[Tracing] Add interoperability between the Datadog Baggage API and the OpenTelemetry Baggage API

tracer/build/supported_calltargets.g.json

@@ -13771,6 +13771,152 @@
     "IsAdoNetIntegration": false,
     "InstrumentationCategory": 1
   },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "ClearBaggage",
+    "TargetReturnType": "OpenTelemetry.Baggage",
+    "TargetParameterTypes": [
+      "OpenTelemetry.Baggage"
+    ],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_ClearBaggageIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "get_Current",
+    "TargetReturnType": "OpenTelemetry.Baggage",
+    "TargetParameterTypes": [],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_GetCurrentIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "RemoveBaggage",
+    "TargetReturnType": "OpenTelemetry.Baggage",
+    "TargetParameterTypes": [
+      "System.String",
+      "OpenTelemetry.Baggage"
+    ],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_RemoveBaggageIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "set_Current",
+    "TargetReturnType": "System.Void",
+    "TargetParameterTypes": [
+      "OpenTelemetry.Baggage"
+    ],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_SetCurrentIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "SetBaggage",
+    "TargetReturnType": "OpenTelemetry.Baggage",
+    "TargetParameterTypes": [
+      "System.String",
+      "System.String",
+      "OpenTelemetry.Baggage"
+    ],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_SetBaggageIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
+  {
+    "IntegrationName": "OpenTelemetry",
+    "AssemblyName": "OpenTelemetry.Api",
+    "TargetTypeName": "OpenTelemetry.Baggage",
+    "TargetMethodName": "SetBaggage",
+    "TargetReturnType": "OpenTelemetry.Baggage",
+    "TargetParameterTypes": [
+      "System.Collections.Generic.IEnumerable`1[System.Collections.Generic.KeyValuePair`2[System.String,System.String]]",
+      "OpenTelemetry.Baggage"
+    ],
+    "MinimumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "MaximumVersion": {
+      "Item1": 1,
+      "Item2": 0,
+      "Item3": 0
+    },
+    "InstrumentationTypeName": "Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry.OTelBaggage_SetBaggageItemsIntegration",
+    "IntegrationKind": 0,
+    "IsAdoNetIntegration": false,
+    "InstrumentationCategory": 1
+  },
   {
     "IntegrationName": "OpenTelemetry",
     "AssemblyName": "OpenTelemetry.Api",

tracer/src/Datadog.Trace/Baggage.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using Datadog.Trace.Util;
@@ -368,6 +369,27 @@ public void Clear()
         }
     }
 
+    /// <summary>
+    /// Converts the baggage items to a new dictionary.
+    /// </summary>
+    /// <returns>A dictionary of the baggage items, or an empty dictionary if there are no items.</returns>
+    public Dictionary<string, string?> AsDictionary()
+    {
+        if (_items is { } items)
+        {
+            lock (items)
+            {
+#if NETCOREAPP3_1_OR_GREATER
+                return new(items);
+#else
+                return new Dictionary<string, string?>(items.ToDictionary(kvp => kvp.Key, kvp => kvp.Value));
+#endif
+            }
+        }
+
+        return [];
+    }
+
     /// <summary>
     /// Adds the baggage items from this baggage instance into <paramref name="destination"/>.
     /// </summary>
@@ -446,7 +468,7 @@ public void Enumerate<T>(T processor)
         }
     }
 
-    private List<KeyValuePair<string, string?>>.Enumerator GetEnumerator() => _items?.GetEnumerator() ?? EmptyList.GetEnumerator();
+    public List<KeyValuePair<string, string?>>.Enumerator GetEnumerator() => _items?.GetEnumerator() ?? EmptyList.GetEnumerator();
 
     IEnumerator<KeyValuePair<string, string?>> IEnumerable<KeyValuePair<string, string?>>.GetEnumerator() => GetEnumerator();
 

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/OpenTelemetry/IApiBaggage.cs

@@ -0,0 +1,40 @@
+// <copyright file="IApiBaggage.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+#nullable enable
+
+using System.Collections.Generic;
+using Datadog.Trace.DuckTyping;
+
+namespace Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry
+{
+    /// <summary>
+    /// OpenTelemetry.Baggage interface for duck-typing
+    /// https://github.com/open-telemetry/opentelemetry-dotnet/blob/db429bf642c1a2c2f71b49f88d63e0a661018298/src/OpenTelemetry.Api/Baggage.cs#L16
+    /// </summary>
+    internal interface IApiBaggage
+    {
+        [DuckField(Name = "baggage")]
+        Dictionary<string, string> Baggage { get; }
+
+        IApiBaggage Create(Dictionary<string, string?>? baggageItems);
+
+        IReadOnlyDictionary<string, string?> GetBaggage();
+
+        string? GetBaggage(string name);
+
+        IBaggageHolder EnsureBaggageHolder();
+    }
+
+    /// <summary>
+    /// Baggage holder interface for duck-typing
+    /// https://github.com/open-telemetry/opentelemetry-dotnet/blob/db429bf642c1a2c2f71b49f88d63e0a661018298/src/OpenTelemetry.Api/Baggage.cs#L371
+    /// </summary>
+    internal interface IBaggageHolder
+    {
+        [DuckField(Name = "Baggage")]
+        IApiBaggage Baggage { get; set; }
+    }
+}

