auto_delete_nightly_test_data: gracefully handle dirs not existing

To avoid cases like the attached bug, simply log when a dir doesn't
exist. Doesn't seem bad to consider this a success.

BUG=b:232843376
TEST=None

Change-Id: I291d1b1ca4007d2402a6707c83ce483470099c84
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/3651935
Auto-Submit: George Burgess <gbiv@chromium.org>
Reviewed-by: Jordan Abrahams-Whitehead <ajordanr@google.com>
Commit-Queue: Jordan Abrahams-Whitehead <ajordanr@google.com>
Tested-by: George Burgess <gbiv@chromium.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/auto_delete_nightly_test_data.py b/auto_delete_nightly_test_data.py
index ca721b24..b625783f 100755
--- a/auto_delete_nightly_test_data.py
+++ b/auto_delete_nightly_test_data.py
@@ -7,8 +7,6 @@
 
 """A crontab script to delete night test data."""
 
-from __future__ import print_function
-
 __author__ = 'shenhan@google.com (Han Shen)'
 
 import argparse
@@ -27,6 +25,7 @@ from cros_utils import command_executer
 from cros_utils import constants
 from cros_utils import misc
 
+
 DIR_BY_WEEKDAY = ('Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun')
 NIGHTLY_TESTS_WORKSPACE = os.path.join(constants.CROSTC_WORKSPACE,
                                        'nightly-tests')
@@ -109,14 +108,24 @@ def ProcessArguments(argv):
 
 def RemoveAllSubdirsMatchingPredicate(
     base_dir: Path, days_to_preserve: int, dry_run: bool,
-    is_name_removal_worthy: Callable[[str], bool]) -> bool:
+    is_name_removal_worthy: Callable[[str], bool]) -> int:
   """Removes all subdirs of base_dir that match the given predicate."""
   secs_to_preserve = 60 * 60 * 24 * days_to_preserve
   now = time.time()
   remove_older_than_time = now - secs_to_preserve
 
+  try:
+    dir_entries = list(base_dir.iterdir())
+  except FileNotFoundError as e:
+    # We get this if the directory itself doesn't exist. Since we're cleaning
+    # tempdirs, that's as good as a success. Further, the prior approach here
+    # was using the `find` binary, which exits successfully if nothing is
+    # found.
+    print(f"Error enumerating {base_dir}'s contents; skipping removal: {e}")
+    return 0
+
   had_errors = False
-  for file in base_dir.iterdir():
+  for file in dir_entries:
     if not is_name_removal_worthy(file.name):
       continue