[#498] cleanup message type details

[elfenpiff]

Notes for Reviewer

In this PR the API used when overriding the MessageTypeDetails is strictly separated from the end user API.

• When overriding the MessageTypeDetails you must use [CustomPayloadMarker] as message type
• You can only loan samples via Publisher::loan_custom_payload()
• You can only receive samples via Subscriber::receive_custom_payload().

The reason is, that in those cases the Sample and SampleMut handle the data a bit different. When calling Publisher::loan_custom_payload(123) and 123 corresponds to the number of elements, this number is stored in the samples header but Sample::payload().len() will return 123 * MessageTypeDetails::payload.size, the bytes used by the sample. When the MessageTypeDetails::payload.size is not overridden, Sample::payload().len() == Header::number_of_elements().

The publish subscribe header contains now the number_of_elements that are contained in the sample. The payload layout was removed. In the C API one can now easily obtain the underlying number of elements by just accessing this number directly from the header - no more payload.len() / sizeof(Payload) stuff.

Pre-Review Checklist for the PR Author

1. [x] Add sensible notes for the reviewer
2. [x] PR title is short, expressive and meaningful
3. [x] Relevant issues are linked in the References section
4. [x] Every source code file has a copyright header with SPDX-License-Identifier: Apache-2.0 OR MIT
5. [x] Branch follows the naming format (iox2-123-introduce-posix-ipc-example)
6. [x] Commits messages are according to this guideline
   • [x] Commit messages have the issue ID ([#123] Add posix ipc example)
   • [x] Commit author matches Eclipse Contributor Agreement (and ECA is signed)
7. [x] Tests follow the best practice for testing
8. [x] Changelog updated in the unreleased section including API breaking changes
9. [x] Assign PR to reviewer
10. [x] All checks have passed (except task-list-completed)

Checklist for the PR Reviewer

• [x] Commits are properly organized and messages are according to the guideline
• [x] Unit tests have been written for new behavior
• [x] Public API is documented
• [x] PR title describes the changes

Post-review Checklist for the PR Author

1. [x] All open points are addressed and tracked via issues

References

Closes #498

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 79.26%. Comparing base (29c71af) to head (6deb81b). Report is 6 commits behind head on main.

Additional details and impacted files

[](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx) ```diff @@ Coverage Diff @@ ## main #499 +/- ## ========================================== + Coverage 79.21% 79.26% +0.05% ========================================== Files 200 200 Lines 23728 23762 +34 ========================================== + Hits 18795 18835 +40 + Misses 4933 4927 -6 ``` | [Files with missing lines](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx) | Coverage Δ | | |---|---|---| | [iceoryx2/src/port/publisher.rs](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&filepath=iceoryx2%2Fsrc%2Fport%2Fpublisher.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx#diff-aWNlb3J5eDIvc3JjL3BvcnQvcHVibGlzaGVyLnJz) | `85.09% <100.00%> (+0.15%)` | :arrow_up: | | [iceoryx2/src/port/subscriber.rs](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&filepath=iceoryx2%2Fsrc%2Fport%2Fsubscriber.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx#diff-aWNlb3J5eDIvc3JjL3BvcnQvc3Vic2NyaWJlci5ycw==) | `93.60% <100.00%> (+0.66%)` | :arrow_up: | | [iceoryx2/src/service/builder/publish\_subscribe.rs](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&filepath=iceoryx2%2Fsrc%2Fservice%2Fbuilder%2Fpublish_subscribe.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx#diff-aWNlb3J5eDIvc3JjL3NlcnZpY2UvYnVpbGRlci9wdWJsaXNoX3N1YnNjcmliZS5ycw==) | `90.60% <ø> (-0.94%)` | :arrow_down: | | [iceoryx2/src/service/header/publish\_subscribe.rs](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&filepath=iceoryx2%2Fsrc%2Fservice%2Fheader%2Fpublish_subscribe.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx#diff-aWNlb3J5eDIvc3JjL3NlcnZpY2UvaGVhZGVyL3B1Ymxpc2hfc3Vic2NyaWJlLnJz) | `100.00% <100.00%> (ø)` | | | [.../src/service/static\_config/message\_type\_details.rs](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499?src=pr&el=tree&filepath=iceoryx2%2Fsrc%2Fservice%2Fstatic_config%2Fmessage_type_details.rs&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx#diff-aWNlb3J5eDIvc3JjL3NlcnZpY2Uvc3RhdGljX2NvbmZpZy9tZXNzYWdlX3R5cGVfZGV0YWlscy5ycw==) | `100.00% <100.00%> (ø)` | | ... and [11 files with indirect coverage changes](https://app.codecov.io/gh/eclipse-iceoryx/iceoryx2/pull/499/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=eclipse-iceoryx)