Fix deadlock in DiscordWebhookSink whenever an error occurs in a cont…

…ext where a SynchronizationContext exists (e.g. Blazor)
discord-csharp · Mar 30, 2024 · 3758697 · 3758697
1 parent 66ebd86
commit 3758697
Showing 1 changed file with 100 additions and 77 deletions.
diff --git a/src/Modix.Services/Utilities/DiscordWebhookSink.cs b/src/Modix.Services/Utilities/DiscordWebhookSink.cs
@@ -1,4 +1,7 @@
 using System;
+using System.Collections.Concurrent;
+using System.Threading;
+using System.Threading.Tasks;
 using Discord;
 using Discord.Webhook;
 using Modix.Services.CodePaste;
@@ -8,104 +11,124 @@
 using Serilog.Core;
 using Serilog.Events;
 
-namespace Modix.Services.Utilities
+namespace Modix.Services.Utilities;
+
+public sealed class DiscordWebhookSink : ILogEventSink, IAsyncDisposable
 {
-    public sealed class DiscordWebhookSink
-        : ILogEventSink,
-            IDisposable
+    private readonly Lazy<CodePasteService> _codePasteService;
+    private readonly DiscordWebhookClient _discordWebhookClient;
+    private readonly IFormatProvider _formatProvider;
+    private readonly JsonSerializerSettings _jsonSerializerSettings;
+    private readonly CancellationTokenSource _cancellationTokenSource;
+    private readonly Task _logEventProcessorTask;
+    private readonly BlockingCollection<LogEvent> _logEventQueue;
+
+    public DiscordWebhookSink(
+        ulong webhookId,
+        string webhookToken,
+        IFormatProvider formatProvider,
+        Lazy<CodePasteService> codePasteService)
     {
-        private readonly Lazy<CodePasteService> _codePasteService;
-        private readonly DiscordWebhookClient _discordWebhookClient;
-        private readonly IFormatProvider _formatProvider;
-        private readonly JsonSerializerSettings _jsonSerializerSettings;
-        public DiscordWebhookSink(
-            ulong webhookId,
-            string webhookToken,
-            IFormatProvider formatProvider,
-            Lazy<CodePasteService> codePasteService)
-        {
-            _codePasteService = codePasteService;
-            _discordWebhookClient = new DiscordWebhookClient(webhookId, webhookToken);
-            _formatProvider = formatProvider;
+        _codePasteService = codePasteService;
+        _discordWebhookClient = new DiscordWebhookClient(webhookId, webhookToken);
+        _formatProvider = formatProvider;
 
-            _jsonSerializerSettings = new JsonSerializerSettings
-            {
-                Formatting = Formatting.Indented,
-                ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
-                ContractResolver = new ExceptionContractResolver()
-            };
-        }
-        public void Emit(LogEvent logEvent)
+        _jsonSerializerSettings = new JsonSerializerSettings
         {
-            const int DiscordStringTruncateLength = 1000;
-
-            var formattedMessage = logEvent.RenderMessage(_formatProvider);
+            Formatting = Formatting.Indented,
+            ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
+            ContractResolver = new ExceptionContractResolver()
+        };
+
+        _cancellationTokenSource = new CancellationTokenSource();
+        _logEventQueue = [];
+        _logEventProcessorTask = Task.Run(ProcessLogEventItemsAsync, _cancellationTokenSource.Token);
+    }
 
-            var message = new EmbedBuilder()
-                    .WithAuthor("DiscordLogger")
-                    .WithTitle("Modix")
-                    .WithTimestamp(DateTimeOffset.UtcNow)
-                    .WithColor(Color.Red);
+    public void Emit(LogEvent logEvent)
+        => _logEventQueue.Add(logEvent);
 
+    public async Task ProcessLogEventItemsAsync()
+    {
+        foreach (var logEvent in _logEventQueue.GetConsumingEnumerable(_cancellationTokenSource.Token))
+        {
             try
             {
-                var messagePayload = $"{formattedMessage}\n{logEvent.Exception?.Message}";
+                const int DiscordStringTruncateLength = 1000;
 
-                message.AddField(new EmbedFieldBuilder()
-                    .WithIsInline(false)
-                    .WithName($"LogLevel: {logEvent.Level}")
-                    .WithValue(Format.Code(messagePayload.TruncateTo(DiscordStringTruncateLength))));
+                var formattedMessage = logEvent.RenderMessage(_formatProvider);
 
-                var eventAsJson = JsonConvert.SerializeObject(logEvent, _jsonSerializerSettings);
+                var message = new EmbedBuilder()
+                        .WithAuthor("DiscordLogger")
+                        .WithTitle("Modix")
+                        .WithTimestamp(DateTimeOffset.UtcNow)
+                        .WithColor(Color.Red);
 
-                var url = _codePasteService.Value.UploadCodeAsync(eventAsJson).GetAwaiter().GetResult();
+                try
+                {
+                    var messagePayload = $"{formattedMessage}\n{logEvent.Exception?.Message}";
 
-                message.AddField(new EmbedFieldBuilder()
-                    .WithIsInline(false)
-                    .WithName("Full Log Event")
-                    .WithValue($"[view on paste.mod.gg]({url})"));
-            }
-            catch (Exception ex)
-            {
-                Console.WriteLine($"Unable to upload log event. {ex}");
+                    message.AddField(new EmbedFieldBuilder()
+                        .WithIsInline(false)
+                        .WithName($"LogLevel: {logEvent.Level}")
+                        .WithValue(Format.Code(messagePayload.TruncateTo(DiscordStringTruncateLength))));
+
+                    var eventAsJson = JsonConvert.SerializeObject(logEvent, _jsonSerializerSettings);
+
+                    var url = await _codePasteService.Value.UploadCodeAsync(eventAsJson);
 
-                var stackTracePayload = $"{formattedMessage}\n{logEvent.Exception?.ToString().TruncateTo(DiscordStringTruncateLength)}".TruncateTo(DiscordStringTruncateLength);
+                    message.AddField(new EmbedFieldBuilder()
+                        .WithIsInline(false)
+                        .WithName("Full Log Event")
+                        .WithValue($"[view on paste.mod.gg]({url})"));
+                }
+                catch (Exception ex)
+                {
+                    Console.WriteLine($"Unable to upload log event. {ex}");
 
-                message.AddField(new EmbedFieldBuilder()
-                    .WithIsInline(false)
-                    .WithName("Stack Trace")
-                    .WithValue(Format.Code(stackTracePayload)));
+                    var stackTracePayload = $"{formattedMessage}\n{logEvent.Exception?.ToString().TruncateTo(DiscordStringTruncateLength)}".TruncateTo(DiscordStringTruncateLength);
 
-                message.AddField(new EmbedFieldBuilder()
-                    .WithIsInline(false)
-                    .WithName("Upload Failure Exception")
-                    .WithValue(Format.Code($"{ex.ToString().TruncateTo(DiscordStringTruncateLength)}")));
+                    message.AddField(new EmbedFieldBuilder()
+                        .WithIsInline(false)
+                        .WithName("Stack Trace")
+                        .WithValue(Format.Code(stackTracePayload)));
+
+                    message.AddField(new EmbedFieldBuilder()
+                        .WithIsInline(false)
+                        .WithName("Upload Failure Exception")
+                        .WithValue(Format.Code($"{ex.ToString().TruncateTo(DiscordStringTruncateLength)}")));
+                }
+
+                await _discordWebhookClient.SendMessageAsync(string.Empty, embeds: [message.Build()], username: "Modix Logger");
+            }
+            catch
+            {
+                // Catching all exceptions as to not crash the processor thread
+                // Wait an arbitrary amount of time before trying to process the next item.
+                await Task.Delay(10000);
             }
-            _discordWebhookClient.SendMessageAsync(string.Empty, embeds: new[] { message.Build() }, username: "Modix Logger");
         }
-
-        public void Dispose()
-            => _discordWebhookClient.Dispose();
     }
 
-    public static class DiscordWebhookSinkExtensions
+    public async ValueTask DisposeAsync()
     {
-        public static LoggerConfiguration DiscordWebhookSink(this LoggerSinkConfiguration config, ulong id, string token, LogEventLevel minLevel, Lazy<CodePasteService> codePasteService)
-        {
-            return config.Sink(new DiscordWebhookSink(id, token, null, codePasteService), minLevel);
-        }
+        _discordWebhookClient.Dispose();
+        await _cancellationTokenSource.CancelAsync();
+        await _logEventProcessorTask;
+        _cancellationTokenSource.Dispose();
     }
+}
 
-    public static class LoggingExtensions
-    {
-        public static string TruncateTo(this string str, int length)
-        {
-            if (str.Length < length)
-            {
-                return str;
-            }
+public static class DiscordWebhookSinkExtensions
+{
+    public static LoggerConfiguration DiscordWebhookSink(this LoggerSinkConfiguration config, ulong id, string token, LogEventLevel minLevel, Lazy<CodePasteService> codePasteService)
+        => config.Sink(new DiscordWebhookSink(id, token, null, codePasteService), minLevel);
+}
 
-            return str.Substring(0, length);
-        }
-    }
+public static class LoggingExtensions
+{
+    public static string TruncateTo(this string str, int length)
+        => str.Length < length
+            ? str
+            : str[..length];
 }