Access To LoggerProvider From Inside A HostedService (ServiceHost)

Question

In .Net 5.0, logs are handled by ILogger and LoggerProvider. I have created a LoggerProvider, which writes logs into a memory list eg. stringlist. Now I want to access to this memory from within the hosted service.
How can I access to the LoggerProvider instance, so that I can access the log list inside by a property.

My LoggerProvider is:

public class MyLoggerProvider : ILoggerProvider
{   
    private List<string> _logList = new List<string>();

    public List<string> LogList
    {
        get
        {
            return _logList;
        }
    }

        public MyLoggerProvider()
        {
            _logList = new List<string>();
        }

        public ILogger CreateLogger(string className)
        {
            return new ServiceLogger(this, className);
        }

        public bool IsEnabled(LogLevel logLevel)
        {
            return true;
        }

        public void AddLogEntry(string logMessage)
        {
        _logList.Add( $"{DateTime.Now:f} :: {logMessage}" );
        }

        public void Dispose()
        {
        _logList~.Clear
        }
    }

And I initialize the ServiceHost with:

public static void Main(string[] args)
{
    CreateHostBuilder(args).Build().RunAsync();
}

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureServices((hostContext, services) =>
        {
            services.AddHostedService<ServiceHost>();
            services.Configure<HostOptions>((option) =>
            {
                option.ShutdownTimeout = TimeSpan.FromMinutes(10);
            });
        })
        .ConfigureLogging((hostContext, logging) =>
        {
            logging.AddProvider(new GuiLoggerProvider());
        })
        .UseWindowsService();

Then I want to access the LogList within the ServiceHost, which is:

public class ServiceHost : IHostedService
{
    private readonly IHost _host;
    private readonly IHostApplicationLifetime _hostApplicationLifetime;
    private readonly IConfiguration _configuration;
    private readonly ILogger _logger;
    private readonly ServiceWorker _serviceWorker;

    public ServiceHost(IHost host, IHostApplicationLifetime hostApplicationLifetime, IConfiguration configuration, ILoggerFactory logger)
    {
        _host = host;
        _hostApplicationLifetime = hostApplicationLifetime;
        _configuration = configuration;
        _logger = logger.CreateLogger(_configuration["AppSettings:ApplicationName"]);
        _serviceWorker = new ServiceWorker(_logger);
    }

    public Task StartAsync(CancellationToken cancellationToken)
    {
        myLoggerProvider =     /* Here I want to access to myLoggerProvider instance */
        List<string> myLogList = myLoggerProvider.LogList;
    }
}

How can I access the MyLoggerProvider instance ?
Is that possible over the IHost _host or should I use the ILogger _logger ?

Answer 1

_logger = logger.CreateLogger(_configuration["AppSettings:ApplicationName"]);

It is the only instance of a logger object in your code you are talking about. You should set a debug breakpoint just after the line and use debug Quickwtatch to look at the content of _logger object and see what is in it.

Answer 2

Yes, I only have one logger instance created within my hosted service, but there are also other loggers instantiated namely the standard loggers of the MS-hosted server.
I may also have multiple logger providers in my project in the future, but I only have to acces the one with the memory.

However, I checked, what's in the logger instance. There are 3 Logger arrays:

- Loggers  (of type LoggerInformation)
- MessageLoggers (of type MessageLogger)
- ScopeLoggers (of type ScopeLogger)

Within the Loggers I have 6 items, which I think, are the loggers of the project, also built ins like console logger, debug logger, etc.
Within the MessageLoggers, I also have 6 loggers, however, I could find myLoggerProvider in this list.
ScopeLoggers are for Scope, however, I also find my provider in that list, as I use scope.

That's, OK

But as these properties are not accessable by standard, I should use reflection to access it as well as I have to loop through all items to find MyLoggerProvider.

Do you have an idea if there is another, simpler way to access MyLogerProvider?

Eg. I have to use the right type of _logger to make these properties accessible.

Answer 3

var data = _logger.MessageLoggers[4].Logger._className;

OR example --- _logger.MessageLoggers[4].Logger._loggerProvider.

I can't see any properties for _loggerProvider in the screen shot.

============================================

foreach (var item in_logger.MessageLoggers)
{
var data = item.Logger._className;
}

===================================

for(int i = 0; i <_logger.MessageLoggers.Count(); i++)
{
var data = _logger.MessageLoggers[i].className;
}

It's just a strong typed collection within ._logger

Answer 4

But how can I access to MessageLoggers or _logger.MessageLoggers respectively. The _logger is of type ILogger.
To which type Have I to cast ?

You can use var and let the compiler to the cast to a type

https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/var

var data = _logger.MessageLoggers[4].Logger._className;

The data is going to be of type string.

You can use var in the local scope and the complier will to the cast.

You can stop on a line in the debugger and use the mouse pointer and hover over a var and Visual Stuido will tell you the type. You can use the type shown and make a cast to the type if you need to do it manually for some reason.