Implement __rmw_take_serialized. (#113)

* Implement __rmw_take_serialized.

This allows us to implement rmw_take_serialized_message
and rmw_take_serialize_message_with_info, both of which
are required for rosbag2.

Note that this implementation copies some parts of __rmw_take.
Given the different types involved (void * ros_message
vs. rmw_serialize_message_t *), I didn't see a readable way
to reduce this duplication.

Signed-off-by: Chris Lalancette <[email protected]>

* Style

Signed-off-by: Yadunund <[email protected]>

---------

Signed-off-by: Chris Lalancette <[email protected]>
Signed-off-by: Yadunund <[email protected]>
Co-authored-by: Yadunund <[email protected]>

rmw_zenoh_cpp/src/rmw_zenoh.cpp

@@ -1634,6 +1634,69 @@ rmw_take_sequence(
   return RMW_RET_UNSUPPORTED;
 }
 
+//==============================================================================
+static rmw_ret_t __rmw_take_serialized(
+  const rmw_subscription_t * subscription,
+  rmw_serialized_message_t * serialized_message,
+  bool * taken,
+  rmw_message_info_t * message_info)
+{
+  RMW_CHECK_ARGUMENT_FOR_NULL(subscription, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(subscription->topic_name, RMW_RET_ERROR);
+  RMW_CHECK_ARGUMENT_FOR_NULL(subscription->data, RMW_RET_ERROR);
+  RMW_CHECK_ARGUMENT_FOR_NULL(serialized_message, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(taken, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_ARGUMENT_FOR_NULL(message_info, RMW_RET_INVALID_ARGUMENT);
+  RMW_CHECK_TYPE_IDENTIFIERS_MATCH(
+    subscription handle,
+    subscription->implementation_identifier, rmw_zenoh_identifier,
+    return RMW_RET_INCORRECT_RMW_IMPLEMENTATION);
+
+  *taken = false;
+
+  auto sub_data = static_cast<rmw_subscription_data_t *>(subscription->data);
+  RMW_CHECK_ARGUMENT_FOR_NULL(sub_data, RMW_RET_INVALID_ARGUMENT);
+
+  if (sub_data->context->impl->is_shutdown) {
+    return RMW_RET_OK;
+  }
+
+  // RETRIEVE SERIALIZED MESSAGE ===============================================
+
+  std::unique_ptr<saved_msg_data> msg_data = sub_data->pop_next_message();
+  if (msg_data == nullptr) {
+    // This tells rcl that the check for a new message was done, but no messages have come in yet.
+    return RMW_RET_OK;
+  }
+
+  if (serialized_message->buffer_capacity < msg_data->payload.payload.len) {
+    rmw_ret_t ret =
+      rmw_serialized_message_resize(serialized_message, msg_data->payload.payload.len);
+    if (ret != RMW_RET_OK) {
+      return ret;  // Error message already set
+    }
+  }
+  serialized_message->buffer_length = msg_data->payload.payload.len;
+  memcpy(
+    serialized_message->buffer, msg_data->payload.payload.start,
+    msg_data->payload.payload.len);
+
+  *taken = true;
+
+  // TODO(clalancette): fill in source_timestamp
+  message_info->source_timestamp = 0;
+  message_info->received_timestamp = msg_data->recv_timestamp;
+  // TODO(clalancette): fill in publication_sequence_number
+  message_info->publication_sequence_number = 0;
+  // TODO(clalancette): fill in reception_sequence_number
+  message_info->reception_sequence_number = 0;
+  message_info->publisher_gid.implementation_identifier = rmw_zenoh_identifier;
+  memcpy(message_info->publisher_gid.data, msg_data->publisher_gid, 16);
+  message_info->from_intra_process = false;
+
+  return RMW_RET_OK;
+}
+
 //==============================================================================
 /// Take an incoming ROS message as a byte stream.
 rmw_ret_t
@@ -1643,11 +1706,11 @@ rmw_take_serialized_message(
   bool * taken,
   rmw_subscription_allocation_t * allocation)
 {
-  static_cast<void>(subscription);
-  static_cast<void>(serialized_message);
-  static_cast<void>(taken);
   static_cast<void>(allocation);
-  return RMW_RET_UNSUPPORTED;
+
+  rmw_message_info_t dummy_msg_info;
+
+  return __rmw_take_serialized(subscription, serialized_message, taken, &dummy_msg_info);
 }
 
 //==============================================================================
@@ -1660,12 +1723,9 @@ rmw_take_serialized_message_with_info(
   rmw_message_info_t * message_info,
   rmw_subscription_allocation_t * allocation)
 {
-  static_cast<void>(subscription);
-  static_cast<void>(serialized_message);
-  static_cast<void>(taken);
-  static_cast<void>(message_info);
   static_cast<void>(allocation);
-  return RMW_RET_UNSUPPORTED;
+
+  return __rmw_take_serialized(subscription, serialized_message, taken, message_info);
 }
 
 //==============================================================================