internal object?GetSubscriptionState(MeterListener listener)
{
LinkedListNode <ListenerSubscription>?current = _subscriptions.First;
while (current is not null)
{
if (object.ReferenceEquals(listener, current.Value.Listener))
{
return(current.Value.State);
}
current = current.Next;
}
return(null);
}
internal override void Observe(MeterListener listener)
{
object?state = GetSubscriptionState(listener);
IEnumerable <Measurement <T> > measurements = Observe();
if (measurements is null)
{
return;
}
foreach (Measurement <T> measurement in measurements)
{
listener.NotifyMeasurement(this, measurement.Value, measurement.Tags, state);
}
}
/// <summary>
/// Publish is activating the instrument to start recording measurements and to allow listeners to start listening to such measurements.
/// </summary>
protected void Publish()
{
List <MeterListener>?allListeners = null;
lock (Instrument.SyncObject)
{
if (Meter.Disposed || !Meter.AddInstrument(this))
{
return;
}
allListeners = MeterListener.GetAllListeners();
}
if (allListeners is not null)
{
foreach (MeterListener listener in allListeners)
{
listener.InstrumentPublished?.Invoke(this, listener);
}
}
}
// Called from MeterListener.Start
internal static void NotifyListenerWithAllPublishedInstruments(MeterListener listener)
{
Action <Instrument, MeterListener>?instrumentPublished = listener.InstrumentPublished;
if (instrumentPublished is null)
{
return;
}
LinkedListNode <Meter>?current = s_allMeters.First;
while (current is not null)
{
LinkedListNode <Instrument>?currentInstrument = current.Value._instruments?.First;
while (currentInstrument is not null)
{
instrumentPublished.Invoke(currentInstrument.Value, listener);
currentInstrument = currentInstrument.Next;
}
current = current.Next;
}
}
internal virtual void Observe(MeterListener listener)
{
Debug.Assert(false);
throw new InvalidOperationException();
}
// Called from MeterListener.DisableMeasurementEvents internal object?DisableMeasurements(MeterListener listener) => _subscriptions.Remove(new ListenerSubscription(listener), (s1, s2) => object.ReferenceEquals(s1.Listener, s2.Listener)).State;
/// <summary>
/// Publish is activating the instrument to start recording measurements and to allow listeners to start listening to such measurements.
/// </summary>
protected void Publish()
{
Meter.AddInstrument(this);
MeterListener.NotifyForPublishedInstrument(this);
}