661 lines
22 KiB
Python
661 lines
22 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2014 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""This layer is responsible for replicating with remote home servers using
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a given transport.
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"""
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from twisted.internet import defer
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from .units import Transaction, Pdu, Edu
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from .persistence import PduActions, TransactionActions
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from synapse.util.logutils import log_function
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import logging
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logger = logging.getLogger(__name__)
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class ReplicationLayer(object):
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"""This layer is responsible for replicating with remote home servers over
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the given transport. I.e., does the sending and receiving of PDUs to
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remote home servers.
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The layer communicates with the rest of the server via a registered
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ReplicationHandler.
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In more detail, the layer:
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* Receives incoming data and processes it into transactions and pdus.
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* Fetches any PDUs it thinks it might have missed.
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* Keeps the current state for contexts up to date by applying the
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suitable conflict resolution.
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* Sends outgoing pdus wrapped in transactions.
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* Fills out the references to previous pdus/transactions appropriately
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for outgoing data.
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"""
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def __init__(self, hs, transport_layer):
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self.server_name = hs.hostname
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self.transport_layer = transport_layer
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self.transport_layer.register_received_handler(self)
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self.transport_layer.register_request_handler(self)
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self.store = hs.get_datastore()
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self.pdu_actions = PduActions(self.store)
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self.transaction_actions = TransactionActions(self.store)
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self._transaction_queue = _TransactionQueue(
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hs, self.transaction_actions, transport_layer
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)
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self.handler = None
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self.edu_handlers = {}
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self.query_handlers = {}
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self._order = 0
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self._clock = hs.get_clock()
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def set_handler(self, handler):
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"""Sets the handler that the replication layer will use to communicate
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receipt of new PDUs from other home servers. The required methods are
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documented on :py:class:`.ReplicationHandler`.
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"""
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self.handler = handler
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def register_edu_handler(self, edu_type, handler):
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if edu_type in self.edu_handlers:
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raise KeyError("Already have an EDU handler for %s" % (edu_type))
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self.edu_handlers[edu_type] = handler
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def register_query_handler(self, query_type, handler):
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"""Sets the handler callable that will be used to handle an incoming
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federation Query of the given type.
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Args:
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query_type (str): Category name of the query, which should match
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the string used by make_query.
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handler (callable): Invoked to handle incoming queries of this type
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handler is invoked as:
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result = handler(args)
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where 'args' is a dict mapping strings to strings of the query
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arguments. It should return a Deferred that will eventually yield an
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object to encode as JSON.
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"""
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if query_type in self.query_handlers:
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raise KeyError("Already have a Query handler for %s" % (query_type))
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self.query_handlers[query_type] = handler
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@defer.inlineCallbacks
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@log_function
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def send_pdu(self, pdu):
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"""Informs the replication layer about a new PDU generated within the
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home server that should be transmitted to others.
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This will fill out various attributes on the PDU object, e.g. the
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`prev_pdus` key.
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*Note:* The home server should always call `send_pdu` even if it knows
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that it does not need to be replicated to other home servers. This is
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in case e.g. someone else joins via a remote home server and then
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backfills.
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TODO: Figure out when we should actually resolve the deferred.
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Args:
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pdu (Pdu): The new Pdu.
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Returns:
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Deferred: Completes when we have successfully processed the PDU
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and replicated it to any interested remote home servers.
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"""
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order = self._order
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self._order += 1
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logger.debug("[%s] Persisting PDU", pdu.pdu_id)
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# Save *before* trying to send
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yield self.store.persist_event(pdu=pdu)
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logger.debug("[%s] Persisted PDU", pdu.pdu_id)
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logger.debug("[%s] transaction_layer.enqueue_pdu... ", pdu.pdu_id)
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# TODO, add errback, etc.
