- Add an OSThread structure which is the generic TLS structure for all C++

runtime/vm/native_api_impl.cc

Index: runtime/vm/native_api_impl.cc
diff --git a/runtime/vm/native_api_impl.cc b/runtime/vm/native_api_impl.cc
index 9395bf3af891c97019babebab57d30c9ecf24b37..9d68624d9c422fdc1cfc03cb8e0a0b2a95376902 100644
--- a/runtime/vm/native_api_impl.cc
+++ b/runtime/vm/native_api_impl.cc
@@ -22,6 +22,27 @@ static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
 }
 
 
+class IsolateSaver {
+ public:
+  explicit IsolateSaver(Isolate* current_isolate)
+      : saved_isolate_(current_isolate) {
+    if (current_isolate != NULL) {
+      ASSERT(current_isolate == Isolate::Current());
+      Thread::ExitIsolate();
+    }
+  }
+  ~IsolateSaver() {
+    if (saved_isolate_ != NULL) {
+      Thread::EnterIsolate(saved_isolate_);
+    }
+  }
+ private:
+  Isolate* saved_isolate_;
+
+  DISALLOW_COPY_AND_ASSIGN(IsolateSaver);
+};
+
+
 DART_EXPORT bool Dart_PostCObject(Dart_Port port_id, Dart_CObject* message) {
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, allocator);
@@ -48,7 +69,6 @@ DART_EXPORT Dart_Port Dart_NewNativePort(const char* name,
   }
   // Start the native port without a current isolate.
   IsolateSaver saver(Isolate::Current());
-  Thread::ExitIsolate();
 
   NativeMessageHandler* nmh = new NativeMessageHandler(name, handler);
   Dart_Port port_id = PortMap::CreatePort(nmh);
@@ -60,7 +80,6 @@ DART_EXPORT Dart_Port Dart_NewNativePort(const char* name,
 DART_EXPORT bool Dart_CloseNativePort(Dart_Port native_port_id) {
   // Close the native port without a current isolate.
   IsolateSaver saver(Isolate::Current());
-  Thread::ExitIsolate();
 
   // TODO(turnidge): Check that the port is native before trying to close.
   return PortMap::ClosePort(native_port_id);