dendrite/federationapi/routing/backfill.go
Till 8e4dc6b4ae
Optimize PrevEventIDs when getting thousands of backwards extremeties (#3308)
Changes how many `PrevEventIDs` we send to other servers when
backfilling, capped to 100 events.

Unsure about how representative this benchmark is..
```
goos: linux
goarch: amd64
pkg: github.com/matrix-org/dendrite/roomserver/api
cpu: Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
                            │    old.txt     │               new.txt               │
                            │     sec/op     │   sec/op     vs base                │
PrevEventIDs/Original1-8         264.9n ± 5%   237.4n ± 7%  -10.36% (p=0.000 n=10)
PrevEventIDs/Original10-8        3.101µ ± 4%   1.590µ ± 2%  -48.72% (p=0.000 n=10)
PrevEventIDs/Original100-8       44.32µ ± 2%   12.80µ ± 4%  -71.11% (p=0.000 n=10)
PrevEventIDs/Original500-8     263.835µ ± 4%   7.907µ ± 4%  -97.00% (p=0.000 n=10)
PrevEventIDs/Original1000-8    578.798µ ± 2%   7.620µ ± 2%  -98.68% (p=0.000 n=10)
PrevEventIDs/Original2000-8   1272.039µ ± 2%   8.241µ ± 9%  -99.35% (p=0.000 n=10)
geomean                          43.81µ        3.659µ       -91.65%

                            │    old.txt     │               new.txt                │
                            │      B/op      │     B/op      vs base                │
PrevEventIDs/Original1-8          72.00 ± 0%     48.00 ± 0%  -33.33% (p=0.000 n=10)
PrevEventIDs/Original10-8        1512.0 ± 0%     500.0 ± 0%  -66.93% (p=0.000 n=10)
PrevEventIDs/Original100-8     11.977Ki ± 0%   7.023Ki ± 0%  -41.36% (p=0.000 n=10)
PrevEventIDs/Original500-8     67.227Ki ± 0%   7.023Ki ± 0%  -89.55% (p=0.000 n=10)
PrevEventIDs/Original1000-8   163.227Ki ± 0%   7.023Ki ± 0%  -95.70% (p=0.000 n=10)
PrevEventIDs/Original2000-8   347.227Ki ± 0%   7.023Ki ± 0%  -97.98% (p=0.000 n=10)
geomean                         12.96Ki        1.954Ki       -84.92%

                            │   old.txt   │              new.txt               │
                            │  allocs/op  │ allocs/op   vs base                │
PrevEventIDs/Original1-8       2.000 ± 0%   1.000 ± 0%  -50.00% (p=0.000 n=10)
PrevEventIDs/Original10-8      6.000 ± 0%   2.000 ± 0%  -66.67% (p=0.000 n=10)
PrevEventIDs/Original100-8     9.000 ± 0%   3.000 ± 0%  -66.67% (p=0.000 n=10)
PrevEventIDs/Original500-8    12.000 ± 0%   3.000 ± 0%  -75.00% (p=0.000 n=10)
PrevEventIDs/Original1000-8   14.000 ± 0%   3.000 ± 0%  -78.57% (p=0.000 n=10)
PrevEventIDs/Original2000-8   16.000 ± 0%   3.000 ± 0%  -81.25% (p=0.000 n=10)
geomean                        8.137        2.335       -71.31%
```
2024-01-20 22:26:57 +01:00

149 lines
4.3 KiB
Go

// Copyright 2018 New Vector 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.
package routing
import (
"encoding/json"
"fmt"
"net/http"
"strconv"
"time"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/dendrite/setup/config"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/gomatrixserverlib/fclient"
"github.com/matrix-org/gomatrixserverlib/spec"
"github.com/matrix-org/util"
)
// Backfill implements the /backfill federation endpoint.
// https://matrix.org/docs/spec/server_server/unstable.html#get-matrix-federation-v1-backfill-roomid
func Backfill(
httpReq *http.Request,
request *fclient.FederationRequest,
rsAPI api.FederationRoomserverAPI,
roomID string,
cfg *config.FederationAPI,
) util.JSONResponse {
var res api.PerformBackfillResponse
var eIDs []string
var limit string
var exists bool
var err error
// Check the room ID's format.
if _, _, err = gomatrixserverlib.SplitID('!', roomID); err != nil {
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: spec.MissingParam("Bad room ID: " + err.Error()),
}
}
// If we don't think we belong to this room then don't waste the effort
// responding to expensive requests for it.
if err := ErrorIfLocalServerNotInRoom(httpReq.Context(), rsAPI, roomID); err != nil {
return *err
}
// Check if all of the required parameters are there.
eIDs, exists = httpReq.URL.Query()["v"]
if !exists {
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: spec.MissingParam("v is missing"),
}
}
limit = httpReq.URL.Query().Get("limit")
if len(limit) == 0 {
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: spec.MissingParam("limit is missing"),
}
}
// Populate the request.
req := api.PerformBackfillRequest{
RoomID: roomID,
// we don't know who the successors are for these events, which won't
// be a problem because we don't use that information when servicing /backfill requests,
// only when making them. TODO: Think of a better API shape
BackwardsExtremities: map[string][]string{
"": eIDs,
},
ServerName: request.Origin(),
VirtualHost: request.Destination(),
}
if req.Limit, err = strconv.Atoi(limit); err != nil {
util.GetLogger(httpReq.Context()).WithError(err).Error("strconv.Atoi failed")
return util.JSONResponse{
Code: http.StatusBadRequest,
JSON: spec.InvalidParam(fmt.Sprintf("limit %q is invalid format", limit)),
}
}
// Enforce a limit of 100 events, as not to hit the DB to hard.
// Synapse has a hard limit of 100 events as well.
if req.Limit > 100 {
req.Limit = 100
}
// Query the Roomserver.
if err = rsAPI.PerformBackfill(httpReq.Context(), &req, &res); err != nil {
util.GetLogger(httpReq.Context()).WithError(err).Error("query.PerformBackfill failed")
return util.JSONResponse{
Code: http.StatusInternalServerError,
JSON: spec.InternalServerError{},
}
}
// Filter any event that's not from the requested room out.
evs := make([]gomatrixserverlib.PDU, 0)
var ev *types.HeaderedEvent
for _, ev = range res.Events {
if ev.RoomID().String() == roomID {
evs = append(evs, ev.PDU)
}
}
eventJSONs := []json.RawMessage{}
for _, e := range gomatrixserverlib.ReverseTopologicalOrdering(
evs,
gomatrixserverlib.TopologicalOrderByPrevEvents,
) {
eventJSONs = append(eventJSONs, e.JSON())
}
// sytest wants these in reversed order, similar to /messages, so reverse them now.
for i := len(eventJSONs)/2 - 1; i >= 0; i-- {
opp := len(eventJSONs) - 1 - i
eventJSONs[i], eventJSONs[opp] = eventJSONs[opp], eventJSONs[i]
}
txn := gomatrixserverlib.Transaction{
Origin: request.Destination(),
PDUs: eventJSONs,
OriginServerTS: spec.AsTimestamp(time.Now()),
}
// Send the events to the client.
return util.JSONResponse{
Code: http.StatusOK,
JSON: txn,
}
}