Merge branch 'master' into 6518-crunch2-dispatch-slurm
[arvados.git] / sdk / python / arvados / collection.py
index f03deedb18aece57b374a2e94c0e29d26b42319c..8450bd1ca086687928c43e09b2d497ae598c5128 100644 (file)
@@ -474,6 +474,7 @@ class ResumableCollectionWriter(CollectionWriter):
 ADD = "add"
 DEL = "del"
 MOD = "mod"
+TOK = "tok"
 FILE = "file"
 COLLECTION = "collection"
 
@@ -487,7 +488,8 @@ class RichCollectionBase(CollectionBase):
 
     def __init__(self, parent=None):
         self.parent = parent
-        self._modified = True
+        self._committed = False
+        self._callback = None
         self._items = {}
 
     def _my_api(self):
@@ -537,24 +539,24 @@ class RichCollectionBase(CollectionBase):
                 if item is None:
                     # create new file
                     if create_type == COLLECTION:
-                        item = Subcollection(self)
+                        item = Subcollection(self, pathcomponents[0])
                     else:
-                        item = ArvadosFile(self)
+                        item = ArvadosFile(self, pathcomponents[0])
                     self._items[pathcomponents[0]] = item
-                    self._modified = True
+                    self._committed = False
                     self.notify(ADD, self, pathcomponents[0], item)
                 return item
             else:
                 if item is None:
                     # create new collection
-                    item = Subcollection(self)
+                    item = Subcollection(self, pathcomponents[0])
                     self._items[pathcomponents[0]] = item
-                    self._modified = True
+                    self._committed = False
                     self.notify(ADD, self, pathcomponents[0], item)
                 if isinstance(item, RichCollectionBase):
                     return item.find_or_create(pathcomponents[1], create_type)
                 else:
-                    raise IOError((errno.ENOTDIR, "Interior path components must be subcollection"))
+                    raise IOError(errno.ENOTDIR, "Not a directory: '%s'" % pathcomponents[0])
         else:
             return self
 
@@ -567,7 +569,7 @@ class RichCollectionBase(CollectionBase):
 
         """
         if not path:
-            raise errors.ArgumentError("Parameter 'path' must not be empty.")
+            raise errors.ArgumentError("Parameter 'path' is empty.")
 
         pathcomponents = path.split("/", 1)
         item = self._items.get(pathcomponents[0])
@@ -580,15 +582,20 @@ class RichCollectionBase(CollectionBase):
                 else:
                     return item
             else:
-                raise IOError((errno.ENOTDIR, "Interior path components must be subcollection"))
+                raise IOError(errno.ENOTDIR, "Is not a directory: %s" % pathcomponents[0])
 
-    def mkdirs(path):
+    @synchronized
+    def mkdirs(self, path):
         """Recursive subcollection create.
 
-        Like `os.mkdirs()`.  Will create intermediate subcollections needed to
-        contain the leaf subcollection path.
+        Like `os.makedirs()`.  Will create intermediate subcollections needed
+        to contain the leaf subcollection path.
 
         """
+
+        if self.find(path) != None:
+            raise IOError(errno.EEXIST, "Directory or file exists: '%s'" % path)
+
         return self.find_or_create(path, COLLECTION)
 
     def open(self, path, mode="r"):
@@ -615,7 +622,7 @@ class RichCollectionBase(CollectionBase):
         create = (mode != "r")
 
         if create and not self.writable():
-            raise IOError((errno.EROFS, "Collection is read only"))
+            raise IOError(errno.EROFS, "Collection is read only")
 
         if create:
             arvfile = self.find_or_create(path, FILE)
@@ -623,9 +630,9 @@ class RichCollectionBase(CollectionBase):
             arvfile = self.find(path)
 
         if arvfile is None:
-            raise IOError((errno.ENOENT, "File not found"))
+            raise IOError(errno.ENOENT, "File not found")
         if not isinstance(arvfile, ArvadosFile):
-            raise IOError((errno.EISDIR, "Path must refer to a file."))
+            raise IOError(errno.EISDIR, "Is a directory: %s" % path)
 
         if mode[0] == "w":
             arvfile.truncate(0)
@@ -633,26 +640,31 @@ class RichCollectionBase(CollectionBase):
         name = os.path.basename(path)
 
         if mode == "r":
-            return ArvadosFileReader(arvfile, name, mode, num_retries=self.num_retries)
+            return ArvadosFileReader(arvfile, num_retries=self.num_retries)
         else:
-            return ArvadosFileWriter(arvfile, name, mode, num_retries=self.num_retries)
+            return ArvadosFileWriter(arvfile, mode, num_retries=self.num_retries)
 
