From a222ac399c5458a8772e8c4b3ddffd61e85e0774 Mon Sep 17 00:00:00 2001
From: Miha Zupan <mihazupan.zupan1@gmail.com>
Date: Mon, 17 Oct 2022 12:58:07 -0700
Subject: [PATCH] Avoid race condition and performance trap in
 EventCountersMetrics

---
 .../EventCountersMetrics.cs                   | 39 ++++++++++++-------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/src/OpenTelemetry.Instrumentation.EventCounters/EventCountersMetrics.cs b/src/OpenTelemetry.Instrumentation.EventCounters/EventCountersMetrics.cs
index e01ce8b968..b7797eeb97 100644
--- a/src/OpenTelemetry.Instrumentation.EventCounters/EventCountersMetrics.cs
+++ b/src/OpenTelemetry.Instrumentation.EventCounters/EventCountersMetrics.cs
@@ -30,7 +30,7 @@ internal sealed class EventCountersMetrics : EventListener
     internal static readonly Meter MeterInstance = new(typeof(EventCountersMetrics).Assembly.GetName().Name, typeof(EventCountersMetrics).Assembly.GetName().Version.ToString());
 
     private readonly EventCountersInstrumentationOptions options;
-    private readonly ConcurrentQueue<EventSource> preInitEventSources = new();
+    private readonly List<EventSource> preInitEventSources = new();
     private readonly ConcurrentDictionary<(string, string), Instrument> instruments = new();
     private readonly ConcurrentDictionary<(string, string), double> values = new();
 
@@ -40,29 +40,42 @@ internal sealed class EventCountersMetrics : EventListener
     /// <param name="options">The options to define the metrics.</param>
     public EventCountersMetrics(EventCountersInstrumentationOptions options)
     {
-        this.options = options;
-
-        while (this.preInitEventSources.TryDequeue(out EventSource eventSource))
+        lock (this.preInitEventSources)
         {
-            if (this.options.ShouldListenToSource(eventSource.Name))
+            this.options = options;
+
+            foreach (EventSource eventSource in this.preInitEventSources)
             {
-                this.EnableEvents(eventSource, EventLevel.LogAlways, EventKeywords.None, GetEnableEventsArguments(this.options));
+                if (this.options.ShouldListenToSource(eventSource.Name))
+                {
+                    this.EnableEvents(eventSource);
+                }
             }
+
+            this.preInitEventSources.Clear();
         }
     }
 
     /// <inheritdoc />
-    protected override void OnEventSourceCreated(EventSource source)
+    protected override void OnEventSourceCreated(EventSource eventSource)
     {
-        if (this.options == null)
-        {
-            this.preInitEventSources.Enqueue(source);
-        }
-        else if (this.options.ShouldListenToSource(source.Name))
+        lock (this.preInitEventSources)
         {
-            this.EnableEvents(source, EventLevel.LogAlways, EventKeywords.None, GetEnableEventsArguments(this.options));
+            if (this.options == null)
+            {
+                this.preInitEventSources.Add(eventSource);
+            }
+            else if (this.options.ShouldListenToSource(eventSource.Name))
+            {
+                this.EnableEvents(eventSource);
+            }
         }
     }
+    
+    private void EnableEvents(EventSource eventSource)
+    {
+         this.EnableEvents(eventSource, EventLevel.Critical, EventKeywords.None, GetEnableEventsArguments(this.options));
+    }
 
     /// <inheritdoc />
     protected override void OnEventWritten(EventWrittenEventArgs eventData)