Support for .NET Standard 2.0 and 2.1

.github/workflows/test.yml

@@ -149,3 +149,7 @@ jobs:
 
       - name: Memory Test (net6.0)
         run: dotMemoryUnit $env:userprofile\.dotnet\tools\nunit.exe --propagate-exit-code -- .\tests\NATS.Client.Core.MemoryTests\bin\Release\net6.0\NATS.Client.Core.MemoryTests.dll
+
+      - name: Platform Test (Windows net481)
+        run: dotnet test -c Release --no-build --logger:"console;verbosity=normal" -f net481 .\tests\NATS.Client.Platform.Windows.Tests\NATS.Client.Platform.Windows.Tests.csproj
+

NATS.Client.sln

@@ -107,6 +107,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Example.OpenTelemetry", "sa
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NATS.Net.OpenTelemetry.Tests", "tests\NATS.Net.OpenTelemetry.Tests\NATS.Net.OpenTelemetry.Tests.csproj", "{B8554582-DE19-41A2-9784-9B27C9F22429}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "NATS.Client.Platform.Windows.Tests", "tests\NATS.Client.Platform.Windows.Tests\NATS.Client.Platform.Windows.Tests.csproj", "{A37994CC-A23A-415E-8B61-9468C7178A55}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -285,6 +287,10 @@ Global
 		{B8554582-DE19-41A2-9784-9B27C9F22429}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{B8554582-DE19-41A2-9784-9B27C9F22429}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{B8554582-DE19-41A2-9784-9B27C9F22429}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A37994CC-A23A-415E-8B61-9468C7178A55}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A37994CC-A23A-415E-8B61-9468C7178A55}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A37994CC-A23A-415E-8B61-9468C7178A55}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A37994CC-A23A-415E-8B61-9468C7178A55}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -334,6 +340,7 @@ Global
 		{2EA0EB68-1AA4-40AC-8FA2-B51532075567} = {4827B3EC-73D8-436D-AE2A-5E29AC95FD0C}
 		{474BA453-9CFF-41C2-B2E7-ADD92CC93E86} = {95A69671-16CA-4133-981C-CC381B7AAA30}
 		{B8554582-DE19-41A2-9784-9B27C9F22429} = {C526E8AB-739A-48D7-8FC4-048978C9B650}
+		{A37994CC-A23A-415E-8B61-9468C7178A55} = {C526E8AB-739A-48D7-8FC4-048978C9B650}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {8CBB7278-D093-448E-B3DE-B5991209A1AA}

src/NATS.Client.Core/Commands/CommandWriter.cs

@@ -113,10 +113,10 @@ public async Task CancelReaderLoopAsync()
 
         if (cts != null)
         {
-#if NET6_0
-            cts.Cancel();
-#else
+#if NET8_0_OR_GREATER
             await cts.CancelAsync().ConfigureAwait(false);
+#else
+            cts.Cancel();
 #endif
         }
 
@@ -133,10 +133,10 @@ public async ValueTask DisposeAsync()
 
         _disposed = true;
 
-#if NET6_0
-        _cts.Cancel();
-#else
+#if NET8_0_OR_GREATER
         await _cts.CancelAsync().ConfigureAwait(false);
+#else
+        _cts.Cancel();
 #endif
 
