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Move calculate state to the state package (#121)

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This commit is contained in:
Mark Haines 2017-05-26 13:51:54 +01:00 committed by GitHub
parent db23640f69
commit a96b124158
6 changed files with 440 additions and 398 deletions
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11
src/github.com/matrix-org/dendrite/roomserver/input/events.go
View File

@ -30,15 +30,6 @@ type RoomEventDatabase interface {
// Returns an error if the there is an error talking to the database
// or if the event IDs aren't in the database.
StateEntriesForEventIDs(eventIDs []string) ([]types.StateEntry, error)
// Lookup the Events for a list of numeric event IDs.
// Returns a sorted list of events.
Events(eventNIDs []types.EventNID) ([]types.Event, error)
// Lookup the state of a room at each event for a list of string event IDs.
// Returns an error if there is an error talking to the database
// or if the room state for the event IDs aren't in the database
StateAtEventIDs(eventIDs []string) ([]types.StateAtEvent, error)
// Store the room state at an event in the database
AddState(roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID, state []types.StateEntry) (types.StateSnapshotNID, error)
// Set the state at an event.
SetState(eventNID types.EventNID, stateNID types.StateSnapshotNID) error
// Lookup the latest events in a room in preparation for an update.
@ -98,7 +89,7 @@ func processRoomEvent(db RoomEventDatabase, ow OutputRoomEventWriter, input api.
}
} else {
// We haven't been told what the state at the event is so we need to calculate it from the prev_events
if stateAtEvent.BeforeStateSnapshotNID, err = calculateAndStoreStateBeforeEvent(db, event, roomNID); err != nil {
if stateAtEvent.BeforeStateSnapshotNID, err = state.CalculateAndStoreStateBeforeEvent(db, event, roomNID); err != nil {
return err
}
}

2
src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go
View File

@ -100,7 +100,7 @@ func doUpdateLatestEvents(
for i := range newLatest {
latestStateAtEvents[i] = newLatest[i].StateAtEvent
}
newStateNID, err := calculateAndStoreStateAfterEvents(db, roomNID, latestStateAtEvents)
newStateNID, err := state.CalculateAndStoreStateAfterEvents(db, roomNID, latestStateAtEvents)
if err != nil {
return err
}

368
src/github.com/matrix-org/dendrite/roomserver/input/state.go
View File

@ -1,368 +0,0 @@
// 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 input
import (
"fmt"
"github.com/matrix-org/dendrite/roomserver/state"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
"github.com/prometheus/client_golang/prometheus"
"sort"
"time"
)
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,
)
}
// calculateAndStoreState 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 calculateAndStoreStateBeforeEvent(
db RoomEventDatabase, 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 := db.StateAtEventIDs(prevEventIDs)
if err != nil {
return 0, err
}
// The state before this event will be the state after the events that came before it.
return calculateAndStoreStateAfterEvents(db, 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 calculateAndStoreStateAfterEvents(db RoomEventDatabase, 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(db.AddState(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 := db.StateBlockNIDs([]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(db.AddState(
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 calculateAndStoreStateAfterManyEvents(db, 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 calculateAndStoreStateAfterManyEvents(
db RoomEventDatabase, roomNID types.RoomNID, prevStates []types.StateAtEvent, metrics calculateStateMetrics,
) (types.StateSnapshotNID, error) {
// Conflict resolution.
// First stage: load the state after each of the prev events.
combined, err := state.LoadCombinedStateAfterEvents(db, prevStates)
if err != nil {
metrics.algorithm = "_load_combined_state"
return metrics.stop(0, err)
}
// 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(stateEntrySorter(combined))]
// Find the conflicts
conflicts := findDuplicateStateKeys(combined)
var state []types.StateEntry
if len(conflicts) > 0 {
metrics.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 := stateEntryMap(conflicts).lookup(entry.StateKeyTuple); !ok {
notConflicted = append(notConflicted, entry)
}
}
resolved, err := resolveConflicts(db, notConflicted, conflicts)
if err != nil {
metrics.algorithm = "_resolve_conflicts"
return metrics.stop(0, err)
}
metrics.algorithm = "full_state_with_conflicts"
state = resolved
} else {
metrics.algorithm = "full_state_no_conflicts"
// 6) There weren't any conflicts
state = combined
}
metrics.fullStateLength = len(state)
// TODO: Check if we can encode the new state as a delta against the
// previous state.
return metrics.stop(db.AddState(roomNID, nil, state))
}
// 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 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.
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.
// Returns a sorted list of those state entries.
func findDuplicateStateKeys(a []types.StateEntry) []types.StateEntry {
var result []types.StateEntry
// j is the starting index of a block of entries with the same state key tuple.
j := 0
for i := 1; i < len(a); i++ {
// Check if the state key tuple matches the start of the block
if a[j].StateKeyTuple != a[i].StateKeyTuple {
// If the state key tuple is different then we've reached the end of a block of duplicates.
// Check if the size of the block is bigger than one.
// If the size is one then there was only a single entry with that state key tuple so we don't add it to the result
if j+1 != i {
// Add the block to the result.
result = append(result, a[j:i]...)
}
// Start a new block for the next state key tuple.
j = i
}
}
// Check if the last block with the same state key tuple had more than one event in it.
if j+1 != len(a) {
result = append(result, a[j:]...)
}
return result
}
type stateEntrySorter []types.StateEntry
func (s stateEntrySorter) Len() int { return len(s) }
func (s stateEntrySorter) Less(i, j int) bool { return s[i].LessThan(s[j]) }
func (s stateEntrySorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

