Ignore local endpoints (irobot-ros#131)

* Refs #18846: PoC ignore local endpoints: extend RCLCPP API

Signed-off-by: JLBuenoLopez-eProsima <[email protected]>

* Refs #18846: PoC ignore local endpoints: modify RCLCPP publish logic

Signed-off-by: JLBuenoLopez-eProsima <[email protected]>

---------

Signed-off-by: JLBuenoLopez-eProsima <[email protected]>
Co-authored-by: JLBuenoLopez-eProsima <[email protected]>

Author: 2 people

rclcpp/include/rclcpp/publisher.hpp

@@ -237,7 +237,7 @@ class Publisher : public PublisherBase
     // It's not possible to do that with an unique_ptr,
     // as do_intra_process_publish takes the ownership of the message.
     bool inter_process_publish_needed =
-      get_subscription_count() > get_intra_process_subscription_count();
+      get_non_local_subscription_count() > 0;
 
     if (inter_process_publish_needed) {
       auto shared_msg =
@@ -306,7 +306,7 @@ class Publisher : public PublisherBase
     }
 
     bool inter_process_publish_needed =
-      get_subscription_count() > get_intra_process_subscription_count();
+      get_non_local_subscription_count() > 0;
 
     if (inter_process_publish_needed) {
       ROSMessageType ros_msg;

rclcpp/include/rclcpp/publisher_base.hpp

@@ -133,6 +133,12 @@ class PublisherBase : public std::enable_shared_from_this<PublisherBase>
   size_t
   get_subscription_count() const;
 
+  /// Get non local subscription count
+  /** \return The number of non local subscriptions. */
+  RCLCPP_PUBLIC
+  size_t
+  get_non_local_subscription_count() const;
+
   /// Get intraprocess subscription count
   /** \return The number of intraprocess subscriptions. */
   RCLCPP_PUBLIC

rclcpp/src/rclcpp/publisher_base.cpp

@@ -253,6 +253,31 @@ PublisherBase::get_subscription_count() const
   return inter_process_subscription_count;
 }
 
+size_t
+PublisherBase::get_non_local_subscription_count() const
+{
+  size_t inter_process_non_local_subscription_count = 0;
+
+  rcl_ret_t status = rcl_publisher_get_non_local_subscription_count(
+    publisher_handle_.get(),
+    &inter_process_non_local_subscription_count);
+
+  if (RCL_RET_PUBLISHER_INVALID == status) {
+    rcl_reset_error();  /* next call will reset error message if not context */
+    if (rcl_publisher_is_valid_except_context(publisher_handle_.get())) {
+      rcl_context_t * context = rcl_publisher_get_context(publisher_handle_.get());
+      if (nullptr != context && !rcl_context_is_valid(context)) {
+        /* publisher is invalid due to context being shutdown */
+        return 0;
+      }
+    }
+  }
+  if (RCL_RET_OK != status) {
+    rclcpp::exceptions::throw_from_rcl_error(status, "failed to get get non local subscription count");
+  }
+  return inter_process_non_local_subscription_count;
+}
+
 size_t
 PublisherBase::get_intra_process_subscription_count() const
 {