b28674435e
* Correctly generate backpagination tokens for events which have the same depth With tests. Unfortunately the code around here is hard to understand. There will be a subsequent PR which fixes this up now that we have a test harness in place. * Add postgres impl * More linting * Fix psql statement so it actually works
420 lines
14 KiB
Go
420 lines
14 KiB
Go
// Copyright 2018 New Vector 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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package routing
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import (
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"context"
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"fmt"
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"net/http"
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"sort"
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"strconv"
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"github.com/matrix-org/dendrite/clientapi/jsonerror"
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"github.com/matrix-org/dendrite/common/config"
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"github.com/matrix-org/dendrite/roomserver/api"
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"github.com/matrix-org/dendrite/syncapi/storage"
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"github.com/matrix-org/dendrite/syncapi/types"
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"github.com/matrix-org/gomatrixserverlib"
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"github.com/matrix-org/util"
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"github.com/sirupsen/logrus"
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)
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type messagesReq struct {
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ctx context.Context
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db storage.Database
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rsAPI api.RoomserverInternalAPI
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federation *gomatrixserverlib.FederationClient
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cfg *config.Dendrite
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roomID string
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from *types.PaginationToken
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to *types.PaginationToken
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wasToProvided bool
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limit int
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backwardOrdering bool
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}
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type messagesResp struct {
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Start string `json:"start"`
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End string `json:"end"`
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Chunk []gomatrixserverlib.ClientEvent `json:"chunk"`
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}
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const defaultMessagesLimit = 10
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// OnIncomingMessagesRequest implements the /messages endpoint from the
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// client-server API.
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// See: https://matrix.org/docs/spec/client_server/latest.html#get-matrix-client-r0-rooms-roomid-messages
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func OnIncomingMessagesRequest(
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req *http.Request, db storage.Database, roomID string,
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federation *gomatrixserverlib.FederationClient,
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rsAPI api.RoomserverInternalAPI,
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cfg *config.Dendrite,
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) util.JSONResponse {
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var err error
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// Extract parameters from the request's URL.
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// Pagination tokens.
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from, err := types.NewPaginationTokenFromString(req.URL.Query().Get("from"))
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if err != nil {
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return util.JSONResponse{
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Code: http.StatusBadRequest,
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JSON: jsonerror.InvalidArgumentValue("Invalid from parameter: " + err.Error()),
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}
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}
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// Direction to return events from.
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dir := req.URL.Query().Get("dir")
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if dir != "b" && dir != "f" {
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return util.JSONResponse{
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Code: http.StatusBadRequest,
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JSON: jsonerror.MissingArgument("Bad or missing dir query parameter (should be either 'b' or 'f')"),
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}
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}
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// A boolean is easier to handle in this case, especially since dir is sure
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// to have one of the two accepted values (so dir == "f" <=> !backwardOrdering).
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backwardOrdering := (dir == "b")
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// Pagination tokens. To is optional, and its default value depends on the
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// direction ("b" or "f").
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var to *types.PaginationToken
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wasToProvided := true
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if s := req.URL.Query().Get("to"); len(s) > 0 {
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to, err = types.NewPaginationTokenFromString(s)
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if err != nil {
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return util.JSONResponse{
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Code: http.StatusBadRequest,
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JSON: jsonerror.InvalidArgumentValue("Invalid to parameter: " + err.Error()),
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}
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}
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} else {
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// If "to" isn't provided, it defaults to either the earliest stream
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// position (if we're going backward) or to the latest one (if we're
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// going forward).
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to, err = setToDefault(req.Context(), db, backwardOrdering, roomID)
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if err != nil {
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util.GetLogger(req.Context()).WithError(err).Error("setToDefault failed")
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return jsonerror.InternalServerError()
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}
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wasToProvided = false
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}
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// Maximum number of events to return; defaults to 10.
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limit := defaultMessagesLimit
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if len(req.URL.Query().Get("limit")) > 0 {
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limit, err = strconv.Atoi(req.URL.Query().Get("limit"))
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if err != nil {
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return util.JSONResponse{
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Code: http.StatusBadRequest,
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JSON: jsonerror.InvalidArgumentValue("limit could not be parsed into an integer: " + err.Error()),
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}
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}
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}
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// TODO: Implement filtering (#587)
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// Check the room ID's format.
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if _, _, err = gomatrixserverlib.SplitID('!', roomID); err != nil {
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return util.JSONResponse{
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Code: http.StatusBadRequest,
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JSON: jsonerror.MissingArgument("Bad room ID: " + err.Error()),
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}
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}
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mReq := messagesReq{
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ctx: req.Context(),
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db: db,
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rsAPI: rsAPI,
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federation: federation,
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cfg: cfg,
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roomID: roomID,
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from: from,
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to: to,
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wasToProvided: wasToProvided,
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limit: limit,
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backwardOrdering: backwardOrdering,
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}
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clientEvents, start, end, err := mReq.retrieveEvents()
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if err != nil {
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util.GetLogger(req.Context()).WithError(err).Error("mreq.retrieveEvents failed")
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return jsonerror.InternalServerError()
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}
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util.GetLogger(req.Context()).WithFields(logrus.Fields{
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"from": from.String(),
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"to": to.String(),
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"limit": limit,
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"backwards": backwardOrdering,
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"return_start": start.String(),
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"return_end": end.String(),
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}).Info("Responding")
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// Respond with the events.