3
src/github.com/matrix-org/dendrite/roomserver/query/query.go
View File

@ -35,9 +35,6 @@ type RoomserverQueryAPIDatabase interface {
// Lookup event references for the latest events in the room and the current state snapshot.
// Returns an error if there was a problem talking to the database.
LatestEventIDs(roomNID types.RoomNID) ([]gomatrixserverlib.EventReference, types.StateSnapshotNID, error)
// Lookup the Events for a list of numeric event IDs.
// Returns a list of events sorted by numeric event ID.
Events(eventNIDs []types.EventNID) ([]types.Event, error)
}
// RoomserverQueryAPI is an implementation of RoomserverQueryAPI

452
src/github.com/matrix-org/dendrite/roomserver/state/state.go
View File

@ -21,11 +21,19 @@ import (
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/matrix-org/util"
"github.com/prometheus/client_golang/prometheus"
"sort"
"time"
)
// A RoomStateDatabase has the storage APIs needed to load state from the database
type RoomStateDatabase interface {
// Store the room state at an event in the database
AddState(roomNID types.RoomNID, stateBlockNIDs []types.StateBlockNID, state []types.StateEntry) (types.StateSnapshotNID, error)
// Lookup the state of a room at each event for a list of string event IDs.
// Returns an error if there is an error talking to the database
// or if the room state for the event IDs aren't in the database
StateAtEventIDs(eventIDs []string) ([]types.StateAtEvent, error)
// Lookup the numeric IDs for a list of string event types.
// Returns a map from string event type to numeric ID for the event type.
EventTypeNIDs(eventTypes []string) (map[string]types.EventTypeNID, error)
@ -45,6 +53,9 @@ type RoomStateDatabase interface {
StateEntriesForTuples(stateBlockNIDs []types.StateBlockNID, stateKeyTuples []types.StateKeyTuple) (
[]types.StateEntryList, error,
)
// Lookup the Events for a list of numeric event IDs.
// Returns a sorted list of events.
Events(eventNIDs []types.EventNID) ([]types.Event, error)
}
// LoadStateAtSnapshot loads the full state of a room at a particular snapshot.
@ -211,6 +222,21 @@ func DifferenceBetweeenStateSnapshots(db RoomStateDatabase, oldStateNID, newStat
}
}
// 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 LoadStateAtSnapshotForStringTuples(
db RoomStateDatabase, stateNID types.StateSnapshotNID, stateKeyTuples []gomatrixserverlib.StateKeyTuple,
) ([]types.StateEntry, error) {
numericTuples, err := stringTuplesToNumericTuples(db, stateKeyTuples)
if err != nil {
return nil, err
}
return loadStateAtSnapshotForNumericTuples(db, 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.
@ -247,21 +273,6 @@ func stringTuplesToNumericTuples(db RoomStateDatabase, stringTuples []gomatrixse
return result, nil
}
// 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 LoadStateAtSnapshotForStringTuples(
db RoomStateDatabase, stateNID types.StateSnapshotNID, stateKeyTuples []gomatrixserverlib.StateKeyTuple,
) ([]types.StateEntry, error) {
numericTuples, err := stringTuplesToNumericTuples(db, stateKeyTuples)
if err != nil {
return nil, err
}
return loadStateAtSnapshotForNumericTuples(db, stateNID, numericTuples)
}
// 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.
@ -305,6 +316,375 @@ func loadStateAtSnapshotForNumericTuples(
return fullState, nil
}
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,
)
}
// 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 CalculateAndStoreStateBeforeEvent(
