Re: [PATCH 2/2] tests: Evict stale files in the functional download cache after a while

[Thomas Huth <thuth@redhat.com>]

On 10/10/2025 11.50, Daniel P. Berrangé wrote:
> On Fri, Oct 10, 2025 at 11:32:43AM +0200, Thomas Huth wrote:
>> From: Thomas Huth <thuth@redhat.com>
>>
>> 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. So add a script that looks at the time stamps
>> of the assets and removes them if they haven't been touched for more
>> than half of a year. Since there might also be some assets around that
>> have been added to the cache before we added the time stamp files,
>> assume a default time stamp that is close to the creation date of this
>> patch, so that we don't delete these files too early.
>>
>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>> ---
>>   MAINTAINERS                       |  1 +
>>   scripts/clean_functional_cache.py | 47 +++++++++++++++++++++++++++++++
>>   tests/Makefile.include            |  1 +
>>   3 files changed, 49 insertions(+)
>>   create mode 100755 scripts/clean_functional_cache.py
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 84cfd85e1fa..4c468d45337 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -4398,6 +4398,7 @@ M: Thomas Huth <thuth@redhat.com>
>>   R: Philippe Mathieu-Daudé <philmd@linaro.org>
>>   R: Daniel P. Berrange <berrange@redhat.com>
>>   F: docs/devel/testing/functional.rst
>> +F: scripts/clean_functional_cache.py
>>   F: tests/functional/qemu_test/
>>   
>>   Windows Hosted Continuous Integration
>> diff --git a/scripts/clean_functional_cache.py b/scripts/clean_functional_cache.py
>> new file mode 100755
>> index 00000000000..e5c4d1acaf3
>> --- /dev/null
>> +++ b/scripts/clean_functional_cache.py
>> @@ -0,0 +1,47 @@
>> +#!/usr/bin/env python3
>> +#
>> +# SPDX-License-Identifier: GPL-2.0-or-later
>> +#
>> +"""Delete stale assets from the download cache of the functional tests"""
>> +
>> +import os
>> +import stat
>> +import sys
>> +import time
>> +from pathlib import Path
>> +
>> +
>> +cache_dir_env = os.getenv('QEMU_TEST_CACHE_DIR')
>> +if cache_dir_env:
>> +    cache_dir = Path(cache_dir_env, "download")
>> +else:
>> +    cache_dir = Path(Path("~").expanduser(), ".cache", "qemu", "download")
> 
> This creates a Path object but then doesn't take advantage of
> any of its functionality, calling os. functions still....

Ok, you got me, looks like I'm still a python ignorant after one year of 
hacking the functional testing framework ;-) Thanks for the hints how to do 
it better!

>> +    try:
>> +        with open(filename + ".stamp", "r", encoding='utf-8') as fh:
>> +            timestamp = int(fh.read())
> 
>     timestamp = file.read_text()

Hmm, but "file" points to the asset, not to the .stamp file, doesn't it?

>> +    except FileNotFoundError:
>> +        # Assume it's an old file that was already in the cache before we
>> +        # added the code for evicting stale assets. Use the release date
>> +        # of QEMU v10.1 as a default timestamp.
>> +        timestamp = time.mktime((2025, 8, 26, 0, 0, 0, 0, 0, 0))
> 
> The prev patch will make the precache task create the .stamp for all
> files that are currently in use by the current branch. So the only
> thing this does is to prevent us deleting cached files that might
> still be needed by a different branch. There will be few of them,
> so if we prematurely delete a handful that's not a big deal. If we
> switch to checking mtime, this except won't even exist.

When hunting regressions that have been introduced recently, I often have to 
do bisecting on revisions from the previous 1 or 2 QEMU releases, so I'd 
prefer keeping the assets of the last few months, even if they have been 
removed from the master branch in a very recent commit.

  Thomas