Publish UpDownCounter and ObservableUpDownCounter Events for System.Diagnostics.Metrics

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/AggregationManager.cs

@@ -275,7 +275,7 @@ private void RemoveInstrumentState(Instrument instrument)
                 {
                     lock (this)
                     {
-                        return CheckTimeSeriesAllowed() ? new RateSumAggregator() : null;
+                        return CheckTimeSeriesAllowed() ? new RateSumAggregator(isMonotonic: true) : null;
                     }
                 };
             }
@@ -285,7 +285,7 @@ private void RemoveInstrumentState(Instrument instrument)
                 {
                     lock (this)
                     {
-                        return CheckTimeSeriesAllowed() ? new RateAggregator() : null;
+                        return CheckTimeSeriesAllowed() ? new RateAggregator(isMonotonic: true) : null;
                     }
                 };
             }
@@ -312,6 +312,26 @@ private void RemoveInstrumentState(Instrument instrument)
                     }
                 };
             }
+            else if (genericDefType == typeof(UpDownCounter<>))
+            {
+                return () =>
+                {
+                    lock (this)
+                    {
+                        return CheckTimeSeriesAllowed() ? new RateSumAggregator(isMonotonic: false) : null;
+                    }
+                };
+            }
+            else if (genericDefType == typeof(ObservableUpDownCounter<>))
+            {
+                return () =>
+                {
+                    lock (this)
+                    {
+                        return CheckTimeSeriesAllowed() ? new RateAggregator(isMonotonic: false) : null;
+                    }
+                };
+            }
             else
             {
                 return null;

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/MetricsEventSource.cs

@@ -191,6 +191,14 @@ public void MultipleSessionsNotSupportedError(string runningSessionId)
             WriteEvent(15, runningSessionId);
         }
 
+        [Event(16, Keywords = Keywords.TimeSeriesValues)]
+        [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+                            Justification = "This calls WriteEvent with all primitive arguments which is safe. Primitives are always serialized properly.")]
+        public void UpDownCounterRateValuePublished(string sessionId, string meterName, string? meterVersion, string instrumentName, string? unit, string tags, string rate)
+        {
+            WriteEvent(16, sessionId, meterName, meterVersion ?? "", instrumentName, unit ?? "", tags, rate);
+        }
+
         /// <summary>
         /// Called when the EventSource gets a command from a EventListener or ETW.
         /// </summary>
@@ -407,8 +415,16 @@ private static void TransmitMetricValue(Instrument instrument, LabeledAggregatio
             {
                 if (stats.AggregationStatistics is RateStatistics rateStats)
                 {
-                    Log.CounterRateValuePublished(sessionId, instrument.Meter.Name, instrument.Meter.Version, instrument.Name, instrument.Unit, FormatTags(stats.Labels),
-                        rateStats.Delta.HasValue ? rateStats.Delta.Value.ToString(CultureInfo.InvariantCulture) : "");
+                    if (rateStats.IsMonotonic)
+                    {
+                        Log.CounterRateValuePublished(sessionId, instrument.Meter.Name, instrument.Meter.Version, instrument.Name, instrument.Unit, FormatTags(stats.Labels),
+                            rateStats.Delta.HasValue ? rateStats.Delta.Value.ToString(CultureInfo.InvariantCulture) : "");
+                    }
+                    else
+                    {
+                        Log.UpDownCounterRateValuePublished(sessionId, instrument.Meter.Name, instrument.Meter.Version, instrument.Name, instrument.Unit, FormatTags(stats.Labels),
+                            rateStats.Delta.HasValue ? rateStats.Delta.Value.ToString(CultureInfo.InvariantCulture) : "");
+                    }
                 }
                 else if (stats.AggregationStatistics is LastValueStatistics lastValueStats)
                 {

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/RateAggregator.cs

@@ -6,6 +6,12 @@ namespace System.Diagnostics.Metrics
     internal sealed class RateSumAggregator : Aggregator
     {
         private double _sum;
+        private bool _isMonotonic;
+
+        public RateSumAggregator(bool isMonotonic)
+        {
+            _isMonotonic = isMonotonic;
+        }
 
         public override void Update(double value)
         {
@@ -19,7 +25,7 @@ public override IAggregationStatistics Collect()
         {
             lock (this)
             {
-                RateStatistics? stats = new RateStatistics(_sum);
+                RateStatistics? stats = new RateStatistics(_sum, _isMonotonic);
                 _sum = 0;
                 return stats;
             }
@@ -30,6 +36,12 @@ internal sealed class RateAggregator : Aggregator
     {
         private double? _prevValue;
         private double _value;
+        private bool _isMonotonic;
+
+        public RateAggregator(bool isMonotonic)
+        {
+            _isMonotonic = isMonotonic;
+        }
 
         public override void Update(double value)
         {
@@ -48,7 +60,7 @@ public override IAggregationStatistics Collect()
                 {
                     delta = _value - _prevValue.Value;
                 }
-                RateStatistics stats = new RateStatistics(delta);
+                RateStatistics stats = new RateStatistics(delta, _isMonotonic);
                 _prevValue = _value;
                 return stats;
             }
@@ -57,11 +69,14 @@ public override IAggregationStatistics Collect()
 
     internal sealed class RateStatistics : IAggregationStatistics
     {
-        public RateStatistics(double? delta)
+        public RateStatistics(double? delta, bool isMonotonic)
         {
             Delta = delta;
+            IsMonotonic = isMonotonic;
         }
 
         public double? Delta { get; }
+
+        public bool IsMonotonic { get; }
     }
 }