Added basic event counters for hosting (#10884)

- Added Request Rate counter (RPS), Total Requests counter, current requests and failed requests.
- Counters do nothing until enabled
- Added tests for counters and improved tests to use unique event source names
- Renamed EventSource to match the convention in the runtime Microsoft.AspNetCore.Hosting

src/Hosting/Hosting/ref/Microsoft.AspNetCore.Hosting.netcoreapp3.0.cs

@@ -145,7 +145,6 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         public static void Initialize(this Microsoft.AspNetCore.Hosting.IHostingEnvironment hostingEnvironment, string contentRootPath, Microsoft.AspNetCore.Hosting.Internal.WebHostOptions options) { }
         public static void Initialize(this Microsoft.AspNetCore.Hosting.IWebHostEnvironment hostingEnvironment, string contentRootPath, Microsoft.AspNetCore.Hosting.Internal.WebHostOptions options) { }
     }
-    [System.Diagnostics.Tracing.EventSourceAttribute(Name="Microsoft-AspNetCore-Hosting")]
     public sealed partial class HostingEventSource : System.Diagnostics.Tracing.EventSource
     {
         internal HostingEventSource() { }
@@ -154,6 +153,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         public void HostStart() { }
         [System.Diagnostics.Tracing.EventAttribute(2, Level=System.Diagnostics.Tracing.EventLevel.Informational)]
         public void HostStop() { }
+        protected override void OnEventCommand(System.Diagnostics.Tracing.EventCommandEventArgs command) { }
         [System.Diagnostics.Tracing.EventAttribute(3, Level=System.Diagnostics.Tracing.EventLevel.Informational)]
         public void RequestStart(string method, string path) { }
         [System.Runtime.CompilerServices.MethodImpl(System.Runtime.CompilerServices.MethodImplOptions.NoInlining)][System.Diagnostics.Tracing.EventAttribute(4, Level=System.Diagnostics.Tracing.EventLevel.Informational)]

src/Hosting/Hosting/src/Internal/HostingApplicationDiagnostics.cs

@@ -136,10 +136,19 @@ namespace Microsoft.AspNetCore.Hosting.Internal
                 StopActivity(httpContext, activity, context.HasDiagnosticListener);
             }
 
-            if (context.EventLogEnabled && exception != null)
+            if (context.EventLogEnabled)
             {
-                // Non-inline
-                HostingEventSource.Log.UnhandledException();
+                if (exception != null)
+                {
+                    // Non-inline
+                    HostingEventSource.Log.UnhandledException();
+                }
+
+                // Count 500 as failed requests
+                if (httpContext.Response.StatusCode >= 500)
+                {
+                    HostingEventSource.Log.RequestFailed();
+                }
             }
 
             // Logging Scope is finshed with

src/Hosting/Hosting/src/Internal/HostingEventSource.cs

@@ -1,17 +1,37 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Diagnostics.Tracing;
 using System.Runtime.CompilerServices;
+using System.Threading;
 
 namespace Microsoft.AspNetCore.Hosting.Internal
 {
-    [EventSource(Name = "Microsoft-AspNetCore-Hosting")]
     public sealed class HostingEventSource : EventSource
     {
         public static readonly HostingEventSource Log = new HostingEventSource();
 
-        private HostingEventSource() { }
+        private IncrementingPollingCounter _requestsPerSecondCounter;
+        private PollingCounter _totalRequestsCounter;
+        private PollingCounter _failedRequestsCounter;
+        private PollingCounter _currentRequestsCounter;
+
+        private long _totalRequests;
+        private long _currentRequests;
+        private long _failedRequests;
+
+        internal HostingEventSource()
+            : this("Microsoft.AspNetCore.Hosting")
+        {
+
+        }
+
+        // Used for testing
+        internal HostingEventSource(string eventSourceName)
+            : base(eventSourceName)
+        {
+        }
 
         // NOTE
         // - The 'Start' and 'Stop' suffixes on the following event names have special meaning in EventSource. They
@@ -35,6 +55,8 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         [Event(3, Level = EventLevel.Informational)]
         public void RequestStart(string method, string path)
         {
+            Interlocked.Increment(ref _totalRequests);
+            Interlocked.Increment(ref _currentRequests);
             WriteEvent(3, method, path);
         }
 
@@ -42,6 +64,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         [Event(4, Level = EventLevel.Informational)]
         public void RequestStop()
         {
+            Interlocked.Decrement(ref _currentRequests);
             WriteEvent(4);
         }
 
