sphinxext fails to build in parallel mode

[Stephen Finucane]

oslo.config 8.1.0 added support for parallel documentation builds to the Sphinx extensions [1]. Unfortunately this was incomplete. Attempting to build docs with 'sphinx-build -j auto' will result in the following traceback:

    waiting for workers...

    Exception occurred:
      File "/home/stephenfin/Development/openstack/nova/.tox/docs/lib/python3.7/site-packages/sphinx/domains/__init__.py", line 301, in merge_domaindata
        self.__class__)
    NotImplementedError: merge_domaindata must be implemented in <class 'oslo_config.sphinxext.ConfigDomain'> to be able to do parallel builds!
    The full traceback has been saved in /tmp/sphinx-err-hgxjvmgk.log, if you want to report the issue to the developers.
    Please also report this if it was a user error, so that a better error message can be provided next time.
    A bug report can be filed in the tracker at <https://github.com/sphinx-doc/sphinx/issues>. Thanks!

[1] https://github.com/openstack/oslo.config/commit/76075a6d992c08a29da76c34fb2a7d9164f721d0

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/751031

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/751031
Committed: https://git.openstack.org/cgit/openstack/oslo.config/commit/?id=01f63b875e6534a90ded876c88115f8e5eb0c7f6
Submitter: Zuul
Branch: master

commit 01f63b875e6534a90ded876c88115f8e5eb0c7f6
Author: Stephen Finucane <email address hidden>
Date: Thu Sep 10 15:58:12 2020 +0100

    sphinxext: Add 'merge_domaindata'

    This is necessary to enable parallel builds. As noted in the Sphinx docs
    [1], this method has the following function:

      Merge in data regarding docnames from a different domaindata inventory
      (coming from a subprocess in parallel builds).

    Given how simple the datatypes we're storing are, this is pretty easy to
    implement.

    [1] https://www.sphinx-doc.org/en/master/extdev/domainapi.html#sphinx.domains.Domain.merge_domaindata

    Change-Id: I46c7903b159f99c68896a4c3c4d20daef848f9c2
    Signed-off-by: Stephen Finucane <email address hidden>
    Closes-Bug: #1895162

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/victoria
Review: https://review.opendev.org/753379

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/753379
Committed: https://git.openstack.org/cgit/openstack/oslo.config/commit/?id=9594106343a68dbb647ee7dcbd9a8a1078c03f61
Submitter: Zuul
Branch: stable/victoria

commit 9594106343a68dbb647ee7dcbd9a8a1078c03f61
Author: Stephen Finucane <email address hidden>
Date: Thu Sep 10 15:58:12 2020 +0100

    sphinxext: Add 'merge_domaindata'

    This is necessary to enable parallel builds. As noted in the Sphinx docs
    [1], this method has the following function:

      Merge in data regarding docnames from a different domaindata inventory
      (coming from a subprocess in parallel builds).

    Given how simple the datatypes we're storing are, this is pretty easy to
    implement.

    [1] https://www.sphinx-doc.org/en/master/extdev/domainapi.html#sphinx.domains.Domain.merge_domaindata

    Change-Id: I46c7903b159f99c68896a4c3c4d20daef848f9c2
    Signed-off-by: Stephen Finucane <email address hidden>
    Closes-Bug: #1895162
    (cherry picked from commit 01f63b875e6534a90ded876c88115f8e5eb0c7f6)

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.config 8.4.0 release.