasks);
}

[AVaksman]

refactor main function to

// Run the example
async function main(inputDir) {
  const index = new Index();
  // Scan the specified directory for files
  const files = fs.readdirSync(inputDir);
  // Separate directories from files
  const allImageFiles = files.map(file => {
    const filename = path.join(inputDir, file);
    if (!fs.statSync(filename).isDirectory()) {
      return filename;
    }
  });
  // Figure out which files have already been processed
  const tasks = allImageFiles
    .filter(filename => filename)
    .map(filename => {
      return cb => {
        index.documentIsProcessed(filename, function(err, processed) {
          if (err) {
            return cb(err);
          }
          if (!processed) {
            // Forward this filename on for further processing
            return cb(null, filename);
          }
          cb();
        });
      };
    });
  // Analyze any remaining unprocessed files
  const imageFilesToProcess = await Promise.all(tasks).filter(
    filename => filename
  );
  if (imageFilesToProcess.length) {
    return getTextFromFiles(index, imageFilesToProcess);
  }
  console.log('All files processed!');
  return Promise.resolve();
}

[AVaksman]

after proposed refactoring promisify is not needed any more, please remove it.

[vijay-qlogic]

Done!

[AVaksman]

This task was completed by JustinBeckwith as part of a bigger PR.
googleapis#297

[vijay-qlogic]

Alright! Closing this PR then.