Design review to allow underscore in event name

src/OpenTelemetry.Exporter.OneCollector/Internal/EventNameManager.cs

@@ -12,6 +12,7 @@ internal sealed class EventNameManager
     // Note: OneCollector will silently drop events which have a name less than 4 characters.
     internal const int MinimumEventFullNameLength = 4;
     internal const int MaximumEventFullNameLength = 100;
+
     private static readonly Regex EventNamespaceValidationRegex = new(@"^[A-Za-z](?:\.?[A-Za-z0-9]+?)*$", RegexOptions.Compiled);
     private static readonly Regex EventNameValidationRegex = new(@"^[A-Za-z][A-Za-z0-9]*$", RegexOptions.Compiled);
 
@@ -20,6 +21,7 @@ internal sealed class EventNameManager
     private readonly IReadOnlyDictionary<string, EventFullName>? eventFullNameMappings;
     private readonly ResolvedEventFullName defaultEventFullName;
     private readonly Hashtable eventNamespaceCache = new(StringComparer.OrdinalIgnoreCase);
+    private readonly Hashtable eventFullNameCache = new(StringComparer.OrdinalIgnoreCase);
 
     public EventNameManager(
         string defaultEventNamespace,
@@ -43,15 +45,43 @@ public EventNameManager(
 #endif
     }
 
-    // Note: This is exposed for unit tests.
+    // Note: These caches are exposed for unit tests.
     internal Hashtable EventNamespaceCache => this.eventNamespaceCache;
 
+    internal Hashtable EventFullNameCache => this.eventFullNameCache;
+
     public static bool IsEventNamespaceValid(string eventNamespace)
         => EventNamespaceValidationRegex.IsMatch(eventNamespace);
 
     public static bool IsEventNameValid(string eventName)
         => EventNameValidationRegex.IsMatch(eventName);
 
+    public ResolvedEventFullName ResolveEventFullName(
+        string eventFullName)
+    {
+        if (this.eventFullNameCache[eventFullName] is ResolvedEventFullName cachedEventFullName)
+        {
+            return cachedEventFullName;
+        }
+
+        byte[] eventFullNameBlob = BuildEventFullName(string.Empty, eventFullName);
+
+        var resolvedEventFullName = new ResolvedEventFullName(
+            eventFullNameBlob,
+            originalEventNamespace: null,
+            originalEventName: null);
+
+        lock (this.eventFullNameCache)
+        {
+            if (this.eventFullNameCache[eventFullName] is null)
+            {
+                this.eventFullNameCache[eventFullName] = resolvedEventFullName;
+            }
+        }
+
+        return resolvedEventFullName;
+    }
+
     public ResolvedEventFullName ResolveEventFullName(
         string? eventNamespace,
         string? eventName)

src/OpenTelemetry.Exporter.OneCollector/Internal/Serialization/LogRecordCommonSchemaJsonSerializer.cs

@@ -89,9 +89,23 @@ protected override void SerializeItemToJson(Resource resource, LogRecord item, C
 
         Debug.Assert(writer != null, "writer was null");
 
-        var resolvedEventFullName = this.eventNameManager.ResolveEventFullName(
-            item.CategoryName,
-            item.EventId.Name);
+        int attributeStartIndex = 0;
+        EventNameManager.ResolvedEventFullName resolvedEventFullName;
+        if (item.Attributes != null
+            && item.Attributes.Count > 0
+            && item.Attributes[0].Key == "{EventFullName}"
+            && item.Attributes[0].Value is string eventFullName
+            && !string.IsNullOrEmpty(eventFullName))
+        {
+            attributeStartIndex++;
+            resolvedEventFullName = this.eventNameManager.ResolveEventFullName(eventFullName);
+        }
+        else
+        {
+            resolvedEventFullName = this.eventNameManager.ResolveEventFullName(
+                item.CategoryName,
+                item.EventId.Name);
+        }
 
         writer!.WriteStartObject();
 
@@ -150,7 +164,7 @@ protected override void SerializeItemToJson(Resource resource, LogRecord item, C
 
         if (item.Attributes != null)
         {
-            for (int i = 0; i < item.Attributes.Count; i++)
+            for (int i = attributeStartIndex; i < item.Attributes.Count; i++)
             {
                 var attribute = item.Attributes[i];
 

test/OpenTelemetry.Exporter.OneCollector.Tests/EventNameManagerTests.cs

@@ -103,6 +103,22 @@ public void EventNameCacheTest()
         Assert.Single((eventNameManager.EventNamespaceCache["Test"] as Hashtable)!);
     }
 
+    [Fact]
+    public void EventFullNameCacheTest()
+    {
+        var eventNameManager = BuildEventNameManagerWithDefaultOptions();
+
+        Assert.Empty(eventNameManager.EventFullNameCache);
+
+        eventNameManager.ResolveEventFullName("Company_Product_EventName");
+
+        Assert.Single(eventNameManager.EventFullNameCache);
+
+        eventNameManager.ResolveEventFullName("company_product_eventName");
+
+        Assert.Single(eventNameManager.EventFullNameCache);
+    }
+
     [Fact]
     public void EventFullNameMappedWhenEventNamespaceMatchesTest()
     {

test/OpenTelemetry.Exporter.OneCollector.Tests/LogRecordCommonSchemaJsonSerializerTests.cs

@@ -204,7 +204,7 @@ public void LogRecordScopesJsonTest()
     }
 
     [Fact]
-    public void LogRecordStateValuesJsonTest()
+    public void LogRecordAttributesJsonTest()
     {
         string json = GetLogRecordJson(1, (index, logRecord) =>
         {
@@ -216,6 +216,24 @@ public void LogRecordStateValuesJsonTest()
             json);
     }
 
+    [Fact]
+    public void LogRecordAttributesWithEventFullNameJsonTest()
+    {
+        string json = GetLogRecordJson(1, (index, logRecord) =>
+        {
+            logRecord.Attributes = new List<KeyValuePair<string, object?>>
+            {
+                new KeyValuePair<string, object?>("{EventFullName}", "company_Product_EventName"),
+                new KeyValuePair<string, object?>("stateKey1", "stateValue1"),
+                new KeyValuePair<string, object?>("stateKey2", "stateValue2"),
+            };
+        });
+
+        Assert.Equal(
+            """{"ver":"4.0","name":"Company_Product_EventName","time":"2032-01-18T10:11:12Z","iKey":"o:tenant-token","data":{"severityText":"Trace","severityNumber":1,"stateKey1":"stateValue1","stateKey2":"stateValue2"}}""" + "\n",
+            json);
+    }
+
     [Fact]
     public void LogRecordTraceContextJsonTest()
     {