Iox #1036 in place creation for shared memory

[elfenpiff]

Pre-Review Checklist for the PR Author

1. Code follows the coding style of CONTRIBUTING.md
2. Tests follow the best practice for testing
3. Changelog updated in the unreleased section including API breaking changes
4. Branch follows the naming format (iox-#123-this-is-a-branch)
5. Commits messages are according to this guideline
   • Commit messages have the issue ID (iox-#123 commit text)
   • Commit messages are signed (git commit -s)
   • Commit author matches Eclipse Contributor Agreement (and ECA is signed)
6. Update the PR title
   • Follow the same conventions as for commit messages
   • Link to the relevant issue
7. Relevant issues are linked
8. Add sensible notes for the reviewer
9. All checks have passed (except task-list-completed)
10. Assign PR to reviewer

Notes for Reviewer

This PR introduces the SharedMemoryBuilder for the SharedMemory class and removes the creation pattern. Furthermore, the leading slash requirement is fixed as well which closes #439

Checklist for the PR Reviewer

• Commits are properly organized and messages are according to the guideline
• Code according to our coding style and naming conventions
• Unit tests have been written for new behavior
  • Each unit test case has a unique UUID
• Public API changes are documented via doxygen
• Copyright owner are updated in the changed files
• PR title describes the changes

Post-review Checklist for the PR Author

1. All open points are addressed and tracked via issues

References

• Closes Don't expose implementation details in shm name #439

[codecov]

Codecov Report

Merging #1053 (cae20a7) into master (27b45e7) will decrease coverage by 0.04%.
The diff coverage is 80.53%.

@@            Coverage Diff             @@
##           master    #1053      +/-   ##
==========================================
- Coverage   76.16%   76.12%   -0.05%     
==========================================
  Files         343      344       +1     
  Lines       13003    13030      +27     
  Branches     1870     1869       -1     
==========================================
+ Hits         9904     9919      +15     
- Misses       2482     2495      +13     
+ Partials      617      616       -1     

Flag	Coverage Δ
unittests	75.34% <80.53%> (-0.06%)	⬇️
unittests_timing	12.52% <0.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...eoryx_hoofs/include/iceoryx_hoofs/cxx/helplets.hpp	97.29% <ø> (ø)
iceoryx_hoofs/source/posix_wrapper/named_pipe.cpp	57.67% <50.00%> (-0.88%)	⬇️
...six_wrapper/shared_memory_object/shared_memory.cpp	64.73% <77.01%> (-4.30%)	⬇️
...fs/internal/posix_wrapper/shared_memory_object.hpp	80.00% <100.00%> (+13.33%)	⬆️
...six_wrapper/shared_memory_object/shared_memory.hpp	100.00% <100.00%> (ø)
...oofs/source/posix_wrapper/shared_memory_object.cpp	82.50% <100.00%> (+1.67%)	⬆️
...lude/iceoryx_posh/internal/mepoo/mepoo_segment.inl	95.34% <100.00%> (-0.11%)	⬇️
...de/iceoryx_posh/internal/mepoo/segment_manager.inl	86.66% <100.00%> (ø)
iceoryx_posh/source/roudi/port_manager.cpp	78.38% <0.00%> (-0.33%)	⬇️
iceoryx_hoofs/source/posix_wrapper/timer.cpp	63.90% <0.00%> (+0.82%)	⬆️
... and 1 more

[elBoberido]

Could you please split this PR up and create a separate PR for the filesystem feature

[elfenpiff]

@elBoberido I created the pull request #1061 and a separate issue #1059 which only handles the C++17 perms enum class.

[elBoberido]

Looks good. Only minor findings

[elBoberido]

Just wondering if cxx::TruncateToCapacity is necessary since the source string is smaller than the destination string. Is the optimization not yet implemented?

[elfenpiff]

It is always required since append is pure runtime since we do not know at compile time what kind of content is already present in the string. With assign this is possible but not with append.

[elBoberido]

Okay, you are right. We have here more information than the compiler. This is nothing for this PR, but would it be possible to have a constexpr cxx::string? This question is directed more towards @FerdinandSpitzschnueffler

[FerdinandSpitzschnueffler]

@elBoberido To be honest, I'm not sure if it would suffice to make all the constructors constexpr (the default c'tor already is), bit I'd like to try and will add a todo to #208

[elBoberido]

Only one minor thing. It's up to you if you want this change.