OS synchronization context

mcs/class/referencesource/mscorlib/system/exception.cs

@@ -1114,6 +1114,9 @@ internal Exception FixRemotingException ()
 
             return this;
         }
+
+		[MethodImplAttribute(MethodImplOptions.InternalCall)]
+		internal static extern void ReportUnhandledException(Exception exception);
 #endif
     }
 

mcs/class/referencesource/mscorlib/system/threading/synchronizationcontext.cs

@@ -293,6 +293,11 @@ private static SynchronizationContext GetThreadLocalContext()
                 context = AndroidPlatform.GetDefaultSyncContext ();
 #endif
 
+#if UNITY_AOT
+            if (context == null)
+                context = OSSpecificSynchronizationContext.Get();
+#endif
+
             return context;
         }
 
@@ -371,4 +376,93 @@ private static int InvokeWaitMethodHelper(SynchronizationContext syncContext, In
         }
 #endif
     }
+
+#if UNITY_AOT
+    class OSSpecificSynchronizationContext : SynchronizationContext
+    {
+        object m_OSSynchronizationContext;
+        private static readonly ConditionalWeakTable<object, OSSpecificSynchronizationContext> s_ContextCache = new ConditionalWeakTable<object, OSSpecificSynchronizationContext>();
+
+        private OSSpecificSynchronizationContext(object osContext)
+        {
+            m_OSSynchronizationContext = osContext;
+        }
+
+        public static OSSpecificSynchronizationContext Get()
+        {
+            var osContext = GetOSContext();
+            if (osContext == null)
+                return null;
+
+            return s_ContextCache.GetValue(osContext, _osContext => new OSSpecificSynchronizationContext(_osContext));
+        }
+
+        public override SynchronizationContext CreateCopy()
+        {
+            return new OSSpecificSynchronizationContext(m_OSSynchronizationContext);
+        }
+
+        public override void Send(SendOrPostCallback d, object state)
+        {
+            throw new NotSupportedException();
+        }
+
+        public override void Post(SendOrPostCallback d, object state)
+        {
+            var callback = Marshal.GetFunctionPointerForDelegate((InvocationEntryDelegate)InvocationEntry);
+            var invocationContext = new InvocationContext(d, state);
+            var invocationContextHandle = GCHandle.Alloc(invocationContext);
+            PostInternal(m_OSSynchronizationContext, callback, GCHandle.ToIntPtr(invocationContextHandle));
+        }
+
+        private delegate void InvocationEntryDelegate(IntPtr arg);
+
+        [MonoPInvokeCallback(typeof(InvocationEntryDelegate))]
+        private static void InvocationEntry(IntPtr arg)
+        {
+			try
+			{
+				var invocationContextHandle = GCHandle.FromIntPtr(arg);
+				var invocationContext = (InvocationContext)invocationContextHandle.Target;
+				invocationContextHandle.Free();
+				invocationContext.Invoke();
+			}
+			catch (Exception e)
+			{
+				Exception.ReportUnhandledException(e);
+			}
+        }
+
+		[AttributeUsage (AttributeTargets.Method)]
+		sealed class MonoPInvokeCallbackAttribute : Attribute
+		{
+			public MonoPInvokeCallbackAttribute(Type t)
+            {
+			}
+		}
+
+        class InvocationContext
+        {
+            private SendOrPostCallback m_Delegate;
+            private object m_State;
+
+            public InvocationContext(SendOrPostCallback d, object state)
+            {
+                m_Delegate = d;
+                m_State = state;
+            }
+
+            public void Invoke()
+            {
+                m_Delegate(m_State);
+            }
+        }
+
+        [MethodImplAttribute(MethodImplOptions.InternalCall)]
+        private extern static object GetOSContext();
+
+        [MethodImplAttribute(MethodImplOptions.InternalCall)]
+        private extern static void PostInternal(object osSynchronizationContext, IntPtr callback, IntPtr arg);
+    }
+#endif
 }

mono/metadata/exception.c

@@ -1183,3 +1183,10 @@ mono_exception_from_name_four_strings_checked (MonoImage *image, const char *nam
 
 	return create_exception_four_strings (klass, a1, a2, a3, a4, error);
 }
+
+void
+ves_icall_System_Exception_ReportUnhandledException(MonoObject *exc)
+{
+	mono_unhandled_exception (exc);
+	mono_invoke_unhandled_exception_hook (exc);
+}

mono/metadata/exception.h

@@ -161,6 +161,9 @@ typedef void  (*MonoUnhandledExceptionFunc)         (MonoObject *exc, void *user
 MONO_API void mono_install_unhandled_exception_hook (MonoUnhandledExceptionFunc func, void *user_data);
 void          mono_invoke_unhandled_exception_hook  (MonoObject *exc);
 