         _channelLock.Writer.TryComplete();
@@ -164,7 +164,11 @@ public ValueTask ConnectAsync(ClientOpts connectOpts, CancellationToken cancella
             return ConnectStateMachineAsync(false, connectOpts, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return ConnectStateMachineAsync(true, connectOpts, cancellationToken);
         }
@@ -184,7 +188,7 @@ public ValueTask ConnectAsync(ClientOpts connectOpts, CancellationToken cancella
             _semLock.Release();
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     public ValueTask PingAsync(PingCommand pingCommand, CancellationToken cancellationToken)
@@ -198,7 +202,11 @@ public ValueTask PingAsync(PingCommand pingCommand, CancellationToken cancellati
             return PingStateMachineAsync(false, pingCommand, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return PingStateMachineAsync(true, pingCommand, cancellationToken);
         }
@@ -219,7 +227,7 @@ public ValueTask PingAsync(PingCommand pingCommand, CancellationToken cancellati
             _semLock.Release();
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     public ValueTask PongAsync(CancellationToken cancellationToken = default)
@@ -233,7 +241,11 @@ public ValueTask PongAsync(CancellationToken cancellationToken = default)
             return PongStateMachineAsync(false, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return PongStateMachineAsync(true, cancellationToken);
         }
@@ -253,7 +265,7 @@ public ValueTask PongAsync(CancellationToken cancellationToken = default)
             _semLock.Release();
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     public ValueTask PublishAsync<T>(string subject, T? value, NatsHeaders? headers, string? replyTo, INatsSerialize<T> serializer, CancellationToken cancellationToken)
@@ -306,7 +318,11 @@ public ValueTask PublishAsync<T>(string subject, T? value, NatsHeaders? headers,
             return PublishStateMachineAsync(false, subject, replyTo, headersBuffer, payloadBuffer, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return PublishStateMachineAsync(true, subject, replyTo, headersBuffer, payloadBuffer, cancellationToken);
         }
@@ -335,7 +351,7 @@ public ValueTask PublishAsync<T>(string subject, T? value, NatsHeaders? headers,
             }
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     public ValueTask SubscribeAsync(int sid, string subject, string? queueGroup, int? maxMsgs, CancellationToken cancellationToken)
@@ -349,7 +365,11 @@ public ValueTask SubscribeAsync(int sid, string subject, string? queueGroup, int
             return SubscribeStateMachineAsync(false, sid, subject, queueGroup, maxMsgs, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return SubscribeStateMachineAsync(true, sid, subject, queueGroup, maxMsgs, cancellationToken);
         }
@@ -369,7 +389,7 @@ public ValueTask SubscribeAsync(int sid, string subject, string? queueGroup, int
             _semLock.Release();
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     public ValueTask UnsubscribeAsync(int sid, int? maxMsgs, CancellationToken cancellationToken)
@@ -383,7 +403,11 @@ public ValueTask UnsubscribeAsync(int sid, int? maxMsgs, CancellationToken cance
             return UnsubscribeStateMachineAsync(false, sid, maxMsgs, cancellationToken);
         }
 
+#if NETSTANDARD2_0
+        if (_flushTask.IsNotCompletedSuccessfully())
+#else
         if (_flushTask is { IsCompletedSuccessfully: false })
+#endif
         {
             return UnsubscribeStateMachineAsync(true, sid, maxMsgs, cancellationToken);
         }
@@ -403,7 +427,7 @@ public ValueTask UnsubscribeAsync(int sid, int? maxMsgs, CancellationToken cance
             _semLock.Release();
         }
 
-        return ValueTask.CompletedTask;
+        return default;
     }
 
     // only used for internal testing
@@ -413,10 +437,17 @@ internal async Task TestStallFlushAsync(TimeSpan timeSpan, CancellationToken can
 
         try
         {
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.ConfigureAwait(false);
             }
+#endif
 
             _flushTask = Task.Delay(timeSpan, cancellationToken);
         }
@@ -630,10 +661,17 @@ private async ValueTask ConnectStateMachineAsync(bool lockHeld, ClientOpts conne
                 throw new ObjectDisposedException(nameof(CommandWriter));
             }
 
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
             }
+#endif
 
             _protocolWriter.WriteConnect(_pipeWriter, connectOpts);
             EnqueueCommand();
@@ -667,10 +705,17 @@ private async ValueTask PingStateMachineAsync(bool lockHeld, PingCommand pingCom
                 throw new ObjectDisposedException(nameof(CommandWriter));
             }
 
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
             }
+#endif
 
             _protocolWriter.WritePing(_pipeWriter);
             _enqueuePing(pingCommand);
@@ -705,10 +750,17 @@ private async ValueTask PongStateMachineAsync(bool lockHeld, CancellationToken c
                 throw new ObjectDisposedException(nameof(CommandWriter));
             }
 
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
             }
+#endif
 
             _protocolWriter.WritePong(_pipeWriter);
             EnqueueCommand();
@@ -725,7 +777,9 @@ private async ValueTask PongStateMachineAsync(bool lockHeld, CancellationToken c
         }
     }
 
+#if !NETSTANDARD
     [AsyncMethodBuilder(typeof(PoolingAsyncValueTaskMethodBuilder))]
+#endif
     private async ValueTask PublishStateMachineAsync(bool lockHeld, string subject, string? replyTo, NatsPooledBufferWriter<byte>? headersBuffer, NatsPooledBufferWriter<byte> payloadBuffer, CancellationToken cancellationToken)
     {
         try
@@ -745,10 +799,17 @@ private async ValueTask PublishStateMachineAsync(bool lockHeld, string subject,
                     throw new ObjectDisposedException(nameof(CommandWriter));
                 }
 
