# -*- 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 . """A U1DB backend that uses CouchDB as its persistence layer.""" import simplejson as json import re import uuid import logging import binascii import socket import time import sys import threading from StringIO import StringIO from collections import defaultdict from urlparse import urljoin from contextlib import contextmanager from couchdb.client import Server, Database from couchdb.http import ( ResourceConflict, ResourceNotFound, ServerError, Session as CouchHTTPSession, ) from u1db import query_parser, vectorclock from u1db.errors import ( DatabaseDoesNotExist, InvalidGeneration, RevisionConflict, InvalidDocId, ConflictedDoc, DocumentDoesNotExist, DocumentAlreadyDeleted, Unauthorized, ) from u1db.backends import CommonBackend, CommonSyncTarget from u1db.remote import http_app from u1db.remote.server_state import ServerState from leap.soledad.common import USER_DB_PREFIX, ddocs, errors from leap.soledad.common.document import SoledadDocument logger = logging.getLogger(__name__) COUCH_TIMEOUT = 120 # timeout for transfers between Soledad server and Couch class InvalidURLError(Exception): """ Exception raised when Soledad encounters a malformed URL. """ class CouchDocument(SoledadDocument): """ This is the document used for maintaining the Couch backend. A CouchDocument can fetch and manipulate conflicts and also holds a reference to the couch document revision. This data is used to ensure an atomic and consistent update of the database. """ def __init__(self, doc_id=None, rev=None, json='{}', has_conflicts=False, syncable=True): """ Container for handling a document that is stored in couch backend. :param doc_id: The unique document identifier. :type doc_id: str :param rev: The revision identifier of the document. :type rev: str :param json: The JSON string for this document. :type json: str :param has_conflicts: Boolean indicating if this document has conflicts :type has_conflicts: bool :param syncable: Should this document be synced with remote replicas? :type syncable: bool """ SoledadDocument.__init__(self, doc_id, rev, json, has_conflicts) self._couch_rev = None self._conflicts = None self._transactions = None def _ensure_fetch_conflicts(self, get_conflicts_fun): """ Ensure conflict data has been fetched from the server. :param get_conflicts_fun: A function which, given the document id and the couch revision, return the conflicted versions of the current document. :type get_conflicts_fun: function """ if self._conflicts is None: self._conflicts = get_conflicts_fun(self.doc_id, couch_rev=self.couch_rev) self.has_conflicts = len(self._conflicts) > 0 def get_conflicts(self): """ Get the conflicted versions of the document. :return: The conflicted versions of the document. :rtype: [CouchDocument] """ return self._conflicts def set_conflicts(self, conflicts): """ Set the conflicted versions of the document. :param conflicts: The conflicted versions of the document. :type conflicts: list """ self._conflicts = conflicts self.has_conflicts = len(self._conflicts) > 0 def add_conflict(self, doc): """ Add a conflict to this document. :param doc: The conflicted version to be added. :type doc: CouchDocument """ if self._conflicts is None: raise Exception("Run self._ensure_fetch_conflicts first!") self._conflicts.append(doc) self.has_conflicts = len(self._conflicts) > 0 def delete_conflicts(self, conflict_revs): """ Delete conflicted versions of this document. :param conflict_revs: The conflicted revisions to be deleted. :type conflict_revs: [str] """ if self._conflicts is None: raise Exception("Run self._ensure_fetch_conflicts first!") conflicts_len = len(self._conflicts) self._conflicts = filter( lambda doc: doc.rev not in conflict_revs, self._conflicts) self.has_conflicts = len(self._conflicts) > 0 def _get_couch_rev(self): return self._couch_rev def _set_couch_rev(self, rev): self._couch_rev = rev couch_rev = property(_get_couch_rev, _set_couch_rev) def _get_transactions(self): return self._transactions def _set_transactions(self, rev): self._transactions = rev transactions = property(_get_transactions, _set_transactions) # monkey-patch the u1db http app to use CouchDocument http_app.Document = CouchDocument def raise_missing_design_doc_error(exc, ddoc_path): """ Raise an appropriate exception when catching a ResourceNotFound when accessing a design document. :param exc: The exception cought. :type exc: ResourceNotFound :param ddoc_path: A list representing the requested path. :type ddoc_path: list :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ path = "".join(ddoc_path) if exc.message[1] == 'missing': raise errors.MissingDesignDocError(path) elif exc.message[1] == 'missing function' or \ exc.message[1].startswith('missing lists function'): raise errors.MissingDesignDocListFunctionError(path) elif exc.message[1] == 'missing_named_view': raise errors.MissingDesignDocNamedViewError(path) elif exc.message[1] == 'deleted': raise errors.MissingDesignDocDeletedError(path) # other errors are