search-destination-cache/lib/redis/index.js

Search destinations by name, address, point of interest or coordinates. Using Redis DB for caching.

/**
 * Client for work with redis as singleton
 *
 * Using:
 *  require('./').getInstance({
 *    // specify redis options here
 *  });
 */

var redis = require('redis');
var _ = require('underscore');

var RedisError = require('./error');

/**
 * Constructor - create a client for work with Redis
 */
function Client (_options) {
  if (Client.caller != Client.getInstance) {
    throw new RedisError('Redis client cannot be instanciated');
  }

  this._useOptions(_options);
  this._initClient();
}

/**
 * Enter point - get instance of client
 */
Client.getInstance = function (options) {
  return new Client(options)._getClient();
};

Client.prototype._useOptions = function (_options) {
  this.options = _.extend({}, _options);
};

Client.prototype._initClient = function () {
  var port = process.env.REDIS_PORT;
  var host = process.env.REDIS_HOST;
  var dbIndex = process.env.REDIS_DB_INDEX_SD; // database index for search destination
  var password = process.env.REDIS_PASSWORD;
  var debug = Boolean(process.env.REDIS_DEBUG);

  if (debug || this._getOptions().debug_mode) {
    redis.debug_mode = true;
  }

  try {
    this._client = new redis.createClient(port, host, this._getOptions());

    this._getClient().on('error', function (error) {
      throw error;
    });

    if (password) {
      this._getClient().auth(password, function (error) {
        if (error) {
          throw new RedisError(error.message);
        }
      });
    }

    if (dbIndex) {
      this._getClient().select(dbIndex, function (error) {
        if (error) {
          throw new RedisError(error.message);
        }
      });
    }
  } catch (error) {
    var mssg = 'Initialization failed Redis client.';
    mssg = _.isEmpty(error)
      ? ''
      : (error.message) ? error.message : (error).toString();
    throw new RedisError(mssg);
  }
}

Client.prototype._checkOptions = function () {
  return _.isObject(this.options);
}

Client.prototype._checkOptionsWithException = function () {
  if (!this._checkOptions())
  {
    throw new Error('Options are not valid.');
  }

  return true;
}

Client.prototype._getOptions = function () {
  this._checkOptionsWithException();

  return _.extend({}, this.options);
}

Client.prototype._checkClient = function () {
  return _.isObject(this._client);
}

Client.prototype._checkClientWithException = function () {
  if (!this._checkClient())
  {
    throw new Error('Client is not a valid');
  }

  return true;
}

Client.prototype._getClient = function () {
  this._checkClientWithException();
  return this._client;
}

module.exports = Client;