[C++ worker]Support ActorHandle type return value (#28077)

Before we support `ActorHandle` type as parameter, this PR adds support for `ActorHandle` type as return type.

cpp/include/ray/api.h

@@ -17,6 +17,7 @@
 #include <ray/api/actor_creator.h>
 #include <ray/api/actor_handle.h>
 #include <ray/api/actor_task_caller.h>
+#include <ray/api/function_manager.h>
 #include <ray/api/logging.h>
 #include <ray/api/object_ref.h>
 #include <ray/api/ray_config.h>
@@ -270,7 +271,8 @@ inline ray::internal::TaskCaller<F> Task(F func) {
   static_assert(!ray::internal::is_python_v<F>, "Must be a cpp function.");
   static_assert(!std::is_member_function_pointer_v<F>,
                 "Incompatible type: member function cannot be called with ray::Task.");
-  ray::internal::RemoteFunctionHolder remote_func_holder(std::move(func));
+  auto func_name = internal::FunctionManager::Instance().GetFunctionName(func);
+  ray::internal::RemoteFunctionHolder remote_func_holder(std::move(func_name));
   return ray::internal::TaskCaller<F>(ray::internal::GetRayRuntime().get(),
                                       std::move(remote_func_holder));
 }
@@ -278,7 +280,8 @@ inline ray::internal::TaskCaller<F> Task(F func) {
 /// Creating an actor.
 template <typename F>
 inline ray::internal::ActorCreator<F> Actor(F create_func) {
-  ray::internal::RemoteFunctionHolder remote_func_holder(std::move(create_func));
+  auto func_name = internal::FunctionManager::Instance().GetFunctionName(create_func);
+  ray::internal::RemoteFunctionHolder remote_func_holder(std::move(func_name));
   return ray::internal::ActorCreator<F>(ray::internal::GetRayRuntime().get(),
                                         std::move(remote_func_holder));
 }

cpp/include/ray/api/actor_handle.h

@@ -15,6 +15,7 @@
 #pragma once
 
 #include <ray/api/actor_task_caller.h>
+#include <ray/api/function_manager.h>
 #include <ray/api/ray_runtime_holder.h>
 
 namespace ray {
@@ -47,7 +48,8 @@ class ActorHandle {
     static_assert(
         std::is_same<ActorType, Self>::value || std::is_base_of<Self, ActorType>::value,
         "Class types must be same.");
-    ray::internal::RemoteFunctionHolder remote_func_holder(actor_func);
+    auto func_name = internal::FunctionManager::Instance().GetFunctionName(actor_func);
+    ray::internal::RemoteFunctionHolder remote_func_holder(func_name);
     return ray::internal::ActorTaskCaller<F>(
         internal::GetRayRuntime().get(), id_, std::move(remote_func_holder));
   }

cpp/include/ray/api/common_types.h

@@ -42,5 +42,15 @@ struct TaskArg {
   std::string_view meta_str;
 };
 
+using ArgsBuffer = msgpack::sbuffer;
+using ArgsBufferList = std::vector<ArgsBuffer>;
+
+using RemoteFunction = std::function<msgpack::sbuffer(const ArgsBufferList &)>;
+using RemoteFunctionMap_t = std::unordered_map<std::string, RemoteFunction>;
+
+using RemoteMemberFunction =
+    std::function<msgpack::sbuffer(msgpack::sbuffer *, const ArgsBufferList &)>;
+using RemoteMemberFunctionMap_t = std::unordered_map<std::string, RemoteMemberFunction>;
+
 }  // namespace internal
 }  // namespace ray

cpp/include/ray/api/function_manager.h

@@ -15,6 +15,7 @@
 #pragma once
 
 #include <ray/api/common_types.h>
+#include <ray/api/ray_runtime_holder.h>
 #include <ray/api/serializer.h>
 #include <ray/api/type_traits.h>
 
@@ -33,6 +34,11 @@ namespace internal {
 template <typename T>
 inline static std::enable_if_t<!std::is_pointer<T>::value, msgpack::sbuffer>
 PackReturnValue(T result) {
+  if constexpr (is_actor_handle_v<T>) {
+    auto serialized_actor_handle =
+        RayRuntimeHolder::Instance().Runtime()->SerializeActorHandle(result.ID());
+    return Serializer::Serialize(serialized_actor_handle);
+  }
   return Serializer::Serialize(std::move(result));
 }
 
