feat: add exception tracker

Author: mt89vein

BookLibrary.Infrastructure/OpenTelemetry/ExceptionTracker.cs

@@ -0,0 +1,167 @@
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using System.Collections.Concurrent;
+using System.Diagnostics.Metrics;
+using System.Runtime.ExceptionServices;
+using System.Runtime.InteropServices;
+
+namespace BookLibrary.Infrastructure.OpenTelemetry;
+
+internal sealed partial class ExceptionTracker : IDisposable
+{
+    private readonly Meter _meter;
+    private readonly ILogger<ExceptionTracker> _logger;
+
+    private readonly Counter<long> _exceptionsCounter;
+
+    private static readonly ConcurrentDictionary<Type, string> _trimmedTypeNames = new();
+
+    private const int LABEL_MAX_LENGTH = 127;
+    private const int LOG_EVERY_N_EXCEPTIONS = 100;
+
+    [ThreadStatic]
+    private static bool _handlingFirstChanceException;
+
+    [ThreadStatic]
+    private static Dictionary<Type, long>? _sampler;
+
+    private static bool _started;
+
+    public ExceptionTracker(
+        IMeterFactory meterFactory,
+        ILogger<ExceptionTracker> logger
+    )
+    {
+        _logger = logger;
+
+        _meter = meterFactory.Create(GetType().FullName!);
+        _exceptionsCounter = _meter.CreateCounter<long>(name: "dotnet.exceptions", description: "Count of throwed exceptions.");
+    }
+
+    public void Dispose()
+    {
+        _meter.Dispose();
+
+        Stop();
+    }
+
+    public void Start()
+    {
+        if (_started)
+        {
+            return;
+        }
+
+        _started = true;
+        AppDomain.CurrentDomain.FirstChanceException += HandleFirstChanceException;
+    }
+
+    public void Stop()
+    {
+        if (!_started)
+        {
+            return;
+        }
+
+        AppDomain.CurrentDomain.FirstChanceException -= HandleFirstChanceException;
+    }
+
+    private void HandleFirstChanceException(object? sender, FirstChanceExceptionEventArgs e)
+    {
+        if (_handlingFirstChanceException)
+        {
+            return;
+        }
+
+        if (e.Exception is TaskCanceledException or OperationCanceledException)
+        {
+            return;
+        }
+
+        _handlingFirstChanceException = true;
+
+        try
+        {
+            var exceptionType = e.Exception.GetType();
+
+            _sampler ??= new Dictionary<Type, long>();
+
+            ref var counter = ref CollectionsMarshal.GetValueRefOrAddDefault(_sampler, exceptionType, out var exists);
+
+            var needLog = !exists || Interlocked.Increment(ref counter) % LOG_EVERY_N_EXCEPTIONS == 0;
+
+            if (needLog)
+            {
+                LogExceptionSample(e.Exception, exceptionType.FullName);
+            }
+
+            _exceptionsCounter.Add(1, new KeyValuePair<string, object?>("error_type", Trim(exceptionType)));
+        }
+        catch (Exception)
+        {
+            // skip
+        }
+        finally
+        {
+            _handlingFirstChanceException = false;
+        }
+    }
+
+    private static string Trim(Type type)
+    {
+        return _trimmedTypeNames.GetOrAdd(type, static type =>
+        {
+            var typeFullName = type.FullName!;
+
+            Span<char> typeLabel = stackalloc char[Math.Min(LABEL_MAX_LENGTH, typeFullName.Length)];
+
+            typeFullName.AsSpan(0, typeLabel.Length).CopyTo(typeLabel);
+
+            var writePos = 0;
+            for (var readPos = 0; readPos < typeLabel.Length; readPos++)
+            {
+                var c = typeLabel[readPos];
+
+                if (char.IsAscii(c))
+                {
+                    typeLabel[writePos++] = c;
+                }
+            }
+
+            typeLabel = typeLabel[..writePos];
+
+            return typeLabel.ToString();
+        });
+    }
+
+    [LoggerMessage(
+        eventId: 0,
+        level: LogLevel.Information,
+        message: "Sample of throwed exception {ExceptionType}"
+    )]
+    private partial void LogExceptionSample(Exception ex, string? exceptionType);
+}
+
+internal sealed class ExceptionTrackerLifecycle : IHostedService
+{
+    private readonly ExceptionTracker _exceptionTracker;
+
+    public ExceptionTrackerLifecycle(ExceptionTracker exceptionTracker)
+    {
+        _exceptionTracker = exceptionTracker;
+    }
+
+    public Task StartAsync(CancellationToken cancellationToken)
+    {
+        _exceptionTracker.Start();
+
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken cancellationToken)
+    {
+        _exceptionTracker.Stop();
+
+        return Task.CompletedTask;
+    }
+}

BookLibrary.Infrastructure/ServiceCollectionExtensions.cs

@@ -1,7 +1,9 @@
 using BookLibrary.Application.Infrastructure;
 using BookLibrary.Infrastructure.Books;
+using BookLibrary.Infrastructure.OpenTelemetry;
 using BookLibrary.Infrastructure.ValueConverters;
 using EntityFramework.Exceptions.PostgreSQL;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
@@ -28,6 +30,8 @@ public static IServiceCollection AddInfrastructure(this IServiceCollection servi
     {
         services.AddSingleton<IUuidGenerator, UuidGenerator>();
         services.AddSingleton(TimeProvider.System);
+        services.AddSingleton<ExceptionTracker>();
+        services.AddHostedService<ExceptionTrackerLifecycle>();
 
         services.AddOutboxItem<ApplicationContext, BookStatChange>(o =>
             {