Issue with delivering a resized image on request with node - node.js

Question

I am using sailsjs, the website is sailsjs.org.
Im tring to create a controller function so that when an image is requested it can be resized and cached the first time a visitor asks for an image, then retrieved from cache the next time a visitor requests it.
I have setup a route to an asset controller:
'get /image/:width/:height/:image': {
controller: 'AssetController',
action: 'image'
},
I have setup a policy to intercept requests for an image from the above route and resize / save the file into a cache:
var fs = require('fs'),
im = require('imagemagick');
module.exports = function imageCacheResize(req, res, next){
var width = req.param('width');
var height = req.param('height');
var file = req.param('image');
if(width && height){
//read from cache
dir = 'assets/images/uploads/cache/'+width+'X'+height+'/';
filename = dir+file;
if (!fs.existsSync(dir)){
fs.mkdirSync(dir);
}
if(!fs.exists(filename)){
//write to file if not exist
var originalFile = 'assets/images/uploads/'+file;
im.resize({
srcPath: originalFile,
dstPath: filename,
width: width
}, function(err, stdout, stderr){
if (err) throw err;
});
}
}
next();
};
I have also got an action/function setup for the controller to handle returning the resized image:
image: function(req, res){
var file = req.param('image');
var filename = 'assets/images/uploads/'+file;
if((typeof req.param('width') != 'undefined')
&&(typeof req.param('height') != 'undefined'))
{
var width = req.param('width');
var height = req.param('height');
}
if(typeof req.param('size') != 'undefined'){
var size = req.param('size');
}
if(width && height){
//read from cache
dir = 'assets/images/uploads/cache/'+width+'X'+height+'/';
file = dir+file;
}else{
file = 'assets/images/uploads/'+file;
}
console.log(file);
res.sendfile(file);
}
All of the code works correctly and creates then saves the resized image, however it does not return the image on the first request but it does on the second.

Answer 1

So it turns out I had not placed the next() commands in the correct place. Seems like whilst waiting for an image resize the code continues and hits the final next().
I have change the image resize policy to this:
var fs = require('fs'),
im = require('imagemagick');
module.exports = function imageCacheResize(req, res, next){
var width = req.param('width');
var height = req.param('height');
var file = req.param('image');
if(width && height){
//read from cache
dir = 'assets/images/uploads/cache/'+width+'X'+height+'/';
filename = dir+file;
if (!fs.existsSync(dir)){
fs.mkdirSync(dir);
}
if(!fs.exists(filename)){
//write to file if not exist
var originalFile = 'assets/images/uploads/'+file;
im.resize({
srcPath: originalFile,
dstPath: filename,
width: width
}, function(err, stdout, stderr){
if (err) throw err;
next();
});
}else{
next();
}
}else{
next();
}
};