Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Workflow.Runtime/WorkflowTraceTransfer.cs

@@ -0,0 +1,50 @@
+using System;
+using System.IO;
+using System.Threading;
+using System.Diagnostics;
+
+/// <summary>
+/// Summary description for Class1
+/// </summary>
+namespace System.Workflow.Runtime
+{
+    internal class WorkflowTraceTransfer : IDisposable
+    {
+        Guid oldGuid;
+        bool transferBackAtClose;
+
+        public WorkflowTraceTransfer(Guid instanceId)
+        {
+            this.oldGuid = Trace.CorrelationManager.ActivityId;
+
+            if (!this.oldGuid.Equals(instanceId)) //Avoid redundant transfers.
+            {
+                WorkflowTrace.Runtime.TraceTransfer(
+                    0,
+                    null,
+                    instanceId
+                    );
+                Trace.CorrelationManager.ActivityId = instanceId;
+                WorkflowTrace.Runtime.TraceEvent(TraceEventType.Start, 0, "Workflow Trace");
+                this.transferBackAtClose = true;
+            }
+        }
+
+        #region IDisposable Members
+
+        public void Dispose()
+        {
+            if (this.transferBackAtClose)
+            {
+                WorkflowTrace.Runtime.TraceTransfer(
+                     0,
+                     null,
+                     oldGuid
+                     );
+                WorkflowTrace.Runtime.TraceEvent(TraceEventType.Stop, 0, "Workflow Trace");
+                Trace.CorrelationManager.ActivityId = oldGuid;
+            }
+        }
+        #endregion
+    }
+}