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Duplicate state v1 to state v2

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This commit is contained in:
Neil Alexander 2020-02-14 15:05:58 +00:00
parent 78ef720a03
commit 9d249472fb
4 changed files with 865 additions and 0 deletions
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3
roomserver/state/state.go
View file

@ -22,6 +22,7 @@ import (
"github.com/matrix-org/dendrite/roomserver/state/database"
v1 "github.com/matrix-org/dendrite/roomserver/state/v1"
v2 "github.com/matrix-org/dendrite/roomserver/state/v2"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
@ -40,6 +41,8 @@ func GetStateResolutionAlgorithm(
switch version {
case StateResolutionAlgorithmV1:
return v1.Prepare(db), nil
case StateResolutionAlgorithmV2:
return v2.Prepare(db), nil
default:
return nil, errors.New("unsupported room version")
}

103
roomserver/state/v2/prometheus.go Normal file
View file

@ -0,0 +1,103 @@
package v2
import (
"time"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/prometheus/client_golang/prometheus"
)
var calculateStateDurations = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_duration_microseconds",
Help: "How long it takes to calculate the state after a list of events",
},
// Takes two labels:
// algorithm:
// The algorithm used to calculate the state or the step it failed on if it failed.
// Labels starting with "_" are used to indicate when the algorithm fails halfway.
// outcome:
// Whether the state was successfully calculated.
//
// The possible values for algorithm are:
// empty_state -> The list of events was empty so the state is empty.
// no_change -> The state hasn't changed.
// single_delta -> There was a single event added to the state in a way that can be encoded as a single delta
// full_state_no_conflicts -> We created a new copy of the full room state, but didn't enounter any conflicts
// while doing so.
// full_state_with_conflicts -> We created a new copy of the full room state and had to resolve conflicts to do so.
// _load_state_block_nids -> Failed loading the state block nids for a single previous state.
// _load_combined_state -> Failed to load the combined state.
// _resolve_conflicts -> Failed to resolve conflicts.
[]string{"algorithm", "outcome"},
)
var calculateStatePrevEventLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_prev_event_length",
Help: "The length of the list of events to calculate the state after",
},
[]string{"algorithm", "outcome"},
)
var calculateStateFullStateLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_full_state_length",
Help: "The length of the full room state.",
},
[]string{"algorithm", "outcome"},
)
var calculateStateConflictLength = prometheus.NewSummaryVec(
prometheus.SummaryOpts{
Namespace: "dendrite",
Subsystem: "roomserver",
Name: "calculate_state_conflict_state_length",
Help: "The length of the conflicted room state.",
},
[]string{"algorithm", "outcome"},
)
type calculateStateMetrics struct {
algorithm string
startTime time.Time
prevEventLength int
fullStateLength int
conflictLength int
}
func (c *calculateStateMetrics) stop(stateNID types.StateSnapshotNID, err error) (types.StateSnapshotNID, error) {
var outcome string
if err == nil {
outcome = "success"
} else {
outcome = "failure"
}
endTime := time.Now()
calculateStateDurations.WithLabelValues(c.algorithm, outcome).Observe(
float64(endTime.Sub(c.startTime).Nanoseconds()) / 1000.,
)
calculateStatePrevEventLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.prevEventLength),
)
calculateStateFullStateLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.fullStateLength),
)
calculateStateConflictLength.WithLabelValues(c.algorithm, outcome).Observe(
float64(c.conflictLength),
)
return stateNID, err
}
func init() {
prometheus.MustRegister(
calculateStateDurations, calculateStatePrevEventLength,
calculateStateFullStateLength, calculateStateConflictLength,
)
}

701
roomserver/state/v2/state.go Normal file
View file

@ -0,0 +1,701 @@
// Copyright 2017 Vector Creations Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package state provides functions for reading state from the database.
// The functions for writing state to the database are the input package.
package v2
import (
"context"
"fmt"
"sort"
"time"
"github.com/matrix-org/dendrite/roomserver/state/database"
"github.com/matrix-org/dendrite/roomserver/state/shared"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
)
type StateResolutionV2 struct {
db database.RoomStateDatabase
}
func Prepare(db database.RoomStateDatabase) StateResolutionV2 {
return StateResolutionV2{
db: db,
}
}
// LoadStateAtSnapshot loads the full state of a room at a particular snapshot.
