ca-apm-probe/lib/probes/koa-router.js

CA APM Node.js Agent monitors real-time health and performance of Node.js applications

/**
 * Copyright (c) 2015 CA. All rights reserved.
 *
 * This software and all information contained therein is confidential and proprietary and
 * shall not be duplicated, used, disclosed or disseminated in any way except as authorized
 * by the applicable license agreement, without the express written permission of CA. All
 * authorized reproductions must be marked with this language.
 *
 * EXCEPT AS SET FORTH IN THE APPLICABLE LICENSE AGREEMENT, TO THE EXTENT
 * PERMITTED BY APPLICABLE LAW, CA PROVIDES THIS SOFTWARE WITHOUT WARRANTY
 * OF ANY KIND, INCLUDING WITHOUT LIMITATION, ANY IMPLIED WARRANTIES OF
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL CA BE
 * LIABLE TO THE END USER OR ANY THIRD PARTY FOR ANY LOSS OR DAMAGE, DIRECT OR
 * INDIRECT, FROM THE USE OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, LOST
 * PROFITS, BUSINESS INTERRUPTION, GOODWILL, OR LOST DATA, EVEN IF CA IS
 * EXPRESSLY ADVISED OF SUCH LOSS OR DAMAGE.
 */

var path = require('path');
var agent = require('../agent');
var proxy = require('../proxy');

var util = require('util');
var logger = require("../logger");


var targetModule = new Object;

module.exports = function (Router) {

    targetModule.router = Router;
    targetModule.methodMap = getMethodsWithProbes();

    // hook instrumentation on use event of koa-router
    proxy.before(Router.prototype, 'use', instrumentKoaRouter);

    // register call backs for methods of route stack
    function instrumentKoaRouter(obj, args, storage) {

        var router = args[1].router;

        if (router && router.stack && router.stack.length) {
            console.log(args[0]);

            var stack = router.stack
            for (var i = 0; i < stack.length; ++i) {
                var layer = stack[i]
                // hook each route
                proxy.callback(layer.stack, 0, instrumentKoaRouterRoutes, null);
            }

        }
    }

    function instrumentKoaRouterRoutes(obj, args, storage) {
        logger.debug('instrumenting koa-router middlewear call');

        var res = args[0].res;
        var req = args[0].req;
        var eventNameFormatted = 'koa.route';
        var ctx = storage.get('ctx') || req.__CA_ctx;

        if (logger.isDebug()) {
            if (ctx) {
                logger.debug('%s[%d %d %d]: path - %s', eventNameFormatted, ctx.txid, ctx.lane, ctx.evtid, req.url);
            }
            else {
                logger.debug('%s - no context', eventNameFormatted);
                logger.debug((new Error('No context')).stack);
            }
        }

        ctx = agent.asynchEventStart(ctx, eventNameFormatted, {
            route: args[0]._matchedRoute,
            http_method: req.method
        });

        storage.set('ctx', ctx);

        var errorObject = new Object();

        var end_save = res.end;
        res.end = function () {
            if (res.finished === false && ctx) {
                ctx = agent.asynchEventDone(ctx, eventNameFormatted, null,
                    errorObject);

                if (ctx) {
                    agent.asynchEventFinish(ctx);
                }
            }

            end_save.apply(res, arguments);
        };



    }

};


function getMethodsWithProbes() {
    if (!targetModule.methodMap) {
        var mt = new Object;
        mt[0] = 'koa#route';
        targetModule.methodMap = mt;
    }
    return targetModule.methodMap;
}

function instrument(methodMap) {
    targetModule.methodMap = methodMap;
}

module.exports.getMethodsWithProbes = getMethodsWithProbes;

module.exports.instrument = instrument.bind(module);