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Diffstat (limited to 'soledad_server/src/leap/soledad_server/couch.py')
| -rw-r--r-- | soledad_server/src/leap/soledad_server/couch.py | 480 |
1 files changed, 480 insertions, 0 deletions
diff --git a/soledad_server/src/leap/soledad_server/couch.py b/soledad_server/src/leap/soledad_server/couch.py new file mode 100644 index 00000000..ed5ad6b3 --- /dev/null +++ b/soledad_server/src/leap/soledad_server/couch.py @@ -0,0 +1,480 @@ +# -*- coding: utf-8 -*- +# couch.py +# Copyright (C) 2013 LEAP +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + + +"""A U1DB backend that uses CouchDB as its persistence layer.""" + +# general imports +import uuid +import re +import simplejson as json + + +from base64 import b64encode, b64decode +from u1db import errors +from u1db.sync import Synchronizer +from u1db.backends.inmemory import InMemoryIndex +from u1db.remote.server_state import ServerState +from u1db.errors import DatabaseDoesNotExist +from couchdb.client import Server, Document as CouchDocument +from couchdb.http import ResourceNotFound + + +from leap.soledad_server.objectstore import ( + ObjectStoreDatabase, + ObjectStoreSyncTarget, +) + + +class InvalidURLError(Exception): + """ + Exception raised when Soledad encounters a malformed URL. + """ + + +class CouchDatabase(ObjectStoreDatabase): + """ + A U1DB backend that uses Couch as its persistence layer. + """ + + U1DB_TRANSACTION_LOG_KEY = 'transaction_log' + U1DB_CONFLICTS_KEY = 'conflicts' + U1DB_OTHER_GENERATIONS_KEY = 'other_generations' + U1DB_INDEXES_KEY = 'indexes' + U1DB_REPLICA_UID_KEY = 'replica_uid' + + COUCH_ID_KEY = '_id' + COUCH_REV_KEY = '_rev' + COUCH_U1DB_ATTACHMENT_KEY = 'u1db_json' + COUCH_U1DB_REV_KEY = 'u1db_rev' + + @classmethod + def open_database(cls, url, create): + """ + Open a U1DB database using CouchDB as backend. + + @param url: the url of the database replica + @type url: str + @param create: should the replica be created if it does not exist? + @type create: bool + + @return: the database instance + @rtype: CouchDatabase + """ + # get database from url + m = re.match('(^https?://[^/]+)/(.+)$', url) + if not m: + raise InvalidURLError + url = m.group(1) + dbname = m.group(2) + server = Server(url=url) + try: + server[dbname] + except ResourceNotFound: + if not create: + raise DatabaseDoesNotExist() + return cls(url, dbname) + + def __init__(self, url, dbname, replica_uid=None, full_commit=True, + session=None): + """ + Create a new Couch data container. + + @param url: the url of the couch database + @type url: str + @param dbname: the database name + @type dbname: str + @param replica_uid: an optional unique replica identifier + @type replica_uid: str + @param full_commit: turn on the X-Couch-Full-Commit header + @type full_commit: bool + @param session: an http.Session instance or None for a default session + @type session: http.Session + """ + self._url = url + self._full_commit = full_commit + self._session = session + self._server = Server(url=self._url, + full_commit=self._full_commit, + session=self._session) + self._dbname = dbname + # this will ensure that transaction and sync logs exist and are + # up-to-date. + try: + self._database = self._server[self._dbname] + except ResourceNotFound: + self._server.create(self._dbname) + self._database = self._server[self._dbname] + ObjectStoreDatabase.__init__(self, replica_uid=replica_uid) + + #------------------------------------------------------------------------- + # methods from Database + #------------------------------------------------------------------------- + + def _get_doc(self, doc_id, check_for_conflicts=False): + """ + Get just the document content, without fancy handling. + + @param doc_id: The unique document identifier + @type doc_id: str + @param include_deleted: If set to True, deleted documents will be + returned with empty content. Otherwise asking for a deleted + document will return None. + @type include_deleted: bool + + @return: a Document object. + @type: u1db.Document + """ + cdoc = self._database.get(doc_id) + if cdoc is None: + return None + has_conflicts = False + if check_for_conflicts: + has_conflicts = self._has_conflicts(doc_id) + doc = self._factory( + doc_id=doc_id, + rev=cdoc[self.COUCH_U1DB_REV_KEY], + has_conflicts=has_conflicts) + contents = self._database.get_attachment( + cdoc, + self.COUCH_U1DB_ATTACHMENT_KEY) + if contents: + doc.content = json.loads(contents.read()) + else: + doc.make_tombstone() + return doc + + def get_all_docs(self, include_deleted=False): + """ + Get the JSON content for all documents in the database. + + @param