mirror of
https://github.com/matrix-org/dendrite
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ec7718e7f8
* s/QueryBackfill/PerformBackfill/g * OutputEvent now includes AddStateEvents which contain the full event of extra state events * Only include adds not the current event * Get adding state right
305 lines
11 KiB
Go
305 lines
11 KiB
Go
package internal
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import (
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"context"
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"github.com/matrix-org/dendrite/roomserver/auth"
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"github.com/matrix-org/dendrite/roomserver/storage"
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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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"github.com/sirupsen/logrus"
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)
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// backfillRequester implements gomatrixserverlib.BackfillRequester
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type backfillRequester struct {
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db storage.Database
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fedClient *gomatrixserverlib.FederationClient
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thisServer gomatrixserverlib.ServerName
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bwExtrems map[string][]string
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// per-request state
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servers []gomatrixserverlib.ServerName
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eventIDToBeforeStateIDs map[string][]string
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eventIDMap map[string]gomatrixserverlib.Event
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}
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func newBackfillRequester(db storage.Database, fedClient *gomatrixserverlib.FederationClient, thisServer gomatrixserverlib.ServerName, bwExtrems map[string][]string) *backfillRequester {
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return &backfillRequester{
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db: db,
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fedClient: fedClient,
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thisServer: thisServer,
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eventIDToBeforeStateIDs: make(map[string][]string),
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eventIDMap: make(map[string]gomatrixserverlib.Event),
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bwExtrems: bwExtrems,
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}
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}
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func (b *backfillRequester) StateIDsBeforeEvent(ctx context.Context, targetEvent gomatrixserverlib.HeaderedEvent) ([]string, error) {
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b.eventIDMap[targetEvent.EventID()] = targetEvent.Unwrap()
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if ids, ok := b.eventIDToBeforeStateIDs[targetEvent.EventID()]; ok {
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return ids, nil
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}
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if len(targetEvent.PrevEventIDs()) == 0 && targetEvent.Type() == "m.room.create" && targetEvent.StateKeyEquals("") {
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util.GetLogger(ctx).WithField("room_id", targetEvent.RoomID()).Info("Backfilled to the beginning of the room")
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b.eventIDToBeforeStateIDs[targetEvent.EventID()] = []string{}
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return nil, nil
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}
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// if we have exactly 1 prev event and we know the state of the room at that prev event, then just roll forward the prev event.
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// Else, we have to hit /state_ids because either we don't know the state at all at this event (new backwards extremity) or
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// we don't know the result of state res to merge forks (2 or more prev_events)
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if len(targetEvent.PrevEventIDs()) == 1 {
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prevEventID := targetEvent.PrevEventIDs()[0]
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prevEvent, ok := b.eventIDMap[prevEventID]
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if !ok {
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goto FederationHit
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}
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prevEventStateIDs, ok := b.eventIDToBeforeStateIDs[prevEventID]
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if !ok {
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goto FederationHit
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}
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newStateIDs := b.calculateNewStateIDs(targetEvent.Unwrap(), prevEvent, prevEventStateIDs)
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if newStateIDs != nil {
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b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
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return newStateIDs, nil
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}
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// else we failed to calculate the new state, so fallthrough
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}
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FederationHit:
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var lastErr error
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logrus.WithField("event_id", targetEvent.EventID()).Info("Requesting /state_ids at event")
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for _, srv := range b.servers { // hit any valid server
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c := gomatrixserverlib.FederatedStateProvider{
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FedClient: b.fedClient,
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RememberAuthEvents: false,
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Server: srv,
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}
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res, err := c.StateIDsBeforeEvent(ctx, targetEvent)
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if err != nil {
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lastErr = err
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continue
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}
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b.eventIDToBeforeStateIDs[targetEvent.EventID()] = res
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return res, nil
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}
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return nil, lastErr
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}
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func (b *backfillRequester) calculateNewStateIDs(targetEvent, prevEvent gomatrixserverlib.Event, prevEventStateIDs []string) []string {
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newStateIDs := prevEventStateIDs[:]
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if prevEvent.StateKey() == nil {
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// state is the same as the previous event
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b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
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return newStateIDs
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}
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missingState := false // true if we are missing the info for a state event ID
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foundEvent := false // true if we found a (type, state_key) match
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// find which state ID to replace, if any
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for i, id := range newStateIDs {
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ev, ok := b.eventIDMap[id]
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if !ok {
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missingState = true