// This is typically the state before an event or the current state of a room.
// Returns a sorted list of state entries or an error if there was a problem talking to the database.
func (v StateResolutionV2) LoadStateAtSnapshot(
ctx context.Context, stateNID types.StateSnapshotNID,
) ([]types.StateEntry, error) {
stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, []types.StateSnapshotNID{stateNID})
if err != nil {
return nil, err
}
// We've asked for exactly one snapshot from the db so we should have exactly one entry in the result.
stateBlockNIDList := stateBlockNIDLists[0]
stateEntryLists, err := v.db.StateEntries(ctx, stateBlockNIDList.StateBlockNIDs)
if err != nil {
return nil, err
}
stateEntriesMap := shared.StateEntryListMap(stateEntryLists)
// Combine all the state entries for this snapshot.
// The order of state block NIDs in the list tells us the order to combine them in.
var fullState []types.StateEntry
for _, stateBlockNID := range stateBlockNIDList.StateBlockNIDs {
entries, ok := stateEntriesMap.Lookup(stateBlockNID)
if !ok {
// This should only get hit if the database is corrupt.
// It should be impossible for an event to reference a NID that doesn't exist
panic(fmt.Errorf("Corrupt DB: Missing state block numeric ID %d", stateBlockNID))
}
fullState = append(fullState, entries...)
}
// Stable sort so that the most recent entry for each state key stays
// remains later in the list than the older entries for the same state key.
sort.Stable(shared.StateEntryByStateKeySorter(fullState))
// Unique returns the last entry and hence the most recent entry for each state key.
fullState = fullState[:util.Unique(shared.StateEntryByStateKeySorter(fullState))]
return fullState, nil
}
// LoadStateAtEvent loads the full state of a room at a particular event.
func (v StateResolutionV2) LoadStateAtEvent(
ctx context.Context, eventID string,
) ([]types.StateEntry, error) {
snapshotNID, err := v.db.SnapshotNIDFromEventID(ctx, eventID)
if err != nil {
return nil, err
}
stateEntries, err := v.LoadStateAtSnapshot(ctx, snapshotNID)
if err != nil {
return nil, err
}
return stateEntries, nil
}
// LoadCombinedStateAfterEvents loads a snapshot of the state after each of the events
// and combines those snapshots together into a single list.
func (v StateResolutionV2) LoadCombinedStateAfterEvents(
ctx context.Context, prevStates []types.StateAtEvent,
) ([]types.StateEntry, error) {
stateNIDs := make([]types.StateSnapshotNID, len(prevStates))
for i, state := range prevStates {
stateNIDs[i] = state.BeforeStateSnapshotNID
}
// Fetch the state snapshots for the state before the each prev event from the database.
// Deduplicate the IDs before passing them to the database.
// There could be duplicates because the events could be state events where
// the snapshot of the room state before them was the same.
stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, shared.UniqueStateSnapshotNIDs(stateNIDs))
if err != nil {
return nil, err
}
var stateBlockNIDs []types.StateBlockNID
for _, list := range stateBlockNIDLists {
stateBlockNIDs = append(stateBlockNIDs, list.StateBlockNIDs...)
}
// Fetch the state entries that will be combined to create the snapshots.
// Deduplicate the IDs before passing them to the database.
// There could be duplicates because a block of state entries could be reused by
// multiple snapshots.
stateEntryLists, err := v.db.StateEntries(ctx, shared.UniqueStateBlockNIDs(stateBlockNIDs))
if err != nil {
return nil, err
}
stateBlockNIDsMap := shared.StateBlockNIDListMap(stateBlockNIDLists)
stateEntriesMap := shared.StateEntryListMap(stateEntryLists)
// Combine the entries from all the snapshots of state after each prev event into a single list.
var combined []types.StateEntry
for _, prevState := range prevStates {
// Grab the list of state data NIDs for this snapshot.
stateBlockNIDs, ok := stateBlockNIDsMap.Lookup(prevState.BeforeStateSnapshotNID)
if !ok {
// This should only get hit if the database is corrupt.
