Vertx request does not end on sendFile throwing - vert.x

Question

I'm new to vert.x and I'm trying to create a simple download service.
I used Request#sendFile(fileName) and it works well, but if I pass a directory path to Request#sendFile(fileName) it throws an exception, which is totally fine.
The problem is that, even if I catch that exception with an handler, I can't send any data nor end the request, an that leaves the http client (the browser) stuck on an endless spinning progress.
That is an example that reproduces the problem:
VertxOptions options = new VertxOptions();
options.setBlockedThreadCheckInterval(1000*60*60);
Vertx vertx = Vertx.vertx(options);
HttpServer server = vertx.createHttpServer();
Router router = Router.router(vertx);
router
.route(HttpMethod.GET,"/foo")
.handler(ctx->{
// this path exist but is not a file, is a directory.
ctx.response().sendFile("docs/pdf",asr->{
if(asr.failed()) {
ctx.response()
.setStatusCode(404)
// I can't end the connection the only thing I can do is close it
// I've commented out this lambda because is not what I want to happen.
// It's just an hack to end the request all the same.
.end("File not found: "+"docs/pdf" /*, (x)->{ctx.response().close();}*/ );
}
});
});
server
.requestHandler(router)
.listen(3000);
I can this problem by checking first if the path references to a file which both exsist and is not a directory (which in fact I did in the real code), but that leaves me with doubt about what would happen if the IOException was something different (like reading a broken file, or an unauthorized file ...).
When this error happens no data is sent through the wire, I've both checked form the browser and sniffing packets TCP packets (0 bytes send from the server to the browser).
The only things that works is closing the connection with Response#close(), which at least closes the keep-alive http connection, and ends the browser request.
What I want to achieve is to send some information back to the client to tell something went wrong, possibly setting the status code to an appropriate 4** error and possibly adding some details to it (either in status text or in the response body).

Answer 1

You should add failureHandler to your router:
route.failureHandler(frc-> {
frc.response().setStatusCode( 400 ).end("Sorry! Not today");
});
see https://vertx.io/docs/vertx-web/java/#_error_handling