CartoDB-SQL-API/batch/pubsub/job-subscriber.js

'use strict';

var Channel = require('./channel');
var debug = require('./../util/debug')('pubsub:subscriber');
var error = require('./../util/debug')('pubsub:subscriber:error');

function JobSubscriber(pool) {
    this.pool = pool;
}

module.exports = JobSubscriber;

JobSubscriber.prototype.subscribe = function (onJobHandler, callback) {
    var self = this;

    self.pool.acquire(Channel.DB, function(err, client) {
        if (err) {
            if (callback) {
                callback(err);
            }
            return error('Error adquiring redis client: ' + err.message);
        }

        self.client = client;
        client.removeAllListeners('message');
        client.unsubscribe(Channel.NAME);
        client.subscribe(Channel.NAME);

        client.on('message', function (channel, user) {
            debug('message received in channel=%s from user=%s', channel, user);
            onJobHandler(user);
        });

        client.on('error', function () {
            self.unsubscribe();
            self.pool.release(Channel.DB, client);
            self.subscribe(onJobHandler);
        });

        if (callback) {
            callback();
        }
    });
};

JobSubscriber.prototype.unsubscribe = function (callback) {
    if (this.client && this.client.connected) {
        this.client.unsubscribe(Channel.NAME, callback);
    } else {
        if (callback) {
            return callback(null);
        }
    }
};