budget/src/Budget.Infrastructure/Data/SlowQueryInterceptor.cs

using System.Data.Common;
using Microsoft.EntityFrameworkCore.Diagnostics;
using Microsoft.Extensions.Logging;

namespace Budget.Infrastructure.Data;

public class SlowQueryInterceptor(ILogger<SlowQueryInterceptor> logger) : DbCommandInterceptor
{
    private static readonly TimeSpan Threshold = TimeSpan.FromMilliseconds(500);

    public override DbDataReader ReaderExecuted(DbCommand command, CommandExecutedEventData eventData, DbDataReader result)
    {
        LogIfSlow(command, eventData.Duration);
        return result;
    }

    public override ValueTask<DbDataReader> ReaderExecutedAsync(DbCommand command, CommandExecutedEventData eventData, DbDataReader result, CancellationToken cancellationToken = default)
    {
        LogIfSlow(command, eventData.Duration);
        return new ValueTask<DbDataReader>(result);
    }

    public override int NonQueryExecuted(DbCommand command, CommandExecutedEventData eventData, int result)
    {
        LogIfSlow(command, eventData.Duration);
        return result;
    }

    public override ValueTask<int> NonQueryExecutedAsync(DbCommand command, CommandExecutedEventData eventData, int result, CancellationToken cancellationToken = default)
    {
        LogIfSlow(command, eventData.Duration);
        return new ValueTask<int>(result);
    }

    public override object? ScalarExecuted(DbCommand command, CommandExecutedEventData eventData, object? result)
    {
        LogIfSlow(command, eventData.Duration);
        return result;
    }

    public override ValueTask<object?> ScalarExecutedAsync(DbCommand command, CommandExecutedEventData eventData, object? result, CancellationToken cancellationToken = default)
    {
        LogIfSlow(command, eventData.Duration);
        return new ValueTask<object?>(result);
    }

    private void LogIfSlow(DbCommand command, TimeSpan duration)
    {
        if (duration >= Threshold)
            logger.LogWarning("Slow query ({Duration}ms): {CommandText}",
                (long)duration.TotalMilliseconds, command.CommandText);
    }
}