+void
+ves_icall_System_Exception_ReportUnhandledException (MonoObject *exc);
+
 MONO_END_DECLS
 
 #endif /* _MONO_METADATA_EXCEPTION_H_ */

mono/metadata/icall-def.h

@@ -293,6 +293,9 @@ HANDLES(ICALL(ENV_18, "internalGetGacPath", ves_icall_System_Environment_GetGacP
 HANDLES(ICALL(ENV_19, "internalGetHome", ves_icall_System_Environment_InternalGetHome))
 ICALL(ENV_20, "set_ExitCode", mono_environment_exitcode_set)
 
+ICALL_TYPE(EXCEPTION, "System.Exception", EXCEPTION_1)
+HANDLES(ICALL(EXCEPTION_1, "ReportUnhandledException", ves_icall_System_Exception_ReportUnhandledException))
+
 ICALL_TYPE(GC, "System.GC", GC_0)
 ICALL(GC_0, "GetCollectionCount", mono_gc_collection_count)
 ICALL(GC_0a, "GetGeneration", mono_gc_get_generation)
@@ -935,6 +938,10 @@ HANDLES(ICALL(NATIVEC_3, "OpenEvent_internal(string,System.Security.AccessContro
 ICALL(NATIVEC_4, "ResetEvent_internal",  ves_icall_System_Threading_Events_ResetEvent_internal)
 ICALL(NATIVEC_5, "SetEvent_internal",    ves_icall_System_Threading_Events_SetEvent_internal)
 
+ICALL_TYPE(OSSYNCCONTEXT, "System.Threading.OSSpecificSynchronizationContext", OSSYNCCONTEXT_1)
+HANDLES(ICALL(OSSYNCCONTEXT_1, "GetOSContext", ves_icall_System_Threading_OSSpecificSynchronizationContext_GetOSContext))
+ICALL(OSSYNCCONTEXT_2, "PostInternal", ves_icall_System_Threading_OSSpecificSynchronizationContext_PostInternal)
+
 ICALL_TYPE(SEMA, "System.Threading.Semaphore", SEMA_1)
 ICALL(SEMA_1, "CreateSemaphore_internal(int,int,string,int&)", ves_icall_System_Threading_Semaphore_CreateSemaphore_internal)
 ICALL(SEMA_2, "OpenSemaphore_internal(string,System.Security.AccessControl.SemaphoreRights,int&)", ves_icall_System_Threading_Semaphore_OpenSemaphore_internal)

mono/metadata/icall.c

@@ -8751,3 +8751,15 @@ mono_register_jit_icall (gconstpointer func, const char *name, MonoMethodSignatu
 	return mono_register_jit_icall_full (func, name, sig, no_wrapper, NULL);
 }
 
+MonoObjectHandle
+ves_icall_System_Threading_OSSpecificSynchronizationContext_GetOSContext ()
+{
+	return NULL_HANDLE;
+}
+
+void
+ves_icall_System_Threading_OSSpecificSynchronizationContext_PostInternal (gpointer callback, gpointer arg)
+{
+	/* This isn't actually reachable since ves_icall_System_Threading_OSSpecificSynchronizationContext_GetOSContext always returns NULL */
+	mono_set_pending_exception (mono_get_exception_not_implemented ("System.Threading.InteropServices.OSSpecificSynchronizationContext.PostInternal internal call is not implemented."));
+}

mono/metadata/threads-types.h

@@ -267,4 +267,10 @@ mono_thread_internal_describe (MonoInternalThread *internal, GString *str);
 gboolean
 mono_thread_internal_is_current (MonoInternalThread *internal);
 
+MonoObjectHandle
+ves_icall_System_Threading_OSSpecificSynchronizationContext_GetOSContext ();
+
+void
+ves_icall_System_Threading_OSSpecificSynchronizationContext_PostInternal (gpointer callback, gpointer arg);
+
 #endif /* _MONO_METADATA_THREADS_TYPES_H_ */