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