path: root/synapse/storage/event_federation.py

# -*- coding: utf-8 -*-
# Copyright 2014 OpenMarket Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from ._base import SQLBaseStore
from syutil.base64util import encode_base64

import logging


logger = logging.getLogger(__name__)


class EventFederationStore(SQLBaseStore):
    """ Responsible for storing and serving up the various graphs associated
    with an event. Including the main event graph and the auth chains for an
    event.

    Also has methods for getting the front (latest) and back (oldest) edges
    of the event graphs. These are used to generate the parents for new events
    and backfilling from another server respectively.
    """

    def get_auth_chain(self, event_id):
        return self.runInteraction(
            "get_auth_chain",
            self._get_auth_chain_txn,
            event_id
        )

    def _get_auth_chain_txn(self, txn, event_id):
        results = self._get_auth_chain_ids_txn(txn, event_id)

        sql = "SELECT * FROM events WHERE event_id = ?"
        rows = []
        for ev_id in results:
            c = txn.execute(sql, (ev_id,))
            rows.extend(self.cursor_to_dict(c))

        return self._parse_events_txn(txn, rows)

    def get_auth_chain_ids(self, event_id):
        return self.runInteraction(
            "get_auth_chain_ids",
            self._get_auth_chain_ids_txn,
            event_id
        )

    def _get_auth_chain_ids_txn(self, txn, event_id):
        results = set()

        base_sql = (
            "SELECT auth_id FROM event_auth WHERE %s"
        )

        front = set([event_id])
        while front:
            sql = base_sql % (
                " OR ".join(["event_id=?"] * len(front)),
            )

            txn.execute(sql, list(front))
            front = [r[0] for r in txn.fetchall()]
            results.update(front)

        return list(results)

    def get_oldest_events_in_room(self, room_id):
        return self.runInteraction(
            "get_oldest_events_in_room",
            self._get_oldest_events_in_room_txn,
            room_id,
        )

    def _get_oldest_events_in_room_txn(self, txn, room_id):
        return self._simple_select_onecol_txn(
            txn,
            table="event_backward_extremities",
            keyvalues={
                "room_id": room_id,
            },
            retcol="event_id",
        )

    def get_latest_events_in_room(self, room_id):
        return self.runInteraction(
            "get_latest_events_in_room",
            self._get_latest_events_in_room,
            room_id,
        )

    def _get_latest_events_in_room(self, txn, room_id):
        sql = (
            "SELECT e.event_id, e.depth FROM events as e "
            "INNER JOIN event_forward_extremities as f "
            "ON e.event_id = f.event_id "
            "WHERE f.room_id = ?"
        )

        txn.execute(sql, (room_id, ))

        results = []
        for event_id, depth in txn.fetchall():
            hashes = self._get_event_reference_hashes_txn(txn, event_id)
            prev_hashes = {
                k: encode_base64(v) for k, v in hashes.items()
                if k == "sha256"
            }
            results.append((event_id, prev_hashes, depth))

        return results

    def _get_latest_state_in_room(self, txn, room_id, type, state_key):
        event_ids = self._simple_select_onecol_txn(
            txn,
            table="state_forward_extremities",
            keyvalues={
                "room_id": room_id,
                "type": type,
                "state_key": state_key,
            },
            retcol="event_id",
        )

        results = []
        for event_id in event_ids:
            hashes = self._get_event_reference_hashes_txn(txn, event_id)
            prev_hashes = {
                k: encode_base64(v) for k, v in hashes.items()
                if k == "sha256"
            }
            results.append((event_id, prev_hashes))

        return results

    def _get_prev_events(self, txn, event_id):
        results = self._get_prev_events_and_state(
            txn,
            event_id,
            is_state=0,
        )

        return [(e_id, h, ) for e_id, h, _ in results]

    def _get_prev_state(self, txn, event_id):
        results = self._get_prev_events_and_state(
            txn,
            event_id,
            is_state=1,
        )

        return [(e_id, h, ) for e_id, h, _ in results]

    def _get_prev_events_and_state(self, txn, event_id, is_state=None):
        keyvalues = {
            "event_id": event_id,
        }

        if is_state is not None:
            keyvalues["is_state"] = is_state

        res = self._simple_select_list_txn(
            txn,
            table="event_edges",
            keyvalues=keyvalues,
            retcols=["prev_event_id", "is_state"],
        )

        results = []
        for d in res:
            hashes = self._get_event_reference_hashes_txn(
                txn,
                d["prev_event_id"]
            )
            prev_hashes = {
                k: encode_base64(v) for k, v in hashes.items()
                if k == "sha256"
            }
            results.append((d["prev_event_id"], prev_hashes, d["is_state"]))

        return results

    def _get_auth_events(self, txn, event_id):
        auth_ids = self._simple_select_onecol_txn(
            txn,
            table="event_auth",
            keyvalues={
                "event_id": event_id,
            },
            retcol="auth_id",
        )

