Make it possible to control multipath TCP support (#780)

Author: brianquinlan

pkgs/cupertino_http/CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 0.0.4
 
 * Add the ability to control caching policy.
+* Add the ability to control multipath TCP connections.
 
 ## 0.0.3
 

pkgs/cupertino_http/example/integration_test/url_session_configuration_test.dart

@@ -54,6 +54,18 @@ void testProperties(URLSessionConfiguration config) {
       config.httpShouldUsePipelining = false;
       expect(config.httpShouldUsePipelining, false);
     });
+    test('multipathServiceType', () {
+      expect(config.multipathServiceType,
+          URLSessionMultipathServiceType.multipathServiceTypeNone);
+      config.multipathServiceType =
+          URLSessionMultipathServiceType.multipathServiceTypeAggregate;
+      expect(config.multipathServiceType,
+          URLSessionMultipathServiceType.multipathServiceTypeAggregate);
+      config.multipathServiceType =
+          URLSessionMultipathServiceType.multipathServiceTypeNone;
+      expect(config.multipathServiceType,
+          URLSessionMultipathServiceType.multipathServiceTypeNone);
+    });
     test('requestCachePolicy', () {
       config.requestCachePolicy = URLRequestCachePolicy.returnCacheDataDontLoad;
       expect(config.requestCachePolicy,

pkgs/cupertino_http/lib/cupertino_http.dart

@@ -62,6 +62,16 @@ enum URLRequestCachePolicy {
   reloadRevalidatingCacheData,
 }
 
+// Controls how multipath TCP should be used.
+//
+// See [NSURLSessionMultipathServiceType](https://developer.apple.com/documentation/foundation/nsurlsessionmultipathservicetype).
+enum URLSessionMultipathServiceType {
+  multipathServiceTypeNone,
+  multipathServiceTypeHandover,
+  multipathServiceTypeInteractive,
+  multipathServiceTypeAggregate,
+}
+
 // Controls how [URLSessionTask] execute will proceed after the response is
 // received.
 //
@@ -202,6 +212,14 @@ class URLSessionConfiguration
   set httpShouldUsePipelining(bool value) =>
       _nsObject.HTTPShouldUsePipelining = value;
 
+  /// What type of Multipath TCP connections to use.
+  ///
+  /// See [NSURLSessionConfiguration.multipathServiceType](https://developer.apple.com/documentation/foundation/nsurlsessionconfiguration/2875967-multipathservicetype)
+  URLSessionMultipathServiceType get multipathServiceType =>
+      URLSessionMultipathServiceType.values[_nsObject.multipathServiceType];
+  set multipathServiceType(URLSessionMultipathServiceType value) =>
+      _nsObject.multipathServiceType = value.index;
+
   // Controls how to deal with response caching.
   //
   // See [NSURLSessionConfiguration.requestCachePolicy](https://developer.apple.com/documentation/foundation/nsurlsessionconfiguration/1411655-requestcachepolicy)