unknown for now raise errors.DesignDocUnknownError("%s: %s" % (path, str(exc.message))) def raise_server_error(exc, ddoc_path): """ Raise an appropriate exception when catching a ServerError when accessing a design document. :param exc: The exception cought. :type exc: ResourceNotFound :param ddoc_path: A list representing the requested path. :type ddoc_path: list :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ path = "".join(ddoc_path) if exc.message[1][0] == 'unnamed_error': raise errors.MissingDesignDocListFunctionError(path) # other errors are unknown for now raise errors.DesignDocUnknownError(path) class MultipartWriter(object): """ A multipart writer adapted from python-couchdb's one so we can PUT documents using couch's multipart PUT. This stripped down version does not allow for nested structures, and contains only the essential things we need to PUT SoledadDocuments to the couch backend. """ CRLF = '\r\n' def __init__(self, fileobj, headers=None, boundary=None): """ Initialize the multipart writer. """ self.fileobj = fileobj if boundary is None: boundary = self._make_boundary() self._boundary = boundary self._build_headers('related', headers) def add(self, mimetype, content, headers={}): """ Add a part to the multipart stream. """ self.fileobj.write('--') self.fileobj.write(self._boundary) self.fileobj.write(self.CRLF) headers['Content-Type'] = mimetype self._write_headers(headers) if content: # XXX: throw an exception if a boundary appears in the content?? self.fileobj.write(content) self.fileobj.write(self.CRLF) def close(self): """ Close the multipart stream. """ self.fileobj.write('--') self.fileobj.write(self._boundary) # be careful not to have anything after '--', otherwise old couch # versions (including bigcouch) will fail. self.fileobj.write('--') def _make_boundary(self): """ Create a boundary to discern multi parts. """ try: from uuid import uuid4 return '==' + uuid4().hex + '==' except ImportError: from random import randrange token = randrange(sys.maxint) format = '%%0%dd' % len(repr(sys.maxint - 1)) return '===============' + (format % token) + '==' def _write_headers(self, headers): """ Write a part header in the buffer stream. """ if headers: for name in sorted(headers.keys()): value = headers[name] self.fileobj.write(name) self.fileobj.write(': ') self.fileobj.write(value) self.fileobj.write(self.CRLF) self.fileobj.write(self.CRLF) def _build_headers(self, subtype, headers): """ Build the main headers of the multipart stream. This is here so we can send headers separete from content using python-couchdb API. """ self.headers = {} self.headers['Content-Type'] = 'multipart/%s; boundary="%s"' % \ (subtype, self._boundary) if headers: for name in sorted(headers.keys()): value = headers[name] self.headers[name] = value class Session(CouchHTTPSession): """ An HTTP session that can be closed. """ def close_connections(self): for key, conns in list(self.conns.items()): for conn in conns: conn.close() @contextmanager def couch_server(url): """ Provide a connection to a couch server and cleanup after use. For database creation and deletion we use an ephemeral connection to the couch server. That connection has to be properly closed, so we provide it as a context manager. :param url: The URL of the Couch server. :type url: str """ session = Session(timeout=COUCH_TIMEOUT) server = Server(url=url, session=session) yield server session.close_connections() class CouchDatabase(CommonBackend): """ A U1DB implementation that uses CouchDB as its persistence layer. """ # We spawn threads to parallelize the CouchDatabase.get_docs() method MAX_GET_DOCS_THREADS = 20 update_handler_lock = defaultdict(threading.Lock) class _GetDocThread(threading.Thread): """ A thread that gets a document from a database. TODO: switch this for a twisted deferred to thread. This depends on replacing python-couchdb for paisley in this module. """ def __init__(self, db, doc_id, check_for_conflicts, release_fun): """ :param db: The database from where to get the document. :type db: CouchDatabase :param doc_id: The doc_id of the document to be retrieved. :type doc_id: str :param check_for_conflicts: Whether the get_doc() method should check for existing conflicts. :type check_for_conflicts: bool :param release_fun: A function that releases a semaphore, to be called after the document is fetched. :type release_fun: function """ threading.Thread.