        results = []
        for auth_id in auth_ids:
            hashes = self._get_event_reference_hashes_txn(txn, auth_id)
            prev_hashes = {
                k: encode_base64(v) for k, v in hashes.items()
                if k == "sha256"
            }
            results.append((auth_id, prev_hashes))

        return results

    def get_min_depth(self, room_id):
        """ For hte given room, get the minimum depth we have seen for it.
        """
        return self.runInteraction(
            "get_min_depth",
            self._get_min_depth_interaction,
            room_id,
        )

    def _get_min_depth_interaction(self, txn, room_id):
        min_depth = self._simple_select_one_onecol_txn(
            txn,
            table="room_depth",
            keyvalues={"room_id": room_id},
            retcol="min_depth",
            allow_none=True,
        )

        return int(min_depth) if min_depth is not None else None

    def _update_min_depth_for_room_txn(self, txn, room_id, depth):
        min_depth = self._get_min_depth_interaction(txn, room_id)

        do_insert = depth < min_depth if min_depth else True

        if do_insert:
            self._simple_insert_txn(
                txn,
                table="room_depth",
                values={
                    "room_id": room_id,
                    "min_depth": depth,
                },
                or_replace=True,
            )

    def _handle_prev_events(self, txn, outlier, event_id, prev_events,
                            room_id):
        """
        For the given event, update the event edges table and forward and
        backward extremities tables.
        """
        for e_id, _ in prev_events:
            # TODO (erikj): This could be done as a bulk insert
            self._simple_insert_txn(
                txn,
                table="event_edges",
                values={
                    "event_id": event_id,
                    "prev_event_id": e_id,
                    "room_id": room_id,
                    "is_state": 0,
                },
                or_ignore=True,
            )

        # Update the extremities table if this is not an outlier.
        if not outlier:
            for e_id, _ in prev_events:
                # TODO (erikj): This could be done as a bulk insert
                self._simple_delete_txn(
                    txn,
                    table="event_forward_extremities",
                    keyvalues={
                        "event_id": e_id,
                        "room_id": room_id,
                    }
                )

            # We only insert as a forward extremity the new event if there are
            # no other events that reference it as a prev event
            query = (
                "INSERT OR IGNORE INTO %(table)s (event_id, room_id) "
                "SELECT ?, ? WHERE NOT EXISTS ("
                "SELECT 1 FROM %(event_edges)s WHERE "
                "prev_event_id = ? "
                ")"
            ) % {
                "table": "event_forward_extremities",
                "event_edges": "event_edges",
            }

            logger.debug("query: %s", query)

            txn.execute(query, (event_id, room_id, event_id))

            # Insert all the prev_events as a backwards thing, they'll get
            # deleted in a second if they're incorrect anyway.
            for e_id, _ in prev_events:
                # TODO (erikj): This could be done as a bulk insert
                self._simple_insert_txn(
                    txn,
                    table="event_backward_extremities",
                    values={
                        "event_id": e_id,
                        "room_id": room_id,
                    },
                    or_ignore=True,
                )

            # Also delete from the backwards extremities table all ones that
            # reference events that we have already seen
            query = (
                "DELETE FROM event_backward_extremities WHERE EXISTS ("
                "SELECT 1 FROM events "
                "WHERE "
                "event_backward_extremities.event_id = events.event_id "
                "AND not events.outlier "
                ")"
            )
            txn.execute(query)

    def get_backfill_events(self, room_id, event_list, limit):
        """Get a list of Events for a given topic that occurred before (and
        including) the events in event_list. Return a list of max size `limit`

        Args:
            txn
            room_id (str)
            event_list (list)
            limit (int)
        """
        return self.runInteraction(
            "get_backfill_events",
            self._get_backfill_events, room_id, event_list, limit
        )

    def _get_backfill_events(self, txn, room_id, event_list, limit):
        logger.debug(
            "_get_backfill_events: %s, %s, %s",
            room_id, repr(event_list), limit
        )

        event_results = event_list

        front = event_list

        query = (
            "SELECT prev_event_id FROM event_edges "
            "WHERE room_id = ? AND event_id = ? "
            "LIMIT ?"
        )

        # We iterate through all event_ids in `front` to select their previous
        # events. These are dumped in `new_front`.
        # We continue until we reach the limit *or* new_front is empty (i.e.,
        # we've run out of things to select
        while front and len(event_results) < limit:

            new_front = []
            for event_id in front:
                logger.debug(
                    "_backfill_interaction: id=%s",
                    event_id
                )

                txn.execute(
                    query,
                    (room_id, event_id, limit - len(event_results))
                )

                for row in txn.fetchall():
                    logger.debug(
                        "_backfill_interaction: got id=%s",
                        *row
                    )
                    new_front.append(row[0])

            front = new_front
            event_results += new_front

        return self._get_events_txn(txn, event_results)