CartoDB-SQL-API/batch/queue_seeker.js

48 lines
1.2 KiB
JavaScript

'use strict';
function QueueSeeker(metadataBackend) {
this.db = 5;
this.channel = 'batch:hosts';
this.redisPrefix = 'batch:queues:';
this.pattern = this.redisPrefix + '*';
this.metadataBackend = metadataBackend;
}
module.exports = QueueSeeker;
QueueSeeker.prototype.seek = function (onMessage, callback) {
var initialCursor = ['0'];
this.onMessage = onMessage;
this._seek(initialCursor, callback);
};
QueueSeeker.prototype._seek = function (cursor, callback) {
var self = this;
var redisParams = [cursor[0], 'MATCH', self.pattern];
self.metadataBackend.redisCmd(self.db, 'SCAN', redisParams, function (err, currentCursor) {
if (err) {
return callback(err);
}
// checks if iteration has ended
if (currentCursor[0] === '0') {
return callback(null);
}
var queues = currentCursor[1];
if (!queues) {
return callback(null);
}
queues.forEach(function (queue) {
var host = queue.substr(self.redisPrefix.length);
self.onMessage(self.channel, host);
});
self._seek(currentCursor, callback);
});
};