dendrite/roomserver/input/latest_events.go

306 lines
10 KiB
Go

// Copyright 2017 Vector Creations Ltd
// Copyright 2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// 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 input
import (
"bytes"
"context"
"github.com/matrix-org/dendrite/common"
"github.com/matrix-org/dendrite/roomserver/api"
"github.com/matrix-org/dendrite/roomserver/state"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
)
// updateLatestEvents updates the list of latest events for this room in the database and writes the
// event to the output log.
// The latest events are the events that aren't referenced by another event in the database:
//
// Time goes down the page. 1 is the m.room.create event (root).
//
// 1 After storing 1 the latest events are {1}
// | After storing 2 the latest events are {2}
// 2 After storing 3 the latest events are {3}
// / \ After storing 4 the latest events are {3,4}
// 3 4 After storing 5 the latest events are {5,4}
// | | After storing 6 the latest events are {5,6}
// 5 6 <--- latest After storing 7 the latest events are {6,7}
// |
// 7 <----- latest
//
// Can only be called once at a time
func updateLatestEvents(
ctx context.Context,
db RoomEventDatabase,
ow OutputRoomEventWriter,
roomNID types.RoomNID,
stateAtEvent types.StateAtEvent,
event gomatrixserverlib.Event,
sendAsServer string,
transactionID *api.TransactionID,
) (err error) {
updater, err := db.GetLatestEventsForUpdate(ctx, roomNID)
if err != nil {
return
}
succeeded := false
defer func() {
txerr := common.EndTransaction(updater, &succeeded)
if err == nil && txerr != nil {
err = txerr
}
}()
u := latestEventsUpdater{
ctx: ctx, db: db, updater: updater, ow: ow, roomNID: roomNID,
stateAtEvent: stateAtEvent, event: event, sendAsServer: sendAsServer,
transactionID: transactionID,
}
if err = u.doUpdateLatestEvents(); err != nil {
return err
}
succeeded = true
return
}
// latestEventsUpdater tracks the state used to update the latest events in the
// room. It mostly just ferries state between the various function calls.
// The state could be passed using function arguments, but it becomes impractical
// when there are so many variables to pass around.
type latestEventsUpdater struct {
ctx context.Context
db RoomEventDatabase
updater types.RoomRecentEventsUpdater
ow OutputRoomEventWriter
roomNID types.RoomNID
stateAtEvent types.StateAtEvent
event gomatrixserverlib.Event
transactionID *api.TransactionID
// Which server to send this event as.
sendAsServer string
// The eventID of the event that was processed before this one.
lastEventIDSent string
// The latest events in the room after processing this event.
latest []types.StateAtEventAndReference
// The state entries removed from and added to the current state of the
// room as a result of processing this event. They are sorted lists.
removed []types.StateEntry
added []types.StateEntry
// The state entries that are removed and added to recover the state before
// the event being processed. They are sorted lists.
stateBeforeEventRemoves []types.StateEntry
stateBeforeEventAdds []types.StateEntry
// The snapshots of current state before and after processing this event
oldStateNID types.StateSnapshotNID
newStateNID types.StateSnapshotNID
}
func (u *latestEventsUpdater) doUpdateLatestEvents() error {
prevEvents := u.event.PrevEvents()
oldLatest := u.updater.LatestEvents()
u.lastEventIDSent = u.updater.LastEventIDSent()
u.oldStateNID = u.updater.CurrentStateSnapshotNID()
hasBeenSent, err := u.updater.HasEventBeenSent(u.stateAtEvent.EventNID)
if err != nil {
return err
} else if hasBeenSent {
// Already sent this event so we can stop processing
return nil
}
if err = u.updater.StorePreviousEvents(u.stateAtEvent.EventNID, prevEvents); err != nil {
return err
}
eventReference := u.event.EventReference()
// Check if this event is already referenced by another event in the room.
alreadyReferenced, err := u.updater.IsReferenced(eventReference)
if err != nil {
return err
}
u.latest = calculateLatest(oldLatest, alreadyReferenced, prevEvents, types.StateAtEventAndReference{
EventReference: eventReference,
StateAtEvent: u.stateAtEvent,
})
if err = u.latestState(); err != nil {
return err
}
updates, err := updateMemberships(u.ctx, u.db, u.updater, u.removed, u.added)
if err != nil {
return err
}
update, err := u.makeOutputNewRoomEvent()
if err != nil {
return err
}
updates = append(updates, *update)
// Send the event to the output logs.
// We do this inside the database transaction to ensure that we only mark an event as sent if we sent it.