-    @synchronized
     def modified(self):
-        """Test if the collection (or any subcollection or file) has been modified."""
-        if self._modified:
-            return True
-        for k,v in self._items.items():
-            if v.modified():
-                return True
-        return False
+        """Determine if the collection has been modified since last commited."""
+        return not self.committed()
+
+    @synchronized
+    def committed(self):
+        """Determine if the collection has been committed to the API server."""
+
+        if self._committed is False:
+            return False
+        for v in self._items.values():
+            if v.committed() is False:
+                return False
+        return True
 
     @synchronized
-    def set_unmodified(self):
-        """Recursively clear modified flag."""
-        self._modified = False
+    def set_committed(self):
+        """Recursively set committed flag to True."""
+        self._committed = True
         for k,v in self._items.items():
-            v.set_unmodified()
+            v.set_committed()
 
     @synchronized
     def __iter__(self):
@@ -683,7 +695,7 @@ class RichCollectionBase(CollectionBase):
     def __delitem__(self, p):
         """Delete an item by name which is directly contained by this collection."""
         del self._items[p]
-        self._modified = True
+        self._committed = False
         self.notify(DEL, self, p, None)
 
     @synchronized
@@ -715,33 +727,33 @@ class RichCollectionBase(CollectionBase):
         """
 
         if not path:
-            raise errors.ArgumentError("Parameter 'path' must not be empty.")
+            raise errors.ArgumentError("Parameter 'path' is empty.")
 
         pathcomponents = path.split("/", 1)
         item = self._items.get(pathcomponents[0])
         if item is None:
-            raise IOError((errno.ENOENT, "File not found"))
+            raise IOError(errno.ENOENT, "File not found")
         if len(pathcomponents) == 1:
             if isinstance(self._items[pathcomponents[0]], RichCollectionBase) and len(self._items[pathcomponents[0]]) > 0 and not recursive:
-                raise IOError((errno.ENOTEMPTY, "Subcollection not empty"))
+                raise IOError(errno.ENOTEMPTY, "Subcollection not empty")
             deleteditem = self._items[pathcomponents[0]]
             del self._items[pathcomponents[0]]
-            self._modified = True
+            self._committed = False
             self.notify(DEL, self, pathcomponents[0], deleteditem)
         else:
             item.remove(pathcomponents[1])
 
     def _clonefrom(self, source):
         for k,v in source.items():
-            self._items[k] = v.clone(self)
+            self._items[k] = v.clone(self, k)
 
     def clone(self):
         raise NotImplementedError()
 
     @must_be_writable
     @synchronized
-    def add(self, source_obj, target_name, overwrite=False):
-        """Copy a file or subcollection to this collection.
+    def add(self, source_obj, target_name, overwrite=False, reparent=False):
+        """Copy or move a file or subcollection to this collection.
 
         :source_obj:
           An ArvadosFile, or Subcollection object
@@ -753,24 +765,74 @@ class RichCollectionBase(CollectionBase):
         :overwrite:
           Whether to overwrite target file if it already exists.
 
+        :reparent:
+          If True, source_obj will be moved from its parent collection to this collection.
+          If False, source_obj will be copied and the parent collection will be
+          unmodified.
+
         """
 
         if target_name in self and not overwrite:
-            raise IOError((errno.EEXIST, "File already exists"))
+            raise IOError(errno.EEXIST, "File already exists")
 
         modified_from = None
         if target_name in self:
             modified_from = self[target_name]
 
