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Correctly generate backpagination tokens for events which have the same depth (#996)

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* Correctly generate backpagination tokens for events which have the same depth

With tests. Unfortunately the code around here is hard to understand.
There will be a subsequent PR which fixes this up now that we have a test
harness in place.

* Add postgres impl

* More linting

* Fix psql statement so it actually works
This commit is contained in:
Kegsay 2020-05-01 11:01:34 +01:00 • committed by GitHub
parent e15f6676ac
commit b28674435e
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GPG key ID: 4AEE18F83AFDEB23
10 changed files with 238 additions and 80 deletions
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27
syncapi/storage/postgres/output_room_events_table.go
View file

@ -94,6 +94,9 @@ const selectEarlyEventsSQL = "" +
" WHERE room_id = $1 AND id > $2 AND id <= $3" +
" ORDER BY id ASC LIMIT $4"
const selectStreamPositionForEventIDSQL = "" +
"SELECT id FROM syncapi_output_room_events WHERE event_id = $1"
const selectMaxEventIDSQL = "" +
"SELECT MAX(id) FROM syncapi_output_room_events"
@ -111,13 +114,14 @@ const selectStateInRangeSQL = "" +
" LIMIT $8"
type outputRoomEventsStatements struct {
insertEventStmt *sql.Stmt
selectEventsStmt *sql.Stmt
selectMaxEventIDStmt *sql.Stmt
selectRecentEventsStmt *sql.Stmt
selectRecentEventsForSyncStmt *sql.Stmt
selectEarlyEventsStmt *sql.Stmt
selectStateInRangeStmt *sql.Stmt
insertEventStmt *sql.Stmt
selectEventsStmt *sql.Stmt
selectMaxEventIDStmt *sql.Stmt
selectRecentEventsStmt *sql.Stmt
selectRecentEventsForSyncStmt *sql.Stmt
selectEarlyEventsStmt *sql.Stmt
selectStateInRangeStmt *sql.Stmt
selectStreamPositionForEventIDStmt *sql.Stmt
}
func (s *outputRoomEventsStatements) prepare(db *sql.DB) (err error) {
@ -146,9 +150,18 @@ func (s *outputRoomEventsStatements) prepare(db *sql.DB) (err error) {
if s.selectStateInRangeStmt, err = db.Prepare(selectStateInRangeSQL); err != nil {
return
}
if s.selectStreamPositionForEventIDStmt, err = db.Prepare(selectStreamPositionForEventIDSQL); err != nil {
return
}
return
}
func (s *outputRoomEventsStatements) selectStreamPositionForEventID(ctx context.Context, eventID string) (types.StreamPosition, error) {
var id int64
err := s.selectStreamPositionForEventIDStmt.QueryRowContext(ctx, eventID).Scan(&id)
return types.StreamPosition(id), err
}
// selectStateInRange returns the state events between the two given PDU stream positions, exclusive of oldPos, inclusive of newPos.
// Results are bucketed based on the room ID. If the same state is overwritten multiple times between the
// two positions, only the most recent state is returned.

