[21065] Bugfix: correct liveliness state in a multiple reader - one writer scenario

[Mario-DL]

Description

This PR corrects a misbehavior given in a single writer - multiple readers scenario. When the writer is destroyed, the WriterProxy is removed from readers. When it is removed from the first one, the LivelinessManager::remove_writer() returns false as --writer.count is 1, hence the liveliness_changed callback is not triggered (callback_ within LivelinessManager is not invoked). When the WriterProxy is deleted from the second reader, the LivelinessManager::remove_writer() correctly removes the writer and fires the callback. The problem in this case is that, later, in WLP::sub_liveliness_changed() the update_liveliness_changed_status() is only called for this later reader, since the first one is not matched anymore and reader->matched_writer_is_matched() returns false, corrupting its liveliness state. In this situation, if the writer wakes up again, the first reader is going to return an alive_count of 2 instead of 1.

The fix proposes that every time we unpair a WriterProxy from a reader, we should also update the liveliness state for that particular reader. The solution tries to avoid defining extra collections for tracking readers/writers.

@Mergifyio backport 2.14.x 2.13.x 2.10.x 2.6.x

Fixes #4610

Contributor Checklist

• Commit messages follow the project guidelines.
• The code follows the style guidelines of this project.
• Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally
• Any new/modified methods have been properly documented using Doxygen.
• NO Any new configuration API has an equivalent XML API (with the corresponding XSD extension)
• Changes are backport compatible: they do NOT break ABI nor change library core behavior.
• Changes are API compatible.
• NO New feature has been added to the versions.md file (if applicable).
• NO New feature has been documented/Current behavior is correctly described in the documentation.
• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.

[MiguelCompany]

@richiprosima Please test_3 this

[MiguelCompany]

Just a small nit, can be applied without running CI again

[MiguelCompany]

@richiprosima Please test_3 linux

[MiguelCompany]

@Mergifyio backport 2.14.x 2.13.x 2.10.x 2.6.x

[mergify]

backport 2.14.x 2.13.x 2.10.x 2.6.x

✅ Backports have been created

• #4881 [21065] Bugfix: correct liveliness state in a multiple reader - one writer scenario (backport #4822) has been created for branch 2.14.x but encountered conflicts
• #4882 [21065] Bugfix: correct liveliness state in a multiple reader - one writer scenario (backport #4822) has been created for branch 2.13.x but encountered conflicts
• #4883 [21065] Bugfix: correct liveliness state in a multiple reader - one writer scenario (backport #4822) has been created for branch 2.10.x but encountered conflicts
• #4884 [21065] Bugfix: correct liveliness state in a multiple reader - one writer scenario (backport #4822) has been created for branch 2.6.x but encountered conflicts