@@ -51,5 +74,40 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         {
             WriteEvent(5);
         }
+
+        internal void RequestFailed()
+        {
+            Interlocked.Increment(ref _failedRequests);
+        }
+
+        protected override void OnEventCommand(EventCommandEventArgs command)
+        {
+            if (command.Command == EventCommand.Enable)
+            {
+                // This is the convention for initializing counters in the RuntimeEventSource (lazily on the first enable command).
+                // They aren't disabled afterwards...
+
+                _requestsPerSecondCounter ??= new IncrementingPollingCounter("requests-per-second", this, () => _totalRequests)
+                {
+                    DisplayName = "Request Rate",
+                    DisplayRateTimeScale = TimeSpan.FromSeconds(1)
+                };
+
+                _totalRequestsCounter ??= new PollingCounter("total-requests", this, () => _totalRequests)
+                {
+                    DisplayName = "Total Requests",
+                };
+
+                _currentRequestsCounter ??= new PollingCounter("current-requests", this, () => _currentRequests)
+                {
+                    DisplayName = "Current Requests"
+                };
+
+                _failedRequestsCounter ??= new PollingCounter("failed-requests", this, () => _failedRequests)
+                {
+                    DisplayName = "Failed Requests"
+                };
+            }
+        }
     }
 }

src/Hosting/Hosting/test/Internal/AsyncEnumerableExtensions.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace System.Collections.Generic
+{
+    internal static class AsyncEnumerableExtensions
+    {
+        public static async Task<T> FirstOrDefault<T>(this IAsyncEnumerator<T> values, Func<T, bool> filter)
+        {
+            while (await values.MoveNextAsync())
+            {
+                if (filter(values.Current))
+                {
+                    return values.Current;
+                }
+            }
+
+            return default;
+        }
+    }
+}

src/Hosting/Hosting/test/Internal/HostingEventSourceTests.cs

@@ -2,8 +2,11 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics.Tracing;
-using System.Reflection;
+using System.Threading;
+using System.Threading.Channels;
+using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Testing;
 using Microsoft.AspNetCore.Testing.xunit;
@@ -17,16 +20,11 @@ namespace Microsoft.AspNetCore.Hosting.Internal
         public void MatchesNameAndGuid()
         {
             // Arrange & Act
-            var eventSourceType = typeof(WebHost).GetTypeInfo().Assembly.GetType(
-                "Microsoft.AspNetCore.Hosting.Internal.HostingEventSource",
-                throwOnError: true,
-                ignoreCase: false);
+            var eventSource = new HostingEventSource();
 
             // Assert
-            Assert.NotNull(eventSourceType);
-            Assert.Equal("Microsoft-AspNetCore-Hosting", EventSource.GetName(eventSourceType));
-            Assert.Equal(Guid.Parse("9e620d2a-55d4-5ade-deb7-c26046d245a8"), EventSource.GetGuid(eventSourceType));
-            Assert.NotEmpty(EventSource.GenerateManifest(eventSourceType, "assemblyPathToIncludeInManifest"));
+            Assert.Equal("Microsoft.AspNetCore.Hosting", eventSource.Name);
+            Assert.Equal(Guid.Parse("9ded64a4-414c-5251-dcf7-1e4e20c15e70"), eventSource.Guid);
         }
 
         [Fact]
@@ -35,7 +33,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             // Arrange
             var expectedEventId = 1;
             var eventListener = new TestEventListener(expectedEventId);
-            var hostingEventSource = HostingEventSource.Log;
+            var hostingEventSource = GetHostingEventSource();
             eventListener.EnableEvents(hostingEventSource, EventLevel.Informational);
 
             // Act
@@ -58,7 +56,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             // Arrange
             var expectedEventId = 2;
             var eventListener = new TestEventListener(expectedEventId);
-            var hostingEventSource = HostingEventSource.Log;
+            var hostingEventSource = GetHostingEventSource();
             eventListener.EnableEvents(hostingEventSource, EventLevel.Informational);
 
             // Act
@@ -115,7 +113,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             // Arrange
             var expectedEventId = 3;
             var eventListener = new TestEventListener(expectedEventId);
-            var hostingEventSource = HostingEventSource.Log;
+            var hostingEventSource = GetHostingEventSource();
             eventListener.EnableEvents(hostingEventSource, EventLevel.Informational);
 
             // Act
@@ -144,7 +142,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             // Arrange
             var expectedEventId = 4;
             var eventListener = new TestEventListener(expectedEventId);
-            var hostingEventSource = HostingEventSource.Log;
+            var hostingEventSource = GetHostingEventSource();
             eventListener.EnableEvents(hostingEventSource, EventLevel.Informational);
 
             // Act
@@ -166,7 +164,7 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             // Arrange
             var expectedEventId = 5;
             var eventListener = new TestEventListener(expectedEventId);
-            var hostingEventSource = HostingEventSource.Log;
+            var hostingEventSource = GetHostingEventSource();
             eventListener.EnableEvents(hostingEventSource, EventLevel.Informational);
 
             // Act
@@ -182,16 +180,65 @@ namespace Microsoft.AspNetCore.Hosting.Internal
             Assert.Empty(eventData.Payload);
         }
 
-        private static Exception GetException()
+        [Fact]
+        public async Task VerifyCountersFireWithCorrectValues()
         {
-            try
-            {
-                throw new InvalidOperationException("An invalid operation has occurred");
-            }
-            catch (Exception ex)
-            {
-                return ex;
-            }
+            // Arrange
+            var eventListener = new CounterListener(new[] {
+                "requests-per-second",
+                "total-requests",
+                "current-requests",
+                "failed-requests"
+            });
+
+            var hostingEventSource = GetHostingEventSource();
+
+            using var timeoutTokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(5));
+
+            var rpsValues = eventListener.GetCounterValues("requests-per-second", timeoutTokenSource.Token).GetAsyncEnumerator();
+            var totalRequestValues = eventListener.GetCounterValues("total-requests", timeoutTokenSource.Token).GetAsyncEnumerator();
+            var currentRequestValues = eventListener.GetCounterValues("current-requests", timeoutTokenSource.Token).GetAsyncEnumerator();
+            var failedRequestValues = eventListener.GetCounterValues("failed-requests", timeoutTokenSource.Token).GetAsyncEnumerator();
+
+            eventListener.EnableEvents(hostingEventSource, EventLevel.Informational, EventKeywords.None,
+                new Dictionary<string, string>
+                {
+                    { "EventCounterIntervalSec", "1" }
+                });
+
+            hostingEventSource.RequestStart("GET", "/");
+
+            Assert.Equal(1, await totalRequestValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(1, await rpsValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(1, await currentRequestValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(0, await failedRequestValues.FirstOrDefault(v => v == 0));
+
+            hostingEventSource.RequestStop();
+
+            Assert.Equal(1, await totalRequestValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(0, await rpsValues.FirstOrDefault(v => v == 0));
+            Assert.Equal(0, await currentRequestValues.FirstOrDefault(v => v == 0));
+            Assert.Equal(0, await failedRequestValues.FirstOrDefault(v => v == 0));
+
+            hostingEventSource.RequestStart("POST", "/");
+
+            Assert.Equal(2, await totalRequestValues.FirstOrDefault(v => v == 2));
+            Assert.Equal(1, await rpsValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(1, await currentRequestValues.FirstOrDefault(v => v == 1));
+            Assert.Equal(0, await failedRequestValues.FirstOrDefault(v => v == 0));
+
+            hostingEventSource.RequestFailed();
+            hostingEventSource.RequestStop();
+
+            Assert.Equal(2, await totalRequestValues.FirstOrDefault(v => v == 2));
+            Assert.Equal(0, await rpsValues.FirstOrDefault(v => v == 0));
+            Assert.Equal(0, await currentRequestValues.FirstOrDefault(v => v == 0));
+            Assert.Equal(1, await failedRequestValues.FirstOrDefault(v => v == 1));
+        }
+
+        private static HostingEventSource GetHostingEventSource()
+        {
+            return new HostingEventSource(Guid.NewGuid().ToString());
         }
 
         private class TestEventListener : EventListener
@@ -216,5 +263,36 @@ namespace Microsoft.AspNetCore.Hosting.Internal
                 }
             }
         }
+
+        private class CounterListener : EventListener
+        {
+            private readonly Dictionary<string, Channel<double>> _counters = new Dictionary<string, Channel<double>>();
+
+            public CounterListener(string[] counterNames)
+            {
+                foreach (var item in counterNames)
+                {
+                    _counters[item] = Channel.CreateUnbounded<double>();
+                }
+            }
+
+            public IAsyncEnumerable<double> GetCounterValues(string counterName, CancellationToken cancellationToken = default)
+            {
+                return _counters[counterName].Reader.ReadAllAsync(cancellationToken);
+            }
+
+            protected override void OnEventWritten(EventWrittenEventArgs eventData)
+            {
+                if (eventData.EventName == "EventCounters")
+                {
+                    var payload = (IDictionary<string, object>)eventData.Payload[0];
+                    var counter = (string)payload["Name"];
+                    payload.TryGetValue("Increment", out var increment);
+                    payload.TryGetValue("Mean", out var mean);
+                    var writer = _counters[counter].Writer;
+                    writer.TryWrite((double)(increment ?? mean));
+                }
+            }
+        }
     }
 }

src/Hosting/Hosting/test/Microsoft.AspNetCore.Hosting.Tests.csproj

@@ -19,6 +19,7 @@
     <Reference Include="Microsoft.Extensions.Hosting" />
     <Reference Include="Microsoft.Extensions.Logging.Testing" />
     <Reference Include="Microsoft.Extensions.Options" />
+    <Reference Include="System.Threading.Channels" />
   </ItemGroup>
 
 </Project>