__init__(self) self._db = db self._doc_id = doc_id self._check_for_conflicts = check_for_conflicts self._release_fun = release_fun self._doc = None def run(self): """ Fetch the document, store it as a property, and call the release function. """ self._doc = self._db._get_doc( self._doc_id, self._check_for_conflicts) self._release_fun() @classmethod def open_database(cls, url, create, replica_uid=None, ensure_ddocs=False): """ 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 :param replica_uid: an optional unique replica identifier :type replica_uid: str :param ensure_ddocs: Ensure that the design docs exist on server. :type ensure_ddocs: 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) with couch_server(url) as server: try: server[dbname] except ResourceNotFound: if not create: raise DatabaseDoesNotExist() server.create(dbname) return cls(url, dbname, replica_uid=replica_uid, ensure_ddocs=ensure_ddocs) def __init__(self, url, dbname, replica_uid=None, ensure_ddocs=True): """ 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 ensure_ddocs: Ensure that the design docs exist on server. :type ensure_ddocs: bool """ # save params self._url = url self._session = Session(timeout=COUCH_TIMEOUT) self._factory = CouchDocument self._real_replica_uid = None # configure couch self._dbname = dbname self._database = Database( urljoin(self._url, self._dbname), self._session) if replica_uid is not None: self._set_replica_uid(replica_uid) if ensure_ddocs: self.ensure_ddocs_on_db() # initialize a thread pool for parallelizing get_docs() self._sem_pool = threading.BoundedSemaphore( value=self.MAX_GET_DOCS_THREADS) def ensure_ddocs_on_db(self): """ Ensure that the design documents used by the backend exist on the couch database. """ # we check for existence of one of the files, and put all of them if # that one does not exist try: self._database['_design/docs'] return except ResourceNotFound: for ddoc_name in ['docs', 'syncs', 'transactions']: ddoc = json.loads( binascii.a2b_base64( getattr(ddocs, ddoc_name))) self._database.save(ddoc) 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 delete_database(self): """ Delete a U1DB CouchDB database. """ with couch_server(self._url) as server: del(server[self._dbname]) self.close_connections() def close(self): """ Release any resources associated with this database. :return: True if db was succesfully closed. :rtype: bool """ self.close_connections() self._url = None self._full_commit = None self._session = None self._database = None return True def close_connections(self): """ Close all open connections to the couch server. """ if self._session is not None: self._session.close_connections() def __del__(self): """ Close the database upon garbage collection. """ self.close() def _set_replica_uid(self, replica_uid): """ Force the replica uid to be set. :param replica_uid: The new replica uid. :type replica_uid: str """ try: # set on existent config document doc = self._database['u1db_config'] doc['replica_uid'] = replica_uid except ResourceNotFound: # or create the config document doc = { '_id': 'u1db_config', 'replica_uid': replica_uid, } self._database.save(doc) self._real_replica_uid = replica_uid def _get_replica_uid(self): """ Get the replica uid. :return: The replica uid. :rtype: str """ if self._real_replica_uid is not None: return self._real_replica_uid try: # grab replica_uid from server doc = self._database['u1db_config'] self._real_replica_uid = doc['replica_uid'] return self._real_replica_uid except ResourceNotFound: # create a unique replica_uid self._real_replica_uid = uuid.uuid4().hex self._set_replica_uid(self._real_replica_uid) return self._real_replica_uid _replica_uid = property(_get_replica_uid, _set_replica_uid) def _get_generation(self): """ Return the current generation. :return: The current generation. :rtype: int :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ # query a couch list function ddoc_path = ['_design', 'transactions', '_list', 'generation', 'log'] res = self._database.resource(*ddoc_path) try: response = res.get_json() return response[2]['generation'] except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) except ServerError as e: raise_server_error(e, ddoc_path) def _get_generation_info(self): """ Return the current generation. :return: A tuple containing the current generation and transaction id. :rtype: (int, str) :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ # query a couch list function ddoc_path = ['_design', 'transactions', '_list', 'generation', 'log'] res = self._database.resource(*ddoc_path) try: response = res.get_json() return (response[2]['generation'], response[2]['transaction_id']) except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) except ServerError as e: raise_server_error(e, ddoc_path) def _get_trans_id_for_gen(self, generation): """ Get the transaction id corresponding to a particular generation. :param generation: The generation for which to get the transaction id. :type generation: int :return: The transaction id for C{generation}. :rtype: str :raise InvalidGeneration: Raised when the generation does not exist. :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ if generation == 0: return '' # query a couch list function ddoc_path = [ '_design', 'transactions', '_list', 'trans_id_for_gen', 'log' ] res = self._database.resource(*ddoc_path) try: response = res.get_json(gen=generation) if response[2] == {}: raise InvalidGeneration return response[2]['transaction_id'] except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) except ServerError as e: raise_server_error(e, ddoc_path) def _get_transaction_log(self): """ This is only for the test