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self._transaction_queue.enqueue_pdu(pdu, order)
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logger.debug("[%s] transaction_layer.enqueue_pdu... done", pdu.pdu_id)
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@log_function
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def send_edu(self, destination, edu_type, content):
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edu = Edu(
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origin=self.server_name,
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destination=destination,
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edu_type=edu_type,
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content=content,
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)
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# TODO, add errback, etc.
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self._transaction_queue.enqueue_edu(edu)
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return defer.succeed(None)
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@log_function
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def make_query(self, destination, query_type, args):
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"""Sends a federation Query to a remote homeserver of the given type
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and arguments.
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Args:
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destination (str): Domain name of the remote homeserver
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query_type (str): Category of the query type; should match the
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handler name used in register_query_handler().
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args (dict): Mapping of strings to strings containing the details
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of the query request.
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Returns:
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a Deferred which will eventually yield a JSON object from the
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response
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"""
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return self.transport_layer.make_query(destination, query_type, args)
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@defer.inlineCallbacks
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@log_function
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def backfill(self, dest, context, limit):
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"""Requests some more historic PDUs for the given context from the
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given destination server.
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Args:
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dest (str): The remote home server to ask.
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context (str): The context to backfill.
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limit (int): The maximum number of PDUs to return.
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Returns:
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Deferred: Results in the received PDUs.
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"""
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extremities = yield self.store.get_oldest_pdus_in_context(context)
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logger.debug("backfill extrem=%s", extremities)
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# If there are no extremeties then we've (probably) reached the start.
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if not extremities:
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return
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transaction_data = yield self.transport_layer.backfill(
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dest, context, extremities, limit)
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logger.debug("backfill transaction_data=%s", repr(transaction_data))
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transaction = Transaction(**transaction_data)
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pdus = [Pdu(outlier=False, **p) for p in transaction.pdus]
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for pdu in pdus:
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yield self._handle_new_pdu(pdu, backfilled=True)
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defer.returnValue(pdus)
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@defer.inlineCallbacks
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@log_function
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def get_pdu(self, destination, pdu_origin, pdu_id, outlier=False):
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"""Requests the PDU with given origin and ID from the remote home
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server.
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This will persist the PDU locally upon receipt.
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Args:
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destination (str): Which home server to query
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pdu_origin (str): The home server that originally sent the pdu.
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pdu_id (str)
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outlier (bool): Indicates whether the PDU is an `outlier`, i.e. if
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it's from an arbitary point in the context as opposed to part
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of the current block of PDUs. Defaults to `False`
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Returns:
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Deferred: Results in the requested PDU.
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"""
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transaction_data = yield self.transport_layer.get_pdu(
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destination, pdu_origin, pdu_id)
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transaction = Transaction(**transaction_data)
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pdu_list = [Pdu(outlier=outlier, **p) for p in transaction.pdus]
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pdu = None
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if pdu_list:
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pdu = pdu_list[0]
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yield self._handle_new_pdu(pdu)
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defer.returnValue(pdu)
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@defer.inlineCallbacks
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@log_function
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def get_state_for_context(self, destination, context):
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"""Requests all of the `current` state PDUs for a given context from
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a remote home server.
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Args:
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destination (str): The remote homeserver to query for the state.
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context (str): The context we're interested in.
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Returns:
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Deferred: Results in a list of PDUs.
