Add new factory overloads.

Source/MQTTnet.AspnetCore/MqttConnectionContext.cs

@@ -11,11 +11,18 @@ using System.Security.Cryptography.X509Certificates;
 using System.Threading;
 using System.Threading.Tasks;
 using MQTTnet.AspNetCore.Extensions;
+using MQTTnet.Internal;
 
 namespace MQTTnet.AspNetCore
 {
-    public class MqttConnectionContext : IMqttChannelAdapter
+    public sealed class MqttConnectionContext : IMqttChannelAdapter
     {
+        readonly AsyncLock _writerLock = new AsyncLock();
+        readonly SpanBasedMqttPacketBodyReader _reader;
+        
+        PipeReader _input;
+        PipeWriter _output;
+        
         public MqttConnectionContext(MqttPacketFormatterAdapter packetFormatterAdapter, ConnectionContext connection)
         {
             PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
@@ -30,10 +37,6 @@ namespace MQTTnet.AspNetCore
             _reader = new SpanBasedMqttPacketBodyReader();
         }
 
-        private PipeReader _input;
-        private PipeWriter _output;
-        private readonly SpanBasedMqttPacketBodyReader _reader;
-
         public string Endpoint
         {
             get
@@ -58,9 +61,8 @@ namespace MQTTnet.AspNetCore
 
         public X509Certificate2 ClientCertificate => Http?.HttpContext?.Connection?.ClientCertificate;
 
-        private IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();
-
         public ConnectionContext Connection { get; }
+        
         public MqttPacketFormatterAdapter PacketFormatterAdapter { get; }
 
         public long BytesSent { get; set; }
@@ -69,7 +71,7 @@ namespace MQTTnet.AspNetCore
         public Action ReadingPacketStartedCallback { get; set; }
         public Action ReadingPacketCompletedCallback { get; set; }
 
-        private readonly SemaphoreSlim _writerSemaphore = new SemaphoreSlim(1, 1);
+        IHttpContextFeature Http => Connection.Features.Get<IHttpContextFeature>();
 
         public async Task ConnectAsync(TimeSpan timeout, CancellationToken cancellationToken)
         {
@@ -165,8 +167,7 @@ namespace MQTTnet.AspNetCore
             var msg = buffer.AsMemory();
             var output = _output;
 
-            await _writerSemaphore.WaitAsync(cancellationToken).ConfigureAwait(false);
-            try
+            using (await _writerLock.WaitAsync(cancellationToken).ConfigureAwait(false))
             {
                 var result = await output.WriteAsync(msg, cancellationToken).ConfigureAwait(false);
                 if (result.IsCompleted)
@@ -176,10 +177,6 @@ namespace MQTTnet.AspNetCore
 
                 PacketFormatterAdapter.FreeBuffer();
             }
-            finally
-            {
-                _writerSemaphore.Release();
-            }
         }
 
         public void Dispose()