suite, it is not part of the api. :return: The complete transaction log. :rtype: [(str, str)] :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ # query a couch view ddoc_path = ['_design', 'transactions', '_view', 'log'] res = self._database.resource(*ddoc_path) try: response = res.get_json() return map( lambda row: (row['id'], row['value']), response[2]['rows']) except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) def _get_doc(self, doc_id, check_for_conflicts=False): """ Extract the document from storage. This can return None if the document doesn't exist. :param doc_id: The unique document identifier :type doc_id: str :param check_for_conflicts: If set to False, then the conflict check will be skipped. :type check_for_conflicts: bool :return: The document. :rtype: CouchDocument """ # get document with all attachments (u1db content and eventual # conflicts) try: result = \ self._database.resource(doc_id).get_json( attachments=True)[2] except ResourceNotFound: return None # restrict to u1db documents if 'u1db_rev' not in result: return None doc = self._factory(doc_id, result['u1db_rev']) # set contents or make tombstone if '_attachments' not in result \ or 'u1db_content' not in result['_attachments']: doc.make_tombstone() else: doc.content = json.loads( binascii.a2b_base64( result['_attachments']['u1db_content']['data'])) # determine if there are conflicts if check_for_conflicts \ and '_attachments' in result \ and 'u1db_conflicts' in result['_attachments']: doc.has_conflicts = True doc.set_conflicts( self._build_conflicts( doc.doc_id, json.loads(binascii.a2b_base64( result['_attachments']['u1db_conflicts']['data'])))) # store couch revision doc.couch_rev = result['_rev'] # store transactions doc.transactions = result['u1db_transactions'] return doc def get_doc(self, doc_id, include_deleted=False): """ Get the JSON string for the given document. :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. :rtype: CouchDocument. """ doc = self._get_doc(doc_id, check_for_conflicts=True) if doc is None: return None if doc.is_tombstone() and not include_deleted: return None 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, [CouchDocument]) The current generation of the database, followed by a list of all the documents in the database. :rtype: (int, [CouchDocument]) """ generation = self._get_generation() results = [] for row in self._database.view('_all_docs'): doc = self.get_doc(row.id, include_deleted=include_deleted) if doc is not None: results.append(doc) return (generation, results) def _put_doc(self, old_doc, doc): """ Put the document in the Couch backend database. Note that C{old_doc} must have been fetched with the parameter C{check_for_conflicts} equal to True, so we can properly update the new document using the conflict information from the old one. :param old_doc: The old document version. :type old_doc: CouchDocument :param doc: The document to be put. :type doc: CouchDocument :raise RevisionConflict: Raised when trying to update a document but couch revisions mismatch. :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ attachments = {} # we save content and conflicts as attachments parts = [] # and we put it using couch's multipart PUT # save content as attachment if doc.is_tombstone() is False: content = doc.get_json() attachments['u1db_content'] = { 'follows': True, 'content_type': 'application/octet-stream', 'length': len(content), } parts.append(content) # save conflicts as attachment if doc.has_conflicts is True: conflicts = json.dumps( map(lambda cdoc: (cdoc.rev, cdoc.content), doc.get_conflicts())) attachments['u1db_conflicts'] = { 'follows': True, 'content_type': 'application/octet-stream', 'length': len(conflicts), } parts.append(conflicts) # store old transactions, if any transactions = old_doc.transactions[:] if old_doc is not None else [] # create a new transaction id and timestamp it so the transaction log # is consistent when querying the database. transactions.append( # here we store milliseconds to keep consistent with javascript # Date.prototype.getTime() which was used before inside a couchdb # update handler. (int(time.time() * 1000), self._allocate_transaction_id())) # build the couch document couch_doc = { '_id': doc.doc_id, 'u1db_rev': doc.rev, 'u1db_transactions': transactions, '_attachments': attachments, } # if we are updating a doc we have to add the couch doc revision if old_doc is not None: couch_doc['_rev'] = old_doc.couch_rev # prepare the multipart PUT buf = StringIO() envelope = MultipartWriter(buf) envelope.add('application/json', json.dumps(couch_doc)) for part in parts: envelope.add('application/octet-stream', part) envelope.close() # try to save and fail if there's a revision conflict try: self._database.resource.put_json( doc.doc_id, body=buf.getvalue(), headers=envelope.headers) # What follows is a workaround for an ugly bug. See: # https://leap.se/code/issues/5448 self.close_connections() except ResourceConflict: raise RevisionConflict() def put_doc(self, doc): """ Update a document. If