Better Cache Additional and Removal

tools/isolate/run_test_from_archive.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Reads a manifest, creates a tree of hardlinks and runs the test.
 
 Keeps a local cache.
 """
 
@@ skipping 170 matching lines @@
       logging.warn('Unknown file %s from cache' % f)
       # Insert as the oldest file. It will be deleted eventually if not
       # accessed.
       self.state.insert(0, f)
 
     # Ensure enough free space.
     while (
         self.min_free_space and
         self.state and
         get_free_space(self.cache_dir) < self.min_free_space):
-      os.remove(self.path(self.state.pop(0)))
+      try:
+        os.remove(self.path(self.state.pop(0)))
+      except OSError as e:
+        logging.error('Error attempting to delete a file\n%s' % e)
 
     # Ensure maximum cache size.
     if self.max_cache_size and self.state:
       sizes = [os.stat(self.path(f)).st_size for f in self.state]
       while sizes and sum(sizes) > self.max_cache_size:
         # Delete the oldest item.
-        os.remove(self.path(self.state.pop(0)))
+        try:
+          os.remove(self.path(self.state.pop(0)))
+        except OSError as e:
+          logging.error('Error attempting to delete a file\n%s' % e)
         sizes.pop(0)
 
     self.save()
 
   def retrieve(self, item):
     """Retrieves a file from the remote and add it to the cache."""
     assert not '/' in item
     try:
       index = self.state.index(item)
       # Was already in cache. Update it's LRU value.
       self.state.pop(index)
       self.state.append(item)
       return False
     except ValueError:
       out = self.path(item)
       download_or_copy(os.path.join(self.remote, item), out)
-      self.state.append(item)
+      if os.path.exists(out):
+        self.state.append(item)
+      else:
+        logging.error('File, %s, not placed in cache' % item)
       return True
     finally:
       self.save()
 
   def path(self, item):
     """Returns the path to one item."""
     return os.path.join(self.cache_dir, item)
 
   def save(self):
     """Saves the LRU ordering."""
@@ skipping 80 matching lines @@
     parser.error('Unsupported args %s' % ' '.join(args))
 
   manifest = json.load(open_remote(options.manifest))
   return run_tha_test(
       manifest, os.path.abspath(options.cache), options.remote,
       options.max_cache_size, options.min_free_space)
 
 
 if __name__ == '__main__':
   sys.exit(main())