EnrichmentScope & EnrichingActivityProcessor

examples/AspNetCore/Controllers/WeatherForecastController.cs

@@ -20,6 +20,7 @@
 using System.Net.Http;
 using Examples.AspNetCore.Models;
 using Microsoft.AspNetCore.Mvc;
+using OpenTelemetry.Trace;
 
 namespace Examples.AspNetCore.Controllers
 {
@@ -35,8 +36,24 @@ public class WeatherForecastController : ControllerBase
         private static HttpClient httpClient = new HttpClient();
 
         [HttpGet]
-        public IEnumerable<WeatherForecast> Get()
+        public IEnumerable<WeatherForecast> Get(int? zipPostalCode = null)
         {
+            using var scope = EnrichmentScope.Begin(
+                target: EnrichmentScopeTarget.NextActivity,
+                enrichmentAction: a =>
+                {
+                    if (zipPostalCode.HasValue)
+                    {
+                        a.AddTag("user.zip_postal", zipPostalCode.Value);
+                    }
+
+                    HttpRequestMessage request = (HttpRequestMessage)a.GetCustomProperty("HttpWebRequest.Request");
+                    if (request != null)
+                    {
+                        a.AddTag("http.content_type", request.Content.Headers.ContentType.ToString());
+                    }
+                });
+
             // Making an http call here to serve as an example of
             // how dependency calls will be captured and treated
             // automatically as child of incoming request.

src/OpenTelemetry/Trace/EnrichingActivityProcessor.cs

@@ -0,0 +1,50 @@
+// <copyright file="EnrichingActivityProcessor.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Diagnostics;
+
+namespace OpenTelemetry.Trace
+{
+    /// <summary>
+    /// An <see cref="ActivityProcessor"/> implementation that enriches <see cref="Activity"/> objects using <see cref="EnrichmentScope"/>s.
+    /// </summary>
+    public class EnrichingActivityProcessor : ActivityProcessor
+    {
+        /// <inheritdoc/>
+        public override void OnEnd(Activity activity)
+        {
+            EnrichmentScope scope = EnrichmentScope.Current;
+            while (scope != null)
+            {
+                try
+                {
+                    scope.EnrichmentAction?.Invoke(activity);
+                }
+                catch
+                {
+                    // todo: Log
+                }
+
+                if (scope.EnrichmentTarget == EnrichmentScopeTarget.NextActivity)
+                {
+                    scope.Dispose();
+                }
+
+                scope = scope.Parent;
+            }
+        }
+    }
+}

src/OpenTelemetry/Trace/EnrichmentScope.cs

@@ -0,0 +1,100 @@
+// <copyright file="EnrichmentScope.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+using System;
+using System.Diagnostics;
+using OpenTelemetry.Context;
+
+namespace OpenTelemetry.Trace
+{
+    /// <summary>
+    /// A class for enriching the data of <see cref="Activity"/> objects.
+    /// </summary>
+    public class EnrichmentScope : IDisposable
+    {
+        private static readonly RuntimeContextSlot<EnrichmentScope> RuntimeContextSlot = RuntimeContext.RegisterSlot<EnrichmentScope>("otel.enrichment_scope");
+
+        private bool disposed;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="EnrichmentScope"/> class.
+        /// </summary>
+        /// <param name="enrichmentAction">Callback action for performing <see cref="Activity"/> enrichment.</param>
+        /// <param name="target">The target for the enrichment scope.</param>
+        private EnrichmentScope(Action<Activity> enrichmentAction, EnrichmentScopeTarget target)
+        {
+            this.EnrichmentAction = enrichmentAction ?? throw new ArgumentNullException(nameof(enrichmentAction));
+            this.EnrichmentTarget = target;
+
+            this.Parent = Current;
+            this.Parent.Child = this;
+
+            RuntimeContextSlot.Set(this);
+        }
+
+        /// <summary>
+        /// Gets the current <see cref="EnrichmentScope"/>.
+        /// </summary>
+        public static EnrichmentScope Current => RuntimeContextSlot.Get();
+
+        /// <summary>
+        /// Gets the parent <see cref="EnrichmentScope"/>.
+        /// </summary>
+        public EnrichmentScope Parent { get; internal set; }
+
+        /// <summary>
+        /// Gets the child <see cref="EnrichmentScope"/>.
+        /// </summary>
+        public EnrichmentScope Child { get; internal set; }
+
+        /// <summary>
+        /// Gets the enrichment action.
+        /// </summary>
+        public Action<Activity> EnrichmentAction { get; private set; }
+
+        /// <summary>
+        /// Gets the enrichment target.
+        /// </summary>
+        public EnrichmentScopeTarget EnrichmentTarget { get; private set; }
+
+        /// <summary>
+        /// Registers an action that will be called to enrich the next <see cref="Activity"/> processed under the current scope if it has been sampled.
+        /// </summary>
+        /// <param name="enrichmentAction">Action to be called.</param>
+        /// <param name="target">The target for the enrichment scope.</param>
+        /// <returns><see cref="IDisposable"/> to cancel the enrichment scope.</returns>
+        public static IDisposable Begin(Action<Activity> enrichmentAction, EnrichmentScopeTarget target = EnrichmentScopeTarget.NextActivity)
+            => new EnrichmentScope(enrichmentAction, target);
+
+        /// <inheritdoc/>
+        public void Dispose()
+        {
+            if (!this.disposed)
+            {
+                this.EnrichmentAction = null;
+
+                this.Parent.Child = this.Child;
+                if (this.Child != null)
+                {
+                    this.Child.Parent = this.Parent;
+                }
+
+                RuntimeContextSlot.Set(this.Parent);
+
+                this.disposed = true;
+            }
+        }
+    }
+}

src/OpenTelemetry/Trace/EnrichmentScopeTarget.cs

@@ -0,0 +1,36 @@
+// <copyright file="EnrichmentScopeTarget.cs" company="OpenTelemetry Authors">
+// Copyright The OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// </copyright>
+
+using System.Diagnostics;
+
+namespace OpenTelemetry.Trace
+{
+    /// <summary>
+    /// Describes the target of an <see cref="EnrichmentScope"/>.
+    /// </summary>
+    public enum EnrichmentScopeTarget
+    {
+        /// <summary>
+        /// The next <see cref="Activity"/> created will be enriched and then the scope will automatically be closed.
+        /// </summary>
+        NextActivity,
+
+        /// <summary>
+        /// All children created under the scope will be enriched until the scope is closed.
+        /// </summary>
+        AllChildren,
+    }
+}