Add acceptable_buffer_backends field in SubscriptionOptionsBase

Signed-off-by: CY Chen <cyc@nvidia.com>

rclcpp/include/rclcpp/generic_subscription.hpp

@@ -80,7 +80,7 @@ public:
       node_base,
       *rclcpp::get_message_typesupport_handle(topic_type, "rosidl_typesupport_cpp", *ts_lib),
       topic_name,
-      options.to_rcl_subscription_options(qos),
+      force_cpu_buffer_backend_(options).to_rcl_subscription_options(qos),
       options.event_callbacks,
       options.use_default_callbacks,
       DeliveredMessageKind::SERIALIZED_MESSAGE),
@@ -182,6 +182,17 @@ public:
 
 private:
   RCLCPP_DISABLE_COPY(GenericSubscription)
+
+  template<typename AllocatorT>
+  static rclcpp::SubscriptionOptionsWithAllocator<AllocatorT>
+  force_cpu_buffer_backend_(
+    const rclcpp::SubscriptionOptionsWithAllocator<AllocatorT> & options)
+  {
+    auto opts = options;
+    opts.acceptable_buffer_backends = "cpu";
+    return opts;
+  }
+
   AnySubscriptionCallback<rclcpp::SerializedMessage, std::allocator<void>> any_callback_;
   // The type support library should stay loaded, so it is stored in the GenericSubscription
   std::shared_ptr<rcpputils::SharedLibrary> ts_lib_;

rclcpp/include/rclcpp/service.hpp

@@ -287,6 +287,7 @@ class Service
   public std::enable_shared_from_this<Service<ServiceT>>
 {
 public:
+  using ServiceType = ServiceT;
   using CallbackType = std::function<
     void (
       const std::shared_ptr<typename ServiceT::Request>,

rclcpp/include/rclcpp/subscription_options.hpp

@@ -89,6 +89,15 @@ struct SubscriptionOptionsBase
   QosOverridingOptions qos_overriding_options;
 
   ContentFilterOptions content_filter_options;
+
+  /// Acceptable buffer backend names for this subscription.
+  /**
+   * Empty string or "cpu" means CPU-only (default for backward compatibility).
+   * "any" means all installed backends are acceptable.
+   * Comma-separated for specific backends, e.g. "cuda,demo".
+   * CPU is always implicitly acceptable regardless of this value.
+   */
+  std::string acceptable_buffer_backends{"cpu"};
 };
 
 /// Structure containing optional configuration for Subscriptions.
@@ -145,6 +154,11 @@ struct SubscriptionOptionsWithAllocator : public SubscriptionOptionsBase
       }
     }
 
+    if (!acceptable_buffer_backends.empty()) {
+      result.rmw_subscription_options.acceptable_buffer_backends =
+        acceptable_buffer_backends.c_str();
+    }
+
     return result;
   }
 

rclcpp_components/src/component_container_mt.cpp

@@ -24,16 +24,16 @@ int main(int argc, char * argv[])
   /// Component container with a multi-threaded executor.
   rclcpp::init(argc, argv);
 
-  auto exec = std::make_shared<rclcpp::executors::MultiThreadedExecutor>();
-  auto node = std::make_shared<rclcpp_components::ComponentManager>();
+  rclcpp::executors::MultiThreadedExecutor::SharedPtr exec = nullptr;
+  const auto node = std::make_shared<rclcpp_components::ComponentManager>();
   if (node->has_parameter("thread_num")) {
     const auto thread_num = node->get_parameter("thread_num").as_int();
     exec = std::make_shared<rclcpp::executors::MultiThreadedExecutor>(
       rclcpp::ExecutorOptions{}, thread_num);
-    node->set_executor(exec);
   } else {
-    node->set_executor(exec);
+    exec = std::make_shared<rclcpp::executors::MultiThreadedExecutor>();
   }
+  node->set_executor(exec);
   exec->add_node(node);
   exec->spin();