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return util.JSONResponse{
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Code: http.StatusOK,
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JSON: messagesResp{
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Chunk: clientEvents,
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Start: start.String(),
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End: end.String(),
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},
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}
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}
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// retrieveEvents retrieve events from the local database for a request on
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// /messages. If there's not enough events to retrieve, it asks another
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// homeserver in the room for older events.
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// Returns an error if there was an issue talking to the database or with the
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// remote homeserver.
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func (r *messagesReq) retrieveEvents() (
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clientEvents []gomatrixserverlib.ClientEvent, start,
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end *types.PaginationToken, err error,
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) {
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// Retrieve the events from the local database.
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streamEvents, err := r.db.GetEventsInRange(
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r.ctx, r.from, r.to, r.roomID, r.limit, r.backwardOrdering,
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)
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if err != nil {
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err = fmt.Errorf("GetEventsInRange: %w", err)
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return
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}
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var events []gomatrixserverlib.HeaderedEvent
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// There can be two reasons for streamEvents to be empty: either we've
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// reached the oldest event in the room (or the most recent one, depending
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// on the ordering), or we've reached a backward extremity.
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if len(streamEvents) == 0 {
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if events, err = r.handleEmptyEventsSlice(); err != nil {
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return
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}
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} else {
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if events, err = r.handleNonEmptyEventsSlice(streamEvents); err != nil {
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return
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}
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}
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// If we didn't get any event, we don't need to proceed any further.
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if len(events) == 0 {
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return []gomatrixserverlib.ClientEvent{}, r.from, r.to, nil
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}
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// Sort the events to ensure we send them in the right order.
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events = gomatrixserverlib.HeaderedReverseTopologicalOrdering(
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events,
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gomatrixserverlib.TopologicalOrderByPrevEvents,
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)
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if r.backwardOrdering {
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// This reverses the array from old->new to new->old
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sort.SliceStable(events, func(i, j int) bool {
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return true
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})
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}
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// Convert all of the events into client events.
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clientEvents = gomatrixserverlib.HeaderedToClientEvents(events, gomatrixserverlib.FormatAll)
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// Get the position of the first and the last event in the room's topology.
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// This position is currently determined by the event's depth, so we could
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// also use it instead of retrieving from the database. However, if we ever
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// change the way topological positions are defined (as depth isn't the most
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// reliable way to define it), it would be easier and less troublesome to
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// only have to change it in one place, i.e. the database.
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startPos, startStreamPos, err := r.db.EventPositionInTopology(
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r.ctx, events[0].EventID(),
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)
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if err != nil {
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err = fmt.Errorf("EventPositionInTopology: for start event %s: %w", events[0].EventID(), err)
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return
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}
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endPos, endStreamPos, err := r.db.EventPositionInTopology(
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r.ctx, events[len(events)-1].EventID(),
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)
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if err != nil {
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err = fmt.Errorf("EventPositionInTopology: for end event %s: %w", events[len(events)-1].EventID(), err)
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return
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}
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// Generate pagination tokens to send to the client using the positions
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// retrieved previously.
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start = types.NewPaginationTokenFromTypeAndPosition(
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types.PaginationTokenTypeTopology, startPos, startStreamPos,
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)
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end = types.NewPaginationTokenFromTypeAndPosition(
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types.PaginationTokenTypeTopology, endPos, endStreamPos,
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)
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if r.backwardOrdering {
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// A stream/topological position is a cursor located between two events.
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// While they are identified in the code by the event on their right (if
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// we consider a left to right chronological order), tokens need to refer
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// to them by the event on their left, therefore we need to decrement the
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// end position we send in the response if we're going backward.
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end.PDUPosition--
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}
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// The lowest token value is 1, therefore we need to manually set it to that
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// value if we're below it.
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if end.PDUPosition < types.StreamPosition(1) {
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end.PDUPosition = types.StreamPosition(1)
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}
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return clientEvents, start, end, err
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}
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// handleEmptyEventsSlice handles the case where the initial request to the
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// database returned an empty slice of events. It does so by checking whether
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// the set is empty because we've reached a backward extremity, and if that is
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// the case, by retrieving as much events as requested by backfilling from
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// another homeserver.
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// Returns an error if there was an issue talking with the database or
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// backfilling.
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func (r *messagesReq) handleEmptyEventsSlice() (
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events []gomatrixserverlib.HeaderedEvent, err error,
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) {
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backwardExtremities, err := r.db.BackwardExtremitiesForRoom(r.ctx, r.roomID)
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// Check if we have backward extremities for this room.
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if len(backwardExtremities) > 0 {
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// If so, retrieve as much events as needed through backfilling.
