DispatchProxyLoggingDecorator.cs

internal class DispatchProxyLoggingDecorator<TDecorated> : DispatchProxy
{
    private TDecorated _decorated;

    private ILogger<DispatchProxyLoggingDecorator<TDecorated>> _logger;

    protected override object Invoke(MethodInfo targetMethod, object[] args)
    {
        try
        {
            _logger.LogInformation("Logging something before invoking {decoratedClass}.{methodName}",
                typeof(TDecorated), targetMethod.Name);

            var result = targetMethod.Invoke(_decorated, args);

            if (result is Task resultTask)
            {
                resultTask.ContinueWith(task =>
                {
                    if (task.IsFaulted)
                    {
                        _logger.LogError(task.Exception,
                            "An unhandled exception was raised during execution of {decoratedClass}.{methodName}",
                            typeof(TDecorated), targetMethod.Name);
                    }
                    _logger.LogInformation("Log something after {decoratedClass}.{methodName} completed",
                        typeof(TDecorated), targetMethod.Name);
                });
            }
            else
            {
                _logger.LogInformation("Logging something after method {decoratedClass}.{methodName} completion.",
                    typeof(TDecorated), targetMethod.Name);
            }

            return result;
        }
        catch (TargetInvocationException ex)
        {
            _logger.LogError(ex.InnerException ?? ex,
                "Error during invocation of {decoratedClass}.{methodName}",
                typeof(TDecorated), targetMethod.Name);
            throw ex.InnerException ?? ex;
        }
    }
    
    public static TDecorated Create(TDecorated decorated, ILogger<DispatchProxyLoggingDecorator<TDecorated>> logger)
    {
        object proxy = Create<TDecorated, DispatchProxyLoggingDecorator<TDecorated>>();
        ((DispatchProxyLoggingDecorator<TDecorated>)proxy).SetParameters(decorated, logger);

        return (TDecorated)proxy;
    }

    private void SetParameters(TDecorated decorated, ILogger<DispatchProxyLoggingDecorator<TDecorated>> logger)
    {
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        _decorated = decorated ?? throw new ArgumentNullException(nameof(decorated));
    }
}