db RoomStateDatabase, 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 := db.StateAtEventIDs(prevEventIDs)
if err != nil {
return 0, err
}
// The state before this event will be the state after the events that came before it.
return CalculateAndStoreStateAfterEvents(db, 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 CalculateAndStoreStateAfterEvents(db RoomStateDatabase, 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(db.AddState(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 := db.StateBlockNIDs([]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(db.AddState(
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 calculateAndStoreStateAfterManyEvents(db, 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 calculateAndStoreStateAfterManyEvents(
db RoomStateDatabase, roomNID types.RoomNID, prevStates []types.StateAtEvent, metrics calculateStateMetrics,
) (types.StateSnapshotNID, error) {
// Conflict resolution.
// First stage: load the state after each of the prev events.
combined, err := LoadCombinedStateAfterEvents(db, prevStates)
if err != nil {
metrics.algorithm = "_load_combined_state"
return metrics.stop(0, err)
}
// 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(stateEntrySorter(combined))]
// Find the conflicts
conflicts := findDuplicateStateKeys(combined)
var state []types.StateEntry
if len(conflicts) > 0 {
metrics.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 := stateEntryMap(conflicts).lookup(entry.StateKeyTuple); !ok {
notConflicted = append(notConflicted, entry)
}
}
resolved, err := resolveConflicts(db, notConflicted, conflicts)
if err != nil {
metrics.algorithm = "_resolve_conflicts"
return metrics.stop(0, err)
}
metrics.algorithm = "full_state_with_conflicts"
state = resolved
} else {
metrics.algorithm = "full_state_no_conflicts"
// 6) There weren't any conflicts
state = combined
}
metrics.fullStateLength = len(state)
// TODO: Check if we can encode the new state as a delta against the
// previous state.
return metrics.stop(db.AddState(roomNID, nil, state))
}
// 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 RoomStateDatabase, 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.
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
}
// stateKeyTuplesNeeded works out which numeric state key tuples we need to authenticate some events.
func stateKeyTuplesNeeded(stateKeyNIDMap map[string]types.EventStateKeyNID, stateNeeded gomatrixserverlib.StateNeeded) []types.StateKeyTuple {
var keyTuples []types.StateKeyTuple
if stateNeeded.Create {
keyTuples = append(keyTuples, types.StateKeyTuple{types.MRoomCreateNID, types.EmptyStateKeyNID})
}
if stateNeeded.PowerLevels {
keyTuples = append(keyTuples, types.StateKeyTuple{types.MRoomPowerLevelsNID, types.EmptyStateKeyNID})
}
if stateNeeded.JoinRules {
keyTuples = append(keyTuples, types.StateKeyTuple{types.MRoomJoinRulesNID, types.EmptyStateKeyNID})
}
for _, member := range stateNeeded.Member {
stateKeyNID, ok := stateKeyNIDMap[member]
if ok {
keyTuples = append(keyTuples, types.StateKeyTuple{types.MRoomMemberNID, stateKeyNID})
}
}
for _, token := range stateNeeded.ThirdPartyInvite {
stateKeyNID, ok := stateKeyNIDMap[token]
if ok {
keyTuples = append(keyTuples, types.StateKeyTuple{types.MRoomThirdPartyInviteNID, 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 loadStateEvents(db RoomStateDatabase, 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
}