the document currently has conflicts, put will fail. If the database specifies a maximum document size and the document exceeds it, put will fail and raise a DocumentTooBig exception. :param doc: A Document with new content. :return: new_doc_rev - The new revision identifier for the document. The Document object will also be updated. :raise InvalidDocId: Raised if the document's id is invalid. :raise DocumentTooBig: Raised if the document size is too big. :raise ConflictedDoc: Raised if the document has conflicts. """ if doc.doc_id is None: raise InvalidDocId() self._check_doc_id(doc.doc_id) self._check_doc_size(doc) old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True) if old_doc and old_doc.has_conflicts: raise ConflictedDoc() if old_doc and doc.rev is None and old_doc.is_tombstone(): new_rev = self._allocate_doc_rev(old_doc.rev) else: if old_doc is not None: if old_doc.rev != doc.rev: raise RevisionConflict() else: if doc.rev is not None: raise RevisionConflict() new_rev = self._allocate_doc_rev(doc.rev) doc.rev = new_rev self._put_doc(old_doc, doc) return new_rev def whats_changed(self, old_generation=0): """ Return a list of documents that have changed since old_generation. :param old_generation: The generation of the database in the old state. :type old_generation: int :return: (generation, trans_id, [(doc_id, generation, trans_id),...]) The current generation of the database, its associated transaction id, and a list of of changed documents since old_generation, represented by tuples with for each document its doc_id and the generation and transaction id corresponding to the last intervening change and sorted by generation (old changes first) :rtype: (int, str, [(str, int, str)]) :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ # query a couch list function ddoc_path = [ '_design', 'transactions', '_list', 'whats_changed', 'log' ] res = self._database.resource(*ddoc_path) try: response = res.get_json(old_gen=old_generation) results = map( lambda row: (row['generation'], row['doc_id'], row['transaction_id']), response[2]['transactions']) results.reverse() cur_gen = old_generation seen = set() changes = [] newest_trans_id = '' for generation, doc_id, trans_id in results: if doc_id not in seen: changes.append((doc_id, generation, trans_id)) seen.add(doc_id) if changes: cur_gen = changes[0][1] # max generation newest_trans_id = changes[0][2] changes.reverse() else: cur_gen, newest_trans_id = self._get_generation_info() return cur_gen, newest_trans_id, changes except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) except ServerError as e: raise_server_error(e, ddoc_path) def delete_doc(self, doc): """ Mark a document as deleted. Will abort if the current revision doesn't match doc.rev. This will also set doc.content to None. :param doc: The document to mark as deleted. :type doc: CouchDocument. :raise DocumentDoesNotExist: Raised if the document does not exist. :raise RevisionConflict: Raised if the revisions do not match. :raise DocumentAlreadyDeleted: Raised if the document is already deleted. :raise ConflictedDoc: Raised if the doc has conflicts. """ old_doc = self._get_doc(doc.doc_id, check_for_conflicts=True) if old_doc is None: raise DocumentDoesNotExist if old_doc.rev != doc.rev: raise RevisionConflict() if old_doc.is_tombstone(): raise DocumentAlreadyDeleted if old_doc.has_conflicts: raise ConflictedDoc() new_rev = self._allocate_doc_rev(doc.rev) doc.rev = new_rev doc.make_tombstone() self._put_doc(old_doc, doc) return new_rev def _build_conflicts(self, doc_id, attached_conflicts): """ Build the conflicted documents list from the conflicts attachment fetched from a couch document. :param attached_conflicts: The document's conflicts as fetched from a couch document attachment. :type attached_conflicts: dict """ conflicts = [] for doc_rev, content in attached_conflicts: doc = self._factory(doc_id, doc_rev) if content is None: doc.make_tombstone() else: doc.content = content conflicts.append(doc) return conflicts def _get_conflicts(self, doc_id, couch_rev=None): """ Get the conflicted versions of a document. If the C{couch_rev} parameter is not None, conflicts for a specific document's couch revision are returned. :param couch_rev: The couch document revision. :type couch_rev: str :return: A list of conflicted versions of the document. :rtype: list """ # request conflicts attachment from server params = {} if couch_rev is not None: params['rev'] = couch_rev # restric document's couch revision resource = self._database.resource(doc_id, 'u1db_conflicts') try: response = resource.get_json(**params) return self._build_conflicts( doc_id, json.loads(response[2].read())) except ResourceNotFound: return [] def get_doc_conflicts(self, doc_id): """ Get the list of conflicts for the given document. The order of the conflicts is such that the first entry is the value that would be returned by "get_doc". :return: A list of the document entries that are conflicted. :rtype: [CouchDocument] """ conflict_docs = self._get_conflicts(doc_id) if