Add code to allow azure functions to force async on

Author: mwatson

Src/StackifyLib/Utils/AsyncTracer.cs

@@ -0,0 +1,76 @@
+#if NET45 || NET451
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+
+namespace StackifyLib.Utils
+{
+    public class AsyncTracer
+    {
+        private static bool _AsyncTracerEnabled = false;
+        private static DateTime _LastEnabledTest = DateTime.MinValue;
+
+        public static bool EnsureAsyncTracer()
+        {
+            if (_AsyncTracerEnabled)
+                return _AsyncTracerEnabled;
+
+            if (_LastEnabledTest > DateTime.UtcNow.AddMinutes(-5))
+            {
+                return _AsyncTracerEnabled;
+            }
+
+            try
+            {
+                var t = Type.GetType("System.Threading.Tasks.AsyncCausalityTracer");
+                if (t != null)
+                {
+                    var field = t.GetField("f_LoggingOn", BindingFlags.NonPublic | BindingFlags.Static);
+
+                    if (field == null)
+                    {
+                        StackifyLib.Utils.StackifyAPILogger.Log("Unable to enable the AsyncCausalityTracer, f_LoggingOn field not found");
+                        return _AsyncTracerEnabled;
+                    }
+                
+
+                    if (field.FieldType.Name == "Boolean")
+                    {
+                        bool current = (bool)field.GetValue(null);
+
+                        if (!current)
+                        {
+                            field.SetValue(null, true);
+                        }
+                    }
+                    else
+                    {
+                        field.SetValue(null, (byte)4); 
+                    }
+
+                    _AsyncTracerEnabled = true;
+                    
+
+
+                }
+                else
+                {
+                    _AsyncTracerEnabled = true; //never going to work.
+                    StackifyLib.Utils.StackifyAPILogger.Log("Unable to enable the AsyncCausalityTracer, class not found");
+                }
+            }
+            catch (Exception ex)
+            {
+                StackifyLib.Utils.StackifyAPILogger.Log("EnsureAsyncTracer Exception: " + ex.ToString());
+                Debug.WriteLine(ex);
+            }
+            _LastEnabledTest = DateTime.UtcNow;
+
+            return _AsyncTracerEnabled;
+        }
+    }
+}
+#endif