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continue
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}
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// The state IDs BEFORE the target event are the state IDs BEFORE the prev_event PLUS the prev_event itself
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if ev.Type() == prevEvent.Type() && ev.StateKey() != nil && *ev.StateKey() == *prevEvent.StateKey() {
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newStateIDs[i] = prevEvent.EventID()
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foundEvent = true
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break
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}
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}
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if !foundEvent && !missingState {
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// we can be certain that this is new state
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newStateIDs = append(newStateIDs, prevEvent.EventID())
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foundEvent = true
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}
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if foundEvent {
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b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
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return newStateIDs
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}
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return nil
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}
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func (b *backfillRequester) StateBeforeEvent(ctx context.Context, roomVer gomatrixserverlib.RoomVersion,
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event gomatrixserverlib.HeaderedEvent, eventIDs []string) (map[string]*gomatrixserverlib.Event, error) {
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// try to fetch the events from the database first
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events, err := b.ProvideEvents(roomVer, eventIDs)
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if err != nil {
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// non-fatal, fallthrough
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logrus.WithError(err).Info("Failed to fetch events")
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} else {
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logrus.Infof("Fetched %d/%d events from the database", len(events), len(eventIDs))
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if len(events) == len(eventIDs) {
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result := make(map[string]*gomatrixserverlib.Event)
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for i := range events {
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result[events[i].EventID()] = &events[i]
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b.eventIDMap[events[i].EventID()] = events[i]
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}
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return result, nil
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}
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}
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c := gomatrixserverlib.FederatedStateProvider{
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FedClient: b.fedClient,
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RememberAuthEvents: false,
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Server: b.servers[0],
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}
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result, err := c.StateBeforeEvent(ctx, roomVer, event, eventIDs)
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if err != nil {
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return nil, err
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}
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for eventID, ev := range result {
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b.eventIDMap[eventID] = *ev
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}
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return result, nil
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}
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// ServersAtEvent is called when trying to determine which server to request from.
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// It returns a list of servers which can be queried for backfill requests. These servers
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// will be servers that are in the room already. The entries at the beginning are preferred servers
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// and will be tried first. An empty list will fail the request.
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func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID string) []gomatrixserverlib.ServerName {
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// eventID will be a prev_event ID of a backwards extremity, meaning we will not have a database entry for it. Instead, use
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// its successor, so look it up.
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successor := ""
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FindSuccessor:
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for sucID, prevEventIDs := range b.bwExtrems {
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for _, pe := range prevEventIDs {
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if pe == eventID {
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successor = sucID
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break FindSuccessor
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}
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}
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}
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if successor == "" {
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logrus.WithField("event_id", eventID).Error("ServersAtEvent: failed to find successor of this event to determine room state")
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return nil
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}
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eventID = successor
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// getMembershipsBeforeEventNID requires a NID, so retrieving the NID for
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// the event is necessary.
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NIDs, err := b.db.EventNIDs(ctx, []string{eventID})
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if err != nil {
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logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get event NID for event")
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return nil
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}
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stateEntries, err := stateBeforeEvent(ctx, b.db, NIDs[eventID])
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if err != nil {
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logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to load state before event")
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return nil
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}
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// possibly return all joined servers depending on history visiblity
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memberEventsFromVis, err := joinEventsFromHistoryVisibility(ctx, b.db, roomID, stateEntries)
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if err != nil {
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logrus.WithError(err).Error("ServersAtEvent: failed calculate servers from history visibility rules")
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return nil
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}
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logrus.Infof("ServersAtEvent including %d current events from history visibility", len(memberEventsFromVis))
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// Retrieve all "m.room.member" state events of "join" membership, which
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// contains the list of users in the room before the event, therefore all
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// the servers in it at that moment.
