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Fix concurrent map reads/writes on t.hadEvents (#1902)

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* Fix concurrent map reads/writes on t.hadEvents

* Add hadEvent function
This commit is contained in:
Neil Alexander 2021-07-07 18:55:44 +01:00 committed by GitHub
parent 5a09290c32
commit f2974721d5
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 26 additions and 10 deletions
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36
federationapi/routing/send.go
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@ -232,7 +232,8 @@ type txnReq struct {
// something that can tell us about which servers are in a room right now
servers federationAPI.ServersInRoomProvider
// a list of events from the auth and prev events which we already had
hadEvents map[string]bool
hadEvents map[string]bool
hadEventsMutex sync.Mutex
// local cache of events for auth checks, etc - this may include events
// which the roomserver is unaware of.
haveEvents map[string]*gomatrixserverlib.HeaderedEvent
@ -240,6 +241,12 @@ type txnReq struct {
work string // metrics
}
func (t *txnReq) hadEvent(eventID string, had bool) {
t.hadEventsMutex.Lock()
defer t.hadEventsMutex.Unlock()
t.hadEvents[eventID] = had
}
// A subset of FederationClient functionality that txn requires. Useful for testing.
type txnFederationClient interface {
LookupState(ctx context.Context, s gomatrixserverlib.ServerName, roomID string, eventID string, roomVersion gomatrixserverlib.RoomVersion) (
@ -595,10 +602,10 @@ func (t *txnReq) processEvent(ctx context.Context, e *gomatrixserverlib.Event) e
// Prepare a map of all the events we already had before this point, so
// that we don't send them to the roomserver again.
for _, eventID := range append(e.AuthEventIDs(), e.PrevEventIDs()...) {
t.hadEvents[eventID] = true
t.hadEvent(eventID, true)
}
for _, eventID := range append(stateResp.MissingAuthEventIDs, stateResp.MissingPrevEventIDs...) {
t.hadEvents[eventID] = false
t.hadEvent(eventID, false)
}
if len(stateResp.MissingAuthEventIDs) > 0 {
@ -673,7 +680,7 @@ withNextEvent:
); err != nil {
return fmt.Errorf("api.SendEvents: %w", err)
}
t.hadEvents[ev.EventID()] = true // if the roomserver didn't know about the event before, it does now
t.hadEvent(ev.EventID(), true) // if the roomserver didn't know about the event before, it does now
t.cacheAndReturn(ev.Headered(stateResp.RoomVersion))
delete(missingAuthEvents, missingAuthEventID)
continue withNextEvent
@ -801,14 +808,23 @@ func (t *txnReq) processEventWithMissingState(
// First of all, send the backward extremity into the roomserver with the
// newly resolved state. This marks the "oldest" point in the backfill and
// sets the baseline state for any new events after this.
// sets the baseline state for any new events after this. We'll make a
// copy of the hadEvents map so that it can be taken downstream without
// worrying about concurrent map reads/writes, since t.hadEvents is meant
// to be protected by a mutex.
hadEvents := map[string]bool{}
t.hadEventsMutex.Lock()
for k, v := range t.hadEvents {
hadEvents[k] = v
}
t.hadEventsMutex.Unlock()
err = api.SendEventWithState(
context.Background(),
t.rsAPI,
api.KindOld,
resolvedState,
backwardsExtremity.Headered(roomVersion),
t.hadEvents,
hadEvents,
)
if err != nil {
return fmt.Errorf("api.SendEventWithState: %w", err)
@ -904,7 +920,7 @@ func (t *txnReq) lookupStateAfterEventLocally(ctx context.Context, roomID, event
// set the event from the haveEvents cache - this means we will share pointers with other prev_event branches for this
// processEvent request, which is better for memory.
stateEvents[i] = t.cacheAndReturn(ev)
t.hadEvents[ev.EventID()] = true
t.hadEvent(ev.EventID(), true)
}
// we should never access res.StateEvents again so we delete it here to make GC faster
res.StateEvents = nil
@ -939,7 +955,7 @@ func (t *txnReq) lookupStateAfterEventLocally(ctx context.Context, roomID, event
}
for i, ev := range queryRes.Events {
authEvents = append(authEvents, t.cacheAndReturn(queryRes.Events[i]).Unwrap())
t.hadEvents[ev.EventID()] = true
t.hadEvent(ev.EventID(), true)
}
queryRes.Events = nil
}
@ -1016,7 +1032,7 @@ func (t *txnReq) getMissingEvents(ctx context.Context, e *gomatrixserverlib.Even
latestEvents := make([]string, len(res.LatestEvents))
for i, ev := range res.LatestEvents {
latestEvents[i] = res.LatestEvents[i].EventID
t.hadEvents[ev.EventID] = true
t.hadEvent(ev.EventID, true)
}
var missingResp *gomatrixserverlib.RespMissingEvents
@ -1152,7 +1168,7 @@ func (t *txnReq) lookupMissingStateViaStateIDs(ctx context.Context, roomID, even
}
for i, ev := range queryRes.Events {
queryRes.Events[i] = t.cacheAndReturn(queryRes.Events[i])
t.hadEvents[ev.EventID()] = true
t.hadEvent(ev.EventID(), true)
evID := queryRes.Events[i].EventID()
if missing[evID] {
delete(missing, evID)