[Dotnet Monitor] Revert To Logging a single payload (not a list)

src/Microsoft.Diagnostics.Monitoring.EventPipe/Counters/CounterPayload.cs

@@ -71,7 +71,6 @@ public CounterPayload(string providerName, string name, string displayName, stri
         public IReadOnlyDictionary<string, string> Metadata { get; }
 
         public EventType EventType { get; set; }
-
     }
 
     public class GaugePayload : CounterPayload

src/Microsoft.Diagnostics.Monitoring.EventPipe/Counters/EventCounterPipeline.cs

@@ -56,7 +56,12 @@ protected override async Task OnEventSourceAvailable(EventPipeEventSource eventS
                 {
                     if (traceEvent.TryGetCounterPayload(_filter, _sessionId, out List<ICounterPayload> counterPayload))
                     {
-                        ExecuteCounterLoggerAction((metricLogger) => metricLogger.Log(counterPayload));
+                        ExecuteCounterLoggerAction((metricLogger) => {
+                            foreach (var payload in counterPayload)
+                            {
+                                metricLogger.Log(payload);
+                            }
+                        });
                     }
                 }
                 catch (Exception)

src/Microsoft.Diagnostics.Monitoring.EventPipe/Counters/ICountersLogger.cs

@@ -2,19 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using System;
-using System.Collections.Generic;
-using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
-
 namespace Microsoft.Diagnostics.Monitoring.EventPipe
 {
     internal interface ICountersLogger
     {
         //TODO Consider making these async.
 
-        void Log(List<ICounterPayload> counter);
+        void Log(ICounterPayload counter);
         void PipelineStarted();
         void PipelineStopped();
     }

src/Microsoft.Diagnostics.Monitoring.EventPipe/Counters/TraceEventExtensions.cs

@@ -74,7 +74,6 @@ public static bool TryGetCounterPayload(this TraceEvent traceEvent, CounterFilte
 
             if (sessionId != null && "System.Diagnostics.Metrics".Equals(traceEvent.ProviderName))
             {
-
                 ICounterPayload individualPayload = null;
 
                 if (traceEvent.EventName == "BeginInstrumentReporting")
@@ -126,9 +125,13 @@ public static bool TryGetCounterPayload(this TraceEvent traceEvent, CounterFilte
             return false;
         }
 
-        public static bool TryGetCounterPayload(this TraceEvent traceEvent, CounterFilter filter, out List<ICounterPayload> payload)
+        public static bool TryGetIndividualCounterPayload(this TraceEvent traceEvent, CounterFilter filter, out ICounterPayload payload)
         {
-            return TryGetCounterPayload(traceEvent, filter, null, out payload);
+            bool gotCounterPayload = TryGetCounterPayload(traceEvent, filter, null, out List<ICounterPayload> payloadsList);
+
+            payload = payloadsList.FirstOrDefault();
+
+            return gotCounterPayload;
         }
 
         private static void HandleGauge(TraceEvent obj, CounterFilter filter, string sessionId, out ICounterPayload payload)
@@ -307,7 +310,6 @@ private static void HandleObservableInstrumentCallbackError(TraceEvent obj, stri
             payload = new ErrorPayload(string.Empty, string.Empty, string.Empty, string.Empty, new(), 0, obj.TimeStamp, errorMessage);
         }
 
-
         //The metadata payload is formatted as a string of comma separated key:value pairs.
         //This limitation means that metadata values cannot include commas; otherwise, the
         //metadata will be parsed incorrectly. If a value contains a comma, then all metadata

src/Microsoft.Diagnostics.Monitoring.EventPipe/Triggers/EventCounter/EventCounterTrigger.cs

@@ -59,9 +59,9 @@ public IReadOnlyDictionary<string, IReadOnlyCollection<string>> GetProviderEvent
         public bool HasSatisfiedCondition(TraceEvent traceEvent)
         {
             // Filter to the counter of interest before forwarding to the implementation
-            if (traceEvent.TryGetCounterPayload(_filter, out List<ICounterPayload> payload))
+            if (traceEvent.TryGetIndividualCounterPayload(_filter, out ICounterPayload payload))
             {
-                return _impl.HasSatisfiedCondition(payload[0]); // Need to check if this is safe - in theory just want the first (and only) result
+                return _impl.HasSatisfiedCondition(payload);
             }
             return false;
         }