chrome/common/extensions/docs/server2/appengine_blobstore.py

   1 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import blob_reference_store as datastore
   6 from blob_reference_store import BlobReferenceStore
   7 from appengine_wrappers import blobstore
   8 from appengine_wrappers import files
   9
  10 BLOBSTORE_GITHUB = 'BlobstoreGithub'
  11
  12 # TODO(kalman): Re-write this class.
  13 #   - It uses BlobReader which is a synchronous method. We should be creating
  14 #     multiple async fetches, one for each partition, then exposing a Future
  15 #     interface which stitches them together.
  16 #   - It's very hard to reuse.
  17
  18 class AppEngineBlobstore(object):
  19   """A wrapper around the blobstore API, which stores the blob keys in
  20   datastore.
  21   """
  22   def __init__(self):
  23     self._datastore = BlobReferenceStore()
  24
  25   def Set(self, key, blob, namespace):
  26     """Add a blob to the blobstore. |version| is used as part of the key so
  27     multiple blobs with the same name can be differentiated.
  28     """
  29     key = namespace + '.' + key
  30     filename = files.blobstore.create()
  31     with files.open(filename, 'a') as f:
  32       f.write(blob)
  33     files.finalize(filename)
  34     blob_key = files.blobstore.get_blob_key(filename)
  35     self._datastore.Set(datastore.BLOB_REFERENCE_BLOBSTORE, key, blob_key)
  36
  37   def Get(self, key, namespace):
  38     """Get a blob with version |version|.
  39     """
  40     key = namespace + '.' + key
  41     blob_key = self._datastore.Get(datastore.BLOB_REFERENCE_BLOBSTORE, key)
  42     if blob_key is None:
  43       return None
  44     blob_reader = blobstore.BlobReader(blob_key)
  45     return blob_reader.read()
  46
  47   def Delete(self, key, namespace):
  48     """Delete the blob with version |version| if it is found.
  49     """
  50     key = namespace + '.' + key
  51     blob_key = self._datastore.Delete(datastore.BLOB_REFERENCE_BLOBSTORE, key)
  52     if blob_key is None:
  53       return
  54     blob_key.delete()