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PONode.js blocking the event loop?
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copied!<p>I am writing an API, and I got stuck at the point where I am mixing asyncronous and syncronous code depending on the incoming request, take a look at the examples below.</p> <p><strong>routes.js</strong></p> <pre><code>module.exports = [ { method: 'GET', path: '/', controller: 'main', action: 'main', description: 'lists the API functionality', access: 'auth' }, { method: 'POST', path: '/users', controller: 'users', action: 'create', description: 'creates a new user', fields: { fullName: { format: { min: 2, max: 64, minWords: 2, disableDoubleSpaces: true }, description: 'the full name of the new user', examples: 'Thomas Richards, Richard Jones, Michael J. Fox, Mike Vercoelen, John Johnson' }, email: { format: { min: 2, max: 64, maxWords: 1, match: 'email' }, description: 'the email address of the new user', examples: 'mike@grubt.com, lilly@gmail.com, thomas.richards@mail.com, peter@mymail.com' }, password: { format: { min: 2, max: 64 }, description: 'the password of the new user', examples: '123abcdfg, 7373kEjQjd, #8klKDNfk' } } } ]; </code></pre> <p>the routes.js file is basically a very essential part of the API, it validates incoming data, routes to the correct controller/action and defines if the method is public, or requires authentication (basic auth).</p> <p><strong>api-server.js</strong></p> <pre><code>var http = require('http'); var url = require('url'); var os = require('os'); var dns = require('dns'); var apiServer = module.exports; var routes = require('./routes.js'); // Routes file from above. var req, res, controller, action, serverInfo, httpServer; apiServer.start = function(){ prepare(function(){ httpServer = http.createServer(handleRequest).listen(3000); }); }; // // We need to do this function, we need the local ip address of the // server. We use this local ip address in logs (mongoDb) so we can // refer to the correct server. // function prepare(callback){ var serverName = os.hostname(); dns.lookup(serverName, function(error, address){ if(error){ throw error; } serverInfo = { name: serverName, address: address }; callback(); }); } function getRoute(){ // loops through routes array, and picks the correct one... } function getAuth(callback){ // parses headers, async authentication (mongoDB). } function getRequestData(callback){ // req.on('data') and req.on('end'), getting request data. } function parseRequestData(callback){ // parse request data at this point. } function validateRequestData(callback){ // loop through route fields (see routes.js) and validate this data with the ones // from the request. } function requireControllerAndCallAction(){ // do actual job. } function handleRequest(request, response){ req = request; res = response; req.route = getRoute(); // First step for a request, syncronous. if(req.route === false){ // 404... } // If in the routing schema access was "auth", // this route requires authentication, so do that... if(req.route.access === 'auth'){ getAuth(function(error, user){ if(error){ // 401 } else { req.user = user; } } } if(req.method === 'POST' || req.method === 'PUT'){ // Async functions. getRequestData(function(){ parseRequestData(function(){ validateRequestData(function(){ requireControllerAndCallAction(); }); }); }); } else { requireControllerAndCallAction(); } } </code></pre> <p>As you can see, some functions are asyncronous (getAuth, getRequestData) and some are syncronous (parseRequestData, validateRequestData).</p> <p>Now here is the thing:</p> <p>Request 1. comes in with method POST, url '/users' and data:</p> <ul> <li>fullName = 'Rick'</li> <li>email: 'rick@'</li> <li>password: 'a'</li> </ul> <p>So we loop through the workflow of the API:</p> <ol> <li><p>get the current route (controller: users, action: create) see the second array element in routes.js</p></li> <li><p>get the request data and on callback: a. parse data b. validate data</p></li> </ol> <p>Now lets IMAGINE, the validation of the data takes 5 seconds (which is retarded, but just for example) and during that validation, a new request comes in, the new request is not handled untill the previous one was finished right?</p>

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