Abort HttpRequests when CancelToken is cancelled

dio/CHANGELOG.md

@@ -7,6 +7,7 @@
 - Fix `IOHttpClientAdapter.onHttpClientCreate` Repeated calls
 - `IOHttpClientAdapter.onHttpClientCreate` has been deprecated and is scheduled for removal in
   Dio 6.0.0 - Please use the replacement `IOHttpClientAdapter.createHttpClient` instead.
+- Using `CancelToken` no longer closes and re-creates `HttpClient` for each request when `IOHttpClientAdapter` is used. 
 
 ## 5.1.2
 

dio/lib/src/adapters/io_adapter.dart

@@ -2,6 +2,8 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:typed_data';
 
+import 'package:async/async.dart';
+
 import '../adapter.dart';
 import '../dio_exception.dart';
 import '../options.dart';
@@ -65,7 +67,23 @@ class IOHttpClientAdapter implements HttpClientAdapter {
         "Can't establish connection after the adapter was closed!",
       );
     }
-    final httpClient = _configHttpClient(cancelFuture, options.connectTimeout);
+    final operation = CancelableOperation.fromFuture(_fetch(
+      options,
+      requestStream,
+      cancelFuture,
+    ));
+    if (cancelFuture != null) {
+      cancelFuture.whenComplete(() => operation.cancel());
+    }
+    return operation.value;
+  }
+
+  Future<ResponseBody> _fetch(
+    RequestOptions options,
+    Stream<Uint8List>? requestStream,
+    Future<void>? cancelFuture,
+  ) async {
+    final httpClient = _configHttpClient(options.connectTimeout);
     final reqFuture = httpClient.openUrl(options.method, options.uri);
 
     late HttpClientRequest request;
@@ -85,6 +103,10 @@ class IOHttpClientAdapter implements HttpClientAdapter {
         request = await reqFuture;
       }
 
+      if (cancelFuture != null) {
+        cancelFuture.whenComplete(() => request.abort());
+      }
+
       // Set Headers
       options.headers.forEach((k, v) {
         if (v != null) request.headers.set(k, v);
@@ -198,17 +220,7 @@ class IOHttpClientAdapter implements HttpClientAdapter {
     );
   }
 
-  HttpClient _configHttpClient(
-    Future<void>? cancelFuture,
-    Duration? connectionTimeout,
-  ) {
-    if (cancelFuture != null) {
-      final client = _createHttpClient();
-      client.userAgent = null;
-      client.idleTimeout = Duration(seconds: 0);
-      cancelFuture.whenComplete(() => client.close(force: true));
-      return client..connectionTimeout = connectionTimeout;
-    }
+  HttpClient _configHttpClient(Duration? connectionTimeout) {
     return (_cachedHttpClient ??= _createHttpClient())
       ..connectionTimeout = connectionTimeout;
   }

dio/pubspec.yaml

@@ -15,6 +15,7 @@ environment:
   sdk: '>=2.15.0 <3.0.0'
 
 dependencies:
+  async: ^2.8.2
   http_parser: ^4.0.0
   meta: ^1.5.0
   path: ^1.8.0
@@ -24,5 +25,5 @@ dev_dependencies:
   test: ^1.5.1
   coverage: ^1.0.3
   crypto: ^3.0.2
-  mockito: ^5.2.0
+  mockito: ^5.3.0
   build_runner: any

dio/test/cancel_token_test.dart

@@ -1,6 +1,10 @@
 import 'package:dio/dio.dart';
+import 'package:dio/src/adapters/io_adapter.dart';
+import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
 
+import 'mock/http_mock.mocks.dart';
+
 void main() {
   group(CancelToken, () {
     test('cancel returns the correct DioException', () async {
@@ -19,5 +23,59 @@ void main() {
     test('cancel without use does not throw (#1765)', () async {
       CancelToken().cancel();
     });
+
+    test('cancels multiple requests', () async {
+      final client = MockHttpClient();
+      final token = CancelToken();
+      const reason = 'cancel';
+      final dio = Dio()
+        ..httpClientAdapter = IOHttpClientAdapter(
+          createHttpClient: () => client,
+        );
+
+      final requests = <MockHttpClientRequest>[];
+      when(client.openUrl(any, any)).thenAnswer((_) async {
+        final request = MockHttpClientRequest();
+        requests.add(request);
+        when(request.close()).thenAnswer((_) async {
+          final response = MockHttpClientResponse();
+          when(response.headers).thenReturn(MockHttpHeaders());
+          when(response.statusCode).thenReturn(200);
+          await Future.delayed(const Duration(milliseconds: 200));
+          return response;
+        });
+        return request;
+      });
+
+      final futures = [
+        dio.get('https://pub.dev', cancelToken: token),
+        dio.get('https://pub.dev', cancelToken: token),
+      ];
+
+      for (final future in futures) {
+        expectLater(
+          future,
+          throwsA((error) =>
+              error is DioError &&
+              error.type == DioErrorType.cancel &&
+              error.error == reason),
+        );
+      }
+
+      await Future.delayed(const Duration(milliseconds: 5));
+      token.cancel(reason);
+
+      expect(requests, hasLength(2));
+
+      try {
+        await Future.wait(futures);
+      } catch (_) {
+        // ignore, just waiting here till all futures are completed
+      }
+
+      for (final request in requests) {
+        verify(request.abort()).called(1);
+      }
+    });
   });
 }

dio/test/mock/http_mock.dart

@@ -6,11 +6,11 @@ import 'http_mock.mocks.dart';
 
 final httpClientMock = MockHttpClient();
 
-@GenerateMocks([
-  HttpClient,
-  HttpClientRequest,
-  HttpClientResponse,
-  HttpHeaders,
+@GenerateNiceMocks([
+  MockSpec<HttpClient>(),
+  MockSpec<HttpClientRequest>(),
+  MockSpec<HttpClientResponse>(),
+  MockSpec<HttpHeaders>(),
 ])
 class MockHttpOverrides extends HttpOverrides {
   @override