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events, err = r.backfill(r.roomID, backwardExtremities, r.limit)
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if err != nil {
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return
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}
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} else {
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// If not, it means the slice was empty because we reached the room's
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// creation, so return an empty slice.
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events = []gomatrixserverlib.HeaderedEvent{}
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}
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return
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}
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// handleNonEmptyEventsSlice handles the case where the initial request to the
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// database returned a non-empty slice of events. It does so by checking whether
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// events are missing from the expected result, and retrieve missing events
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// through backfilling if needed.
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// Returns an error if there was an issue while backfilling.
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func (r *messagesReq) handleNonEmptyEventsSlice(streamEvents []types.StreamEvent) (
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events []gomatrixserverlib.HeaderedEvent, err error,
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) {
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// Check if we have enough events.
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isSetLargeEnough := len(streamEvents) >= r.limit
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if !isSetLargeEnough {
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// it might be fine we don't have up to 'limit' events, let's find out
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if r.backwardOrdering {
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if r.wasToProvided {
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// The condition in the SQL query is a strict "greater than" so
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// we need to check against to-1.
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streamPos := types.StreamPosition(streamEvents[len(streamEvents)-1].StreamPosition)
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isSetLargeEnough = (r.to.PDUPosition-1 == streamPos)
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}
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} else {
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streamPos := types.StreamPosition(streamEvents[0].StreamPosition)
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isSetLargeEnough = (r.from.PDUPosition-1 == streamPos)
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}
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}
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// Check if the slice contains a backward extremity.
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backwardExtremities, err := r.db.BackwardExtremitiesForRoom(r.ctx, r.roomID)
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if err != nil {
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return
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}
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// Backfill is needed if we've reached a backward extremity and need more
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// events. It's only needed if the direction is backward.
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if len(backwardExtremities) > 0 && !isSetLargeEnough && r.backwardOrdering {
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var pdus []gomatrixserverlib.HeaderedEvent
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// Only ask the remote server for enough events to reach the limit.
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pdus, err = r.backfill(r.roomID, backwardExtremities, r.limit-len(streamEvents))
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if err != nil {
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return
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}
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// Append the PDUs to the list to send back to the client.
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events = append(events, pdus...)
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}
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// Append the events ve previously retrieved locally.
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events = append(events, r.db.StreamEventsToEvents(nil, streamEvents)...)
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return
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}
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// backfill performs a backfill request over the federation on another
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// homeserver in the room.
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// See: https://matrix.org/docs/spec/server_server/latest#get-matrix-federation-v1-backfill-roomid
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// It also stores the PDUs retrieved from the remote homeserver's response to
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// the database.
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// Returns with an empty string if the remote homeserver didn't return with any
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// event, or if there is no remote homeserver to contact.
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// Returns an error if there was an issue with retrieving the list of servers in
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// the room or sending the request.
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func (r *messagesReq) backfill(roomID string, fromEventIDs []string, limit int) ([]gomatrixserverlib.HeaderedEvent, error) {
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var res api.QueryBackfillResponse
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err := r.rsAPI.QueryBackfill(context.Background(), &api.QueryBackfillRequest{
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RoomID: roomID,
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EarliestEventsIDs: fromEventIDs,
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Limit: limit,
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ServerName: r.cfg.Matrix.ServerName,
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}, &res)
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if err != nil {
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return nil, fmt.Errorf("QueryBackfill failed: %w", err)
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}
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util.GetLogger(r.ctx).WithField("new_events", len(res.Events)).Info("Storing new events from backfill")
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// TODO: we should only be inserting events into the database from the roomserver's kafka output stream.
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// Currently, this can race with live events for the room and cause problems. It's also just a bit unclear
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// when you have multiple entry points to write events.
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// Store the events in the database, while marking them as unfit to show
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// up in responses to sync requests.
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for i := range res.Events {
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if _, err = r.db.WriteEvent(
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r.ctx,
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&res.Events[i],
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[]gomatrixserverlib.HeaderedEvent{},
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[]string{},
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[]string{},
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nil, true,
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); err != nil {
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return nil, err
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}
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}
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return res.Events, nil
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}
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// setToDefault returns the default value for the "to" query parameter of a
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// request to /messages if not provided. It defaults to either the earliest
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// topological position (if we're going backward) or to the latest one (if we're
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// going forward).
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// Returns an error if there was an issue with retrieving the latest position
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// from the database
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func setToDefault(
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ctx context.Context, db storage.Database, backwardOrdering bool,
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roomID string,
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) (to *types.PaginationToken, err error) {
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if backwardOrdering {
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// go 1 earlier than the first event so we correctly fetch the earliest event
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to = types.NewPaginationTokenFromTypeAndPosition(types.PaginationTokenTypeTopology, 0, 0)
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} else {
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var pos, stream types.StreamPosition
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pos, stream, err = db.MaxTopologicalPosition(ctx, roomID)
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if err != nil {
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return
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}
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to = types.NewPaginationTokenFromTypeAndPosition(types.PaginationTokenTypeTopology, pos, stream)
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}
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return
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}
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