add slow query logging

CHANGELOG.md

@@ -34,6 +34,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   - This button will extract up to 30 seconds of the media item and zip it
 - Add `Target Loudness` (LUFS/LKFS) to ffmpeg profile when loudness normalization is enabled
   - Default value is `-16`; some sources normalize to a quieter value, e.g. `-24`
+- Add environment variables to help troubleshoot performance
+  - `ETV_SLOW_QUERY_MS` - milliseconds threshold for logging slow database queries (at DEBUG level)
+    - e.g. if this is set to `1000`, queries taking longer than 1 second will be logged
 
 ### Fixed
 - Fix startup on systems unsupported by NvEncSharp

ErsatzTV.Core/SystemEnvironment.cs

@@ -36,6 +36,12 @@ public class SystemEnvironment
         }
 
         MaximumUploadMb = maximumUploadMb;
+
+        string slowQueryMsVariable = Environment.GetEnvironmentVariable("ETV_SLOW_QUERY_MS");
+        if (int.TryParse(slowQueryMsVariable, out int slowQueryMs))
+        {
+            SlowQueryMs = slowQueryMs;
+        }
     }
 
     public static string BaseUrl { get; }
@@ -45,4 +51,5 @@ public class SystemEnvironment
     public static int StreamingPort { get; }
     public static bool AllowSharedPlexServers { get; }
     public static int MaximumUploadMb { get; }
+    public static int? SlowQueryMs { get; }
 }

ErsatzTV/SlowQueryInterceptor.cs

@@ -0,0 +1,24 @@
+using System.Data.Common;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+
+namespace ErsatzTV;
+
+public class SlowQueryInterceptor(int threshold) : DbCommandInterceptor
+{
+    public override ValueTask<DbDataReader> ReaderExecutedAsync(
+        DbCommand command,
+        CommandExecutedEventData eventData,
+        DbDataReader result,
+        CancellationToken cancellationToken = default)
+    {
+        if (eventData.Duration.TotalMilliseconds > threshold)
+        {
+            Serilog.Log.Logger.Debug(
+                "[SLOW QUERY] ({Milliseconds}ms): {Command}",
+                eventData.Duration.TotalMilliseconds,
+                command.CommandText);
+        }
+
+        return base.ReaderExecutedAsync(command, eventData, result, cancellationToken);
+    }
+}

ErsatzTV/Startup.cs

@@ -408,6 +408,12 @@ public class Startup
         var sqliteConnectionString = $"Data Source={FileSystemLayout.DatabasePath};foreign keys=true;";
         string mySqlConnectionString = Configuration.GetValue<string>("MySql:ConnectionString");
 
+        SlowQueryInterceptor interceptor = null;
+        if (SystemEnvironment.SlowQueryMs.HasValue)
+        {
+            interceptor = new SlowQueryInterceptor(SystemEnvironment.SlowQueryMs.Value);
+        }
+
         services.AddDbContext<TvContext>(
             options =>
             {
@@ -438,6 +444,11 @@ public class Startup
                         }
                     );
                 }
+
+                if (interceptor != null)
+                {
+                    options.AddInterceptors(interceptor);
+                }
             },
             ServiceLifetime.Scoped,
             ServiceLifetime.Singleton);
@@ -467,6 +478,11 @@ public class Startup
                     }
                 );
             }
+
+            if (interceptor != null)
+            {
+                options.AddInterceptors(interceptor);
+            }
         });
 
         if (databaseProvider == Provider.Sqlite.Name)