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"""
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transaction_data = yield self.transport_layer.get_context_state(
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destination, context)
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transaction = Transaction(**transaction_data)
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pdus = [Pdu(outlier=True, **p) for p in transaction.pdus]
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for pdu in pdus:
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yield self._handle_new_pdu(pdu)
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defer.returnValue(pdus)
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@defer.inlineCallbacks
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@log_function
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def on_context_pdus_request(self, context):
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pdus = yield self.pdu_actions.get_all_pdus_from_context(
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context
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)
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defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
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@defer.inlineCallbacks
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@log_function
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def on_backfill_request(self, context, versions, limit):
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pdus = yield self.pdu_actions.backfill(context, versions, limit)
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defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
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@defer.inlineCallbacks
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@log_function
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def on_incoming_transaction(self, transaction_data):
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transaction = Transaction(**transaction_data)
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for p in transaction.pdus:
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if "age" in p:
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p["age_ts"] = int(self._clock.time_msec()) - int(p["age"])
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del p["age"]
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pdu_list = [Pdu(**p) for p in transaction.pdus]
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logger.debug("[%s] Got transaction", transaction.transaction_id)
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response = yield self.transaction_actions.have_responded(transaction)
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if response:
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logger.debug("[%s] We've already responed to this request",
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transaction.transaction_id)
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defer.returnValue(response)
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return
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logger.debug("[%s] Transacition is new", transaction.transaction_id)
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dl = []
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for pdu in pdu_list:
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dl.append(self._handle_new_pdu(pdu))
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if hasattr(transaction, "edus"):
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for edu in [Edu(**x) for x in transaction.edus]:
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self.received_edu(edu.origin, edu.edu_type, edu.content)
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results = yield defer.DeferredList(dl)
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ret = []
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for r in results:
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if r[0]:
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ret.append({})
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else:
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logger.exception(r[1])
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ret.append({"error": str(r[1])})
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logger.debug("Returning: %s", str(ret))
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yield self.transaction_actions.set_response(
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transaction,
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200, response
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)
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defer.returnValue((200, response))
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def received_edu(self, origin, edu_type, content):
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if edu_type in self.edu_handlers:
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self.edu_handlers[edu_type](origin, content)
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else:
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logger.warn("Received EDU of type %s with no handler", edu_type)
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@defer.inlineCallbacks
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@log_function
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def on_context_state_request(self, context):
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results = yield self.store.get_current_state_for_context(
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context
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)
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logger.debug("Context returning %d results", len(results))
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pdus = [Pdu.from_pdu_tuple(p) for p in results]
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defer.returnValue((200, self._transaction_from_pdus(pdus).get_dict()))
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@defer.inlineCallbacks
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@log_function
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def on_pdu_request(self, pdu_origin, pdu_id):
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pdu = yield self._get_persisted_pdu(pdu_id, pdu_origin)
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if pdu:
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defer.returnValue(
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(200, self._transaction_from_pdus([pdu]).get_dict())
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)
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else:
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defer.returnValue((404, ""))
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@defer.inlineCallbacks
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@log_function
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def on_pull_request(self, origin, versions):
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transaction_id = max([int(v) for v in versions])
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response = yield self.pdu_actions.after_transaction(
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transaction_id,
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origin,
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self.server_name
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)
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if not response:
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response = []
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defer.returnValue(
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(200, self._transaction_from_pdus(response).get_dict())
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)
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@defer.inlineCallbacks
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def on_query_request(self, query_type, args):
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if query_type in self.query_handlers:
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response = yield self.query_handlers[query_type](args)
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defer.returnValue((200, response))
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else:
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defer.returnValue((404, "No handler for Query type '%s'"
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% (query_type)
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))
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@defer.inlineCallbacks
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@log_function
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def _get_persisted_pdu(self, pdu_id, pdu_origin):
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""" Get a PDU from the database with given origin and id.
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Returns:
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Deferred: Results in a `Pdu`.
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"""
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pdu_tuple = yield self.store.get_pdu(pdu_id, pdu_origin)
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defer.returnValue(Pdu.from_pdu_tuple(pdu_tuple))
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def _transaction_from_pdus(self, pdu_list):
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"""Returns a new Transaction containing the given PDUs suitable for
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transmission.