// It should be impossible for an event to reference a NID that doesn't exist
panic(fmt.Errorf("Corrupt DB: Missing state snapshot numeric ID %d", prevState.BeforeStateSnapshotNID))
}
// Combine all the state entries for this snapshot.
// The order of state block NIDs in the list tells us the order to combine them in.
var fullState []types.StateEntry
for _, stateBlockNID := range stateBlockNIDs {
entries, ok := stateEntriesMap.Lookup(stateBlockNID)
if !ok {
// This should only get hit if the database is corrupt.
// It should be impossible for an event to reference a NID that doesn't exist
panic(fmt.Errorf("Corrupt DB: Missing state block numeric ID %d", stateBlockNID))
}
fullState = append(fullState, entries...)
}
if prevState.IsStateEvent() {
// If the prev event was a state event then add an entry for the event itself
// so that we get the state after the event rather than the state before.
fullState = append(fullState, prevState.StateEntry)
}
// Stable sort so that the most recent entry for each state key stays
// remains later in the list than the older entries for the same state key.
sort.Stable(shared.StateEntryByStateKeySorter(fullState))
// Unique returns the last entry and hence the most recent entry for each state key.
fullState = fullState[:util.Unique(shared.StateEntryByStateKeySorter(fullState))]
// Add the full state for this StateSnapshotNID.
combined = append(combined, fullState...)
}
return combined, nil
}
// DifferenceBetweeenStateSnapshots works out which state entries have been added and removed between two snapshots.
func (v StateResolutionV2) DifferenceBetweeenStateSnapshots(
ctx context.Context, oldStateNID, newStateNID types.StateSnapshotNID,
) (removed, added []types.StateEntry, err error) {
if oldStateNID == newStateNID {
// If the snapshot NIDs are the same then nothing has changed
return nil, nil, nil
}
var oldEntries []types.StateEntry
var newEntries []types.StateEntry
if oldStateNID != 0 {
oldEntries, err = v.LoadStateAtSnapshot(ctx, oldStateNID)
if err != nil {
return nil, nil, err
}
}
if newStateNID != 0 {
newEntries, err = v.LoadStateAtSnapshot(ctx, newStateNID)
if err != nil {
return nil, nil, err
}
}
var oldI int
var newI int
for {
switch {
case oldI == len(oldEntries):
// We've reached the end of the old entries.
// The rest of the new list must have been newly added.
added = append(added, newEntries[newI:]...)
return
case newI == len(newEntries):
// We've reached the end of the new entries.
// The rest of the old list must be have been removed.
removed = append(removed, oldEntries[oldI:]...)
return
case oldEntries[oldI] == newEntries[newI]:
// The entry is in both lists so skip over it.
oldI++
newI++
case oldEntries[oldI].LessThan(newEntries[newI]):
// The lists are sorted so the old entry being less than the new entry means that it only appears in the old list.
removed = append(removed, oldEntries[oldI])
oldI++
default:
// Reaching the default case implies that the new entry is less than the old entry.
// Since the lists are sorted this means that it only appears in the new list.
added = append(added, newEntries[newI])
newI++
}
}
}
// LoadStateAtSnapshotForStringTuples loads the state for a list of event type and state key pairs at a snapshot.
// This is used when we only want to load a subset of the room state at a snapshot.
// If there is no entry for a given event type and state key pair then it will be discarded.
// This is typically the state before an event or the current state of a room.
// Returns a sorted list of state entries or an error if there was a problem talking to the database.
func (v StateResolutionV2) LoadStateAtSnapshotForStringTuples(
ctx context.Context,
stateNID types.StateSnapshotNID,
stateKeyTuples []gomatrixserverlib.StateKeyTuple,
) ([]types.StateEntry, error) {
numericTuples, err := v.stringTuplesToNumericTuples(ctx, stateKeyTuples)
if err != nil {
return nil, err
}
return v.loadStateAtSnapshotForNumericTuples(ctx, stateNID, numericTuples)
}
// stringTuplesToNumericTuples converts the string state key tuples into numeric IDs
// If there isn't a numeric ID for either the event type or the event state key then the tuple is discarded.
