Making HttpConnection restartable (C#) #1147

moozzyk · 2017-11-22T19:52:41Z

~~(a.k.a. Opening Pandora box)~~

BrennanConroy · 2017-11-27T17:04:02Z

src/Microsoft.AspNetCore.SignalR.Client.Core/HubConnection.cs


        private int _nextId = 0;
        private volatile bool _startCalled;

-        public Task Closed { get; }
+        public event Action<Exception> Closed;


Shouldn't this be a wrapper around _connection.Closed?

No. This way the only event that is hooked to HttpConnection is the one from hubConnection and the user subscribes to the object they are using.

BrennanConroy · 2017-11-27T17:06:07Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

            {
                return Task.FromException(
-                    new InvalidOperationException("Cannot start a connection that is not in the Initial state."));
+                    new InvalidOperationException("Cannot start a connection that is not in the Disconnected state."));


nameof(ConnectionState.Disconnected)!

Fixed. Initially it was not possible because state was tracked as int not an enum.

BrennanConroy · 2017-11-27T17:12:31Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

-            _logger.StoppingClient(_connectionId);
-
-            if (Interlocked.Exchange(ref _connectionState, ConnectionState.Disconnected) == ConnectionState.Initial)
+            lock(_stateChangeLock)


BrennanConroy · 2017-11-27T17:16:28Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

-        private class ConnectionState
+        private ConnectionState ChangeState(ConnectionState from, ConnectionState to)
+        {
+            lock(_stateChangeLock)


BrennanConroy · 2017-11-27T17:20:33Z

src/Microsoft.AspNetCore.Sockets.Abstractions/IConnection.cs

        Task DisposeAsync();

        IDisposable OnReceived(Func<byte[], object, Task> callback, object state);

-        Task Closed { get; }
+        event Action<Exception> Closed;


Used to be Func<Exception, Task>, any reason we don't go back to that?

I am not sure we want it (and what we had was not implemented correctly). I think we need to try which pattern works better for restarting the connection from this event.

BrennanConroy · 2017-11-27T17:46:59Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

+            var startTask = connection.StartAsync();
+            await allowStopTcs.Task;
+
+            await Task.WhenAll(startTask.OrTimeout(), connection.StopAsync().OrTimeout());


Just OrTimeout the WhenAll call

BrennanConroy · 2017-11-27T17:48:18Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

+        }
+
+        [Fact]
+        public async Task CanStartConnectionStoppedWithError()


CanStartConnectionAfterStoppedWithError?

BrennanConroy · 2017-11-27T17:49:00Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

+                await connection.SendAsync(new byte[] { 0x42 }).OrTimeout();
+            }
+            catch { }
+            await closeTcs.Task.OrTimeout().OrTimeout();


Dupe OrTimeout

BrennanConroy · 2017-11-27T17:49:33Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

+        [Fact]
+        public async Task CanStopStoppedConnection()
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();


BrennanConroy · 2017-11-27T17:54:09Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/TestConnection.cs

@@ -134,16 +138,16 @@ private byte[] FormatMessageToArray(byte[] message)
                        }
                    }
                }
-                _closeTcs.TrySetResult(null);
+                Closed(null);


Closed?.Invoke(...)

BrennanConroy · 2017-12-07T17:29:13Z

src/Microsoft.AspNetCore.SignalR.Client.Core/HubConnection.cs

@@ -364,6 +365,8 @@ private void Shutdown(Exception ex = null)
                }
                _pendingCalls.Clear();
            }
+
+            Closed?.Invoke(ex);


try catch, don't trust user code

BrennanConroy · 2017-12-07T17:35:41Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

-                    if (t.IsCanceled)
-                    {
-                        _closedTcs.TrySetCanceled();
+                        Closed?.Invoke(t.Exception.InnerException);


Can't trust user code, should wrap this

analogrelay · 2017-12-07T23:54:18Z

This needs a bunch of rebasing and adjusting after merging #1165 . I'll do that and ping this when I'm done.

analogrelay · 2017-12-08T23:35:41Z

Ok, it should be 🆙 to 📅 now. I had to refactor some things to handle the new AbortAsync. Also, some tests seem to have been broken by the fact that Dispose waits on Start to finish, but I fixed that.

Finally, there was a test for Received not firing after Dispose is called which isn't really possible since the state changes that trigger that all occur after the channel is marked completed anyway. The test was broken so I just removed it (because it is no longer relevant).

analogrelay · 2017-12-08T23:36:51Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

@@ -355,46 +592,63 @@ public void CannotStartConnectionWithInvalidTransportType(TransportType requeste
        [Fact]
        public async Task EventQueueTimeout()


Turns out this test wasn't actually working and it was hiding an issue in the EventQueue drain logic :)

analogrelay · 2017-12-08T23:38:16Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

            }
            finally
            {
                await connection.DisposeAsync();
            }
        }

-        [Fact]
-        public async Task ReceivedCallbackNotRaisedAfterConnectionIsDisposed()


