public void Log <TState>(MSLogLevel logLevel, EventId eventId, TState state, Exception exception,
Func <TState, Exception, string> formatter)
{
var lvl = logLevel switch
{
MSLogLevel.Trace => LogLevel.Debug,
MSLogLevel.Debug => LogLevel.Debug,
// EFCore feels the need to log individual DB commands as "Information" so I'm slapping debug on it.
MSLogLevel.Information => LogLevel.Debug,
MSLogLevel.Warning => LogLevel.Warning,
MSLogLevel.Error => LogLevel.Error,
MSLogLevel.Critical => LogLevel.Fatal,
MSLogLevel.None => LogLevel.Debug,
_ => LogLevel.Debug
};
_sawmill.Log(lvl, formatter(state, exception));
}
private async Task ListenerThread(CancellationToken cancel)
{
try
{
while (!cancel.IsCancellationRequested)
{
var getContextTask = _listener.GetContextAsync();
var ctx = await getContextTask.WaitAsync(cancel);
// Task.Run this so it gets run on another thread pool thread.
_ = Task.Run(async() =>
{
var resp = ctx.Response;
var req = ctx.Request;
try
{
var stream = resp.OutputStream;
// prometheus-net is a terrible library and have to do all this insanity,
// just to handle the ScrapeFailedException correctly.
// Ridiculous.
await _registry.CollectAndExportAsTextAsync(new WriteWrapStream(() =>
{
resp.ContentType = "text/plain; version=0.0.4; charset=utf-8";
resp.StatusCode = 200;
var acceptEncoding = req.Headers["Accept-Encoding"];
var gzip = acceptEncoding != null && acceptEncoding.Contains("gzip");
if (gzip)
{
stream = new GZipStream(stream, CompressionLevel.Fastest);
resp.Headers["Content-Encoding"] = "gzip";
}
return(stream);
}), cancel);
await stream.DisposeAsync();
}
catch (ScrapeFailedException e)
{
resp.StatusCode = 503;
if (!string.IsNullOrWhiteSpace(e.Message))
{
await using var sw = new StreamWriter(resp.OutputStream);
await sw.WriteAsync(e.Message);
}
}
catch (OperationCanceledException)
{
// Nada.
}
catch (Exception e)
{
_sawmill.Log(LogLevel.Error, e, "Exception in metrics listener");
resp.StatusCode = 500;
}
finally
{
resp.Close();
}
}, CancellationToken.None);
}
}
finally
{
_listener.Stop();
_listener.Close();
}
}