-        # Actually make the copy.
-        dup = source_obj.clone(self)
-        self._items[target_name] = dup
-        self._modified = True
+        # Actually make the move or copy.
+        if reparent:
+            source_obj._reparent(self, target_name)
+            item = source_obj
+        else:
+            item = source_obj.clone(self, target_name)
+
+        self._items[target_name] = item
+        self._committed = False
 
         if modified_from:
-            self.notify(MOD, self, target_name, (modified_from, dup))
+            self.notify(MOD, self, target_name, (modified_from, item))
         else:
-            self.notify(ADD, self, target_name, dup)
+            self.notify(ADD, self, target_name, item)
+
+    def _get_src_target(self, source, target_path, source_collection, create_dest):
+        if source_collection is None:
+            source_collection = self
+
+        # Find the object
+        if isinstance(source, basestring):
+            source_obj = source_collection.find(source)
+            if source_obj is None:
+                raise IOError(errno.ENOENT, "File not found")
+            sourcecomponents = source.split("/")
+        else:
+            source_obj = source
+            sourcecomponents = None
+
+        # Find parent collection the target path
+        targetcomponents = target_path.split("/")
+
+        # Determine the name to use.
+        target_name = targetcomponents[-1] if targetcomponents[-1] else sourcecomponents[-1]
+
+        if not target_name:
+            raise errors.ArgumentError("Target path is empty and source is an object.  Cannot determine destination filename to use.")
+
+        if create_dest:
+            target_dir = self.find_or_create("/".join(targetcomponents[0:-1]), COLLECTION)
+        else:
+            if len(targetcomponents) > 1:
+                target_dir = self.find("/".join(targetcomponents[0:-1]))
+            else:
+                target_dir = self
+
+        if target_dir is None:
+            raise IOError(errno.ENOENT, "Target directory not found.")
+
+        if target_name in target_dir and isinstance(self[target_name], RichCollectionBase) and sourcecomponents:
+            target_dir = target_dir[target_name]
+            target_name = sourcecomponents[-1]
+
+        return (source_obj, target_dir, target_name)
 
     @must_be_writable
     @synchronized
@@ -792,42 +854,57 @@ class RichCollectionBase(CollectionBase):
         :overwrite:
           Whether to overwrite target file if it already exists.
         """
-        if source_collection is None:
-            source_collection = self
 
-        # Find the object to copy
-        if isinstance(source, basestring):
-            source_obj = source_collection.find(source)
-            if source_obj is None:
-                raise IOError((errno.ENOENT, "File not found"))
-            sourcecomponents = source.split("/")
-        else:
-            source_obj = source
-            sourcecomponents = None
+        source_obj, target_dir, target_name = self._get_src_target(source, target_path, source_collection, True)
+        target_dir.add(source_obj, target_name, overwrite, False)
 
-        # Find parent collection the target path
-        targetcomponents = target_path.split("/")
+    @must_be_writable
+    @synchronized
+    def rename(self, source, target_path, source_collection=None, overwrite=False):
+        """Move a file or subcollection from `source_collection` to a new path in this collection.
 
-        # Determine the name to use.
-        target_name = targetcomponents[-1] if targetcomponents[-1] else (sourcecomponents[-1] if sourcecomponents else None)
+        :source:
+          A string with a path to source file or subcollection.
 
-        if not target_name:
-            raise errors.ArgumentError("Target path is empty and source is an object.  Cannot determine destination filename to use.")
+        :target_path:
+          Destination file or path.  If the target path already exists and is a
+          subcollection, the item will be placed inside the subcollection.  If
+          the target path already exists and is a file, this will raise an error
+          unless you specify `overwrite=True`.
 
-        target_dir = self.find_or_create("/".join(targetcomponents[0:-1]), COLLECTION)
+        :source_collection:
+          Collection to copy `source_path` from (default `self`)
 
-        if target_name in target_dir and isinstance(self[target_name], RichCollectionBase) and sourcecomponents:
-            target_dir = target_dir[target_name]
-            target_name = sourcecomponents[-1]
+        :overwrite:
+          Whether to overwrite target file if it already exists.
+        """
+
+        source_obj, target_dir, target_name = self._get_src_target(source, target_path, source_collection, False)
+        if not source_obj.writable():
+            raise IOError(errno.EROFS, "Source collection is read only.")
+        target_dir.add(source_obj, target_name, overwrite, True)
+
+    def portable_manifest_text(self, stream_name="."):
+        """Get the manifest text for this collection, sub collections and files.
+
+        This method does not flush outstanding blocks to Keep.  It will return
+        a normalized manifest with access tokens stripped.
+
+        :stream_name:
+          Name to use for this stream (directory)
 
-        target_dir.add(source_obj, target_name, overwrite)
+        """
+        return self._get_manifest_text(stream_name, True, True)
 
     @synchronized
     def manifest_text(self, stream_name=".", strip=False, normalize=False):
         """Get the manifest text for this collection, sub collections and files.
 
