Source codes

1 files changed, 138 insertions, 0 deletions

diff --git a/WhisperNet/Internal/NativeLogger.cs b/WhisperNet/Internal/NativeLogger.cs
new file mode 100644
index 0000000..b4b4eb2
--- /dev/null
+++ b/WhisperNet/Internal/NativeLogger.cs
@@ -0,0 +1,138 @@
+using System.Runtime.CompilerServices;
+using System.Runtime.ExceptionServices;
+using System.Runtime.InteropServices;
+
+namespace Whisper.Internal
+{
+	/// <summary>Utility class to supply logging function pointer to the C++ library,<br/>
+	/// and provide custom calling conventions to ComLight runtime to convert error messages printed in C++ into .NET exception messages</summary>
+	public static class NativeLogger
+	{
+		internal static void startup() { }
+
+		static NativeLogger()
+		{
+			sink = logSink;
+			sLoggerSetup setup = default;
+			setup.sink = sink;
+			setup.level = eLogLevel.Warning;
+			Library.setupLogger( ref setup );
+		}
+
+		internal static void setup( eLogLevel lvl, eLoggerFlags flags, pfnLogMessage? pfn )
+		{
+			logMessage = pfn;
+
+			sLoggerSetup setup = default;
+			setup.sink = sink;
+			setup.level = lvl;
+			setup.flags = flags;
+			Library.setupLogger( ref setup );
+		}
+
+		// This field is here to protect the function pointer from being collected by the GC
+		static readonly pfnLoggerSink sink;
+
+		static void logSink( IntPtr context, eLogLevel lvl, string message )
+		{
+			if( lvl == eLogLevel.Error )
+				state.setText( message );
+			logMessage?.Invoke( lvl, message );
+		}
+
+		sealed class ThreadState
+		{
+			string? errorText = null;
+			ExceptionDispatchInfo? dispatchInfo = null;
+
+			public void setText( string text ) => errorText = text;
+			public void capture( Exception ex ) => dispatchInfo = ExceptionDispatchInfo.Capture( ex );
+
+			public void clear()
+			{
+				errorText = null;
+				dispatchInfo = null;
+			}
+
+			public void Deconstruct( out string? text, out ExceptionDispatchInfo? edi )
+			{
+				text = errorText;
+				edi = dispatchInfo;
+				errorText = null;
+				dispatchInfo = null;
+			}
+		}
+
+		[ThreadStatic]
+		static ThreadState state = new ThreadState();
+
+		internal static void captureException( Exception ex ) =>
+			state.capture( ex );
+
+		static pfnLogMessage? logMessage = null;
+
+		/// <summary>Called internally by ComLight runtime</summary>
+		[MethodImpl( MethodImplOptions.AggressiveInlining )]
+		public static void prologue()
+		{
+			// https://stackoverflow.com/a/2043505/126995
+			if( null != state )
+				state.clear();
+			else
+				createState();
+		}
+
+		[MethodImpl( MethodImplOptions.NoInlining )]
+		static void createState()
+		{
+			state = new ThreadState();
+		}
+
+		/// <summary>Epilogue implementation for unsuccessful status codes</summary>
+		[MethodImpl( MethodImplOptions.NoInlining )]
+		static void throwException( int hr )
+		{
+			// Move state from the thread local object into local variables, and clear that object
+			(string? text, ExceptionDispatchInfo? edi) = state;
+
+			if( null != edi && edi.SourceException.HResult == hr )
+			{
+				// The error comes from a callback, and we have original context of that exception.
+				// Re-throw the original exception.
+				// This uses the original error message, and even correctly deals with the stack trace.
+				edi.Throw();
+			}
+
+			if( null != text )
+			{
+				// C++ code has printed an error on the current thread, between prologue and epilogue.
+				// Use that text for the exception message.
+				Exception? ex = Marshal.GetExceptionForHR( hr );
+				throw new ApplicationException( text, ex );
+			}
+
+			// We don’t have any additional info about the exception.
+			// Throw an exception from just the HRESULT code.
+			Marshal.ThrowExceptionForHR( hr );
+		}
+
+		/// <summary>Called internally by ComLight runtime</summary>
+		[MethodImpl( MethodImplOptions.AggressiveInlining )]
+		public static void throwForHR( int hr )
+		{
+			if( hr >= 0 )
+				return; // SUCCEEDED
+			throwException( hr );
+		}
+
+		/// <summary>Called internally by ComLight runtime</summary>
+		[MethodImpl( MethodImplOptions.AggressiveInlining )]
+		public static bool throwAndReturnBool( int hr )
+		{
+			if( hr >= 0 )
+				return 0 == hr;
+			throwException( hr );
+			return false;
+		}
+	}
+}
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