The download cache of the functional tests is currently only growing.
But sometimes tests get removed or changed to use different assets,
thus we should clean up the stale old assets after a while when they
are not in use anymore.

This little patch series now introduces time stamps for the assets in
the cache (first patch) that we update during each test run, so we can
check these time stamps regularly and evict stale assets after half
of a year not being used anymore (that should be enough time to still
keep the assets around for a while in case you want to diagnose a
problem that is still some months old).

v3:
- Simplify the code in _save_time_stamp() (thanks, Daniel!)

v2:
- Add some wordings to the 1st patch why we cannot use mtime/atime here
- Use functions from Path object instead from "os" (thanks to Daniel!)

Thomas Huth (2):
  tests/functional: Set current time stamp of assets when using them
  tests: Evict stale files in the functional download cache after a
    while

 MAINTAINERS                         |  1 +
 scripts/clean_functional_cache.py   | 45 +++++++++++++++++++++++++++++
 tests/Makefile.include              |  1 +
 tests/functional/qemu_test/asset.py | 13 +++++++++
 4 files changed, 60 insertions(+)
 create mode 100755 scripts/clean_functional_cache.py

-- 
2.51.0