include_deleted: If set to True, deleted documents will be + returned with empty content. Otherwise deleted documents will not + be included in the results. + @type include_deleted: bool + + @return: (generation, [Document]) + The current generation of the database, followed by a list of all + the documents in the database. + @rtype: tuple + """ + generation = self._get_generation() + results = [] + for doc_id in self._database: + if doc_id == self.U1DB_DATA_DOC_ID: + continue + doc = self._get_doc(doc_id, check_for_conflicts=True) + if doc.content is None and not include_deleted: + continue + results.append(doc) + return (generation, results) + + def _put_doc(self, doc): + """ + Update a document. + + This is called everytime we just want to do a raw put on the db (i.e. + without index updates, document constraint checks, and conflict + checks). + + @param doc: The document to update. + @type doc: u1db.Document + + @return: The new revision identifier for the document. + @rtype: str + """ + # prepare couch's Document + cdoc = CouchDocument() + cdoc[self.COUCH_ID_KEY] = doc.doc_id + # we have to guarantee that couch's _rev is consistent + old_cdoc = self._database.get(doc.doc_id) + if old_cdoc is not None: + cdoc[self.COUCH_REV_KEY] = old_cdoc[self.COUCH_REV_KEY] + # store u1db's rev + cdoc[self.COUCH_U1DB_REV_KEY] = doc.rev + # save doc in db + self._database.save(cdoc) + # store u1db's content as json string + if not doc.is_tombstone(): + self._database.put_attachment( + cdoc, doc.get_json(), + filename=self.COUCH_U1DB_ATTACHMENT_KEY) + else: + self._database.delete_attachment( + cdoc, + self.COUCH_U1DB_ATTACHMENT_KEY) + + def get_sync_target(self): + """ + Return a SyncTarget object, for another u1db to synchronize with. + + @return: The sync target. + @rtype: CouchSyncTarget + """ + return CouchSyncTarget(self) + + def create_index(self, index_name, *index_expressions): + """ + Create a named index, which can then be queried for future lookups. + + @param index_name: A unique name which can be used as a key prefix. + @param index_expressions: Index expressions defining the index + information. + """ + if index_name in self._indexes: + if self._indexes[index_name]._definition == list( + index_expressions): + return + raise errors.IndexNameTakenError + index = InMemoryIndex(index_name, list(index_expressions)) + for doc_id in self._database: + if doc_id == self.U1DB_DATA_DOC_ID: # skip special file + continue + doc = self._get_doc(doc_id) + if doc.content is not None: + index.add_json(doc_id, doc.get_json()) + self._indexes[index_name] = index + # save data in object store + self._store_u1db_data() + + def close(self): + """ + Release any resources associated with this database. + + @return: True if db was succesfully closed. + @rtype: bool + """ + # TODO: fix this method so the connection is properly closed and + # test_close (+tearDown, which deletes the db) works without problems. + self._url = None + self._full_commit = None + self._session = None + #self._server = None + self._database = None + return True + + def sync(self, url, creds=None, autocreate=True): + """ + Synchronize documents with remote replica exposed at url. + + @param url: The url of the target replica to sync with. + @type url: str + @param creds: optional dictionary giving credentials. + to authorize the operation with the server. + @type creds: dict + @param autocreate: Ask the target to create the db if non-existent. + @type autocreate: bool + + @return: The local generation before the synchronisation was performed. + @rtype: int + """ + return Synchronizer(self, CouchSyncTarget(url, creds=creds)).sync( + autocreate=autocreate) + + #------------------------------------------------------------------------- + # methods from ObjectStoreDatabase + #------------------------------------------------------------------------- + + def _init_u1db_data(self): + """ + Initialize U1DB info data structure in the couch db. + + A U1DB database needs to keep track of all database transactions, + document conflicts, the generation of other replicas it has seen, + indexes created by users and so on. + + In this implementation, all this information is stored in a special + document stored in the couch db with id equals to + CouchDatabse.U1DB_DATA_DOC_ID. + + This method initializes the document that will hold such information. + """ + if self._replica_uid is None: + self._replica_uid = uuid.uuid4().hex + # TODO: prevent user from overwriting a document with the same doc_id + # as this one. + doc = self._factory(doc_id=self.U1DB_DATA_DOC_ID) + doc.content = { + self.U1DB_TRANSACTION_LOG_KEY: b64encode(json.dumps([])), + self.U1DB_CONFLICTS_KEY: b64encode(json.dumps({})), + self.U1DB_OTHER_GENERATIONS_KEY: b64encode(json.dumps({})), + self.U1DB_INDEXES_KEY: b64encode(json.dumps({})), + self.U1DB_REPLICA_UID_KEY: b64encode(self._replica_uid), + } + self._put_doc(doc) + + def _fetch_u1db_data(self): + """ + Fetch U1DB info from the couch db. + + See C{_init_u1db_data} documentation. + """ + # retrieve u1db data from couch db + cdoc = self._database.get(self.U1DB_DATA_DOC_ID) + jsonstr = self._database.get_attachment( + cdoc, self.COUCH_U1DB_ATTACHMENT_KEY).read() + content = json.loads(jsonstr) + # set u1db database info + self._transaction_log = json.loads( + b64decode(content[self.U1DB_TRANSACTION_LOG_KEY])) + self._conflicts = json.loads( + b64decode(content[self.U1DB_CONFLICTS_KEY])) + self._other_generations = json.loads( + b64decode(content[self.U1DB_OTHER_GENERATIONS_KEY])) + self._indexes = self._load_indexes_from_json( + b64decode(content[self.U1DB_INDEXES_KEY])) + self._replica_uid = b64decode(content[self.U1DB_REPLICA_UID_KEY]) + # save couch _rev + self._couch_rev = cdoc[self.COUCH_REV_KEY] + + def _store_u1db_data(self): + """ + Store U1DB info in the couch db. + + See C{_init_u1db_data} documentation. + """ + doc = self._factory(doc_id=self.U1DB_DATA_DOC_ID) + doc.content = { + # Here, the b64 encode ensures that document content + # does not cause strange behaviour in couchdb because + # of encoding. + self.U1DB_TRANSACTION_LOG_KEY: + b64encode(json.dumps(self._transaction_log)), + self.U1DB_CONFLICTS_KEY: b64encode(json.dumps(self._conflicts)), + self.U1DB_OTHER_GENERATIONS_KEY: + b64encode(json.dumps(self._other_generations)), + self.U1DB_INDEXES_KEY: b64encode(self._dump_indexes_as_json()), + self.U1DB_REPLICA_UID_KEY: b64encode(self._replica_uid), + self.COUCH_REV_KEY: self._couch_rev} + self._put_doc(doc) + + #------------------------------------------------------------------------- + # Couch specific methods + #------------------------------------------------------------------------- + + INDEX_NAME_KEY = 'name' + INDEX_DEFINITION_KEY = 'definition' + INDEX_VALUES_KEY = 'values' + + def delete_database(self): + """ + Delete a U1DB CouchDB database. + """ + del(self._server[self._dbname]) + + def _dump_indexes_as_json(self): + """ + Dump index definitions as JSON string. + """ + indexes = {} + for name, idx in self._indexes.iteritems(): + indexes[name] = {} + for attr in [self.INDEX_NAME_KEY, self.INDEX_DEFINITION_KEY, + self.INDEX_VALUES_KEY]: + indexes[name][attr] = getattr(idx, '_' + attr) + return json.dumps(indexes) + + def _load_indexes_from_json(self, indexes): + """ + Load index definitions from JSON string. + + @param indexes: A JSON serialization of a list of [('index-name', + ['field', 'field2'])]. + @type indexes: str + + @return: A dictionary with the index definitions. + @rtype: dict + """ + dict = {} + for name, idx_dict in json.loads(indexes).iteritems(): + idx = InMemoryIndex(name, idx_dict[self.INDEX_DEFINITION_KEY]) + idx._values = idx_dict[self.INDEX_VALUES_KEY] + dict[name] = idx + return dict + + +class CouchSyncTarget(ObjectStoreSyncTarget): + """ + Functionality for using a CouchDatabase as a synchronization target. + """ + + +class CouchServerState(ServerState): + """ + Inteface of the WSGI server with the CouchDB backend. + """ + + def __init__(self, couch_url): + self._couch_url = couch_url + + def open_database(self, dbname): + """ + Open a couch database. + + @param dbname: The name of the database to open. + @type dbname: str + + @return: The CouchDatabase object. + @rtype: CouchDatabase + """ + # TODO: open couch + return CouchDatabase.open_database( + self._couch_url + '/' + dbname, + create=False) + + def ensure_database(self, dbname): + """ + Ensure couch database exists. + + @param dbname: The name of the database to ensure. + @type dbname: str + + @return: The CouchDatabase object and the replica uid. + @rtype: (CouchDatabase, str) + """ + db = CouchDatabase.open_database( + self._couch_url + '/' + dbname, + create=True) + return db, db._replica_uid + + def delete_database(self, dbname): + """ + Delete couch database. + + @param dbname: The name of the database to delete. + @type dbname: str + """ + CouchDatabase.delete_database(self._couch_url + '/' + dbname) + + def _set_couch_url(self, url): + """ + Set the couchdb URL + + @param url: CouchDB URL + @type url: str + """ + self._couch_url = url + + def _get_couch_url(self): + """ + Return CouchDB URL + + @rtype: str + """ + return self._couch_url + + couch_url = property(_get_couch_url, _set_couch_url, doc='CouchDB URL') |