// findDuplicateStateKeys finds the state entries where the state key tuple appears more than once in a sorted list.
// Returns a sorted list of those state entries.
func findDuplicateStateKeys(a []types.StateEntry) []types.StateEntry {
var result []types.StateEntry
// j is the starting index of a block of entries with the same state key tuple.
j := 0
for i := 1; i < len(a); i++ {
// Check if the state key tuple matches the start of the block
if a[j].StateKeyTuple != a[i].StateKeyTuple {
// If the state key tuple is different then we've reached the end of a block of duplicates.
// Check if the size of the block is bigger than one.
// If the size is one then there was only a single entry with that state key tuple so we don't add it to the result
if j+1 != i {
// Add the block to the result.
result = append(result, a[j:i]...)
}
// Start a new block for the next state key tuple.
j = i
}
}
// Check if the last block with the same state key tuple had more than one event in it.
if j+1 != len(a) {
result = append(result, a[j:]...)
}
return result
}
type stateEntrySorter []types.StateEntry
func (s stateEntrySorter) Len() int { return len(s) }
func (s stateEntrySorter) Less(i, j int) bool { return s[i].LessThan(s[j]) }
func (s stateEntrySorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
type stateBlockNIDListMap []types.StateBlockNIDList
func (m stateBlockNIDListMap) lookup(stateNID types.StateSnapshotNID) (stateBlockNIDs []types.StateBlockNID, ok bool) {
@ -360,3 +740,45 @@ func (s stateBlockNIDSorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
func uniqueStateBlockNIDs(nids []types.StateBlockNID) []types.StateBlockNID {
return nids[:util.SortAndUnique(stateBlockNIDSorter(nids))]
}
// Map from event type, state key tuple to numeric event ID.
// Implemented using binary search on a sorted array.
type stateEntryMap []types.StateEntry
// lookup an entry in the event map.
func (m stateEntryMap) lookup(stateKey types.StateKeyTuple) (eventNID types.EventNID, ok bool) {
// Since the list is sorted we can implement this using binary search.
// This is faster than using a hash map.
// We don't have to worry about pathological cases because the keys are fixed
// size and are controlled by us.
list := []types.StateEntry(m)
i := sort.Search(len(list), func(i int) bool {
return !list[i].StateKeyTuple.LessThan(stateKey)
})
if i < len(list) && list[i].StateKeyTuple == stateKey {
ok = true
eventNID = list[i].EventNID
}
return
}
// Map from numeric event ID to event.
// Implemented using binary search on a sorted array.
type eventMap []types.Event
// lookup an entry in the event map.
func (m eventMap) lookup(eventNID types.EventNID) (event *types.Event, ok bool) {
// Since the list is sorted we can implement this using binary search.
// This is faster than using a hash map.
// We don't have to worry about pathological cases because the keys are fixed
// size are controlled by us.
list := []types.Event(m)
i := sort.Search(len(list), func(i int) bool {
return list[i].EventNID >= eventNID
})
if i < len(list) && list[i].EventNID == eventNID {
ok = true
event = &list[i]
}
return
}

2
src/github.com/matrix-org/dendrite/roomserver/input/state_test.go → src/github.com/matrix-org/dendrite/roomserver/state/state_test.go
View File

@ -12,7 +12,7 @@
// See the License for the specific language governing permissions and
// limitations under the License.
package input
package state
import (
"github.com/matrix-org/dendrite/roomserver/types"