[cpp worker] support Ray::Get() static method (#9809)

cpp/include/ray/api.h

@@ -39,6 +39,14 @@ class Ray {
   template <typename T>
   static ObjectRef<T> Put(const T &obj);
 
+  /// Get a single object from the object store.
+  /// This method will be blocked until the object is ready.
+  ///
+  /// \param[in] object The object reference which should be returned.
+  /// \return shared pointer of the result.
+  template <typename T>
+  static std::shared_ptr<T> Get(const ObjectRef<T> &object);
+
   /// Get a list of objects from the object store.
   /// This method will be blocked until all the objects are ready.
   ///
@@ -77,10 +85,6 @@ class Ray {
 
   static std::once_flag is_inited_;
 
-  /// Used by ObjectRef to implement .Get()
-  template <typename T>
-  static std::shared_ptr<T> Get(const ObjectRef<T> &object);
-
   template <typename ReturnType, typename FuncType, typename ExecFuncType,
             typename... ArgTypes>
   static TaskCaller<ReturnType> TaskInternal(FuncType &func, ExecFuncType &exec_func,

cpp/src/ray/test/api_test.cc

@@ -42,6 +42,19 @@ TEST(RayApiTest, PutTest) {
   EXPECT_EQ(1, *i1);
 }
 
+TEST(RayApiTest, StaticGetTest) {
+  Ray::Init();
+  /// `Get` member function
+  auto obj_ref1 = Ray::Put(100);
+  auto res1 = obj_ref1.Get();
+  EXPECT_EQ(100, *res1);
+
+  /// `Get` static function
+  auto obj_ref2 = Ray::Put(200);
+  auto res2 = Ray::Get(obj_ref2);
+  EXPECT_EQ(200, *res2);
+}
+
 TEST(RayApiTest, WaitTest) {
   Ray::Init();
   auto r0 = Ray::Task(Return1).Remote();