// Returns an error if there was a problem talking to the database.
func (v StateResolutionV2) stringTuplesToNumericTuples(
ctx context.Context,
stringTuples []gomatrixserverlib.StateKeyTuple,
) ([]types.StateKeyTuple, error) {
eventTypes := make([]string, len(stringTuples))
stateKeys := make([]string, len(stringTuples))
for i := range stringTuples {
eventTypes[i] = stringTuples[i].EventType
stateKeys[i] = stringTuples[i].StateKey
}
eventTypes = util.UniqueStrings(eventTypes)
eventTypeMap, err := v.db.EventTypeNIDs(ctx, eventTypes)
if err != nil {
return nil, err
}
stateKeys = util.UniqueStrings(stateKeys)
stateKeyMap, err := v.db.EventStateKeyNIDs(ctx, stateKeys)
if err != nil {
return nil, err
}
var result []types.StateKeyTuple
for _, stringTuple := range stringTuples {
var numericTuple types.StateKeyTuple
var ok1, ok2 bool
numericTuple.EventTypeNID, ok1 = eventTypeMap[stringTuple.EventType]
numericTuple.EventStateKeyNID, ok2 = stateKeyMap[stringTuple.StateKey]
// Discard the tuple if there wasn't a numeric ID for either the event type or the state key.
if ok1 && ok2 {
result = append(result, numericTuple)
}
}
return result, nil
}
// loadStateAtSnapshotForNumericTuples loads the state for a list of event type and state key pairs at a snapshot.
// This is used when we only want to load a subset of the room state at a snapshot.
// If there is no entry for a given event type and state key pair then it will be discarded.
// This is typically the state before an event or the current state of a room.
// Returns a sorted list of state entries or an error if there was a problem talking to the database.
func (v StateResolutionV2) loadStateAtSnapshotForNumericTuples(
ctx context.Context,
stateNID types.StateSnapshotNID,
stateKeyTuples []types.StateKeyTuple,
) ([]types.StateEntry, error) {
stateBlockNIDLists, err := v.db.StateBlockNIDs(ctx, []types.StateSnapshotNID{stateNID})
if err != nil {
return nil, err
}
// We've asked for exactly one snapshot from the db so we should have exactly one entry in the result.
stateBlockNIDList := stateBlockNIDLists[0]
stateEntryLists, err := v.db.StateEntriesForTuples(
ctx, stateBlockNIDList.StateBlockNIDs, stateKeyTuples,
)
if err != nil {
return nil, err
}
stateEntriesMap := shared.StateEntryListMap(stateEntryLists)
// Combine all the state entries for this snapshot.
// The order of state block NIDs in the list tells us the order to combine them in.
var fullState []types.StateEntry
for _, stateBlockNID := range stateBlockNIDList.StateBlockNIDs {
entries, ok := stateEntriesMap.Lookup(stateBlockNID)
if !ok {
// If the block is missing from the map it means that none of its entries matched a requested tuple.
// This can happen if the block doesn't contain an update for one of the requested tuples.
// If none of the requested tuples are in the block then it can be safely skipped.
continue
}
fullState = append(fullState, entries...)
}
// Stable sort so that the most recent entry for each state key stays
// remains later in the list than the older entries for the same state key.
sort.Stable(shared.StateEntryByStateKeySorter(fullState))
// Unique returns the last entry and hence the most recent entry for each state key.
fullState = fullState[:util.Unique(shared.StateEntryByStateKeySorter(fullState))]
return fullState, nil
}
// LoadStateAfterEventsForStringTuples loads the state for a list of event type
// and state key pairs after list of events.
// This is used when we only want to load a subset of the room state after a list of events.
// If there is no entry for a given event type and state key pair then it will be discarded.
// This is typically the state before an event.