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"""
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pdus = [p.get_dict() for p in pdu_list]
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for p in pdus:
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if "age_ts" in pdus:
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p["age"] = int(self.clock.time_msec()) - p["age_ts"]
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return Transaction(
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origin=self.server_name,
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pdus=pdus,
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ts=int(self._clock.time_msec()),
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destination=None,
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)
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@defer.inlineCallbacks
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@log_function
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def _handle_new_pdu(self, pdu, backfilled=False):
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# We reprocess pdus when we have seen them only as outliers
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existing = yield self._get_persisted_pdu(pdu.pdu_id, pdu.origin)
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if existing and (not existing.outlier or pdu.outlier):
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logger.debug("Already seen pdu %s %s", pdu.pdu_id, pdu.origin)
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defer.returnValue({})
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return
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# Get missing pdus if necessary.
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is_new = yield self.pdu_actions.is_new(pdu)
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if is_new and not pdu.outlier:
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# We only backfill backwards to the min depth.
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min_depth = yield self.store.get_min_depth_for_context(pdu.context)
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if min_depth and pdu.depth > min_depth:
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for pdu_id, origin in pdu.prev_pdus:
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exists = yield self._get_persisted_pdu(pdu_id, origin)
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if not exists:
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logger.debug("Requesting pdu %s %s", pdu_id, origin)
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try:
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yield self.get_pdu(
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pdu.origin,
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pdu_id=pdu_id,
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pdu_origin=origin
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)
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logger.debug("Processed pdu %s %s", pdu_id, origin)
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except:
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# TODO(erikj): Do some more intelligent retries.
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logger.exception("Failed to get PDU")
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# Persist the Pdu, but don't mark it as processed yet.
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yield self.store.persist_event(pdu=pdu)
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if not backfilled:
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ret = yield self.handler.on_receive_pdu(pdu, backfilled=backfilled)
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else:
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ret = None
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yield self.pdu_actions.mark_as_processed(pdu)
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defer.returnValue(ret)
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def __str__(self):
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return "<ReplicationLayer(%s)>" % self.server_name
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class ReplicationHandler(object):
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"""This defines the methods that the :py:class:`.ReplicationLayer` will
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use to communicate with the rest of the home server.
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"""
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def on_receive_pdu(self, pdu):
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raise NotImplementedError("on_receive_pdu")
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class _TransactionQueue(object):
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"""This class makes sure we only have one transaction in flight at
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a time for a given destination.
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It batches pending PDUs into single transactions.
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"""
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def __init__(self, hs, transaction_actions, transport_layer):
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self.server_name = hs.hostname
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self.transaction_actions = transaction_actions
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self.transport_layer = transport_layer
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self._clock = hs.get_clock()
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# Is a mapping from destinations -> deferreds. Used to keep track
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# of which destinations have transactions in flight and when they are
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# done
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self.pending_transactions = {}
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# Is a mapping from destination -> list of
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# tuple(pending pdus, deferred, order)
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self.pending_pdus_by_dest = {}
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# destination -> list of tuple(edu, deferred)
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self.pending_edus_by_dest = {}
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# HACK to get unique tx id
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self._next_txn_id = int(self._clock.time_msec())
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@defer.inlineCallbacks
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@log_function
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def enqueue_pdu(self, pdu, order):
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# We loop through all destinations to see whether we already have
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# a transaction in progress. If we do, stick it in the pending_pdus
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# table and we'll get back to it later.