len(conflict_docs) == 0: return [] this_doc = self._get_doc(doc_id, check_for_conflicts=True) return [this_doc] + conflict_docs def _get_replica_gen_and_trans_id(self, other_replica_uid): """ Return the last known generation and transaction id for the other db replica. When you do a synchronization with another replica, the Database keeps track of what generation the other database replica was at, and what the associated transaction id was. This is used to determine what data needs to be sent, and if two databases are claiming to be the same replica. :param other_replica_uid: The identifier for the other replica. :type other_replica_uid: str :return: A tuple containing the generation and transaction id we encountered during synchronization. If we've never synchronized with the replica, this is (0, ''). :rtype: (int, str) """ # query a couch view result = self._database.view('syncs/log') if len(result[other_replica_uid].rows) == 0: return (0, '') return ( result[other_replica_uid].rows[0]['value']['known_generation'], result[other_replica_uid].rows[0]['value']['known_transaction_id'] ) def _set_replica_gen_and_trans_id(self, other_replica_uid, other_generation, other_transaction_id): """ Set the last-known generation and transaction id for the other database replica. We have just performed some synchronization, and we want to track what generation the other replica was at. See also _get_replica_gen_and_trans_id. :param other_replica_uid: The U1DB identifier for the other replica. :type other_replica_uid: str :param other_generation: The generation number for the other replica. :type other_generation: int :param other_transaction_id: The transaction id associated with the generation. :type other_transaction_id: str """ self._do_set_replica_gen_and_trans_id( other_replica_uid, other_generation, other_transaction_id) def _do_set_replica_gen_and_trans_id( self, other_replica_uid, other_generation, other_transaction_id): """ Set the last-known generation and transaction id for the other database replica. We have just performed some synchronization, and we want to track what generation the other replica was at. See also _get_replica_gen_and_trans_id. :param other_replica_uid: The U1DB identifier for the other replica. :type other_replica_uid: str :param other_generation: The generation number for the other replica. :type other_generation: int :param other_transaction_id: The transaction id associated with the generation. :type other_transaction_id: str :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ # query a couch update function ddoc_path = ['_design', 'syncs', '_update', 'put', 'u1db_sync_log'] res = self._database.resource(*ddoc_path) try: with CouchDatabase.update_handler_lock[self._get_replica_uid()]: res.put_json( body={ 'other_replica_uid': other_replica_uid, 'other_generation': other_generation, 'other_transaction_id': other_transaction_id, }, headers={'content-type': 'application/json'}) except ResourceNotFound as e: raise_missing_design_doc_error(e, ddoc_path) def _add_conflict(self, doc, my_doc_rev, my_content): """ Add a conflict to the document. Note that this method does not actually update the backend; rather, it updates the CouchDocument object which will provide the conflict data when the atomic document update is made. :param doc: The document to have conflicts added to. :type doc: CouchDocument :param my_doc_rev: The revision of the conflicted document. :type my_doc_rev: str :param my_content: The content of the conflicted document as a JSON serialized string. :type my_content: str """ doc._ensure_fetch_conflicts(self._get_conflicts) doc.add_conflict( self._factory(doc_id=doc.doc_id, rev=my_doc_rev, json=my_content)) def _delete_conflicts(self, doc, conflict_revs): """ Delete the conflicted revisions from the list of conflicts of C{doc}. Note that this method does not actually update the backend; rather, it updates the CouchDocument object which will provide the conflict data when the atomic document update is made. :param doc: The document to have conflicts deleted. :type doc: CouchDocument :param conflict_revs: A list of the revisions to be deleted. :param conflict_revs: [str] """ doc._ensure_fetch_conflicts(self._get_conflicts) doc.delete_conflicts(conflict_revs) def _prune_conflicts(self, doc, doc_vcr): """ Prune conflicts that are older then the current document's revision, or whose content match to the current document's content. :param doc: The document to have conflicts pruned. :type doc: CouchDocument :param doc_vcr: A vector clock representing the current document's revision. :type doc_vcr: u1db.vectorclock.VectorClock """ if doc.has_conflicts is True: autoresolved = False c_revs_to_prune = [] for c_doc in doc.get_conflicts(): c_vcr = vectorclock.VectorClockRev(c_doc.rev) if doc_vcr.is_newer(c_vcr): c_revs_to_prune.append(c_doc.rev) elif doc.same_content_as(c_doc): c_revs_to_prune.append(c_doc.rev) doc_vcr.maximize(c_vcr) autoresolved = True if autoresolved: doc_vcr.increment(self._replica_uid) doc.rev = doc_vcr.as_str() self._delete_conflicts(doc, c_revs_to_prune) def _force_doc_sync_conflict(self, doc): """ Add a conflict and force a document put. :param doc: The document to be put. :type doc: CouchDocument """ my_doc = self._get_doc(doc.doc_id, check_for_conflicts=True) self._prune_conflicts(doc, vectorclock.VectorClockRev(doc.rev)) self._add_conflict(doc, my_doc.rev, my_doc.get_json()) doc.has_conflicts = True self._put_doc(my_doc, doc) def resolve_doc(self, doc, conflicted_doc_revs): """ Mark a document as no longer conflicted. We take the list of revisions that the client knows about that it is superseding. This may be a different list from the actual current conflicts, in which case only those are removed as conflicted. This may fail if the conflict list is significantly different from the supplied information. (sync could have happened in the background from the time you GET_DOC_CONFLICTS until the point where you RESOLVE) :param doc: A Document with the new content to be inserted. :type doc: CouchDocument :param conflicted_doc_revs: A list of revisions that the new content supersedes. :type conflicted_doc_revs: [str] :raise MissingDesignDocError: Raised when tried to access a missing design document. :raise MissingDesignDocListFunctionError: Raised when trying to access a missing list function on a design document. :raise MissingDesignDocNamedViewError: Raised when trying to access a missing named view on a design document. :raise MissingDesignDocDeletedError: Raised when trying to access a deleted design document. :raise MissingDesignDocUnknownError: Raised when failed to access a design document for an yet unknown reason. """ cur_doc = self._get_doc(doc.doc_id, check_for_conflicts=True) new_rev = self._ensure_maximal_rev(cur_doc.rev, conflicted_doc_revs) superseded_revs = set(conflicted_doc_revs) doc.rev = new_rev # this backend stores conflicts as properties of the documents, so we # have to copy these conflicts over to the document being updated. if cur_doc.rev in superseded_revs: # the newer doc version will supersede the one in the database, so # we copy conflicts before updating the backend. doc.set_conflicts(cur_doc.get_conflicts()) # copy conflicts over. self._delete_conflicts(doc, superseded_revs) self._put_doc(cur_doc, doc) else: # the newer doc version does not supersede the one in the # database, so we will add a conflict to the database and copy # those over to the document the user has in her hands. self._add_conflict(cur_doc, new_rev, doc.get_json()) self._delete_conflicts(cur_doc, superseded_revs) self._put_doc(cur_doc, cur_doc) # just update conflicts # backend has been updated with current conflicts, now copy them # to the current document. doc.set_conflicts(cur_doc.get_conflicts()) def _put_doc_if_newer(self, doc, save_conflict, replica_uid, replica_gen, replica_trans_id=''): """ Insert/update document into the database with a given revision. This api is used during synchronization operations. If a document would conflict and save_conflict is set to True, the content will be selected as the 'current' content for doc.doc_id, even though doc.rev doesn't supersede the currently stored revision. The currently stored document will be added to the list of conflict alternatives for the given doc_id. This forces the new content to be 'current' so that we get convergence after synchronizing, even if people don't resolve conflicts. Users can then notice that their content is out of date, update it, and synchronize again. (The alternative is that users could synchronize and think the data has propagated, but their local copy looks fine, and the remote copy is never updated again.) :param doc: A document object :type doc: CouchDocument :param save_conflict: If this document is a conflict, do you want to save it as a conflict, or just ignore it. :type save_conflict: bool :param replica_uid: A unique replica identifier. :type replica_uid: str :param replica_gen: The generation of the replica corresponding to the this document. The replica arguments are optional, but are used during synchronization. :type replica_gen: int :param replica_trans_id: The transaction_id associated with the generation. :type replica_trans_id: str :return: (state, at_gen) - If we don't have doc_id already, or if doc_rev supersedes the existing document revision, then the content will be inserted, and state is 'inserted'. If doc_rev is less than or equal to the existing revision, then the put is ignored and state is respecitvely 'superseded' or 'converged'. If doc_rev is not strictly superseded or supersedes, then state is 'conflicted'. The document will not be inserted if save_conflict is False. For 'inserted' or 'converged', at_gen is the insertion/current generation. :rtype: (str, int) """ cur_doc = self._get_doc(doc.doc_id, check_for_conflicts=True) # at this point, `doc` has arrived from the other syncing party, and # we will decide what to do with it. # First, we prepare the arriving doc to update couch database. old_doc = doc doc = self._factory(doc.doc_id, doc.rev, doc.get_json()) if