apminsight/lib/instrument/modules/express.js

monitor nodejs applications

// supported upto 4.6.2

var wrapper = require("./../wrapper");
var utils = require("./../../util/utils");

var moduleName = "Express",
    middleWare = "Middleware";
var moduleInfo = {
    functions: [
        {
            functionName: "application.render",
            component: moduleName
        },
        {
            functionName: "response.json",
            component: moduleName,
            sync: true
        },
        {
            functionName: "response.jsonp",
            component: moduleName,
            sync: true
        },
        {
            functionName: "response.redirect",
            component: moduleName,
            sync: true,
            extractInfo: getRedirectUrl
        },
        {
            // internally calls the app.render, so may be not needed to instrument
            functionName: "response.render",
            component: moduleName
        },
        {
            functionName: "response.send",
            component: moduleName,
            extractInfo: addBytesOut
        },
        {
            functionName: "response.sendFile",
            component: moduleName
        }
    ]
};

var innerModules = ["application", "Router"];

var routingMethods = [
    "checkout",
    "copy",
    "delete",
    "get",
    "head",
    "lock",
    "merge",
    "mkactivity",
    "mkcol",
    "move",
    "m-search",
    "notify",
    "options",
    "patch",
    "post",
    "purge",
    "put",
    "report",
    "search",
    "subscribe",
    "trace",
    "unlock",
    "unsubscribe",
    "use",
    "all",
    "param"
];

innerModules.forEach(function (eachModules) {
    routingMethods.forEach(function (eachRoutingMethods) {
        var functionInfo = {};
        functionInfo.functionName = eachModules + "." + eachRoutingMethods;
        functionInfo.wrapper = wrapMiddleWare;
        functionInfo.component = middleWare;
        moduleInfo.functions.push(functionInfo);
    });
});

function wrapMiddleWare(actual) {
    return function () {
        // check and wrap handlers
        if (arguments) {
            for (var index = 0; index < arguments.length; index++) {
                if (arguments[index] && utils.isFunction(arguments[index])) {
                    arguments[index] = wrapHandler(arguments[index]);
                } else if (Array.isArray(arguments[index])) {
                    arguments[index] = checkAndWrapArrayArguments(
                        arguments[index]
                    );
                }
            }
        }
        return actual.apply(this, arguments);
    };
}

function checkAndWrapArrayArguments(args) {
    var wrappedArgs;
    if (args) {
        wrappedArgs = [];
        for (var index = 0; index < args.length; index++) {
            if (args[index] && utils.isFunction(args[index])) {
                wrappedArgs.push(wrapHandler(args[index]));
            } else if (Array.isArray(args[index])) {
                wrappedArgs.push(checkAndWrapArrayArguments(args[index]));
            } else {
                wrappedArgs.push(args[index]);
            }
        }
    }
    return wrappedArgs;
}

/* eslint-disable no-unused-vars */
function wrapHandler(handler) {
    if (handler.length > 3) {
        return function (err, req, res, next) {
            return handleMiddleware(this, handler, arguments);
        };
    }
    return function (req, res, next) {
        return handleMiddleware(this, handler, arguments);
    };
}
/* eslint-enable no-unused-vars */

function handleMiddleware(invoker, handler, args) {
    var curTxn = apmInsightAgentInstance.getCurTxn();
    if (!curTxn || curTxn.isCompleted()) {
        return handler.apply(invoker, args);
    }
    var parentTracker = apmInsightAgentInstance.getCurTracker();
    var handlerName = handler.name ? handler.name : "Anonymous";
    var trackerName = "Express - Middleware -" + handlerName;
    var trackerInfo = {
        trackerName: trackerName,
        component: middleWare,
        sync: true
    };
    var syncOpnInfo = {
        txn: curTxn,
        syncParentTracker: parentTracker,
        trackerInfo: trackerInfo
    };
    wrapper.invokeSyncOpn(handler, invoker, args, syncOpnInfo);
}

/* eslint-disable no-unused-vars */
function getRedirectUrl(invoker, params, returnObj, tracker, asyncOpnInfo) {
    if (!params || params.length == 0) {
        return;
    }
    var info = {};
    if (params[0] && typeof params[0] === "string") {
        info.url = params[0];
    } else if (
        params.length > 1 &&
        params[1] &&
        typeof params[1] === "string"
    ) {
        info.url = params[1];
    }
    tracker.updateInfo(info);
}

function addBytesOut(invoker, params, returnObj, tracker, asyncOpnInfo) {
    var bytesOut = 0;
    var txn = apmInsightAgentInstance.getCurTxn();
    var data = params[0];
    if (txn && !txn.isCompleted()) {
        if (Buffer.isBuffer(params[0]) || utils.isBoolean(params[0])) {
            data = params[0].toString();
        }
        if (utils.isObject(params[0])) {
            data = JSON.stringify(params[0]);
        }
        bytesOut += utils.isNonEmptyString(data) ? Buffer.byteLength(data) : 0;
        txn.setBytesOut(bytesOut);
    }
}
/* eslint-enable no-unused-vars */

module.exports = moduleInfo;