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/OpenTelemetry/OTelBaggage_ClearBaggageIntegration.cs

@@ -0,0 +1,49 @@
+// <copyright file="OTelBaggage_ClearBaggageIntegration.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+#nullable enable
+
+using System;
+using System.ComponentModel;
+using Datadog.Trace;
+using Datadog.Trace.ClrProfiler.CallTarget;
+using Datadog.Trace.Configuration;
+using Datadog.Trace.DuckTyping;
+
+namespace Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry
+{
+    /// <summary>
+    /// OpenTelemetry.Api Baggage.ClearBaggage calltarget instrumentation
+    /// </summary>
+    [InstrumentMethod(
+        AssemblyName = "OpenTelemetry.Api",
+        TypeName = "OpenTelemetry.Baggage",
+        MethodName = "ClearBaggage",
+        ReturnTypeName = "OpenTelemetry.Baggage",
+        ParameterTypeNames = new[] { "OpenTelemetry.Baggage" },
+        MinimumVersion = "1.0.0",
+        MaximumVersion = "1.0.0",
+        IntegrationName = nameof(Configuration.IntegrationId.OpenTelemetry))]
+    [Browsable(false)]
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    public sealed class OTelBaggage_ClearBaggageIntegration
+    {
+        internal const IntegrationId IntegrationId = Configuration.IntegrationId.OpenTelemetry;
+
+        internal static CallTargetReturn<TReturn> OnMethodEnd<TTarget, TReturn>(TTarget instance, TReturn returnValue, Exception exception, in CallTargetState state)
+        {
+            if (Tracer.Instance.CurrentTraceSettings.Settings.IsIntegrationEnabled(IntegrationId)
+                && exception is null)
+            {
+                // Important: Before returning to the caller, the static OpenTelemetry.Baggage APIs set the to-be-returned baggage object as OpenTelemetry.Baggage.Current.
+                // However, this is not done through the public setter (which we instrument), but through the backing field, so we must manually update Datadog.Trace.Baggage.Current
+                // so it remains in-sync.
+                Baggage.Current.Clear();
+            }
+
+            return new CallTargetReturn<TReturn>(returnValue);
+        }
+    }
+}

tracer/src/Datadog.Trace/ClrProfiler/AutoInstrumentation/OpenTelemetry/OTelBaggage_GetCurrentIntegration.cs

@@ -0,0 +1,51 @@
+// <copyright file="OTelBaggage_GetCurrentIntegration.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+#nullable enable
+
+using System;
+using System.ComponentModel;
+using Datadog.Trace;
+using Datadog.Trace.ClrProfiler.CallTarget;
+using Datadog.Trace.Configuration;
+using Datadog.Trace.DuckTyping;
+
+namespace Datadog.Trace.ClrProfiler.AutoInstrumentation.OpenTelemetry
+{
+    /// <summary>
+    /// OpenTelemetry.Api Baggage.get_Current calltarget instrumentation
+    /// </summary>
+    [InstrumentMethod(
+        AssemblyName = "OpenTelemetry.Api",
+        TypeName = "OpenTelemetry.Baggage",
+        MethodName = "get_Current",
+        ReturnTypeName = "OpenTelemetry.Baggage",
+        ParameterTypeNames = new string[0],
+        MinimumVersion = "1.0.0",
+        MaximumVersion = "1.0.0",
+        IntegrationName = nameof(Configuration.IntegrationId.OpenTelemetry))]
+    [Browsable(false)]
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    public sealed class OTelBaggage_GetCurrentIntegration
+    {
+        internal const IntegrationId IntegrationId = Configuration.IntegrationId.OpenTelemetry;
+
+        internal static CallTargetState OnMethodBegin<TInstance>(TInstance apiBaggage)
+            where TInstance : IApiBaggage
+        {
+            if (Tracer.Instance.CurrentTraceSettings.Settings.IsIntegrationEnabled(IntegrationId))
+            {
+                // Since Datadog.Trace.Baggage.Current may have been updated since the last time OpenTelemetry.Baggage.Current was accessed,
+                // we must update the underlying OpenTelemetry.Baggage.Current store with the latest Datadog.Trace.Baggage.Current items.
+                // Note: When the user sets OpenTelemetry.Baggage.Current, those changes will override the contents of Datadog.Trace.Baggage.Current,
+                // so we can always consider Datadog.Trace.Baggage.Current as being up-to-date.
+                var baggageHolder = apiBaggage.EnsureBaggageHolder();
+                baggageHolder.Baggage = apiBaggage.Create(Baggage.Current.AsDictionary());
+            }
+
+            return CallTargetState.GetDefault();
+        }
+    }
+}