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Diffstat (limited to 'mediagoblin/storage/mountstorage.py')
| -rw-r--r-- | mediagoblin/storage/mountstorage.py | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/mediagoblin/storage/mountstorage.py b/mediagoblin/storage/mountstorage.py new file mode 100644 index 00000000..6adb7a0d --- /dev/null +++ b/mediagoblin/storage/mountstorage.py @@ -0,0 +1,156 @@ +# GNU MediaGoblin -- federated, autonomous media hosting +# Copyright (C) 2011 MediaGoblin contributors. See AUTHORS. +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU Affero General Public License as published by +# the Free Software Foundation, either version 3 of the License, or +# (at your option) any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU Affero General Public License for more details. +# +# You should have received a copy of the GNU Affero General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +from medigoblin.storage import StorageInterface, clean_listy_filepath + + +class MountStorage(StorageInterface): + """ + Experimental "Mount" virtual Storage Interface + + This isn't an interface to some real storage, instead it's a + redirecting interface, that redirects requests to other + "StorageInterface"s. + + For example, say you have the paths: + + 1. ['user_data', 'cwebber', 'avatar.jpg'] + 2. ['user_data', 'elrond', 'avatar.jpg'] + 3. ['media_entries', '34352f304c3f4d0ad8ad0f043522b6f2', 'thumb.jpg'] + + You could mount media_entries under CloudFileStorage and user_data + under BasicFileStorage. Then 1 would be passed to + BasicFileStorage under the path ['cwebber', 'avatar.jpg'] and 3 + would be passed to CloudFileStorage under + ['34352f304c3f4d0ad8ad0f043522b6f2', 'thumb.jpg']. + + In other words, this is kind of like mounting /home/ and /etc/ + under different filesystems on your operating system... but with + mediagoblin filestorages :) + + To set this up, you currently need to call the mount() method with + the target path and a backend, that shall be available under that + target path. You have to mount things in a sensible order, + especially you can't mount ["a", "b"] before ["a"]. + """ + def __init__(self, **kwargs): + self.mounttab = {} + + def mount(self, dirpath, backend): + """ + Mount a new backend under dirpath + """ + new_ent = clean_listy_filepath(dirpath) + + print "Mounting:", repr(new_ent) + already, rem_1, table, rem_2 = self._resolve_to_backend(new_ent, True) + print "===", repr(already), repr(rem_1), repr(rem_2), len(table) + + assert (len(rem_2) > 0) or (None not in table), \ + "That path is already mounted" + assert (len(rem_2) > 0) or (len(table) == 0), \ + "A longer path is already mounted here" + + for part in rem_2: + table[part] = {} + table = table[part] + table[None] = backend + + def _resolve_to_backend(self, filepath, extra_info=False): + """ + extra_info = True is for internal use! + + Normally, returns the backend and the filepath inside that backend. + + With extra_info = True it returns the last directory node and the + remaining filepath from there in addition. + """ + table = self.mounttab + filepath = filepath[:] + res_fp = None + while True: + new_be = table.get(None) + if (new_be is not None) or res_fp is None: + res_be = new_be + res_fp = filepath[:] + res_extra = (table, filepath[:]) + # print "... New res: %r, %r, %r" % (res_be, res_fp, res_extra) + if len(filepath) == 0: + break + query = filepath.pop(0) + entry = table.get(query) + if entry is not None: + table = entry + res_extra = (table, filepath[:]) + else: + break + if extra_info: + return (res_be, res_fp) + res_extra + else: + return (res_be, res_fp) + + def resolve_to_backend(self, filepath): + backend, filepath = self._resolve_to_backend(filepath) + if backend is None: + raise Error("Path not mounted") + return backend, filepath + + def __repr__(self, table=None, indent=[]): + res = [] + if table is None: + res.append("MountStorage<") + table = self.mounttab + v = table.get(None) + if v: + res.append(" " * len(indent) + repr(indent) + ": " + repr(v)) + for k, v in table.iteritems(): + if k == None: + continue + res.append(" " * len(indent) + repr(k) + ":") + res += self.__repr__(v, indent + [k]) + if table is self.mounttab: + res.append(">") + return "\n".join(res) + else: + return res + + def file_exists(self, filepath): + backend, filepath = self.resolve_to_backend(filepath) + return backend.file_exists(filepath) + + def get_file(self, filepath, mode='r'): + backend, filepath = self.resolve_to_backend(filepath) + return backend.get_file(filepath, mode) + + def delete_file(self, filepath): + backend, filepath = self.resolve_to_backend(filepath) + return backend.delete_file(filepath) + + def file_url(self, filepath): + backend, filepath = self.resolve_to_backend(filepath) + return backend.file_url(filepath) + + def get_local_path(self, filepath): + backend, filepath = self.resolve_to_backend(filepath) + return backend.get_local_path(filepath) + + def copy_locally(self, filepath, dest_path): + """ + Need to override copy_locally, because the local_storage + attribute is not correct. + """ + backend, filepath = self.resolve_to_backend(filepath) + backend.copy_locally(filepath, dest_path) |