node-red/nodes/io/lib/mqttConnectionPool.js

/**
 * Copyright 2013 IBM Corp.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 **/
var util = require("util");
var mqtt = require("./mqtt");
var settings = require("../../../red/red").settings;

var connections = {};

function matchTopic(ts,t) { 
    var re = new RegExp("^"+ts.replace(/([\[\]\?\(\)\\\\$\^\*\.|])/g,"\\$1").replace(/\+/g,"[^/]+").replace(/#$/,".*"));
    return re.test(t);
}

module.exports = {
    get: function(broker,port) {
        var id = broker+":"+port;
        if (!connections[id]) {
            connections[id] = function() {
                var client = mqtt.createClient(port,broker);
                client.setMaxListeners(0);
                var options = {keepalive:15,clientId:'mqtt_' + (1+Math.random()*4294967295).toString(16)};
                var queue = [];
                var subscriptions = [];
                var connecting = false;
                var obj = {
                    _instances: 0,
                    publish: function(msg) {
                        if (client.isConnected()) {
                            client.publish(msg.topic,msg.payload,msg.qos,msg.retain);
                        } else {
                            if (!connecting) {
                                connecting = true;
                                client.connect(options);
                            }
                            queue.push(msg);
                        }
                    },
                    subscribe: function(topic,qos,callback) {
                        subscriptions.push({topic:topic,qos:qos,callback:callback});
                        client.on('message',function(mtopic,mpayload,mqos,mretain) {
                                if (matchTopic(topic,mtopic)) {
                                    callback(mtopic,mpayload,mqos,mretain);
                                }
                        });
                        if (client.isConnected()) {
                            client.subscribe(topic,qos);
                        }
                    },
                    on: function(a,b){
                        client.on(a,b);
                    },
                    once: function(a,b){
                        client.once(a,b);
                    },
                    connect: function() {
                        if (!client.isConnected() && !connecting) {
                            connecting = true;
                            client.connect(options);
                        }
                    },
                    disconnect: function() {
                        this._instances -= 1;
                        if (this._instances == 0) {
                            client.disconnect();
                            client = null;
                            delete connections[id];
                        }
                    }
                };
                client.on('connect',function() {
                        
                        util.log('[mqtt] connected to broker tcp://'+broker+':'+port);

                        connecting = false;
                        for (var s in subscriptions) {
                            var topic = subscriptions[s].topic;
                            var qos = subscriptions[s].qos;
                            var callback = subscriptions[s].callback;
                            client.subscribe(topic,qos);
                        }
                        //console.log("connected - publishing",queue.length,"messages");
                        while(queue.length) {
                            var msg = queue.shift();
                            //console.log(msg);
                            client.publish(msg.topic,msg.payload,msg.qos,msg.retain);
                        }
                });
                client.on('connectionlost', function(err) {
                        util.log('[mqtt] connection lost to broker tcp://'+broker+':'+port);
                        setTimeout(function() {
                                if (client) {
                                    client.connect(options);
                                }
                        }, settings.mqttReconnectTime||5000);
                });
                client.on('disconnect', function() {
                        util.log('[mqtt] disconnected from broker tcp://'+broker+':'+port);
                });

                return obj
            }();
        }
        connections[id]._instances += 1;
        return connections[id];
    }
};