132 lines
4.6 KiB
Go
132 lines
4.6 KiB
Go
// Copyright 2017-2018 New Vector Ltd
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// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sqlite3
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import (
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"context"
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"database/sql"
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"fmt"
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"strings"
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"github.com/matrix-org/dendrite/internal/sqlutil"
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"github.com/matrix-org/dendrite/roomserver/storage/tables"
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"github.com/matrix-org/dendrite/roomserver/types"
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)
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// TODO: previous_reference_sha256 was NOT NULL before but it broke sytest because
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// sytest sends no SHA256 sums in the prev_events references in the soft-fail tests.
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// In Postgres an empty BYTEA field is not NULL so it's fine there. In SQLite it
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// seems to care that it's empty and therefore hits a NOT NULL constraint on insert.
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// We should really work out what the right thing to do here is.
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const previousEventSchema = `
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CREATE TABLE IF NOT EXISTS roomserver_previous_events (
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previous_event_id TEXT NOT NULL,
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previous_reference_sha256 BLOB,
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event_nids TEXT NOT NULL,
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UNIQUE (previous_event_id, previous_reference_sha256)
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);
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`
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// Insert an entry into the previous_events table.
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// If there is already an entry indicating that an event references that previous event then
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// add the event NID to the list to indicate that this event references that previous event as well.
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// This should only be modified while holding a "FOR UPDATE" lock on the row in the rooms table for this room.
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// The lock is necessary to avoid data races when checking whether an event is already referenced by another event.
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const insertPreviousEventSQL = `
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INSERT OR REPLACE INTO roomserver_previous_events
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(previous_event_id, previous_reference_sha256, event_nids)
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VALUES ($1, $2, $3)
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`
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const selectPreviousEventNIDsSQL = `
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SELECT event_nids FROM roomserver_previous_events
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WHERE previous_event_id = $1 AND previous_reference_sha256 = $2
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`
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// Check if the event is referenced by another event in the table.
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// This should only be done while holding a "FOR UPDATE" lock on the row in the rooms table for this room.
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const selectPreviousEventExistsSQL = `
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SELECT 1 FROM roomserver_previous_events
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WHERE previous_event_id = $1 AND previous_reference_sha256 = $2
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`
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type previousEventStatements struct {
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db *sql.DB
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insertPreviousEventStmt *sql.Stmt
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selectPreviousEventNIDsStmt *sql.Stmt
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selectPreviousEventExistsStmt *sql.Stmt
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}
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func createPrevEventsTable(db *sql.DB) error {
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_, err := db.Exec(previousEventSchema)
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return err
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}
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func preparePrevEventsTable(db *sql.DB) (tables.PreviousEvents, error) {
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s := &previousEventStatements{
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db: db,
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}
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return s, sqlutil.StatementList{
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{&s.insertPreviousEventStmt, insertPreviousEventSQL},
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{&s.selectPreviousEventNIDsStmt, selectPreviousEventNIDsSQL},
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{&s.selectPreviousEventExistsStmt, selectPreviousEventExistsSQL},
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}.Prepare(db)
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}
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func (s *previousEventStatements) InsertPreviousEvent(
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ctx context.Context,
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txn *sql.Tx,
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previousEventID string,
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previousEventReferenceSHA256 []byte,
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eventNID types.EventNID,
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) error {
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var eventNIDs string
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eventNIDAsString := fmt.Sprintf("%d", eventNID)
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selectStmt := sqlutil.TxStmt(txn, s.selectPreviousEventExistsStmt)
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err := selectStmt.QueryRowContext(ctx, previousEventID, previousEventReferenceSHA256).Scan(&eventNIDs)
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if err != nil && err != sql.ErrNoRows {
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return fmt.Errorf("selectStmt.QueryRowContext.Scan: %w", err)
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}
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var nids []string
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if eventNIDs != "" {
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nids = strings.Split(eventNIDs, ",")
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for _, nid := range nids {
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if nid == eventNIDAsString {
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return nil
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}
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}
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eventNIDs = strings.Join(append(nids, eventNIDAsString), ",")
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} else {
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eventNIDs = eventNIDAsString
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}
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insertStmt := sqlutil.TxStmt(txn, s.insertPreviousEventStmt)
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_, err = insertStmt.ExecContext(
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ctx, previousEventID, previousEventReferenceSHA256, eventNIDs,
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)
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return err
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}
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// Check if the event reference exists
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// Returns sql.ErrNoRows if the event reference doesn't exist.
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func (s *previousEventStatements) SelectPreviousEventExists(
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ctx context.Context, txn *sql.Tx, eventID string, eventReferenceSHA256 []byte,
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) error {
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var ok int64
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stmt := sqlutil.TxStmt(txn, s.selectPreviousEventExistsStmt)
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return stmt.QueryRowContext(ctx, eventID, eventReferenceSHA256).Scan(&ok)
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}
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