Flow EventSources to EventPipe on Windows (dotnet/coreclr#18217)

Signed-off-by: dotnet-bot-corefx-mirror <dotnet-bot@microsoft.com>

Author: brianrob

src/Common/src/CoreLib/System/Diagnostics/Tracing/EventProvider.cs

@@ -30,6 +30,13 @@ namespace Microsoft.Diagnostics.Tracing
 namespace System.Diagnostics.Tracing
 #endif
 {
+    internal enum EventProviderType
+    {
+        None = 0,
+        ETW,
+        EventPipe
+    };
+
     // New in CLR4.0
     internal enum ControllerCommand
     {
@@ -120,15 +127,28 @@ public enum WriteEventErrorCode : int
         // it registers a callback from native code you MUST dispose it BEFORE shutdown, otherwise
         // you may get native callbacks during shutdown when we have destroyed the delegate.  
         // EventSource has special logic to do this, no one else should be calling EventProvider.  
-        internal EventProvider()
+        internal EventProvider(EventProviderType providerType)
         {
+            switch (providerType)
+            {
+                case EventProviderType.ETW:
 #if PLATFORM_WINDOWS
-            m_eventProvider = new EtwEventProvider();
-#elif FEATURE_PERFTRACING
-            m_eventProvider = new EventPipeEventProvider();
+                    m_eventProvider = new EtwEventProvider();
 #else
-            m_eventProvider = new NoOpEventProvider();
+                    m_eventProvider = new NoOpEventProvider();
 #endif
+                    break;
+                case EventProviderType.EventPipe:
+#if FEATURE_PERFTRACING
+                    m_eventProvider = new EventPipeEventProvider();
+#else
+                    m_eventProvider = new NoOpEventProvider();
+#endif
+                    break;
+                default:
+                    m_eventProvider = new NoOpEventProvider();
+                    break;
+            };
         }
 
         /// <summary>
@@ -475,7 +495,7 @@ private unsafe void GetSessionInfo(SessionInfoCallback action, ref List<SessionI
                 var structBase = (byte*)providerInstance;
                 providerInstance = (UnsafeNativeMethods.ManifestEtw.TRACE_PROVIDER_INSTANCE_INFO*)&structBase[providerInstance->NextOffset];
             }
-#else 
+#else
 #if !ES_BUILD_PCL && PLATFORM_WINDOWS  // TODO command arguments don't work on PCL builds...
             // This code is only used in the Nuget Package Version of EventSource.  because
             // the code above is using APIs baned from UWP apps.     
@@ -1276,8 +1296,7 @@ unsafe IntPtr IEventProvider.DefineEventHandle(uint eventID, string eventName, I
         }
     }
 
-#elif !FEATURE_PERFTRACING
-
+#endif
     internal sealed class NoOpEventProvider : IEventProvider
     {
         unsafe uint IEventProvider.EventRegister(
@@ -1314,10 +1333,8 @@ int IEventProvider.EventActivityIdControl(UnsafeNativeMethods.ManifestEtw.Activi
         // Define an EventPipeEvent handle.
         unsafe IntPtr IEventProvider.DefineEventHandle(uint eventID, string eventName, Int64 keywords, uint eventVersion, uint level, byte *pMetadata, uint metadataLength)
         {
-            throw new System.NotSupportedException();
+            return IntPtr.Zero;
         }
     }
-
-#endif
 }