fix: in the stream mode, request cannot be canceled

[lh900519]

New Pull Request Checklist

• I have read the Documentation
• I have searched for a similar pull request in the project and found none
• I have updated this branch with the latest main branch to avoid conflicts (via merge from master or rebase)
• I have added the required tests to prove the fix/feature I'm adding
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• I have run the tests without failures
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Additional context and info (if any)

[kuhnroyal]

Thanks for your PR!

Do you have any additional information for the root problem?
The fix currently won't work when thinking about parallel requests, the closing of the HTTP client may kill other requests.
Please provide a test that reproduces the problem.

[lh900519]

import 'dart:async';
import 'dart:convert';
import 'dart:typed_data';

import 'package:dio/dio.dart';

void main() async {
  final dio = Dio();
  clientStream(dio, '1');
  clientStream(dio, '2');
}

Future clientStream(Dio dio, String name) async {
  try {
    final token = CancelToken();
    Timer(const Duration(seconds: 3), () {
      token.cancel("----Canceled");
    });
    const url = "https://hacker-news.firebaseio.com/v0/topstories.json";
    Response<ResponseBody> rs = await dio.get<ResponseBody>(
      url,
      options: Options(
        headers: {
          "Authorization": 'vhdrjb token"',
          "Accept": "text/event-stream",
          "Cache-Control": "no-cache",
        },
        responseType: ResponseType.stream,
      ), // set responseType to `stream`
      cancelToken: token,
    );

    rs.data?.stream
        .transform(unit8Transformer)
        .transform(const Utf8Decoder())
        .transform(const LineSplitter())
        .listen((event) {
      if (event.startsWith("event:")) {
        print("$name $event isCancelled:${token.isCancelled}");
      }
      if (event.startsWith("data:")) {
        print(
            "$name ${event.substring(0, 5)} isCancelled:${token.isCancelled}");
      }
    });
  } catch (e) {
    print('error $e');
  }
}

StreamTransformer<Uint8List, List<int>> unit8Transformer =
    StreamTransformer.fromHandlers(
  handleData: (data, sink) {
    sink.add(List<int>.from(data));
  },
);

Run the code with dart test.dart
The request was canceled using CancelToken after 3 seconds, but the terminal did not stop and continued to output.

This PR does not reuse _cachedHttpClient for stream type requests, but creates a new httpclient, and closes the newly created httpclient when using CancelToken. The processing of stream types here is the same as in 5.1.2.

[AlexV525]

If you have a reproducible example, please make it a test, we need tests to avoid further breakages.

[AlexV525]

These are not well-formatted (with trailing commas).

[AlexV525]

If we create new clients here, what about the closing after the client has been used?

[AlexV525]

I'd prefer forceNotCachedClient for better understanding, or someone else can have better namings.

[kuhnroyal]

I am also wondering if there is an upstream issue for this problem. We abort() the request correctly, why does this not work?

[kuhnroyal]

Maybe this is the source of the problem? dart-lang/sdk#51267

[AlexV525]

Converting this to a draft until we get progress with the implementation and tests.

[AlexV525]

Should be covered by #2032.