get-create-index-progress.js

/**
 * @param {mongodb#Database} db
 * @param {String} ns `${db}.${collection}` See http://npm.im/mongodb-ns
 * @param {String} name - The index name to get progress on.
 *
 * @see https://docs.mongodb.com/v3.0/reference/method/db.currentOp/#active-indexing-operations
 */
function getIndexBuildProgress(db, ns, name) {
  /**
   * TODO (imlucas) Update query to constrain on `name`.
   */
  const query = {
    ns: ns,
    $or: [
      {op:"query", "query.createIndexes":{$exists: true}},
      {op: "insert", ns: /\.system\.indexes\b/}
    ]
  };
  
  /**
   * Result struct:
   *
   *  const res = {
   *    state: 'UNKNOWN',
   *    message: '',
   *    completed: 0,
   *    total: 0,
   *    indeterminate: false
   *  };
   */

  const onNoResults = () => {
    getIndexDetails(ns, name, (err, index) => {
      if (err) {
        return done(err);
      }

      if (index) {
        return done(null, {
          state: 'COMPLETE',
          message: `${name} on ${ns} has been built successfully!`
        });
      }

      return done(null, {
        state: 'UNKNOWN',
        indeterminate: true,
        message: `The current status of building ${name} on ${ns} could not be determined`
      });
    });
  };

  db.currentOp(query, (err, ops) => {
    if (err) {
      if (isNotAuthorized(err)) {
        return done(null, {
          state: 'UNAUTHORIZED',
          indeterminate: true,
          message: `Building ${name} on ${ns}`
        });
      }
      return done(err);
    }
    
    if (ops.length === 0) {
      return onNoResults();
    }

    if (ops.length > 1) {
      warn(`Expected to get single result from currentOp but got ${ops.length}`);
    }
    
    const op = _.first(ops);

    /**
     * @see also 
     * - https://www.npmjs.com/package/request-progress
     * - https://www.npmjs.com/package/progress
     */
     
    return done(null, {
      state: 'PROGRESS',
      completed: op.done,
      total: op.total,
      message: op.msg
    });
  });
}