Implement state conflict resolution (#37)

* Implement state conflict resolution
This commit is contained in:
Mark Haines 2017-03-15 13:47:12 +00:00 committed by GitHub
parent 742e4aca85
commit f2163c31c6

View File

@ -6,6 +6,7 @@ import (
"github.com/matrix-org/dendrite/roomserver/types" "github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib" "github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util" "github.com/matrix-org/util"
"sort"
) )
// calculateAndStoreState calculates a snapshot of the state of a room before an event. // calculateAndStoreState calculates a snapshot of the state of a room before an event.
@ -99,7 +100,16 @@ func calculateAndStoreStateAfterManyEvents(db RoomEventDatabase, roomNID types.R
if len(conflicts) > 0 { if len(conflicts) > 0 {
// 5) There are conflicting state events, for each conflict workout // 5) There are conflicting state events, for each conflict workout
// what the appropriate state event is. // what the appropriate state event is.
resolved, err := resolveConflicts(db, combined, conflicts)
// Work out which entries aren't conflicted.
var notConflicted []types.StateEntry
for _, entry := range combined {
if _, ok := stateEntryMap(conflicts).lookup(entry.StateKeyTuple); !ok {
notConflicted = append(notConflicted, entry)
}
}
resolved, err := resolveConflicts(db, notConflicted, conflicts)
if err != nil { if err != nil {
return 0, err return 0, err
} }
@ -114,8 +124,88 @@ func calculateAndStoreStateAfterManyEvents(db RoomEventDatabase, roomNID types.R
return db.AddState(roomNID, nil, state) return db.AddState(roomNID, nil, state)
} }
func resolveConflicts(db RoomEventDatabase, combined, conflicted []types.StateEntry) ([]types.StateEntry, error) { // loadStateEvents loads the matrix events for a list of state entries.
panic(fmt.Errorf("Not implemented")) // Returns a list of state events in no particular order and a map from string event ID back to state entry.
// The map can be used to recover which numeric state entry a given event is for.
// Returns an error if there was a problem talking to the database.
func loadStateEvents(db RoomEventDatabase, entries []types.StateEntry) ([]gomatrixserverlib.Event, map[string]types.StateEntry, error) {
eventNIDs := make([]types.EventNID, len(entries))
for i := range entries {
eventNIDs[i] = entries[i].EventNID
}
events, err := db.Events(eventNIDs)
if err != nil {
return nil, nil, err
}
eventIDMap := map[string]types.StateEntry{}
result := make([]gomatrixserverlib.Event, len(entries))
for i := range entries {
event, ok := eventMap(events).lookup(entries[i].EventNID)
if !ok {
panic(fmt.Errorf("Corrupt DB: Missing event numeric ID %d", entries[i].EventNID))
}
result[i] = event.Event
eventIDMap[event.Event.EventID()] = entries[i]
}
return result, eventIDMap, nil
}
// resolveConflicts resolves a list of conflicted state entries. It takes two lists.
// The first is a list of all state entries that are not conflicted.
// The second is a list of all state entries that are conflicted
// A state entry is conflicted when there is more than one numeric event ID for the same state key tuple.
// Returns a list that combines the entries without conflicts with the result of state resolution for the entries with conflicts.
// The returned list is sorted by state key tuple.
// Returns an error if there was a problem talking to the database.
func resolveConflicts(db RoomEventDatabase, notConflicted, conflicted []types.StateEntry) ([]types.StateEntry, error) {
// Load the conflicted events
conflictedEvents, eventIDMap, err := loadStateEvents(db, conflicted)
if err != nil {
return nil, err
}
// Work out which auth events we need to load.
needed := gomatrixserverlib.StateNeededForAuth(conflictedEvents)
// Find the numeric IDs for the necessary state keys.
var neededStateKeys []string
neededStateKeys = append(neededStateKeys, needed.Member...)
neededStateKeys = append(neededStateKeys, needed.ThirdPartyInvite...)
stateKeyNIDMap, err := db.EventStateKeyNIDs(neededStateKeys)
if err != nil {
return nil, err
}
// Load the necessary auth events.
tuplesNeeded := stateKeyTuplesNeeded(stateKeyNIDMap, needed)
var authEntries []types.StateEntry
for _, tuple := range tuplesNeeded {
if eventNID, ok := stateEntryMap(notConflicted).lookup(tuple); ok {
authEntries = append(authEntries, types.StateEntry{tuple, eventNID})
}
}
authEvents, _, err := loadStateEvents(db, authEntries)
if err != nil {
return nil, err
}
// Resolve the conflicts.
fmt.Println("Resolving", len(conflicted), "conflicts with", len(authEvents), "authEvents")
resolvedEvents := gomatrixserverlib.ResolveStateConflicts(conflictedEvents, authEvents)
// Map from the full events back to numeric state entries.
for _, resolvedEvent := range resolvedEvents {
entry, ok := eventIDMap[resolvedEvent.EventID()]
if !ok {
panic(fmt.Errorf("Missing state entry for event ID %q", resolvedEvent.EventID()))
}
notConflicted = append(notConflicted, entry)
}
// Sort the result so it can be searched.
sort.Sort(stateEntrySorter(notConflicted))
return notConflicted, nil
} }
// findDuplicateStateKeys finds the state entries where the state key tuple appears more than once in a sorted list. // findDuplicateStateKeys finds the state entries where the state key tuple appears more than once in a sorted list.