Make isolate cache resilient to unexpectedly deleted items.

client/tests/isolateserver_test.py

 #!/usr/bin/env python
 # Copyright 2013 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 # pylint: disable=W0212,W0223,W0231,W0613
 
 import base64
-import collections
 import hashlib
 import json
 import logging
 import io
 import os
 import StringIO
 import sys
 import tarfile
 import tempfile
 import unittest
-import urllib
 import zlib
 
 # net_utils adjusts sys.path.
 import net_utils
 
 import auth
 import isolated_format
 import isolateserver
 import isolate_storage
 import test_utils
-from depot_tools import auto_stub
 from depot_tools import fix_encoding
 from utils import file_path
 from utils import fs
 from utils import logging_utils
 from utils import threading_utils
 
 import isolateserver_mock
 
 
 CONTENTS = {
@@ skipping 1397 matching lines @@
 
     # Assert that trimming is done in constructor too.
     self._policies = isolateserver.CachePolicies(100, 1000, 2)
     with self.get_cache() as cache:
       assertItems([(h_c, 1), (h_large, len(large))])
       self.assertEqual(None, cache._protected)
       self.assertEqual(1101, cache._free_disk)
       self.assertEqual(2, cache.initial_number_items)
       self.assertEqual(100, cache.initial_size)
 
+  def test_some_file_brutally_deleted(self):
+    h_a = self.to_hash('a')[0]
+
+    self._free_disk = 1100
+    with self.get_cache() as cache:
+      cache.write(h_a, 'a')
+      self.assertTrue(cache.touch(h_a, isolateserver.UNKNOWN_FILE_SIZE))
+      self.assertTrue(cache.touch(h_a, 1))
+
+    os.remove(os.path.join(self.tempdir, h_a))
+
+    with self.get_cache() as cache:
+      # 'Ghost' entry loaded with state.json is still there.
+      self.assertEqual({h_a}, cache.cached_set())
+      # 'touch' detects the file is missing by returning False.
+      self.assertFalse(cache.touch(h_a, isolateserver.UNKNOWN_FILE_SIZE))
+      self.assertFalse(cache.touch(h_a, 1))
+      # Evicting it still works, kills the 'ghost' entry.
+      cache.evict(h_a)
+      self.assertEqual(set(), cache.cached_set())
+
 
 def clear_env_vars():
   for e in ('ISOLATE_DEBUG', 'ISOLATE_SERVER'):
     os.environ.pop(e, None)
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   if '-v' in sys.argv:
     unittest.TestCase.maxDiff = None
   logging.basicConfig(
       level=(logging.DEBUG if '-v' in sys.argv else logging.CRITICAL))
   clear_env_vars()
   unittest.main()