Potentially breaking change in HttpClient behavior

[Alexander Aprelev]

We have recently improved performance of HttpClient open/openUrl methods so that they return a connection right away, rather than schedule it to be returned on the next event cycle. Scheduling was done to help with the case where a cached connection went stale, closed by the server, but was not marked as closed by the client yet. This delay was removed based on the assumption that a well-formed client has retry logic built-in, which retries the connect request if the given connection was stale or gets closed before the client manages to connect.

Given that we want to emphasize that having a retry mechanism is rather important to ensure a given http client is robust. Below is a simple example of getUrlWithRetry. In general, you should take into account whether it is safe to retry a failed http request as you might not want to automatically retry a POST http request that has side-effects on the server, and whether retry attempts should be progressively delayed.

Future<List<String>> getUrlWithRetry(HttpClient httpClient, Uri url,

  {int maxRetries: 5}) async {

for (var attempt = 0; attempt < maxRetries; attempt++) {

  try {

    final request = await httpClient.openUrl('GET', url);

    final response = await request.close();

    return await response

        .transform(new Utf8Decoder(allowMalformed: true)).toList();

  } catch (e) {

    // ...

  }

}

}

[mythz]

Does this still allow us to modify the HTTP Request before it's sent? e.g. are we still able to do stuff like:

final request = await httpClient.openUrl('GET', url);

req.headers.add(HttpHeaders.authorizationHeader, 'Bearer ' + bearerToken);

req.headers.chunkedTransferEncoding = false;

req.write(bodyStr);

[Alexander Aprelev]

Right, nothing changes in the way how HttpRequest can be modified before it is sent.

--
For more ways to connect visit https://www.dartlang.org/community
---
You received this message because you are subscribed to the Google Groups "Dart Misc" group.
To unsubscribe from this group and stop receiving emails from it, send an email to misc+uns...@dartlang.org.
To view this discussion on the web visit https://groups.google.com/a/dartlang.org/d/msgid/misc/fd144206-96dc-4e47-9a61-005a87898afb%40dartlang.org.