// (n.b. this means that it's possible that the same event will be sent twice if the transaction fails but
// the write to the output log succeeds)
// TODO: This assumes that writing the event to the output log is synchronous. It should be possible to
// send the event asynchronously but we would need to ensure that 1) the events are written to the log in
// the correct order, 2) that pending writes are resent across restarts. In order to avoid writing all the
// necessary bookkeeping we'll keep the event sending synchronous for now.
if err = u.ow.WriteOutputEvents(u.event.RoomID(), updates); err != nil {
return err
}
if err = u.updater.SetLatestEvents(u.roomNID, u.latest, u.stateAtEvent.EventNID, u.newStateNID); err != nil {
return err
}
return u.updater.MarkEventAsSent(u.stateAtEvent.EventNID)
}
func (u *latestEventsUpdater) latestState() error {
var err error
// TODO: get the correct room version
roomState, err := state.GetStateResolutionAlgorithm(state.StateResolutionAlgorithmV1, u.db)
if err != nil {
return err
}
latestStateAtEvents := make([]types.StateAtEvent, len(u.latest))
for i := range u.latest {
latestStateAtEvents[i] = u.latest[i].StateAtEvent
}
u.newStateNID, err = roomState.CalculateAndStoreStateAfterEvents(
u.ctx, u.roomNID, latestStateAtEvents,
)
if err != nil {
return err
}
u.removed, u.added, err = roomState.DifferenceBetweeenStateSnapshots(
u.ctx, u.oldStateNID, u.newStateNID,
)
if err != nil {
return err
}
u.stateBeforeEventRemoves, u.stateBeforeEventAdds, err = roomState.DifferenceBetweeenStateSnapshots(
u.ctx, u.newStateNID, u.stateAtEvent.BeforeStateSnapshotNID,
)
return err
}
func calculateLatest(
oldLatest []types.StateAtEventAndReference,
alreadyReferenced bool,
prevEvents []gomatrixserverlib.EventReference,
newEvent types.StateAtEventAndReference,
) []types.StateAtEventAndReference {
var alreadyInLatest bool
var newLatest []types.StateAtEventAndReference
for _, l := range oldLatest {
keep := true
for _, prevEvent := range prevEvents {
if l.EventID == prevEvent.EventID && bytes.Equal(l.EventSHA256, prevEvent.EventSHA256) {
// This event can be removed from the latest events cause we've found an event that references it.
// (If an event is referenced by another event then it can't be one of the latest events in the room
// because we have an event that comes after it)
keep = false
break
}
}
if l.EventNID == newEvent.EventNID {
alreadyInLatest = true
}
if keep {
// Keep the event in the latest events.
newLatest = append(newLatest, l)
}
}
if !alreadyReferenced && !alreadyInLatest {
// This event is not referenced by any of the events in the room
// and the event is not already in the latest events.
// Add it to the latest events
newLatest = append(newLatest, newEvent)
}
return newLatest
}
func (u *latestEventsUpdater) makeOutputNewRoomEvent() (*api.OutputEvent, error) {
latestEventIDs := make([]string, len(u.latest))
for i := range u.latest {
latestEventIDs[i] = u.latest[i].EventID
}
ore := api.OutputNewRoomEvent{
Event: u.event,
LastSentEventID: u.lastEventIDSent,
LatestEventIDs: latestEventIDs,
TransactionID: u.transactionID,
}
var stateEventNIDs []types.EventNID
for _, entry := range u.added {
stateEventNIDs = append(stateEventNIDs, entry.EventNID)
}
for _, entry := range u.removed {
stateEventNIDs = append(stateEventNIDs, entry.EventNID)
}
for _, entry := range u.stateBeforeEventRemoves {
stateEventNIDs = append(stateEventNIDs, entry.EventNID)
}
for _, entry := range u.stateBeforeEventAdds {
stateEventNIDs = append(stateEventNIDs, entry.EventNID)
}
stateEventNIDs = stateEventNIDs[:util.SortAndUnique(eventNIDSorter(stateEventNIDs))]
eventIDMap, err := u.db.EventIDs(u.ctx, stateEventNIDs)
if err != nil {
return nil, err
}
for _, entry := range u.added {
ore.AddsStateEventIDs = append(ore.AddsStateEventIDs, eventIDMap[entry.EventNID])
}
for _, entry := range u.removed {
ore.RemovesStateEventIDs = append(ore.RemovesStateEventIDs, eventIDMap[entry.EventNID])
}
for _, entry := range u.stateBeforeEventRemoves {
ore.StateBeforeRemovesEventIDs = append(ore.StateBeforeRemovesEventIDs, eventIDMap[entry.EventNID])
}
for _, entry := range u.stateBeforeEventAdds {
ore.StateBeforeAddsEventIDs = append(ore.StateBeforeAddsEventIDs, eventIDMap[entry.EventNID])
}
ore.SendAsServer = u.sendAsServer
return &api.OutputEvent{
Type: api.OutputTypeNewRoomEvent,
NewRoomEvent: &ore,
}, nil
}
type eventNIDSorter []types.EventNID
func (s eventNIDSorter) Len() int { return len(s) }
func (s eventNIDSorter) Less(i, j int) bool { return s[i] < s[j] }
func (s eventNIDSorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }