Domains implicit binding (nesting contexts)

[gagle]

I want to send to the user a response when an error occurs but I don't have any reference to the response object inside the error handler:

var domain = require ("domain");
var http = require ("http");

var d = domain.create ();
d.on ("error", function (error){
    console.error (error);
    //res.writeHead (500)
    //res.end ()
});
d.run (function (){
    http.createServer (function (req, res){
        null.error
    }).listen (1337, "localhost");
});

The docs are a bit confusing to me:

In order to prevent excessive memory usage, Domain objects themselves are not implicitly added as children of the active domain. If they were, then it would be too easy to prevent request and response objects from being properly garbage collected.

If you want to nest Domain objects as children of a parent Domain, then you must explicitly add them, and then dispose of them later.

Is it ok if I do the following or I'll produce memory leaks?

var domain = require ("domain");
var http = require ("http");

var d = domain.create ();
d.on ("error", function (error){
    console.error (error);
});
d.run (function (){
    http.createServer (function (req, res){
        var dreq = domain.create ();
        dreq.add (req);
        dreq.add (res);
        dreq.on ("error", function (error){
            //The null.error is handled here
            res.writeHead (500);
            res.end ();
            console.error (error);
            dreq.exit ();
        });
        dreq.run (function (){
            null.error
        });
    }).listen (1337, "localhost");
});

Thanks

[bnoordhuis]

That should work and it won't create memory leaks.

It's IMO not a very safe or scalable approach, though. In a non-trivial application, how will you know when it's safe to use the response object in the domain's error handler? If the error was generated by the response object, boom! - you're dead.

In the future, please direct questions to the mailing or IRC. The bug tracker is not really the place for it.