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destinations = set([
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d for d in pdu.destinations
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if d != self.server_name
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])
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logger.debug("Sending to: %s", str(destinations))
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if not destinations:
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return
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deferreds = []
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for destination in destinations:
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deferred = defer.Deferred()
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self.pending_pdus_by_dest.setdefault(destination, []).append(
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(pdu, deferred, order)
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)
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self._attempt_new_transaction(destination)
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deferreds.append(deferred)
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yield defer.DeferredList(deferreds)
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# NO inlineCallbacks
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def enqueue_edu(self, edu):
|
|
destination = edu.destination
|
|
|
|
deferred = defer.Deferred()
|
|
self.pending_edus_by_dest.setdefault(destination, []).append(
|
|
(edu, deferred)
|
|
)
|
|
|
|
def eb(failure):
|
|
if not deferred.called:
|
|
deferred.errback(failure)
|
|
else:
|
|
logger.exception("Failed to send edu", failure)
|
|
self._attempt_new_transaction(destination).addErrback(eb)
|
|
|
|
return deferred
|
|
|
|
@defer.inlineCallbacks
|
|
@log_function
|
|
def _attempt_new_transaction(self, destination):
|
|
if destination in self.pending_transactions:
|
|
return
|
|
|
|
# list of (pending_pdu, deferred, order)
|
|
pending_pdus = self.pending_pdus_by_dest.pop(destination, [])
|
|
pending_edus = self.pending_edus_by_dest.pop(destination, [])
|
|
|
|
if not pending_pdus and not pending_edus:
|
|
return
|
|
|
|
logger.debug("TX [%s] Attempting new transaction", destination)
|
|
|
|
# Sort based on the order field
|
|
pending_pdus.sort(key=lambda t: t[2])
|
|
|
|
pdus = [x[0] for x in pending_pdus]
|
|
edus = [x[0] for x in pending_edus]
|
|
deferreds = [x[1] for x in pending_pdus + pending_edus]
|
|
|
|
try:
|
|
self.pending_transactions[destination] = 1
|
|
|
|
logger.debug("TX [%s] Persisting transaction...", destination)
|
|
|
|
transaction = Transaction.create_new(
|
|
ts=self._clock.time_msec(),
|
|
transaction_id=self._next_txn_id,
|
|
origin=self.server_name,
|
|
destination=destination,
|
|
pdus=pdus,
|
|
edus=edus,
|
|
)
|
|
|
|
self._next_txn_id += 1
|
|
|
|
yield self.transaction_actions.prepare_to_send(transaction)
|
|
|
|
logger.debug("TX [%s] Persisted transaction", destination)
|
|
logger.debug("TX [%s] Sending transaction...", destination)
|
|
|
|
# Actually send the transaction
|
|
|
|
# FIXME (erikj): This is a bit of a hack to make the Pdu age
|
|
# keys work
|
|
def cb(transaction):
|
|
now = int(self._clock.time_msec())
|
|
if "pdus" in transaction:
|
|
for p in transaction["pdus"]:
|
|
if "age_ts" in p:
|
|
p["age"] = now - int(p["age_ts"])
|
|
|
|
return transaction
|
|
|
|
code, response = yield self.transport_layer.send_transaction(
|
|
transaction,
|
|
on_send_callback=cb,
|
|
)
|
|
|
|
logger.debug("TX [%s] Sent transaction", destination)
|
|
logger.debug("TX [%s] Marking as delivered...", destination)
|
|
|
|
yield self.transaction_actions.delivered(
|
|
transaction, code, response
|
|
)
|
|
|
|
logger.debug("TX [%s] Marked as delivered", destination)
|
|
logger.debug("TX [%s] Yielding to callbacks...", destination)
|
|
|
|
for deferred in deferreds:
|
|
if code == 200:
|
|
deferred.callback(None)
|
|
else:
|
|
deferred.errback(RuntimeError("Got status %d" % code))
|
|
|
|
# Ensures we don't continue until all callbacks on that
|
|
# deferred have fired
|
|
yield deferred
|
|
|
|
logger.debug("TX [%s] Yielded to callbacks", destination)
|
|
|
|
except Exception as e:
|
|
logger.error("TX Problem in _attempt_transaction")
|
|
|
|
# We capture this here as there as nothing actually listens
|
|
# for this finishing functions deferred.
|
|
logger.exception(e)
|
|
|
|
for deferred in deferreds:
|
|
deferred.errback(e)
|
|
|
|
finally:
|
|
# We want to be *very* sure we delete this after we stop processing
|
|
self.pending_transactions.pop(destination, None)
|
|
|
|
# Check to see if there is anything else to send.
|
|
self._attempt_new_transaction(destination)
|