Add EventListener microbenchmarks

src/benchmarks/micro/libraries/System.Diagnostics.Tracing/Perf_EventListener.cs

@@ -0,0 +1,90 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using BenchmarkDotNet.Attributes;
+using MicroBenchmarks;
+
+namespace System.Diagnostics.Tracing
+{
+    [BenchmarkCategory(Categories.Libraries)]
+    public class Perf_EventListener
+    {
+        private enum TestEnum
+        {
+            Foo = 123
+        }
+
+        private sealed class BenchmarkEventSource : EventSource
+        {
+            public BenchmarkEventSource() : base(nameof(Perf_EventListener)) { }
+
+            [Event(1)]
+            public void EventNoParams() => WriteEvent(1);
+
+            [Event(2)]
+            public void EventIntParams(int arg1, int arg2, int arg3) => WriteEvent(2, arg1, arg2, arg3);
+
+            [Event(3)]
+            public void EventStringParams(string arg1, string arg2, string arg3) => WriteEvent(3, arg1, arg2, arg3);
+
+            [Event(4)]
+            public unsafe void EventMixedParams(int arg1, string arg2, TestEnum arg3)
+            {
+                arg2 ??= "";
+
+                fixed (char* arg2Ptr = arg2)
+                {
+                    const int NumEventDatas = 3;
+                    EventData* descrs = stackalloc EventData[NumEventDatas];
+
+                    descrs[0] = new EventData
+                    {
+                        DataPointer = (IntPtr)(&arg1),
+                        Size = sizeof(int)
+                    };
+                    descrs[1] = new EventData
+                    {
+                        DataPointer = (IntPtr)(arg2Ptr),
+                        Size = (arg2.Length + 1) * sizeof(char)
+                    };
+                    descrs[2] = new EventData
+                    {
+                        DataPointer = (IntPtr)(&arg3),
+                        Size = sizeof(TestEnum)
+                    };
+
+                    WriteEventCore(4, NumEventDatas, descrs);
+                }
+            }
+        }
+
+        private sealed class BenchmarkEventListener : EventListener
+        {
+            protected override void OnEventSourceCreated(EventSource eventSource)
+            {
+                if (eventSource.Name == nameof(Perf_EventListener))
+                {
+                    EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.None);
+                }
+            }
+
+            protected override void OnEventWritten(EventWrittenEventArgs eventData) { }
+        }
+
+        private static readonly BenchmarkEventSource _eventSource = new BenchmarkEventSource();
+        private static readonly BenchmarkEventListener _eventListener = new BenchmarkEventListener();
+
+        [Benchmark]
+        public void WriteEvent_NoParams() => _eventSource.EventNoParams();
+
+        [Benchmark]
+        public void WriteEvent_IntParams() => _eventSource.EventIntParams(1, 2, 3);
+
+        [Benchmark]
+        public void WriteEvent_StringParams() => _eventSource.EventStringParams("foo", "bar", "foobar");
+
+        [Benchmark]
+        public void WriteEvent_MixedParams() => _eventSource.EventMixedParams(123, "foo", TestEnum.Foo);
+    }
+}