@@ -48,16 +54,6 @@ inline static msgpack::sbuffer PackVoid() {
 
 msgpack::sbuffer PackError(std::string error_msg);
 
-using ArgsBuffer = msgpack::sbuffer;
-using ArgsBufferList = std::vector<ArgsBuffer>;
-
-using RemoteFunction = std::function<msgpack::sbuffer(const ArgsBufferList &)>;
-using RemoteFunctionMap_t = std::unordered_map<std::string, RemoteFunction>;
-
-using RemoteMemberFunction =
-    std::function<msgpack::sbuffer(msgpack::sbuffer *, const ArgsBufferList &)>;
-using RemoteMemberFunctionMap_t = std::unordered_map<std::string, RemoteMemberFunction>;
-
 /// It's help to invoke functions and member functions, the class Invoker<Function> help
 /// do type erase.
 template <typename Function>

cpp/include/ray/api/object_ref.h

@@ -16,6 +16,7 @@
 
 #include <ray/api/ray_runtime_holder.h>
 #include <ray/api/serializer.h>
+#include <ray/api/type_traits.h>
 
 #include <memory>
 #include <msgpack.hpp>
@@ -118,6 +119,12 @@ inline static std::shared_ptr<T> GetFromRuntime(const ObjectRef<T> &object) {
         packed_object->data(), packed_object->size(), internal::XLANG_HEADER_LEN);
   }
 
+  if constexpr (ray::internal::is_actor_handle_v<T>) {
+    auto actor_handle = ray::internal::Serializer::Deserialize<std::string>(
+        packed_object->data(), packed_object->size());
+    return std::make_shared<T>(T::FromBytes(actor_handle));
+  }
+
   return ray::internal::Serializer::Deserialize<std::shared_ptr<T>>(
       packed_object->data(), packed_object->size());
 }

cpp/include/ray/api/ray_runtime.h

@@ -14,7 +14,7 @@
 
 #pragma once
 
-#include <ray/api/function_manager.h>
+#include <ray/api/common_types.h>
 #include <ray/api/task_options.h>
 #include <ray/api/xlang_function.h>
 
@@ -38,9 +38,7 @@ struct RemoteFunctionHolder {
     this->class_name = class_name;
     this->lang_type = lang_type;
   }
-  template <typename F>
+  RemoteFunctionHolder(std::string func_name) {
-  RemoteFunctionHolder(F func) {
-    auto func_name = FunctionManager::Instance().GetFunctionName(func);
     if (func_name.empty()) {
       throw RayException(
           "Function not found. Please use RAY_REMOTE to register this function.");

cpp/include/ray/api/task_options.h

@@ -14,6 +14,8 @@
 
 #pragma once
 
+#include <ray/api/ray_exception.h>
+
 #include <cmath>
 
 namespace ray {

cpp/src/ray/test/cluster/cluster_mode_test.cc

@@ -242,9 +242,15 @@ TEST(RayClusterModeTest, ActorHandleTest) {
   auto actor1 = ray::Actor(RAY_FUNC(Counter::FactoryCreate)).Remote();
   auto obj1 = actor1.Task(&Counter::Plus1).Remote();
   EXPECT_EQ(1, *obj1.Get());
+  // Test `ActorHandle` type object as parameter.
   auto actor2 = ray::Actor(RAY_FUNC(Counter::FactoryCreate)).Remote();
   auto obj2 = actor2.Task(&Counter::Plus1ForActor).Remote(actor1);
   EXPECT_EQ(2, *obj2.Get());
+  // Test `ActorHandle` type object as return value.
+  std::string child_actor_name = "child_actor_name";
+  auto child_actor =
+      actor1.Task(&Counter::CreateChildActor).Remote(child_actor_name).Get();
+  EXPECT_EQ(1, *child_actor->Task(&Counter::Plus1).Remote().Get());
 }
 
 TEST(RayClusterModeTest, PythonInvocationTest) {