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memberEvents, err := getMembershipsAtState(ctx, b.db, stateEntries, true)
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if err != nil {
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logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get memberships before event")
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return nil
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}
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memberEvents = append(memberEvents, memberEventsFromVis...)
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// Store the server names in a temporary map to avoid duplicates.
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serverSet := make(map[gomatrixserverlib.ServerName]bool)
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for _, event := range memberEvents {
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serverSet[event.Origin()] = true
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}
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var servers []gomatrixserverlib.ServerName
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for server := range serverSet {
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if server == b.thisServer {
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continue
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}
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servers = append(servers, server)
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}
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b.servers = servers
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return servers
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}
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// Backfill performs a backfill request to the given server.
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// https://matrix.org/docs/spec/server_server/latest#get-matrix-federation-v1-backfill-roomid
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func (b *backfillRequester) Backfill(ctx context.Context, server gomatrixserverlib.ServerName, roomID string,
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fromEventIDs []string, limit int) (*gomatrixserverlib.Transaction, error) {
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tx, err := b.fedClient.Backfill(ctx, server, roomID, limit, fromEventIDs)
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return &tx, err
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}
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func (b *backfillRequester) ProvideEvents(roomVer gomatrixserverlib.RoomVersion, eventIDs []string) ([]gomatrixserverlib.Event, error) {
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ctx := context.Background()
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nidMap, err := b.db.EventNIDs(ctx, eventIDs)
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if err != nil {
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logrus.WithError(err).WithField("event_ids", eventIDs).Error("Failed to find events")
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return nil, err
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}
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eventNIDs := make([]types.EventNID, len(nidMap))
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i := 0
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for _, nid := range nidMap {
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eventNIDs[i] = nid
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i++
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}
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eventsWithNids, err := b.db.Events(ctx, eventNIDs)
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if err != nil {
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logrus.WithError(err).WithField("event_nids", eventNIDs).Error("Failed to load events")
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return nil, err
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}
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events := make([]gomatrixserverlib.Event, len(eventsWithNids))
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for i := range eventsWithNids {
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events[i] = eventsWithNids[i].Event
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}
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return events, nil
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}
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// joinEventsFromHistoryVisibility returns all CURRENTLY joined members if the provided state indicated a 'shared' history visibility.
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// TODO: Long term we probably want a history_visibility table which stores eventNID | visibility_enum so we can just
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// pull all events and then filter by that table.
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func joinEventsFromHistoryVisibility(
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ctx context.Context, db storage.Database, roomID string, stateEntries []types.StateEntry) ([]types.Event, error) {
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var eventNIDs []types.EventNID
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for _, entry := range stateEntries {
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// Filter the events to retrieve to only keep the membership events
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if entry.EventTypeNID == types.MRoomHistoryVisibilityNID && entry.EventStateKeyNID == types.EmptyStateKeyNID {
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eventNIDs = append(eventNIDs, entry.EventNID)
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break
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}
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}
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// Get all of the events in this state
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stateEvents, err := db.Events(ctx, eventNIDs)
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if err != nil {
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return nil, err
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}
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events := make([]gomatrixserverlib.Event, len(stateEvents))
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for i := range stateEvents {
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events[i] = stateEvents[i].Event
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}
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visibility := auth.HistoryVisibilityForRoom(events)
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if visibility != "shared" {
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logrus.Infof("ServersAtEvent history visibility not shared: %s", visibility)
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return nil, nil
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}
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// get joined members
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roomNID, err := db.RoomNID(ctx, roomID)
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if err != nil {
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return nil, err
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}
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joinEventNIDs, err := db.GetMembershipEventNIDsForRoom(ctx, roomNID, true, false)
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if err != nil {
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return nil, err
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}
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return db.Events(ctx, joinEventNIDs)
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}
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