This is the test that I mentioned in other comments. It is not really relevant any more as the channel is closed before the state changes to make this event no-op occur.

analogrelay · 2017-12-11T17:46:31Z

Should be green after this next build. ping @BrennanConroy @mikaelm12

This one is unfortunately a bit of a tricky one, and I'm thinking I might do some test refactoring after this PR to make them clearer as they're a bit messy now (due to how tests tend to grow organically)

~~(a.k.a. Opening Pandora box)~~

BrennanConroy · 2017-12-11T20:23:41Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

@@ -306,7 +320,11 @@ private static Uri CreateConnectUrl(Uri url, NegotiationResponse negotiationResp
                await _transport.StartAsync(connectUrl, applicationSide, GetTransferMode(), _connectionId, this);

                // actual transfer mode can differ from the one that was requested so set it on the feature
-                Debug.Assert(_transport.Mode.HasValue, "transfer mode not set after transport started");
+                if(!_transport.Mode.HasValue)


BrennanConroy · 2017-12-11T20:24:46Z

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

+        //     first AbortAsync call is still set at the time CloseAsync gets to calling the Closed event. However, this can't happen because the
+        //     StartAsync method can't be called until the connection state is changed to Disconnected, which happens AFTER the close code
+        //     captures and resets _abortException.
+        public async Task AbortAsync(Exception ex) => await StopAsyncCore(ex ?? throw new ArgumentNullException(nameof(ex))).ForceAsync();


super nit: public API we should name the argument exception

BrennanConroy · 2017-12-11T20:40:12Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.AbortAsync.cs

@@ -0,0 +1,272 @@
+using System;


BrennanConroy · 2017-12-11T20:42:07Z

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.AbortAsync.cs

+                    await connection.StartAsync().OrTimeout();
+
+                    // Stop normally
+                    var stopTask = connection.StopAsync();


fretje · 2018-01-15T12:23:37Z

samples/ClientSample/HubSample.cs

                try
                {
                    await connection.StartAsync();
-                    return connection;
                }


Don't you need to return here? Otherwise this method will never return... or am I missing something?

The return value was changed from Task<HubConnection> to Task

Yes indeed, but that still means you need a return statement right? Just without the connection...

Correct, unless you're using async await
https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/await

As far as I understand it, the await keyword will just wait for the execution of StartAsync() to finish before continuing with the method. It will not return from the method. As this is inside a while(true) loop, I think it will never return.

What @fretje means is that this is an infinite loop:

while (true) { try { await connection.StartAsync(); } catch (Exception) { } }

@acjh Thanks! Yes you guys are right, this is broken. Would either of you like to make a PR to fix it?

BrennanConroy reviewed Nov 27, 2017

View reviewed changes

muratg requested a review from analogrelay November 30, 2017 20:51

muratg assigned analogrelay Nov 30, 2017

muratg removed the request for review from analogrelay November 30, 2017 20:51

muratg added this to the 2.1.0-preview1 milestone Nov 30, 2017

moozzyk force-pushed the pawelka/restartable branch from 018d79f to ecab6f6 Compare November 30, 2017 23:36

BrennanConroy reviewed Dec 7, 2017

View reviewed changes

analogrelay force-pushed the pawelka/restartable branch from 337785a to ce39b47 Compare December 7, 2017 23:53

analogrelay reviewed Dec 8, 2017

View reviewed changes

analogrelay mentioned this pull request Dec 11, 2017

Object Disposed Exception on OnReceived callback #1199

Closed

Making HttpConnection restartable (C#)

d51f576

~~(a.k.a. Opening Pandora box)~~

analogrelay force-pushed the pawelka/restartable branch from e9bc9eb to d51f576 Compare December 11, 2017 19:38

BrennanConroy reviewed Dec 11, 2017

View reviewed changes

pr feedback

5522c4e

BrennanConroy approved these changes Dec 11, 2017

View reviewed changes

moar feedback

bc18bf7

analogrelay mentioned this pull request Dec 12, 2017

AllExcept for Groups - GroupExcept #1204

Merged

analogrelay merged commit 66ab939 into dev Dec 12, 2017

analogrelay deleted the pawelka/restartable branch December 12, 2017 18:08

analogrelay mentioned this pull request Dec 12, 2017

clean up HttpConnectionTests #1208

Merged

fretje reviewed Jan 15, 2018

View reviewed changes

grahambunce mentioned this pull request Jun 28, 2018

How does a client tell the server what group it wants to be in or what user it is? dotnet/AspNetCore.Docs#7255

Closed

		@@ -355,46 +592,63 @@ public void CannotStartConnectionWithInvalidTransportType(TransportType requeste
		[Fact]
		public async Task EventQueueTimeout()

Making HttpConnection restartable (C#) #1147

Making HttpConnection restartable (C#) #1147

Uh oh!

Conversation

moozzyk commented Nov 22, 2017

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

analogrelay commented Dec 7, 2017

Uh oh!

analogrelay commented Dec 8, 2017

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

analogrelay commented Dec 11, 2017

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Uh oh!