// Returns a sorted list of state entries or an error if there was a problem talking to the database.
func (v StateResolutionV2) LoadStateAfterEventsForStringTuples(
ctx context.Context,
prevStates []types.StateAtEvent,
stateKeyTuples []gomatrixserverlib.StateKeyTuple,
) ([]types.StateEntry, error) {
numericTuples, err := v.stringTuplesToNumericTuples(ctx, stateKeyTuples)
if err != nil {
return nil, err
}
return v.loadStateAfterEventsForNumericTuples(ctx, prevStates, numericTuples)
}
func (v StateResolutionV2) loadStateAfterEventsForNumericTuples(
ctx context.Context,
prevStates []types.StateAtEvent,
stateKeyTuples []types.StateKeyTuple,
) ([]types.StateEntry, error) {
if len(prevStates) == 1 {
// Fast path for a single event.
prevState := prevStates[0]
result, err := v.loadStateAtSnapshotForNumericTuples(
ctx, prevState.BeforeStateSnapshotNID, stateKeyTuples,
)
if err != nil {
return nil, err
}
if prevState.IsStateEvent() {
// The result is current the state before the requested event.
// We want the state after the requested event.
// If the requested event was a state event then we need to
// update that key in the result.
// If the requested event wasn't a state event then the state after
// it is the same as the state before it.
for i := range result {
if result[i].StateKeyTuple == prevState.StateKeyTuple {
result[i] = prevState.StateEntry
}
}
}
return result, nil
}
// Slow path for more that one event.
// Load the entire state so that we can do conflict resolution if we need to.
// TODO: The are some optimistations we could do here:
// 1) We only need to do conflict resolution if there is a conflict in the
// requested tuples so we might try loading just those tuples and then
// checking for conflicts.
// 2) When there is a conflict we still only need to load the state
// needed to do conflict resolution which would save us having to load
// the full state.
// TODO: Add metrics for this as it could take a long time for big rooms
// with large conflicts.
fullState, _, _, err := v.calculateStateAfterManyEvents(ctx, prevStates)
if err != nil {
return nil, err
}
// Sort the full state so we can use it as a map.
sort.Sort(shared.StateEntrySorter(fullState))
// Filter the full state down to the required tuples.
var result []types.StateEntry
for _, tuple := range stateKeyTuples {
eventNID, ok := shared.StateEntryMap(fullState).Lookup(tuple)
if ok {
result = append(result, types.StateEntry{
StateKeyTuple: tuple,
EventNID: eventNID,
})
}
}
sort.Sort(shared.StateEntrySorter(result))
return result, nil
}
// CalculateAndStoreStateBeforeEvent calculates a snapshot of the state of a room before an event.
// Stores the snapshot of the state in the database.
// Returns a numeric ID for the snapshot of the state before the event.
func (v StateResolutionV2) CalculateAndStoreStateBeforeEvent(
ctx context.Context,
event gomatrixserverlib.Event,
roomNID types.RoomNID,
) (types.StateSnapshotNID, error) {
// Load the state at the prev events.
prevEventRefs := event.PrevEvents()
prevEventIDs := make([]string, len(prevEventRefs))
for i := range prevEventRefs {
prevEventIDs[i] = prevEventRefs[i].EventID
}
prevStates, err := v.db.StateAtEventIDs(ctx, prevEventIDs)
if err != nil {
return 0, err
}
// The state before this event will be the state after the events that came before it.
return v.CalculateAndStoreStateAfterEvents(ctx, roomNID, prevStates)
}
// CalculateAndStoreStateAfterEvents finds the room state after the given events.
// Stores the resulting state in the database and returns a numeric ID for that snapshot.
func (v StateResolutionV2) CalculateAndStoreStateAfterEvents(
ctx context.Context,
roomNID types.RoomNID,
prevStates []types.StateAtEvent,
) (types.StateSnapshotNID, error) {
metrics := calculateStateMetrics{startTime: time.Now(), prevEventLength: len(prevStates)}
if len(prevStates) == 0 {
// 2) There weren't any prev_events for this event so the state is
// empty.
metrics.algorithm = "empty_state"
return metrics.stop(v.db.AddState(ctx, roomNID, nil, nil))
}
if len(prevStates) == 1 {
prevState := prevStates[0]
if prevState.EventStateKeyNID == 0 {
// 3) None of the previous events were state events and they all
// have the same state, so this event has exactly the same state
// as the previous events.
