207 lines
7.1 KiB
Go
207 lines
7.1 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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"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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)
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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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func updateLatestEvents(
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db RoomEventDatabase, ow OutputRoomEventWriter, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
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) (err error) {
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updater, err := db.GetLatestEventsForUpdate(roomNID)
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if err != nil {
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return
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}
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defer func() {
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if err == nil {
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// Commit if there wasn't an error.
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// Set the returned err value if we encounter an error committing.
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// This only works because err is a named return.
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err = updater.Commit()
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} else {
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// Ignore any error we get rolling back since we don't want to
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// clobber the current error
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// TODO: log the error here.
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updater.Rollback()
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}
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}()
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err = doUpdateLatestEvents(db, updater, ow, roomNID, stateAtEvent, event)
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return
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}
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func doUpdateLatestEvents(
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db RoomEventDatabase, updater types.RoomRecentEventsUpdater, ow OutputRoomEventWriter, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
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) error {
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var err error
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var prevEvents []gomatrixserverlib.EventReference
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prevEvents = event.PrevEvents()
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oldLatest := updater.LatestEvents()
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lastEventIDSent := updater.LastEventIDSent()
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oldStateNID := updater.CurrentStateSnapshotNID()
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if hasBeenSent, err := updater.HasEventBeenSent(stateAtEvent.EventNID); 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 = updater.StorePreviousEvents(stateAtEvent.EventNID, prevEvents); err != nil {
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return err
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}
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eventReference := event.EventReference()
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// Check if this event is already referenced by another event in the room.
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var alreadyReferenced bool
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if alreadyReferenced, err = updater.IsReferenced(eventReference); err != nil {
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return err
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}
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newLatest := calculateLatest(oldLatest, alreadyReferenced, prevEvents, types.StateAtEventAndReference{
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EventReference: eventReference,
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StateAtEvent: stateAtEvent,
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})
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latestStateAtEvents := make([]types.StateAtEvent, len(newLatest))
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for i := range newLatest {
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latestStateAtEvents[i] = newLatest[i].StateAtEvent
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}
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newStateNID, err := calculateAndStoreStateAfterEvents(db, roomNID, latestStateAtEvents)
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if err != nil {
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return err
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}
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removed, added, err := state.DifferenceBetweeenStateSnapshots(db, oldStateNID, newStateNID)
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if err != nil {
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return err
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}
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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 = writeEvent(db, ow, lastEventIDSent, event, newLatest, removed, added); err != nil {
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return err
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}
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if err = updater.SetLatestEvents(roomNID, newLatest, stateAtEvent.EventNID, newStateNID); err != nil {
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return err
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}
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if err = updater.MarkEventAsSent(stateAtEvent.EventNID); err != nil {
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return err
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}
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return nil
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}
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func calculateLatest(oldLatest []types.StateAtEventAndReference, alreadyReferenced bool, prevEvents []gomatrixserverlib.EventReference, newEvent types.StateAtEventAndReference) []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.Compare(l.EventSHA256, prevEvent.EventSHA256) == 0 {
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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 writeEvent(
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db RoomEventDatabase, ow OutputRoomEventWriter, lastEventIDSent string,
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event gomatrixserverlib.Event, latest []types.StateAtEventAndReference,
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removed, added []types.StateEntry,
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) error {
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latestEventIDs := make([]string, len(latest))
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for i := range latest {
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latestEventIDs[i] = latest[i].EventID
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}
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ore := api.OutputRoomEvent{
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Event: event.JSON(),
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LastSentEventID: lastEventIDSent,
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LatestEventIDs: latestEventIDs,
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}
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var stateEventNIDs []types.EventNID
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for _, entry := range added {
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stateEventNIDs = append(stateEventNIDs, entry.EventNID)
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}
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for _, entry := range removed {
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stateEventNIDs = append(stateEventNIDs, entry.EventNID)
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}
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eventIDMap, err := db.EventIDs(stateEventNIDs)
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if err != nil {
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return err
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}
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for _, entry := range added {
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ore.AddsStateEventIDs = append(ore.AddsStateEventIDs, eventIDMap[entry.EventNID])
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}
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for _, entry := range removed {
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ore.RemovesStateEventIDs = append(ore.RemovesStateEventIDs, eventIDMap[entry.EventNID])
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}
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// TODO: Fill out VisibilityStateIDs
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return ow.WriteOutputRoomEvent(ore)
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}
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