+        This method will flush outstanding blocks to Keep.  By default, it will
+        not normalize an unmodified manifest or strip access tokens.
+
         :stream_name:
-          Name of the stream (directory)
+          Name to use for this stream (directory)
 
         :strip:
           If True, remove signing tokens from block locators if present.
@@ -841,7 +918,29 @@ class RichCollectionBase(CollectionBase):
 
         """
 
-        if self.modified() or self._manifest_text is None or normalize:
+        self._my_block_manager().commit_all()
+        return self._get_manifest_text(stream_name, strip, normalize)
+
+    @synchronized
+    def _get_manifest_text(self, stream_name, strip, normalize):
+        """Get the manifest text for this collection, sub collections and files.
+
+        :stream_name:
+          Name to use for this stream (directory)
+
+        :strip:
+          If True, remove signing tokens from block locators if present.
+          If False (default), block locators are left unchanged.
+
+        :normalize:
+          If True, always export the manifest text in normalized form
+          even if the Collection is not modified.  If False (default) and the collection
+          is not modified, return the original manifest text even if it is not
+          in normalized form.
+
+        """
+
+        if not self.committed() or self._manifest_text is None or normalize:
             stream = {}
             buf = []
             sorted_keys = sorted(self.keys())
@@ -861,7 +960,7 @@ class RichCollectionBase(CollectionBase):
             if stream:
                 buf.append(" ".join(normalize_stream(stream_name, stream)) + "\n")
             for dirname in [s for s in sorted_keys if isinstance(self[s], RichCollectionBase)]:
-                buf.append(self[dirname].manifest_text(stream_name=os.path.join(stream_name, dirname), strip=strip))
+                buf.append(self[dirname].manifest_text(stream_name=os.path.join(stream_name, dirname), strip=strip, normalize=True))
             return "".join(buf)
         else:
             if strip:
@@ -881,15 +980,17 @@ class RichCollectionBase(CollectionBase):
             holding_collection = Collection(api_client=self._my_api(), keep_client=self._my_keep())
         for k in self:
             if k not in end_collection:
-               changes.append((DEL, os.path.join(prefix, k), self[k].clone(holding_collection)))
+               changes.append((DEL, os.path.join(prefix, k), self[k].clone(holding_collection, "")))
         for k in end_collection:
             if k in self:
                 if isinstance(end_collection[k], Subcollection) and isinstance(self[k], Subcollection):
                     changes.extend(self[k].diff(end_collection[k], os.path.join(prefix, k), holding_collection))
                 elif end_collection[k] != self[k]:
-                    changes.append((MOD, os.path.join(prefix, k), self[k].clone(holding_collection), end_collection[k].clone(holding_collection)))
+                    changes.append((MOD, os.path.join(prefix, k), self[k].clone(holding_collection, ""), end_collection[k].clone(holding_collection, "")))
+                else:
+                    changes.append((TOK, os.path.join(prefix, k), self[k].clone(holding_collection, ""), end_collection[k].clone(holding_collection, "")))
             else:
-                changes.append((ADD, os.path.join(prefix, k), end_collection[k].clone(holding_collection)))
+                changes.append((ADD, os.path.join(prefix, k), end_collection[k].clone(holding_collection, "")))
         return changes
 
     @must_be_writable
@@ -901,12 +1002,14 @@ class RichCollectionBase(CollectionBase):
         alternate path indicating the conflict.
 
         """
+        if changes:
+            self._committed = False
         for change in changes:
             event_type = change[0]
             path = change[1]
             initial = change[2]
             local = self.find(path)
-            conflictpath = "%s~conflict-%s~" % (path, time.strftime("%Y-%m-%d-%H:%M:%S",
+            conflictpath = "%s~%s~conflict~" % (path, time.strftime("%Y%m%d-%H%M%S",
                                                                     time.gmtime()))
             if event_type == ADD:
                 if local is None:
@@ -916,7 +1019,7 @@ class RichCollectionBase(CollectionBase):
                     # There is already local file and it is different:
                     # save change to conflict file.
                     self.copy(initial, conflictpath)
-            elif event_type == MOD:
+            elif event_type == MOD or event_type == TOK:
                 final = change[3]
                 if local == initial:
                     # Local matches the "initial" item so it has not
@@ -941,9 +1044,27 @@ class RichCollectionBase(CollectionBase):
 
     def portable_data_hash(self):
         """Get the portable data hash for this collection's manifest."""
-        stripped = self.manifest_text(strip=True)
+        stripped = self.portable_manifest_text()
         return hashlib.md5(stripped).hexdigest() + '+' + str(len(stripped))
 
+    @synchronized
+    def subscribe(self, callback):
+        if self._callback is None:
+            self._callback = callback
+        else:
+            raise errors.ArgumentError("A callback is already set on this collection.")
+
+    @synchronized
+    def unsubscribe(self):
+        if self._callback is not None:
+            self._callback = None
+
+    @synchronized
+    def notify(self, event, collection, name, item):
+        if self._callback:
+            self._callback(event, collection, name, item)
+        self.root_collection().notify(event, collection, name, item)
+
     @synchronized
     def __eq__(self, other):
         if other is self:
@@ -962,6 +1083,12 @@ class RichCollectionBase(CollectionBase):
     def __ne__(self, other):
         return not self.__eq__(other)
 
+    @synchronized
+    def flush(self):
+        """Flush bufferblocks to Keep."""
+        for e in self.values():
+            e.flush()
+
 
 class Collection(RichCollectionBase):
     """Represents the root of an Arvados Collection.
@@ -1044,9 +1171,9 @@ class Collection(RichCollectionBase):
         self._manifest_locator = None
         self._manifest_text = None
         self._api_response = None
+        self._past_versions = set()
 
         self.lock = threading.RLock()
-        self.callbacks = []
         self.events = None
 
         if manifest_locator_or_text:
@@ -1058,7 +1185,7 @@ class Collection(RichCollectionBase):
                 self._manifest_text = manifest_locator_or_text
             else:
                 raise errors.ArgumentError(
-                    "Argument to CollectionReader must be a manifest or a collection UUID")
+                    "Argument to CollectionReader is not a manifest or a collection UUID")
 
             try:
                 self._populate()
@@ -1074,6 +1201,10 @@ class Collection(RichCollectionBase):
     def writable(self):
         return True
 
+    @synchronized
+    def known_past_version(self, modified_at_and_portable_data_hash):
+        return modified_at_and_portable_data_hash in self._past_versions
+
     @synchronized
     @retry_method
     def update(self, other=None, num_retries=None):
@@ -1083,9 +1214,19 @@ class Collection(RichCollectionBase):
             if self._manifest_locator is None:
                 raise errors.ArgumentError("`other` is None but collection does not have a manifest_locator uuid")
             response = self._my_api().collections().get(uuid=self._manifest_locator).execute(num_retries=num_retries)
+            if (self.known_past_version((response.get("modified_at"), response.get("portable_data_hash"))) and
+                response.get("portable_data_hash") != self.portable_data_hash()):
+                # The record on the server is different from our current one, but we've seen it before,
+                # so ignore it because it's already been merged.
+                # However, if it's the same as our current record, proceed with the update, because we want to update
+                # our tokens.
+                return
+            else:
+                self._past_versions.add((response.get("modified_at"), response.get("portable_data_hash")))
             other = CollectionReader(response["manifest_text"])
         baseline = CollectionReader(self._manifest_text)
         self.apply(baseline.diff(other))
+        self._manifest_text = self.manifest_text()
 
     @synchronized
     def _my_api(self):
@@ -1109,6 +1250,10 @@ class Collection(RichCollectionBase):
             self._block_manager = _BlockManager(self._my_keep())
         return self._block_manager
 
+    def _remember_api_response(self, response):
+        self._api_response = response
+        self._past_versions.add((response.get("modified_at"), response.get("portable_data_hash")))
+
     def _populate_from_api_server(self):
         # As in KeepClient itself, we must wait until the last
         # possible moment to instantiate an API client, in order to
@@ -1118,9 +1263,9 @@ class Collection(RichCollectionBase):
         # clause, just like any other Collection lookup
         # failure. Return an exception, or None if successful.
         try:
-            self._api_response = self._my_api().collections().get(
+            self._remember_api_response(self._my_api().collections().get(
                 uuid=self._manifest_locator).execute(
-                    num_retries=self.num_retries)
+                    num_retries=self.num_retries))
             self._manifest_text = self._api_response['manifest_text']
             return None
         except Exception as e:
@@ -1179,9 +1324,12 @@ class Collection(RichCollectionBase):
 
     def __exit__(self, exc_type, exc_value, traceback):
         """Support scoped auto-commit in a with: block."""
-        if exc_type is not None:
+        if exc_type is None:
             if self.writable() and self._has_collection_uuid():
                 self.save()
+        self.stop_threads()
+
+    def stop_threads(self):
         if self._block_manager is not None:
             self._block_manager.stop_threads()
 
@@ -1200,7 +1348,7 @@ class Collection(RichCollectionBase):
         return self._manifest_locator
 
     @synchronized
-    def clone(self, new_parent=None, readonly=False, new_config=None):
+    def clone(self, new_parent=None, new_name=None, readonly=False, new_config=None):
         if new_config is None:
             new_config = self._config
         if readonly:
@@ -1249,8 +1397,8 @@ class Collection(RichCollectionBase):
         """Save collection to an existing collection record.
 
         Commit pending buffer blocks to Keep, merge with remote record (if
-        merge=True, the default), write the manifest to Keep, and update the
-        collection record.
+        merge=True, the default), and update the collection record.  Returns
+        the current manifest text.
 
         Will raise AssertionError if not associated with a collection record on
         the API server.  If you want to save a manifest to Keep only, see
@@ -1264,40 +1412,48 @@ class Collection(RichCollectionBase):
           Retry count on API calls (if None,  use the collection default)
 
         """
-        if self.modified():
+        if not self.committed():
             if not self._has_collection_uuid():
-                raise AssertionError("Collection manifest_locator must be a collection uuid.  Use save_new() for new collections.")
+                raise AssertionError("Collection manifest_locator is not a collection uuid.  Use save_new() for new collections.")
+
             self._my_block_manager().commit_all()
+
             if merge:
                 self.update()
-            self._my_keep().put(self.manifest_text(strip=True), num_retries=num_retries)
 
             text = self.manifest_text(strip=False)
-            self._api_response = self._my_api().collections().update(
+            self._remember_api_response(self._my_api().collections().update(
                 uuid=self._manifest_locator,
                 body={'manifest_text': text}
                 ).execute(
-                    num_retries=num_retries)
+                    num_retries=num_retries))
             self._manifest_text = self._api_response["manifest_text"]
-            self.set_unmodified()
+            self.set_committed()
+
+        return self._manifest_text
 
 
     @must_be_writable
     @synchronized
     @retry_method
-    def save_new(self, name=None, create_collection_record=True, owner_uuid=None, ensure_unique_name=False, num_retries=None):
+    def save_new(self, name=None,
+                 create_collection_record=True,
+                 owner_uuid=None,
+                 ensure_unique_name=False,
+                 num_retries=None):
         """Save collection to a new collection record.
 
-        Commit pending buffer blocks to Keep, write the manifest to Keep, and
-        create a new collection record (if create_collection_record True).
-        After creating a new collection record, this Collection object will be
-        associated with the new record used by `save()`.
+        Commit pending buffer blocks to Keep and, when create_collection_record
+        is True (default), create a new collection record.  After creating a
+        new collection record, this Collection object will be associated with
+        the new record used by `save()`.  Returns the current manifest text.
 
         :name:
           The collection name.
 
         :create_collection_record:
-          If True, create a collection record.  If False, only save the manifest to keep.
+           If True, create a collection record on the API server.
+           If False, only commit blocks to Keep and return the manifest text.
 
