feat(logging): 添加异步日志输出器的错误处理回调功能

- 在 AsyncLogAppender 构造函数中添加 processingErrorHandler 参数用于处理后台异常
- 实现 ReportProcessingError 方法安全上报后台处理异常而不影响处理循环
- 更新文档注释说明异常处理机制和错误回调用途
- 修改测试用例验证异常处理回调功能的正确性
- 确保错误观察者异常不会终止日志处理线程
- 移除直接写入控制台错误输出的逻辑改为统一回调处理

GFramework.Core.Tests/Logging/AsyncLogAppenderTests.cs

@@ -1,6 +1,5 @@
 using GFramework.Core.Abstractions.Logging;
 using GFramework.Core.Logging.Appenders;
-using NUnit.Framework;
 
 namespace GFramework.Core.Tests.Logging;
 
@@ -152,8 +151,12 @@ public class AsyncLogAppenderTests
     [Test]
     public void Append_WhenInnerAppenderThrows_ShouldNotCrash()
     {
+        var reportedExceptions = new List<Exception>();
         var innerAppender = new ThrowingAppender();
-        using var asyncAppender = new AsyncLogAppender(innerAppender, bufferSize: 1000);
+        using var asyncAppender = new AsyncLogAppender(
+            innerAppender,
+            bufferSize: 1000,
+            processingErrorHandler: reportedExceptions.Add);
 
         // 即使内部 Appender 抛出异常，也不应该影响调用线程
         Assert.DoesNotThrow(() =>
@@ -165,7 +168,33 @@ public class AsyncLogAppenderTests
             }
         });
 
-        Thread.Sleep(100); // 等待后台处理
+        asyncAppender.Flush();
+
+        Assert.That(reportedExceptions, Has.Count.EqualTo(10));
+        Assert.That(reportedExceptions, Has.All.TypeOf<InvalidOperationException>());
+        Assert.That(reportedExceptions.Select(static exception => exception.Message),
+            Has.All.EqualTo("Test exception"));
+    }
+
+    [Test]
+    public void Append_WhenProcessingErrorHandlerThrows_ShouldStillNotCrash()
+    {
+        var innerAppender = new ThrowingAppender();
+        using var asyncAppender = new AsyncLogAppender(
+            innerAppender,
+            bufferSize: 1000,
+            processingErrorHandler: static _ => throw new InvalidOperationException("Observer failure"));
+
+        Assert.DoesNotThrow(() =>
+        {
+            for (int i = 0; i < 10; i++)
+            {
+                var entry = new LogEntry(DateTime.UtcNow, LogLevel.Info, "TestLogger", $"Message {i}", null, null);
+                asyncAppender.Append(entry);
+            }
+        });
+
+        Assert.That(asyncAppender.Flush(), Is.True);
     }
 
     // 辅助测试类

GFramework.Core/Logging/Appenders/AsyncLogAppender.cs

@@ -4,14 +4,24 @@ using GFramework.Core.Abstractions.Logging;
 namespace GFramework.Core.Logging.Appenders;
 
 /// <summary>
-///     异步日志输出器，使用 Channel 实现非阻塞日志写入
+///     异步日志输出器，使用 <see cref="Channel{T}" /> 将调用线程与慢速日志目标解耦。
 /// </summary>
-public sealed class AsyncLogAppender : ILogAppender, IDisposable
+/// <remarks>
+///     <para>
+///         该输出器在后台线程中顺序消费日志条目，因此调用方不会因为文件 IO 或其他慢速输出目标而阻塞。
+///     </para>
+///     <para>
+///         内部输出器抛出的异常不会重新抛回调用线程；如需观察后台处理失败，请在构造函数中提供
+///         <c>processingErrorHandler</c> 回调。
+///     </para>
+/// </remarks>
+public sealed class AsyncLogAppender : ILogAppender
 {
     private readonly Channel<LogEntry> _channel;
     private readonly CancellationTokenSource _cts;
     private readonly SemaphoreSlim _flushSemaphore = new(0, 1);
     private readonly ILogAppender _innerAppender;
+    private readonly Action<Exception>? _processingErrorHandler;
     private readonly Task _processingTask;
     private bool _disposed;
     private volatile bool _flushRequested;
@@ -21,9 +31,17 @@ public sealed class AsyncLogAppender : ILogAppender, IDisposable
     /// </summary>
     /// <param name="innerAppender">内部日志输出器</param>
     /// <param name="bufferSize">缓冲区大小（默认 10000）</param>
-    public AsyncLogAppender(ILogAppender innerAppender, int bufferSize = 10000)
+    /// <param name="processingErrorHandler">
+    ///     后台处理日志时的错误回调。
+    ///     默认值为 <see langword="null" />，表示吞掉内部异常以避免污染宿主标准错误输出。
+    /// </param>
+    public AsyncLogAppender(
+        ILogAppender innerAppender,
+        int bufferSize = 10000,
+        Action<Exception>? processingErrorHandler = null)
     {
         _innerAppender = innerAppender ?? throw new ArgumentNullException(nameof(innerAppender));
+        _processingErrorHandler = processingErrorHandler;
 
         if (bufferSize <= 0)
             throw new ArgumentException("Buffer size must be greater than 0.", nameof(bufferSize));
@@ -138,7 +156,8 @@ public sealed class AsyncLogAppender : ILogAppender, IDisposable
     }
 
     /// <summary>
-    ///     后台处理日志的异步方法
+    ///     后台处理日志的异步方法。
+    ///     该循环必须始终保持存活，因此所有内部异常都通过回调上报并被吞掉。
     /// </summary>
     private async Task ProcessLogsAsync(CancellationToken cancellationToken)
     {
@@ -152,8 +171,8 @@ public sealed class AsyncLogAppender : ILogAppender, IDisposable
                 }
                 catch (Exception ex)
                 {
-                    // 记录内部错误到控制台（避免递归）
-                    await Console.Error.WriteLineAsync($"[AsyncLogAppender] Error processing log entry: {ex.Message}");
+                    // 后台消费失败只通过显式回调暴露，避免测试宿主将 stderr 误判为测试告警。
+                    ReportProcessingError(ex);
                 }
 
                 // 检查是否有刷新请求且通道已空
@@ -175,7 +194,7 @@ public sealed class AsyncLogAppender : ILogAppender, IDisposable
         }
         catch (Exception ex)
         {
-            await Console.Error.WriteLineAsync($"[AsyncLogAppender] Fatal error in processing task: {ex}");
+            ReportProcessingError(ex);
         }
         finally
         {
@@ -184,10 +203,31 @@ public sealed class AsyncLogAppender : ILogAppender, IDisposable
             {
                 _innerAppender.Flush();
             }
-            catch
+            catch (Exception ex)
             {
-                // 忽略刷新错误
+                ReportProcessingError(ex);
             }
         }
     }
+
+    /// <summary>
+    ///     上报后台处理异常，同时隔离观察者自身抛出的错误，避免终止处理循环。
+    /// </summary>
+    /// <param name="exception">后台处理中捕获到的异常。</param>
+    private void ReportProcessingError(Exception exception)
+    {
+        if (_processingErrorHandler is null)
+        {
+            return;
+        }
+
+        try
+        {
+            _processingErrorHandler(exception);
+        }
+        catch
+        {
+            // 错误观察者只用于诊断，绝不能反向影响日志处理线程的生命周期。
+        }
+    }
 }