From a96b124158ae82e15c37969d86b97e51259fa630 Mon Sep 17 00:00:00 2001 From: Mark Haines Date: Fri, 26 May 2017 13:51:54 +0100 Subject: [PATCH] Move calculate state to the state package (#121) --- .../dendrite/roomserver/input/events.go | 11 +- .../roomserver/input/latest_events.go | 2 +- .../dendrite/roomserver/input/state.go | 368 -------------- .../dendrite/roomserver/query/query.go | 3 - .../dendrite/roomserver/state/state.go | 452 +++++++++++++++++- .../roomserver/{input => state}/state_test.go | 2 +- 6 files changed, 440 insertions(+), 398 deletions(-) delete mode 100644 src/github.com/matrix-org/dendrite/roomserver/input/state.go rename src/github.com/matrix-org/dendrite/roomserver/{input => state}/state_test.go (99%) diff --git a/src/github.com/matrix-org/dendrite/roomserver/input/events.go b/src/github.com/matrix-org/dendrite/roomserver/input/events.go index 61bc571c..513d10ce 100644 --- a/src/github.com/matrix-org/dendrite/roomserver/input/events.go +++ b/src/github.com/matrix-org/dendrite/roomserver/input/events.go @@ -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 } } diff --git a/src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go b/src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go index b6a591cc..ad5c15a7 100644 --- a/src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go +++ b/src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go @@ -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 } diff --git a/src/github.com/matrix-org/dendrite/roomserver/input/state.go b/src/github.com/matrix-org/dendrite/roomserver/input/state.go deleted file mode 100644 index 0d35be14..00000000 --- a/src/github.com/matrix-org/dendrite/roomserver/input/state.go +++ /dev/null @@ -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] } diff --git a/src/github.com/matrix-org/dendrite/roomserver/query/query.go b/src/github.com/matrix-org/dendrite/roomserver/query/query.go index bf15e6b9..35db3bcb 100644 --- a/src/github.com/matrix-org/dendrite/roomserver/query/query.go +++ b/src/github.com/matrix-org/dendrite/roomserver/query/query.go @@ -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 diff --git a/src/github.com/matrix-org/dendrite/roomserver/state/state.go b/src/github.com/matrix-org/dendrite/roomserver/state/state.go index 5109489e..e9657fd9 100644 --- a/src/github.com/matrix-org/dendrite/roomserver/state/state.go +++ b/src/github.com/matrix-org/dendrite/roomserver/state/state.go @@ -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 +} diff --git a/src/github.com/matrix-org/dendrite/roomserver/input/state_test.go b/src/github.com/matrix-org/dendrite/roomserver/state/state_test.go similarity index 99% rename from src/github.com/matrix-org/dendrite/roomserver/input/state_test.go rename to src/github.com/matrix-org/dendrite/roomserver/state/state_test.go index a8269fbc..78d29f78 100644 --- a/src/github.com/matrix-org/dendrite/roomserver/input/state_test.go +++ b/src/github.com/matrix-org/dendrite/roomserver/state/state_test.go @@ -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"