CosmosClient: Fixes missing Trace when converting HTTP Timeout to 503

Microsoft.Azure.Cosmos/src/HttpClient/CosmosHttpClientCore.cs

@@ -16,6 +16,7 @@ namespace Microsoft.Azure.Cosmos
     using System.Threading.Tasks;
     using Microsoft.Azure.Cosmos.Core.Trace;
     using Microsoft.Azure.Cosmos.Resource.CosmosExceptions;
+    using Microsoft.Azure.Cosmos.Tracing;
     using Microsoft.Azure.Cosmos.Tracing.TraceData;
     using Microsoft.Azure.Documents;
     using Microsoft.Azure.Documents.Collections;
@@ -307,20 +308,25 @@ public override Task<HttpResponseMessage> SendHttpAsync(
                 throw new ArgumentNullException(nameof(createRequestMessageAsync));
             }
 
-            return this.SendHttpHelperAsync(
-                createRequestMessageAsync,
-                resourceType,
-                timeoutPolicy,
-                clientSideRequestStatistics,
-                cancellationToken);
+            using (ITrace trace = Trace.GetRootTrace(nameof(SendHttpAsync), TraceComponent.Transport, TraceLevel.Info))
+            {
+                return this.SendHttpHelperAsync(
+                    createRequestMessageAsync,
+                    resourceType,
+                    timeoutPolicy,
+                    clientSideRequestStatistics,
+                    cancellationToken,
+                    trace);
+            }
         }
 
         private async Task<HttpResponseMessage> SendHttpHelperAsync(
             Func<ValueTask<HttpRequestMessage>> createRequestMessageAsync,
             ResourceType resourceType,
             HttpTimeoutPolicy timeoutPolicy,
             IClientSideRequestStatistics clientSideRequestStatistics,
-            CancellationToken cancellationToken)
+            CancellationToken cancellationToken,
+            ITrace trace)
         {
             DateTime startDateTimeUtc = DateTime.UtcNow;
             IEnumerator<(TimeSpan requestTimeout, TimeSpan delayForNextRequest)> timeoutEnumerator = timeoutPolicy.GetTimeoutEnumerator();
@@ -387,13 +393,15 @@ private async Task<HttpResponseMessage> SendHttpHelperAsync(
 
                                     if (timeoutPolicy.ShouldThrow503OnTimeout)
                                     {
+                                        trace.AddDatum("Client Side Request Stats", clientSideRequestStatistics);
                                         throw CosmosExceptionFactory.CreateServiceUnavailableException(
                                             message: message,
                                             headers: new Headers()
                                             {
                                                 ActivityId = System.Diagnostics.Trace.CorrelationManager.ActivityId.ToString(),
                                                 SubStatusCode = SubStatusCodes.TransportGenerated503
                                             },
+                                            trace: trace,
                                             innerException: e);
                                     }
 

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/CosmosHttpClientCoreTests.cs

@@ -301,6 +301,9 @@ async Task<HttpResponseMessage> sendFunc(HttpRequestMessage request, Cancellatio
                         CosmosException cosmosException = (CosmosException)e;
                         Assert.AreEqual(cosmosException.StatusCode, System.Net.HttpStatusCode.ServiceUnavailable);
                         Assert.AreEqual((int)cosmosException.SubStatusCode,(int)SubStatusCodes.TransportGenerated503);
+
+                        Assert.IsNotNull(cosmosException.Trace);
+                        Assert.AreNotEqual(cosmosException.Trace.Data.Count, 0);
                     }
                 }