Which libgdx backends honor HttpRequest timeout and cancellation?

Answer to the Core Question

All three supported libgdx backends – Desktop (LWJGL), Android, and HTML5 (GWT) – use the HttpRequest.setTimeout value to abort a request after the specified interval. In practice:

• Desktop: The timeout is forwarded to java.net.HttpURLConnection as both connection and read timeouts. When the interval expires, the connection throws a SocketTimeoutException and the HttpResponseListener receives the callback with statusCode == -1.
• Android: The behaviour mirrors Desktop. The timeout is applied to the underlying HttpURLConnection (or the legacy Apache client in very old libgdx releases). An expired timeout triggers the same exception and listener callback.
• HTML5: The timeout is mapped to RequestBuilder.setTimeoutMillis. When the timer fires, the browser aborts the XHR and the listener’s onHttpResponse is not invoked – the request simply terminates with status 0.

Cancellation Semantics

Calling HttpRequest.setCancel(true) initiates a best‑effort abort:

• Desktop & Android: The request’s disconnect() (or abort() on the old Apache client) is called. The underlying socket is closed only after the current blocked I/O operation finishes. The listener will still be notified, typically with a timeout‑style exception.
• HTML5: RequestBuilder.cancel() aborts the XHR immediately. Because the browser does not fire the listener for an aborted request, you will not see a callback unless you implement your own flag.

Do I Need Platform‑Specific Fallbacks?

For most use‑cases the built‑in timeout and cancellation work fine. However, if you need absolute certainty that the network channel is gone when the user navigates away, add a small platform‑specific guard:

1. On Desktop and Android, keep a reference to the HttpRequest and, after calling setCancel(true), poll the connection’s state or use a ScheduledTask to double‑check that no ESTABLISHED sockets remain.
2. On HTML5, schedule a timeout task that sets a flag when the request is aborted, and clear that flag in onHttpResponse if the callback arrives. This way you can be certain the request has truly finished.

Practical Verification Steps

HttpRequest request = new HttpRequest(HttpMethod.GET).setUrl("https://example.com/slow");
request.setTimeout(50); // 50 ms
request.setCancel(true); // cancel immediately
request.setListener(new HttpResponseListener() {
    public void onHttpResponse(HttpResponse response) {
        System.out.println("status: " + response.getStatusCode());
    }
    public void onHttpRequestFailed(Throwable t) {
        System.out.println("failed: " + t.getMessage());
    }
});
Gdx.net.sendHttpRequest(request);

Run the snippet on each platform and observe:

• Desktop/Android: you’ll see a SocketTimeoutException or a status of –1.
• HTML5: the request aborts silently; no callback is fired. If you need confirmation, add a ScheduledTask that sets a flag after 50 ms.

Missing Diagnostic Detail

To give a more precise recommendation, could you tell me which libgdx version you’re targeting? Older Android releases used the legacy Apache client, which behaves slightly differently for cancellation.