// when receiving DiagnosticCounter events we may have buffered them to wait for
// duplicate instrument events. If we've waited long enough then we should remove
// them from the buffer and render them.
private void HandleBufferedEvents()
{
DateTime now = DateTime.Now;
lock (this)
{
while (_bufferedEvents.Count != 0)
{
CounterPayload payload = _bufferedEvents.Peek();
ProviderEventState providerEventState = _providerEventStates[payload.ProviderName];
if (providerEventState.InstrumentEventObserved)
{
_bufferedEvents.Dequeue();
}
else if (providerEventState.FirstReceiveTimestamp + TimeSpan.FromSeconds(BufferDelaySecs) < now)
{
_bufferedEvents.Dequeue();
_renderer.CounterPayloadReceived(payload, _pauseCmdSet);
}
else
{
// technically an event that is eligible to be unbuffered earlier could be waiting behind a
// buffered event that will wait longer, but we don't expect this variation to matter for
// our scenarios. At worst an event might wait up to 2*BufferDelaySecs. If there is a scenario
// where it matters we could scan the entire queue rather than just the front of it.
break;
}
}
}
}
private void HandleDiagnosticCounter(TraceEvent obj)
{
IDictionary <string, object> payloadVal = (IDictionary <string, object>)(obj.PayloadValue(0));
IDictionary <string, object> payloadFields = (IDictionary <string, object>)(payloadVal["Payload"]);
// If it's not a counter we asked for, ignore it.
string name = payloadFields["Name"].ToString();
if (!_counterList.Contains(obj.ProviderName, name))
{
return;
}
// init providerEventState if this is the first time we've seen an event from this provider
if (!_providerEventStates.TryGetValue(obj.ProviderName, out ProviderEventState providerState))
{
providerState = new ProviderEventState()
{
FirstReceiveTimestamp = obj.TimeStamp
};
_providerEventStates.Add(obj.ProviderName, providerState);
}
// we give precedence to instrument events over diagnostic counter events. If we are seeing
// both then drop this one.
if (providerState.InstrumentEventObserved)
{
return;
}
CounterPayload payload = null;
if (payloadFields["CounterType"].Equals("Sum"))
{
payload = new RatePayload(
obj.ProviderName,
name,
payloadFields["DisplayName"].ToString(),
payloadFields["DisplayUnits"].ToString(),
null,
(double)payloadFields["Increment"],
_interval,
obj.TimeStamp);
}
else
{
payload = new GaugePayload(
obj.ProviderName,
name,
payloadFields["DisplayName"].ToString(),
payloadFields["DisplayUnits"].ToString(),
null,
(double)payloadFields["Mean"],
obj.TimeStamp);
}
// If we saw the first event for this provider recently then a duplicate instrument event may still be
// coming. We'll buffer this event for a while and then render it if it remains unduplicated for
// a while.
// This is all best effort, if we do show the DiagnosticCounter event and then an instrument event shows up
// later the renderer may obsserve some odd behavior like changes in the counter metadata, oddly timed reporting
// intervals, or counters that stop reporting.
// I'm gambling this is good enough that the behavior will never be seen in practice, but if it is we could
// either adjust the time delay or try to improve how the renderers handle it.
if (providerState.FirstReceiveTimestamp + TimeSpan.FromSeconds(BufferDelaySecs) >= obj.TimeStamp)
{
_bufferedEvents.Enqueue(payload);
}
else
{
_renderer.CounterPayloadReceived(payload, _pauseCmdSet);
}
}