Merge pull request #69 from mhutch/more-logging-helpers

Add helpers for logging enumeration exceptions

Core/Logging/LoggerExtensions.LoggedEnumerable.cs

@@ -0,0 +1,96 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+using Microsoft.Extensions.Logging;
+
+namespace MonoDevelop.Xml.Logging;
+
+public static partial class LoggerExtensions
+{
+	class LoggedEnumerable<T> : IEnumerable<T>
+	{
+		readonly IEnumerable<T> enumerable;
+		readonly ILogger logger;
+		readonly string? originMember;
+
+		public LoggedEnumerable (IEnumerable<T> enumerable, ILogger logger, string originMember)
+		{
+			this.enumerable = enumerable;
+			this.logger = logger;
+			this.originMember = originMember;
+		}
+
+		void Log (Exception ex) => logger.LogInternalError (ex, originMember);
+
+		public IEnumerator<T> GetEnumerator ()
+		{
+			try {
+				var enumerator = enumerable.GetEnumerator ();
+				return new LoggedEnumerator (this, enumerator);
+			} catch (Exception ex) {
+				Log (ex);
+				throw;
+			}
+		}
+
+		IEnumerator IEnumerable.GetEnumerator () => GetEnumerator ();
+
+		class LoggedEnumerator : IEnumerator<T>
+		{
+			readonly LoggedEnumerable<T> parent;
+			readonly IEnumerator<T> enumerator;
+
+			public LoggedEnumerator (LoggedEnumerable<T> parent, IEnumerator<T> enumerator)
+			{
+				this.parent = parent;
+				this.enumerator = enumerator;
+			}
+
+			public T Current {
+				get {
+					try {
+						return enumerator.Current;
+					} catch (Exception ex) {
+						parent.Log (ex);
+						throw;
+					}
+				}
+			}
+
+			object? IEnumerator.Current => Current;
+
+			public void Dispose ()
+			{
+				try {
+					enumerator.Dispose ();
+				} catch (Exception ex) {
+					parent.Log (ex);
+					throw;
+				}
+			}
+
+			public bool MoveNext ()
+			{
+				try {
+					return enumerator.MoveNext ();
+				} catch (Exception ex) {
+					parent.Log (ex);
+					return false;
+				}
+			}
+
+			public void Reset ()
+			{
+				try {
+					enumerator.Reset ();
+				} catch (Exception ex) {
+					parent.Log (ex);
+				}
+			}
+		}
+	}
+}

Core/Logging/LoggerExtensions.cs

@@ -20,21 +20,37 @@ public static void LogExceptionsAndForget (this Task task, ILogger logger, [Call
 		task.CatchAndLogIfFaulted (logger, originMember);
 	}
 
-	public static Task<T> WithExceptionLogger<T> (this Task<T> task, ILogger logger, [CallerMemberName] string? originMember = default)
+	/// <summary>
+	/// Attaches a continution to the task that logs any exception thrown by the task, and returns the task.
+	/// </summary>
+	public static Task WithExceptionLogger (this Task task, ILogger logger, [CallerMemberName] string? originMember = default)
 	{
 		task.CatchAndLogIfFaulted (logger, originMember);
 		return task;
 	}
 
-	/// <summary>
-	/// Attaches a continution to the task that logs any exception thrown by the task, and returns the task.
-	/// </summary>
-	public static Task WithExceptionLogger (this Task task, ILogger logger, [CallerMemberName] string? originMember = default)
+	public static Task<T> WithExceptionLogger<T> (this Task<T> task, ILogger logger, [CallerMemberName] string? originMember = default)
 	{
 		task.CatchAndLogIfFaulted (logger, originMember);
 		return task;
 	}
 
+	public static Task<IEnumerable<T>> WithExceptionLogger<T> (this Task<IEnumerable<T>> task, ILogger logger, [CallerMemberName] string? originMember = default)
+	{
+		return task.ContinueWith (t => {
+			try {
+				return t.Result.WithExceptionLogger (logger, originMember);
+			} catch (Exception ex) {
+				LogInternalError (logger, ex, originMember);
+				throw;
+			}
+		},
+		TaskContinuationOptions.ExecuteSynchronously);
+	}
+
+	public static IEnumerable<T> WithExceptionLogger<T> (this IEnumerable<T> enumerable, ILogger logger, [CallerMemberName] string? originMember = default)
+		=> new LoggedEnumerable<T> (enumerable, logger, originMember ?? throw new ArgumentNullException (nameof (originMember)));
+
 	static Task CatchAndLogIfFaulted (this Task task, ILogger logger, string? originMember)
 	{
 		if (originMember is null) {
@@ -44,7 +60,7 @@ static Task CatchAndLogIfFaulted (this Task task, ILogger logger, string? origin
 		_ = task.ContinueWith (
 			t => LogExceptions (logger, originMember, t),
 			default,
-			TaskContinuationOptions.OnlyOnFaulted,
+			TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.ExecuteSynchronously,
 			TaskScheduler.Default
 		);