// This should be the common case.
metrics.algorithm = "no_change"
return metrics.stop(prevState.BeforeStateSnapshotNID, nil)
}
// The previous event was a state event so we need to store a copy
// of the previous state updated with that event.
stateBlockNIDLists, err := v.db.StateBlockNIDs(
ctx, []types.StateSnapshotNID{prevState.BeforeStateSnapshotNID},
)
if err != nil {
metrics.algorithm = "_load_state_blocks"
return metrics.stop(0, err)
}
stateBlockNIDs := stateBlockNIDLists[0].StateBlockNIDs
if len(stateBlockNIDs) < maxStateBlockNIDs {
// 4) The number of state data blocks is small enough that we can just
// add the state event as a block of size one to the end of the blocks.
metrics.algorithm = "single_delta"
return metrics.stop(v.db.AddState(
ctx, roomNID, stateBlockNIDs, []types.StateEntry{prevState.StateEntry},
))
}
// If there are too many deltas then we need to calculate the full state
// So fall through to calculateAndStoreStateAfterManyEvents
}
return v.calculateAndStoreStateAfterManyEvents(ctx, roomNID, prevStates, metrics)
}
// maxStateBlockNIDs is the maximum number of state data blocks to use to encode a snapshot of room state.
// Increasing this number means that we can encode more of the state changes as simple deltas which means that
// we need fewer entries in the state data table. However making this number bigger will increase the size of
// the rows in the state table itself and will require more index lookups when retrieving a snapshot.
// TODO: Tune this to get the right balance between size and lookup performance.
const maxStateBlockNIDs = 64
// calculateAndStoreStateAfterManyEvents finds the room state after the given events.
// This handles the slow path of calculateAndStoreStateAfterEvents for when there is more than one event.
// Stores the resulting state and returns a numeric ID for the snapshot.
func (v StateResolutionV2) calculateAndStoreStateAfterManyEvents(
ctx context.Context,
roomNID types.RoomNID,
prevStates []types.StateAtEvent,
metrics calculateStateMetrics,
) (types.StateSnapshotNID, error) {
state, algorithm, conflictLength, err :=
v.calculateStateAfterManyEvents(ctx, prevStates)
metrics.algorithm = algorithm
if err != nil {
return metrics.stop(0, err)
}
// TODO: Check if we can encode the new state as a delta against the
// previous state.
metrics.conflictLength = conflictLength
metrics.fullStateLength = len(state)
return metrics.stop(v.db.AddState(ctx, roomNID, nil, state))
}
func (v StateResolutionV2) calculateStateAfterManyEvents(
ctx context.Context, prevStates []types.StateAtEvent,
) (state []types.StateEntry, algorithm string, conflictLength int, err error) {
var combined []types.StateEntry
// Conflict resolution.
// First stage: load the state after each of the prev events.
combined, err = v.LoadCombinedStateAfterEvents(ctx, prevStates)
if err != nil {
algorithm = "_load_combined_state"
return
}
// Collect all the entries with the same type and key together.
// We don't care about the order here because the conflict resolution
// algorithm doesn't depend on the order of the prev events.
// Remove duplicate entires.
combined = combined[:util.SortAndUnique(shared.StateEntrySorter(combined))]
// Find the conflicts
conflicts := shared.FindDuplicateStateKeys(combined)
if len(conflicts) > 0 {
conflictLength = len(conflicts)
// 5) There are conflicting state events, for each conflict workout
// what the appropriate state event is.
// Work out which entries aren't conflicted.
var notConflicted []types.StateEntry
for _, entry := range combined {
if _, ok := shared.StateEntryMap(conflicts).Lookup(entry.StateKeyTuple); !ok {
notConflicted = append(notConflicted, entry)
}
}
var resolved []types.StateEntry
resolved, err = v.resolveConflicts(ctx, notConflicted, conflicts)
if err != nil {
algorithm = "_resolve_conflicts"
return
}
algorithm = "full_state_with_conflicts"
state = resolved
} else {
algorithm = "full_state_no_conflicts"
// 6) There weren't any conflicts
state = combined
}
return
}
// 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 (v StateResolutionV2) resolveConflicts(
ctx context.Context,
notConflicted, conflicted []types.StateEntry,
) ([]types.StateEntry, error) {
// Load the conflicted events
conflictedEvents, eventIDMap, err := v.loadStateEvents(ctx, 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 := v.db.EventStateKeyNIDs(ctx, neededStateKeys)
if err != nil {
return nil, err
}
// Load the necessary auth events.
