#include <rmw_entity.h>
Data Fields | |
| bool | from_intra_process |
| uint64_t | publication_sequence_number |
| rmw_gid_t | publisher_gid |
| rmw_time_point_value_t | received_timestamp |
| uint64_t | reception_sequence_number |
| rmw_time_point_value_t | source_timestamp |
Detailed Description
Per-sample metadata — upstream rmw_message_info_t, field for field.
Phase 376 W4. Today this metadata reaches Rust callers through MESSAGE_INFO_TABLE, a side table in nros-rmw-cffi keyed on the subscription's backend_data ADDRESS. That table is a workaround, not a design, and it never crosses the seam it exists for: only the Rust trampoline writes it, so a C or C++ backend has no symbol to call and message info is permanently absent for them. It also claims a pool slot per subscription and never releases it, so a reused handle address inherits the previous subscription's metadata.
Passing the struct by pointer on the take call — which is what upstream does — removes all of that: the caller owns the storage, it lives exactly as long as the call, and every backend can fill it.
Retiring the side table is NOT part of this change; the take_with_info slots are the mechanism that makes retiring it possible.
Field Documentation
◆ from_intra_process
| bool rmw_message_info_t::from_intra_process |
True when the sample never left the image (Zephyr's Z_FEATURE_LOCAL_SUBSCRIBER, DDS intra-process).
◆ publication_sequence_number
| uint64_t rmw_message_info_t::publication_sequence_number |
Publisher-side sequence, or RMW_MESSAGE_INFO_SEQUENCE_NUMBER_UNSUPPORTED. Whether this is real is what feature_supported answers.
◆ publisher_gid
| rmw_gid_t rmw_message_info_t::publisher_gid |
Which publisher sent it. All-zero data = unknown.
◆ received_timestamp
| rmw_time_point_value_t rmw_message_info_t::received_timestamp |
Subscriber's clock at reception, ns. 0 = receptions are not stamped.
◆ reception_sequence_number
| uint64_t rmw_message_info_t::reception_sequence_number |
Subscriber-side reception count, or the same sentinel.
◆ source_timestamp
| rmw_time_point_value_t rmw_message_info_t::source_timestamp |
Publisher's clock at publication, ns. 0 = no source timestamp.
The documentation for this struct was generated from the following file:
- include/nros/rmw_entity.h
