SampledLoggingActionFilter.cs

using Microsoft.AspNetCore.Mvc.Filters;
using PostSharp.Patterns.Diagnostics;
using System;
using System.Threading.Tasks;

namespace MicroserviceExample
{
  [Log(AttributeExclude = true)]
  public class SampledLoggingActionFilter : IAsyncActionFilter
  {
    private static readonly Random random = new Random();
    private static LoggingVerbosityConfiguration verbosityManager;

    public static void Initialize(LoggingBackend backend)
    {
      verbosityManager = backend.CreateVerbosityConfiguration();
      // Verbosity is High (Debug level) by default.
    }

    public static bool IsInitialized => verbosityManager != null;

    private static bool IsLogged(ActionExecutingContext context)
    {
      lock (random)
      {
        // Log 10% of requests.
        return random.NextDouble() < 0.1;
      }
    }

    public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
    {

      if (IsInitialized && IsLogged(context))
      {
        using (verbosityManager.Use())
        {
          await next();
        }
      }
      else
      {
        await next();
      }

    }
  }
}