Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

Source

"use strict";

var levelup = require("levelup");
var sublevel = require("level-sublevel");
var AbstractPersistence = require("./abstract");
var JSONB = require("json-buffer");
var util = require("util");
var ttl = require('level-ttl');
var Matcher = require("./matcher");
var async = require("async");
var extend = require("extend");
var defaults = {
  ttl: {
    // TTL for subscriptions is 1 hour
    subscriptions: 60 * 60 * 1000,

    // TTL for packets is 1 hour
    packets: 60 * 60 * 1000,

    // the checkFrequency is 1 minute
    checkFrequency: 60 * 1000
  }
};

LevelUpPersistence

function
LevelUpPersistence()

@param: {Object}optionsThe options to create this persistance
@param: {Function}callbackCalled when ready.

Description

A LevelUp-based persistance.

The current options include:
- path, the path to the database
- ttl, an object containing three values:
* checkFrequency, the frequency at which the
the expiration will be checked. It defaults to 1 minute.
* subscriptions, the time (ms) after which subscriptions
will expire. It defaults to 1 hour.
* packets, the time (ms) after which packets will expire.
It defaults to 1 hour.
- db, the AbstractLevelDown implementation.
- all other levelup otions.

Source

function LevelUpPersistence(options, callback) {
  if (!(this instanceof LevelUpPersistence)) {
    return new LevelUpPersistence(options, callback);
  }

  this.options = extend(true, {}, defaults, options);
  this.options.valueEncoding = {
    encode : function (val) { return JSONB.stringify(val); },
    decode : function (val) { return JSONB.parse(val); },
    buffer : false,
    type   : "JSON-Buffers"
  };

  this.db = ttl(levelup(this.options.path, this.options), options.ttl);
  this._retained = this.db.sublevel("retained");
  this._clientSubscriptions = this.db.sublevel("clientSubscriptions");
  this._subscriptions = this.db.sublevel("subscriptions");
  this._offlinePackets = this.db.sublevel("offlinePackets");
  this._subMatcher = new Matcher();
  this._packetCounter = 0;
  this._lastStoredPacketTime = Date.now();

  var that = this;
  var stream = this._subscriptions.createReadStream();
  stream.on("data", function(data) {
    that._subMatcher.add(data.value.topic, data.key);
  });
  stream.on("end", function() {
    if (callback) {
      callback(null, that);
    }
  });
}

util.inherits(LevelUpPersistence, AbstractPersistence);

exports

property
module.exports

Description

Export it as a module

Source

module.exports = LevelUpPersistence;

Mosca lib/persistence/levelup.js