tests/functional: Set current time stamp of assets when using them

We are going to remove obsolete assets from the cache, so keep
the time stamps of the assets that we use up-to-date to have a way
to detect stale assets later.

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20251014083424.103202-2-thuth@redhat.com>

tests/functional/qemu_test/asset.py

@@ -10,6 +10,7 @@ import logging
 import os
 import stat
 import sys
+import time
 import unittest
 import urllib.request
 from time import sleep
@@ -113,6 +114,16 @@ class Asset:
         self.log.debug("Time out while waiting for %s!", tmp_cache_file)
         raise
 
+    def _save_time_stamp(self):
+        '''
+        Update the time stamp of the asset in the cache. Unfortunately, we
+        cannot use the modification or access time of the asset file itself,
+        since e.g. the functional jobs in the gitlab CI reload the files
+        from the gitlab cache and thus always have recent file time stamps,
+        so we have to save our asset time stamp to a separate file instead.
+        '''
+        self.cache_file.with_suffix(".stamp").write_text(f"{int(time.time())}")
+
     def fetch(self):
         if not self.cache_dir.exists():
             self.cache_dir.mkdir(parents=True, exist_ok=True)
@@ -120,6 +131,7 @@ class Asset:
         if self.valid():
             self.log.debug("Using cached asset %s for %s",
                            self.cache_file, self.url)
+            self._save_time_stamp()
             return str(self.cache_file)
 
         if not self.fetchable():
@@ -208,6 +220,7 @@ class Asset:
             tmp_cache_file.unlink()
             raise AssetError(self, "Hash does not match %s" % self.hash)
         tmp_cache_file.replace(self.cache_file)
+        self._save_time_stamp()
         # Remove write perms to stop tests accidentally modifying them
         os.chmod(self.cache_file, stat.S_IRUSR | stat.S_IRGRP)