tuplesNeeded := v.stateKeyTuplesNeeded(stateKeyNIDMap, needed)
var authEntries []types.StateEntry
for _, tuple := range tuplesNeeded {
if eventNID, ok := shared.StateEntryMap(notConflicted).Lookup(tuple); ok {
authEntries = append(authEntries, types.StateEntry{
StateKeyTuple: tuple,
EventNID: eventNID,
})
}
}
authEvents, _, err := v.loadStateEvents(ctx, authEntries)
if err != nil {
return nil, err
}
// Resolve the conflicts.
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(shared.StateEntrySorter(notConflicted))
return notConflicted, nil
}
// stateKeyTuplesNeeded works out which numeric state key tuples we need to authenticate some events.
func (v StateResolutionV2) stateKeyTuplesNeeded(stateKeyNIDMap map[string]types.EventStateKeyNID, stateNeeded gomatrixserverlib.StateNeeded) []types.StateKeyTuple {
var keyTuples []types.StateKeyTuple
if stateNeeded.Create {
keyTuples = append(keyTuples, types.StateKeyTuple{
EventTypeNID: types.MRoomCreateNID,
EventStateKeyNID: types.EmptyStateKeyNID,
})
}
if stateNeeded.PowerLevels {
keyTuples = append(keyTuples, types.StateKeyTuple{
EventTypeNID: types.MRoomPowerLevelsNID,
EventStateKeyNID: types.EmptyStateKeyNID,
})
}
if stateNeeded.JoinRules {
keyTuples = append(keyTuples, types.StateKeyTuple{
EventTypeNID: types.MRoomJoinRulesNID,
EventStateKeyNID: types.EmptyStateKeyNID,
})
}
for _, member := range stateNeeded.Member {
stateKeyNID, ok := stateKeyNIDMap[member]
if ok {
keyTuples = append(keyTuples, types.StateKeyTuple{
EventTypeNID: types.MRoomMemberNID,
EventStateKeyNID: stateKeyNID,
})
}
}
for _, token := range stateNeeded.ThirdPartyInvite {
stateKeyNID, ok := stateKeyNIDMap[token]
if ok {
keyTuples = append(keyTuples, types.StateKeyTuple{
EventTypeNID: types.MRoomThirdPartyInviteNID,
EventStateKeyNID: stateKeyNID,
})
}
}
return keyTuples
}
// loadStateEvents loads the matrix events for a list of state entries.
// 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 (v StateResolutionV2) loadStateEvents(
ctx context.Context, 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 := v.db.Events(ctx, 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 := shared.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
}

58
roomserver/state/v2/state_test.go Normal file
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@ -0,0 +1,58 @@
// Copyright 2017 Vector Creations Ltd
// Copyright 2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package v2
import (
"testing"
"github.com/matrix-org/dendrite/roomserver/types"
)
func TestFindDuplicateStateKeys(t *testing.T) {
testCases := []struct {
Input []types.StateEntry
Want []types.StateEntry
}{{
Input: []types.StateEntry{
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 1}, EventNID: 1},
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 1}, EventNID: 2},
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 2, EventStateKeyNID: 2}, EventNID: 3},
},
Want: []types.StateEntry{
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 1}, EventNID: 1},
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 1}, EventNID: 2},
},
}, {
Input: []types.StateEntry{
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 1}, EventNID: 1},
{StateKeyTuple: types.StateKeyTuple{EventTypeNID: 1, EventStateKeyNID: 2}, EventNID: 2},
},
Want: nil,
}}
for _, test := range testCases {
got := findDuplicateStateKeys(test.Input)
if len(got) != len(test.Want) {
t.Fatalf("Wanted %v, got %v", test.Want, got)
}
for i := range got {
if got[i] != test.Want[i] {
t.Fatalf("Wanted %v, got %v", test.Want, got)
}
}
}
}