mirror of
https://github.com/1f349/dendrite.git
synced 2024-11-14 15:51:37 +00:00
125 lines
4.3 KiB
Go
125 lines
4.3 KiB
Go
// Copyright 2018 New Vector 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 postgres
|
|
|
|
import (
|
|
"context"
|
|
"database/sql"
|
|
|
|
"github.com/matrix-org/dendrite/common"
|
|
)
|
|
|
|
// The purpose of this table is to keep track of backwards extremities for a room.
|
|
// Backwards extremities are the earliest (DAG-wise) known events which we have
|
|
// the entire event JSON. These event IDs are used in federation requests to fetch
|
|
// even earlier events.
|
|
//
|
|
// We persist the previous event IDs as well, one per row, so when we do fetch even
|
|
// earlier events we can simply delete rows which referenced it. Consider the graph:
|
|
// A
|
|
// | Event C has 1 prev_event ID: A.
|
|
// B C
|
|
// |___| Event D has 2 prev_event IDs: B and C.
|
|
// |
|
|
// D
|
|
// The earliest known event we have is D, so this table has 2 rows.
|
|
// A backfill request gives us C but not B. We delete rows where prev_event=C. This
|
|
// still means that D is a backwards extremity as we do not have event B. However, event
|
|
// C is *also* a backwards extremity at this point as we do not have event A. Later,
|
|
// when we fetch event B, we delete rows where prev_event=B. This then removes D as
|
|
// a backwards extremity because there are no more rows with event_id=B.
|
|
const backwardExtremitiesSchema = `
|
|
-- Stores output room events received from the roomserver.
|
|
CREATE TABLE IF NOT EXISTS syncapi_backward_extremities (
|
|
-- The 'room_id' key for the event.
|
|
room_id TEXT NOT NULL,
|
|
-- The event ID for the last known event. This is the backwards extremity.
|
|
event_id TEXT NOT NULL,
|
|
-- The prev_events for the last known event. This is used to update extremities.
|
|
prev_event_id TEXT NOT NULL,
|
|
|
|
PRIMARY KEY(room_id, event_id, prev_event_id)
|
|
);
|
|
`
|
|
|
|
const insertBackwardExtremitySQL = "" +
|
|
"INSERT INTO syncapi_backward_extremities (room_id, event_id, prev_event_id)" +
|
|
" VALUES ($1, $2, $3)" +
|
|
" ON CONFLICT DO NOTHING"
|
|
|
|
const selectBackwardExtremitiesForRoomSQL = "" +
|
|
"SELECT DISTINCT event_id FROM syncapi_backward_extremities WHERE room_id = $1"
|
|
|
|
const deleteBackwardExtremitySQL = "" +
|
|
"DELETE FROM syncapi_backward_extremities WHERE room_id = $1 AND prev_event_id = $2"
|
|
|
|
type backwardExtremitiesStatements struct {
|
|
insertBackwardExtremityStmt *sql.Stmt
|
|
selectBackwardExtremitiesForRoomStmt *sql.Stmt
|
|
deleteBackwardExtremityStmt *sql.Stmt
|
|
}
|
|
|
|
func (s *backwardExtremitiesStatements) prepare(db *sql.DB) (err error) {
|
|
_, err = db.Exec(backwardExtremitiesSchema)
|
|
if err != nil {
|
|
return
|
|
}
|
|
if s.insertBackwardExtremityStmt, err = db.Prepare(insertBackwardExtremitySQL); err != nil {
|
|
return
|
|
}
|
|
if s.selectBackwardExtremitiesForRoomStmt, err = db.Prepare(selectBackwardExtremitiesForRoomSQL); err != nil {
|
|
return
|
|
}
|
|
if s.deleteBackwardExtremityStmt, err = db.Prepare(deleteBackwardExtremitySQL); err != nil {
|
|
return
|
|
}
|
|
return
|
|
}
|
|
|
|
func (s *backwardExtremitiesStatements) insertsBackwardExtremity(
|
|
ctx context.Context, txn *sql.Tx, roomID, eventID string, prevEventID string,
|
|
) (err error) {
|
|
_, err = txn.Stmt(s.insertBackwardExtremityStmt).ExecContext(ctx, roomID, eventID, prevEventID)
|
|
return
|
|
}
|
|
|
|
func (s *backwardExtremitiesStatements) selectBackwardExtremitiesForRoom(
|
|
ctx context.Context, roomID string,
|
|
) (eventIDs []string, err error) {
|
|
rows, err := s.selectBackwardExtremitiesForRoomStmt.QueryContext(ctx, roomID)
|
|
if err != nil {
|
|
return
|
|
}
|
|
defer common.CloseAndLogIfError(ctx, rows, "selectBackwardExtremitiesForRoom: rows.close() failed")
|
|
|
|
for rows.Next() {
|
|
var eID string
|
|
if err = rows.Scan(&eID); err != nil {
|
|
return
|
|
}
|
|
|
|
eventIDs = append(eventIDs, eID)
|
|
}
|
|
|
|
return eventIDs, rows.Err()
|
|
}
|
|
|
|
func (s *backwardExtremitiesStatements) deleteBackwardExtremity(
|
|
ctx context.Context, txn *sql.Tx, roomID, knownEventID string,
|
|
) (err error) {
|
|
_, err = txn.Stmt(s.deleteBackwardExtremityStmt).ExecContext(ctx, roomID, knownEventID)
|
|
return
|
|
}
|