         :owner_uuid:
           the user, or project uuid that will own this collection.
@@ -1313,38 +1469,27 @@ class Collection(RichCollectionBase):
 
         """
         self._my_block_manager().commit_all()
-        self._my_keep().put(self.manifest_text(strip=True), num_retries=num_retries)
         text = self.manifest_text(strip=False)
 
         if create_collection_record:
             if name is None:
-                name = "Collection created %s" % (time.strftime("%Y-%m-%d %H:%M:%S %Z", time.localtime()))
+                name = "New collection"
+                ensure_unique_name = True
 
             body = {"manifest_text": text,
                     "name": name}
             if owner_uuid:
                 body["owner_uuid"] = owner_uuid
 
-            self._api_response = self._my_api().collections().create(ensure_unique_name=ensure_unique_name, body=body).execute(num_retries=num_retries)
+            self._remember_api_response(self._my_api().collections().create(ensure_unique_name=ensure_unique_name, body=body).execute(num_retries=num_retries))
             text = self._api_response["manifest_text"]
 
             self._manifest_locator = self._api_response["uuid"]
 
-        self._manifest_text = text
-        self.set_unmodified()
-
-    @synchronized
-    def subscribe(self, callback):
-        self.callbacks.append(callback)
+            self._manifest_text = text
+            self.set_committed()
 
-    @synchronized
-    def unsubscribe(self, callback):
-        self.callbacks.remove(callback)
-
-    @synchronized
-    def notify(self, event, collection, name, item):
-        for c in self.callbacks:
-            c(event, collection, name, item)
+        return text
 
     @synchronized
     def _import_manifest(self, manifest_text):
@@ -1375,6 +1520,7 @@ class Collection(RichCollectionBase):
                 segments = []
                 streamoffset = 0L
                 state = BLOCKS
+                self.find_or_create(stream_name, COLLECTION)
                 continue
 
             if state == BLOCKS:
@@ -1400,27 +1546,34 @@ class Collection(RichCollectionBase):
                         raise errors.SyntaxError("File %s conflicts with stream of the same name.", filepath)
                 else:
                     # error!
-                    raise errors.SyntaxError("Invalid manifest format")
+                    raise errors.SyntaxError("Invalid manifest format, expected file segment but did not match format: '%s'" % tok)
 
             if sep == "\n":
                 stream_name = None
                 state = STREAM_NAME
 
-        self.set_unmodified()
+        self.set_committed()
+
+    @synchronized
+    def notify(self, event, collection, name, item):
+        if self._callback:
+            self._callback(event, collection, name, item)
 
 
 class Subcollection(RichCollectionBase):
     """This is a subdirectory within a collection that doesn't have its own API
     server record.
 
-    It falls under the umbrella of the root collection.
+    Subcollection locking falls under the umbrella lock of its root collection.
 
     """
 
-    def __init__(self, parent):
+    def __init__(self, parent, name):
         super(Subcollection, self).__init__(parent)
         self.lock = self.root_collection().lock
         self._manifest_text = None
+        self.name = name
+        self.num_retries = parent.num_retries
 
     def root_collection(self):
         return self.parent.root_collection()
@@ -1437,21 +1590,25 @@ class Subcollection(RichCollectionBase):
     def _my_block_manager(self):
         return self.root_collection()._my_block_manager()
 
-    def notify(self, event, collection, name, item):
-        return self.root_collection().notify(event, collection, name, item)
-
     def stream_name(self):
-        for k, v in self.parent.items():
-            if v is self:
-                return os.path.join(self.parent.stream_name(), k)
-        return '.'
+        return os.path.join(self.parent.stream_name(), self.name)
 
     @synchronized
-    def clone(self, new_parent):
-        c = Subcollection(new_parent)
+    def clone(self, new_parent, new_name):
+        c = Subcollection(new_parent, new_name)
         c._clonefrom(self)
         return c
 
+    @must_be_writable
+    @synchronized
+    def _reparent(self, newparent, newname):
+        self._committed = False
+        self.flush()
+        self.parent.remove(self.name, recursive=True)
+        self.parent = newparent
+        self.name = newname
+        self.lock = self.parent.root_collection().lock
+
 
 class CollectionReader(Collection):
     """A read-only collection object.