pr-ws-monitor/lib/index.js

Websockets monitoring

"use strict";

const EventEmitter = require("events");

var defaults = {
    "ts": 1000, // 1-sec
    "error": 60000, // 1-min
    "audit": 15000 // 15-sec (4-times within error-interval)
};

function getOptions(options) {
    var opts = options || {};

    opts = Object.assign.apply(null, Object.keys(defaults).map(prop => ({
        [prop]: opts[prop]
    })));
    Object.keys(defaults).forEach(function each(o) {
        opts[o] = opts[o] || defaults[o];
    });

    return opts;
}

function getObjectData(self) {
    self._wsmon = self._wsmon || {};

    return self._wsmon;
}

class WsMonitor extends EventEmitter {
    constructor(wss, options) {
        var data;

        super();
        data = getObjectData(this);
        data.wss = wss;
        data.opts = getOptions(options);
    }

    start() {
        var data = getObjectData(this);

        // check client-tracking
        if (data.wss.options.clientTracking === false) {
            this.emit("error", "need to enable clientTracking in ws-server");
        }
        // setup now time-stamp
        data.now = Date.now();
        data.nowId = setInterval(function nowTs() {
            data.now = Date.now();
        }, data.opts.ts);
        // setup time-stamp for existing connections
        data.wss.clients.forEach(function eachSock(sock) {
            sock._updateSockTs = function _updateSockTs() {
                sock._ats = data.now;
            };
            sock._ats = data.now;
            sock.on("pong", sock._updateSockTs);
            sock.on("message", sock._updateSockTs);
        });
        // setup time-stamp for new connections
        data.wss.on("connection", function sockConnection(sock) {
            sock._updateSockTs = function _updateSockTs() {
                sock._ats = data.now;
            };
            sock._ats = data.now;
            sock.on("pong", sock._updateSockTs);
            sock.on("message", sock._updateSockTs);
        });
        // setup auditing
        data.auditId = setInterval(function auditConnections() {
            data.wss.clients.forEach(function eachSock(sock) {
                var lag = Date.now() - sock._ats;

                if (lag > data.opts.error) {
                    sock.removeListener("pong", sock._updateSockTs);
                    sock.removeListener("message", sock._updateSockTs);
                    sock.close();
                } else if (lag > data.opts.audit) {
                    sock.ping("WsMonitor PING", {}, false);
                }
            });
        }, data.opts.audit);
    }

    stop() {
        var data = getObjectData(this);

        // clear now & audit
        if (data.nowId) {
            clearInterval(data.nowId);
            data.nowId = null;
        }
        if (data.auditId) {
            clearInterval(data.auditId);
            data.auditId = null;
        }
        data.wss.clients.forEach(function eachSock(sock) {
            sock.removeListener("pong", sock._updateSockTs);
            sock.removeListener("message", sock._updateSockTs);
        });
    }
}

// export
module.exports = WsMonitor;