Clean up leaks in the WasmHttpMessageHandler. (#11616)

- Most of the leaks present themselves during a Cancel of a streaming request.

1 files changed, 14 insertions, 2 deletions

diff --git a/sdks/wasm/WasmHttpMessageHandler.cs b/sdks/wasm/WasmHttpMessageHandler.cs
index 5aa8b1d47e0..89e0bff577f 100644
--- a/sdks/wasm/WasmHttpMessageHandler.cs
+++ b/sdks/wasm/WasmHttpMessageHandler.cs
@@ -129,18 +129,23 @@ namespace WebAssembly.Net.Http.HttpClient
                 }
 
                 JSObject abortController = null;
+                JSObject signal = null;
+                WasmHttpReadStream wasmHttpReadStream = null;
+
                 CancellationTokenRegistration abortRegistration = default(CancellationTokenRegistration);
                 if (cancellationToken.CanBeCanceled)
                 {
                     abortController = (JSObject)global.Invoke("__mono_wasm_abortcontroller_hook__");
-                    var signal = abortController.GetObjectProperty("signal");
+                    signal = (JSObject)abortController.GetObjectProperty("signal");
                     requestObject.SetObjectProperty("signal", signal);
                     abortRegistration = cancellationToken.Register(() =>
                     {
                         if (abortController.JSHandle != -1)
                         {
                             abortController.Invoke("abort");
+                            abortController?.Dispose();
                         }
+                        wasmHttpReadStream?.Dispose();
                     });
                 }
 
@@ -168,7 +173,7 @@ namespace WebAssembly.Net.Http.HttpClient
                 HttpResponseMessage httpresponse = new HttpResponseMessage((HttpStatusCode)Enum.Parse(typeof(HttpStatusCode), status.Status.ToString()));
 
                 httpresponse.Content = StreamingSupported && StreamingEnabled
-                    ? new StreamContent(new WasmHttpReadStream(status))
+                    ? new StreamContent(wasmHttpReadStream = new WasmHttpReadStream(status))
                     : (HttpContent)new WasmHttpContent(status);
 
                 // Fill the response headers
@@ -196,6 +201,13 @@ namespace WebAssembly.Net.Http.HttpClient
                 }
 
                 tcs.SetResult(httpresponse);
+
+                // Do not remove the following line of code.  The httpresponse is used in the lambda above when parsing the Headers.
+                // if a local is captured (used) by a lambda it becomes heap memory as we translate them into fields on an object.
+                // If we do not null the field out it will not be GC'd
+                httpresponse = null;
+
+                signal?.Dispose();
             }
             catch (Exception exception)
             {