[OE-core] Lock external repository in custom FSTYPE

[Stefan Agner]

Hi,

We use meta-updater, which has a custom FSTYPE to build a OSTree
repository. We share that repository across multiple bitbake executions.
The underlying OSTree tools lock the OSTree repository before trying to
interact, and if it fails ("error: Locking repo exclusive failed:
Resource temporarily unavailable") then the complete build fails (see
also https://github.com/advancedtelematic/meta-updater/issues/412).

Now I'd rather prefer that two bitbake tasks would serialize the access
to the OSTree repository. Is there a mechanism in bitbake to lock (and
wait) for the repository to be not in use?

We tried using bb.utils.lockfile, but the task is written in shell. Also
inline Python would not work since locking/unlocking need to be done
within one Python script as far as I understand.

--
Stefan