+#if NETSTANDARD2_0
+                if (_flushTask.IsNotCompletedSuccessfully())
+                {
+                    await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+                }
+#else
                 if (_flushTask is { IsCompletedSuccessfully: false })
                 {
                     await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
                 }
+#endif
 
                 _protocolWriter.WritePublish(_pipeWriter, subject, replyTo, headersBuffer?.WrittenMemory, payloadBuffer.WrittenMemory);
                 EnqueueCommand();
@@ -794,10 +855,17 @@ private async ValueTask SubscribeStateMachineAsync(bool lockHeld, int sid, strin
                 throw new ObjectDisposedException(nameof(CommandWriter));
             }
 
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
             }
+#endif
 
             _protocolWriter.WriteSubscribe(_pipeWriter, sid, subject, queueGroup, maxMsgs);
             EnqueueCommand();
@@ -831,10 +899,17 @@ private async ValueTask UnsubscribeStateMachineAsync(bool lockHeld, int sid, int
                 throw new ObjectDisposedException(nameof(CommandWriter));
             }
 
+#if NETSTANDARD2_0
+            if (_flushTask.IsNotCompletedSuccessfully())
+            {
+                await _flushTask!.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
+            }
+#else
             if (_flushTask is { IsCompletedSuccessfully: false })
             {
                 await _flushTask.WaitAsync(_defaultCommandTimeout, cancellationToken).ConfigureAwait(false);
             }
+#endif
 
             _protocolWriter.WriteUnsubscribe(_pipeWriter, sid, maxMsgs);
             EnqueueCommand();

src/NATS.Client.Core/Commands/NatsPooledBufferWriter.cs

@@ -193,6 +193,7 @@ private void ResizeBuffer(int sizeHint)
     {
         var minimumSize = (uint)_index + (uint)sizeHint;
 
+#if !NETSTANDARD
         // The ArrayPool<T> class has a maximum threshold of 1024 * 1024 for the maximum length of
         // pooled arrays, and once this is exceeded it will just allocate a new array every time
         // of exactly the requested size. In that case, we manually round up the requested size to
@@ -202,6 +203,7 @@ private void ResizeBuffer(int sizeHint)
         {
             minimumSize = BitOperations.RoundUpToPowerOf2(minimumSize);
         }
+#endif
 
         _pool.Resize(ref _array, (int)minimumSize);
     }

src/NATS.Client.Core/INatsSerialize.cs

@@ -375,7 +375,11 @@ public void Serialize(IBufferWriter<byte> bufferWriter, T value)
             return (T)(object)Encoding.UTF8.GetString(buffer);
         }
 
+#if NETSTANDARD2_0
+        var span = buffer.IsSingleSegment ? buffer.First.Span : buffer.ToArray();
+#else
         var span = buffer.IsSingleSegment ? buffer.FirstSpan : buffer.ToArray();
+#endif
 
         if (typeof(T) == typeof(DateTime) || typeof(T) == typeof(DateTime?))
         {
@@ -621,7 +625,11 @@ public void Serialize(IBufferWriter<byte> bufferWriter, T value)
         {
             if (readOnlySequence.IsSingleSegment)
             {
+#if NETSTANDARD2_0
+                bufferWriter.Write(readOnlySequence.First.Span);
+#else
                 bufferWriter.Write(readOnlySequence.FirstSpan);
+#endif
             }
             else
             {

src/NATS.Client.Core/Internal/ActivityEndingMsgReader.cs

@@ -109,7 +109,11 @@ public override bool TryPeek(out NatsMsg<T> item)
         return _inner.TryPeek(out item);
     }
 
+#if NETSTANDARD2_0
+    public async IAsyncEnumerable<NatsMsg<T>> ReadAllAsync([EnumeratorCancellation] CancellationToken cancellationToken = default)
+#else
     public override async IAsyncEnumerable<NatsMsg<T>> ReadAllAsync([EnumeratorCancellation] CancellationToken cancellationToken = default)
+#endif
     {
         var handle = GCHandle.Alloc(_sub);
         try

src/NATS.Client.Core/Internal/BufferExtensions.cs

@@ -29,7 +29,11 @@ public static ReadOnlySpan<byte> ToSpan(this ReadOnlySequence<byte> buffer)
     {
         if (buffer.IsSingleSegment)
         {
+#if NETSTANDARD2_0
+            return buffer.First.Span;
+#else
             return buffer.FirstSpan;
+#endif
         }
 
         return buffer.ToArray();