CartoDB-SQL-API/batch/pubsub/job-subscriber.js
2016-10-11 19:01:39 +02:00

75 lines
1.9 KiB
JavaScript

'use strict';
var Channel = require('./channel');
var QueueSeeker = require('./queue-seeker');
var debug = require('./../util/debug')('pubsub:subscriber');
var error = require('./../util/debug')('pubsub:subscriber:error');
var SUBSCRIBE_INTERVAL_IN_MILLISECONDS = 10 * 60 * 1000; // 10 minutes
function _subscribe(client, channel, queueSeeker, onMessage, callback) {
client.removeAllListeners('message');
client.unsubscribe(channel);
client.subscribe(channel);
client.on('message', function (channel, host) {
debug('message received from: ' + channel + ':' + host);
onMessage(channel, host);
});
queueSeeker.seek(onMessage, function (err) {
if (err) {
error(err);
if (callback) {
callback(err);
}
} else {
debug('queues found successfully');
if (callback) {
callback();
}
}
});
}
function JobSubscriber(pool) {
this.pool = pool;
this.queueSeeker = new QueueSeeker(pool);
}
module.exports = JobSubscriber;
JobSubscriber.prototype.subscribe = function (onMessage, callback) {
var self = this;
this.pool.acquire(Channel.DB, function (err, client) {
if (err) {
return error('Error adquiring redis client: ' + err.message);
}
self.client = client;
self.seekerInterval = setInterval(
_subscribe,
SUBSCRIBE_INTERVAL_IN_MILLISECONDS,
self.client,
Channel.NAME,
self.queueSeeker,
onMessage
);
_subscribe(self.client, Channel.NAME, self.queueSeeker, onMessage, callback);
});
};
JobSubscriber.prototype.unsubscribe = function () {
clearInterval(this.seekerInterval);
if (this.client && this.client.connected) {
this.client.unsubscribe(Channel.NAME);
}
};