cur_doc is not None: doc.couch_rev = cur_doc.couch_rev # fetch conflicts because we will eventually manipulate them doc._ensure_fetch_conflicts(self._get_conflicts) # from now on, it works just like u1db sqlite backend doc_vcr = vectorclock.VectorClockRev(doc.rev) if cur_doc is None: cur_vcr = vectorclock.VectorClockRev(None) else: cur_vcr = vectorclock.VectorClockRev(cur_doc.rev) self._validate_source(replica_uid, replica_gen, replica_trans_id) if doc_vcr.is_newer(cur_vcr): rev = doc.rev self._prune_conflicts(doc, doc_vcr) if doc.rev != rev: # conflicts have been autoresolved state = 'superseded' else: state = 'inserted' self._put_doc(cur_doc, doc) elif doc.rev == cur_doc.rev: # magical convergence state = 'converged' elif cur_vcr.is_newer(doc_vcr): # Don't add this to seen_ids, because we have something newer, # so we should send it back, and we should not generate a # conflict state = 'superseded' elif cur_doc.same_content_as(doc): # the documents have been edited to the same thing at both ends doc_vcr.maximize(cur_vcr) doc_vcr.increment(self._replica_uid) doc.rev = doc_vcr.as_str() self._put_doc(cur_doc, doc) state = 'superseded' else: state = 'conflicted' if save_conflict: self._force_doc_sync_conflict(doc) if replica_uid is not None and replica_gen is not None: self._set_replica_gen_and_trans_id( replica_uid, replica_gen, replica_trans_id) # update info old_doc.rev = doc.rev if doc.is_tombstone(): old_doc.is_tombstone() else: old_doc.content = doc.content old_doc.has_conflicts = doc.has_conflicts return state, self._get_generation() def get_docs(self, doc_ids, check_for_conflicts=True, include_deleted=False): """ Get the JSON content for many documents. :param doc_ids: A list of document identifiers. :type doc_ids: list :param check_for_conflicts: If set to False, then the conflict check will be skipped, and 'None' will be returned instead of True/False. :type check_for_conflictsa: bool :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. :return: iterable giving the Document object for each document id in matching doc_ids order. :rtype: iterable """ # Workaround for: # # http://bugs.python.org/issue7980 # https://leap.se/code/issues/5449 # # python-couchdb uses time.strptime, which is not thread safe. In # order to avoid the problem described on the issues above, we preload # strptime here by evaluating the conversion of an arbitrary date. # This will not be needed when/if we switch from python-couchdb to # paisley. time.strptime('Mar 8 1917', '%b %d %Y') # spawn threads to retrieve docs threads = [] for doc_id in doc_ids: self._sem_pool.acquire() t = self._GetDocThread(self, doc_id, check_for_conflicts, self._sem_pool.release) t.start() threads.append(t) # join threads and yield docs for t in threads: t.join() if t._doc.is_tombstone() and not include_deleted: continue yield t._doc class CouchSyncTarget(CommonSyncTarget): """ Functionality for using a CouchDatabase as a synchronization target. """ def get_sync_info(self, source_replica_uid): source_gen, source_trans_id = self._db._get_replica_gen_and_trans_id( source_replica_uid) my_gen, my_trans_id = self._db._get_generation_info() return ( self._db._replica_uid, my_gen, my_trans_id, source_gen, source_trans_id) def record_sync_info(self, source_replica_uid, source_replica_generation, source_replica_transaction_id): if self._trace_hook: self._trace_hook('record_sync_info') self._db._set_replica_gen_and_trans_id( source_replica_uid, source_replica_generation, source_replica_transaction_id) class CouchServerState(ServerState): """ Inteface of the WSGI server with the CouchDB backend. """ def __init__(self, couch_url, shared_db_name, tokens_db_name): """ Initialize the couch server state. :param couch_url: The URL for the couch database. :type couch_url: str :param shared_db_name: The name of the shared database. :type shared_db_name: str :param tokens_db_name: The name of the tokens database. :type tokens_db_name: str """ self._couch_url = couch_url self._shared_db_name = shared_db_name self._tokens_db_name = tokens_db_name 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 """ return CouchDatabase( self._couch_url, dbname, ensure_ddocs=False) def ensure_database(self, dbname): """ Ensure couch database exists. Usually, this method is used by the server to ensure the existence of a database. In our setup, the Soledad user that accesses the underlying couch server should never have permission to create (or delete) databases. But, in case it ever does, by raising an exception here we have one more guarantee that no modified client will be able to enforce creation of a database when syncing. :param dbname: The name of the database to ensure. :type dbname: str :return: The CouchDatabase object and the replica uid. :rtype: (CouchDatabase, str) """ raise Unauthorized() def delete_database(self, dbname): """ Delete couch database. :param dbname: The name of the database to delete. :type dbname: str """ raise Unauthorized() 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')