41
syncapi/storage/postgres/output_room_events_topology_table.go
View file

@ -32,35 +32,44 @@ CREATE TABLE IF NOT EXISTS syncapi_output_room_events_topology (
-- The place of the event in the room's topology. This can usually be determined
-- from the event's depth.
topological_position BIGINT NOT NULL,
stream_position BIGINT NOT NULL,
-- The 'room_id' key for the event.
room_id TEXT NOT NULL
);
-- The topological order will be used in events selection and ordering
CREATE UNIQUE INDEX IF NOT EXISTS syncapi_event_topological_position_idx ON syncapi_output_room_events_topology(topological_position, room_id);
CREATE UNIQUE INDEX IF NOT EXISTS syncapi_event_topological_position_idx ON syncapi_output_room_events_topology(topological_position, stream_position, room_id);
`
const insertEventInTopologySQL = "" +
"INSERT INTO syncapi_output_room_events_topology (event_id, topological_position, room_id)" +
" VALUES ($1, $2, $3)" +
" ON CONFLICT (topological_position, room_id) DO UPDATE SET event_id = $1"
"INSERT INTO syncapi_output_room_events_topology (event_id, topological_position, room_id, stream_position)" +
" VALUES ($1, $2, $3, $4)" +
" ON CONFLICT (topological_position, stream_position, room_id) DO UPDATE SET event_id = $1"
const selectEventIDsInRangeASCSQL = "" +
"SELECT event_id FROM syncapi_output_room_events_topology" +
" WHERE room_id = $1 AND topological_position > $2 AND topological_position <= $3" +
" ORDER BY topological_position ASC LIMIT $4"
" WHERE room_id = $1 AND" +
"(topological_position > $2 AND topological_position < $3) OR" +
"(topological_position = $4 AND stream_position <= $5)" +
" ORDER BY topological_position ASC, stream_position ASC LIMIT $6"
const selectEventIDsInRangeDESCSQL = "" +
"SELECT event_id FROM syncapi_output_room_events_topology" +
" WHERE room_id = $1 AND topological_position > $2 AND topological_position <= $3" +
" ORDER BY topological_position DESC LIMIT $4"
" WHERE room_id = $1 AND" +
"(topological_position > $2 AND topological_position < $3) OR" +
"(topological_position = $4 AND stream_position <= $5)" +
" ORDER BY topological_position DESC, stream_position DESC LIMIT $6"
const selectPositionInTopologySQL = "" +
"SELECT topological_position FROM syncapi_output_room_events_topology" +
" WHERE event_id = $1"
// Select the max topological position for the room, then sort by stream position and take the highest,
// returning both topological and stream positions.
const selectMaxPositionInTopologySQL = "" +
"SELECT MAX(topological_position) FROM syncapi_output_room_events_topology" +
" WHERE room_id = $1"
"SELECT topological_position, stream_position FROM syncapi_output_room_events_topology" +
" WHERE topological_position=(" +
"SELECT MAX(topological_position) FROM syncapi_output_room_events_topology WHERE room_id=$1" +
") ORDER BY stream_position DESC LIMIT 1"
const selectEventIDsFromPositionSQL = "" +
"SELECT event_id FROM syncapi_output_room_events_topology" +
@ -104,10 +113,10 @@ func (s *outputRoomEventsTopologyStatements) prepare(db *sql.DB) (err error) {
// insertEventInTopology inserts the given event in the room's topology, based
// on the event's depth.
func (s *outputRoomEventsTopologyStatements) insertEventInTopology(
ctx context.Context, event *gomatrixserverlib.HeaderedEvent,
ctx context.Context, event *gomatrixserverlib.HeaderedEvent, pos types.StreamPosition,
) (err error) {
_, err = s.insertEventInTopologyStmt.ExecContext(
ctx, event.EventID(), event.Depth(), event.RoomID(),
ctx, event.EventID(), event.Depth(), event.RoomID(), pos,
)
return
}
@ -116,7 +125,7 @@ func (s *outputRoomEventsTopologyStatements) insertEventInTopology(
// given range in a given room's topological order.
// Returns an empty slice if no events match the given range.
func (s *outputRoomEventsTopologyStatements) selectEventIDsInRange(
ctx context.Context, roomID string, fromPos, toPos types.StreamPosition,
ctx context.Context, roomID string, fromPos, toPos, toMicroPos types.StreamPosition,
limit int, chronologicalOrder bool,
) (eventIDs []string, err error) {
// Decide on the selection's order according to whether chronological order
@ -129,7 +138,7 @@ func (s *outputRoomEventsTopologyStatements) selectEventIDsInRange(
}
// Query the event IDs.
rows, err := stmt.QueryContext(ctx, roomID, fromPos, toPos, limit)
rows, err := stmt.QueryContext(ctx, roomID, fromPos, toPos, toPos, toMicroPos, limit)
if err == sql.ErrNoRows {
// If no event matched the request, return an empty slice.
return []string{}, nil
@ -161,8 +170,8 @@ func (s *outputRoomEventsTopologyStatements) selectPositionInTopology(
func (s *outputRoomEventsTopologyStatements) selectMaxPositionInTopology(
ctx context.Context, roomID string,
) (pos types.StreamPosition, err error) {
err = s.selectMaxPositionInTopologyStmt.QueryRowContext(ctx, roomID).Scan(&pos)
) (pos types.StreamPosition, spos types.StreamPosition, err error) {
err = s.selectMaxPositionInTopologyStmt.QueryRowContext(ctx, roomID).Scan(&pos, &spos)
return
}

18
syncapi/storage/postgres/syncserver.go
View file

@ -159,7 +159,7 @@ func (d *SyncServerDatasource) WriteEvent(
}
pduPosition = pos
if err = d.topology.insertEventInTopology(ctx, ev); err != nil {
if err = d.topology.insertEventInTopology(ctx, ev, pos); err != nil {
return err
}
@ -240,12 +240,13 @@ func (d *SyncServerDatasource) GetEventsInRange(
if from.Type == types.PaginationTokenTypeTopology {
// Determine the backward and forward limit, i.e. the upper and lower
// limits to the selection in the room's topology, from the direction.
var backwardLimit, forwardLimit types.StreamPosition
var backwardLimit, forwardLimit, forwardMicroLimit types.StreamPosition
if backwardOrdering {
// Backward ordering is antichronological (latest event to oldest
// one).
backwardLimit = to.PDUPosition
forwardLimit = from.PDUPosition
forwardMicroLimit = from.EDUTypingPosition
} else {
// Forward ordering is chronological (oldest event to latest one).
backwardLimit = from.PDUPosition
@ -255,7 +256,7 @@ func (d *SyncServerDatasource) GetEventsInRange(
// Select the event IDs from the defined range.
var eIDs []string
eIDs, err = d.topology.selectEventIDsInRange(
ctx, roomID, backwardLimit, forwardLimit, limit, !backwardOrdering,
ctx, roomID, backwardLimit, forwardLimit, forwardMicroLimit, limit, !backwardOrdering,
)
if err != nil {
return
@ -301,7 +302,7 @@ func (d *SyncServerDatasource) BackwardExtremitiesForRoom(
func (d *SyncServerDatasource) MaxTopologicalPosition(
ctx context.Context, roomID string,
) (types.StreamPosition, error) {
) (depth types.StreamPosition, stream types.StreamPosition, err error) {
return d.topology.selectMaxPositionInTopology(ctx, roomID)
}
@ -318,8 +319,13 @@ func (d *SyncServerDatasource) EventsAtTopologicalPosition(
func (d *SyncServerDatasource) EventPositionInTopology(
ctx context.Context, eventID string,
) (types.StreamPosition, error) {
return d.topology.selectPositionInTopology(ctx, eventID)
) (depth types.StreamPosition, stream types.StreamPosition, err error) {
depth, err = d.topology.selectPositionInTopology(ctx, eventID)
if err != nil {
return
}
stream, err = d.events.selectStreamPositionForEventID(ctx, eventID)
return
}
func (d *SyncServerDatasource) SyncStreamPosition(ctx context.Context) (types.StreamPosition, error) {