dendrite/roomserver/storage/postgres/event_json_table.go
Kiril Vladimiroff d5dbe546e4
Always defer *sql.Rows.Close and consult with Err (#844)
* Always defer *sql.Rows.Close and consult with Err

database/sql.Rows.Next() makes sure to call Close only after exhausting
result rows which would NOT happen when returning early from a bad Scan.
Close being idempotent makes it a great candidate to get always deferred
regardless of what happens later on the result set.

This change also makes sure call Err() after exhausting Next() and
propagate non-nil results from it as the documentation advises.

Closes #764

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

* Override named result parameters in last returns

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

* Do the same over new changes that got merged

Signed-off-by: Kiril Vladimiroff <kiril@vladimiroff.org>

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>
2020-02-11 14:12:21 +00:00

106 lines
3.4 KiB
Go

// Copyright 2017-2018 New Vector Ltd
// Copyright 2019-2020 The Matrix.org Foundation C.I.C.
//
// 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/roomserver/types"
)
const eventJSONSchema = `
-- Stores the JSON for each event. This kept separate from the main events
-- table to keep the rows in the main events table small.
CREATE TABLE IF NOT EXISTS roomserver_event_json (
-- Local numeric ID for the event.
event_nid BIGINT NOT NULL PRIMARY KEY,
-- The JSON for the event.
-- Stored as TEXT because this should be valid UTF-8.
-- Not stored as a JSONB because we always just pull the entire event
-- so there is no point in postgres parsing it.
-- Not stored as JSON because we already validate the JSON in the server
-- so there is no point in postgres validating it.
-- TODO: Should we be compressing the events with Snappy or DEFLATE?
event_json TEXT NOT NULL
);
`
const insertEventJSONSQL = "" +
"INSERT INTO roomserver_event_json (event_nid, event_json) VALUES ($1, $2)" +
" ON CONFLICT DO NOTHING"
// Bulk event JSON lookup by numeric event ID.
// Sort by the numeric event ID.
// This means that we can use binary search to lookup by numeric event ID.
const bulkSelectEventJSONSQL = "" +
"SELECT event_nid, event_json FROM roomserver_event_json" +
" WHERE event_nid = ANY($1)" +
" ORDER BY event_nid ASC"
type eventJSONStatements struct {
insertEventJSONStmt *sql.Stmt
bulkSelectEventJSONStmt *sql.Stmt
}
func (s *eventJSONStatements) prepare(db *sql.DB) (err error) {
_, err = db.Exec(eventJSONSchema)
if err != nil {
return
}
return statementList{
{&s.insertEventJSONStmt, insertEventJSONSQL},
{&s.bulkSelectEventJSONStmt, bulkSelectEventJSONSQL},
}.prepare(db)
}
func (s *eventJSONStatements) insertEventJSON(
ctx context.Context, eventNID types.EventNID, eventJSON []byte,
) error {
_, err := s.insertEventJSONStmt.ExecContext(ctx, int64(eventNID), eventJSON)
return err
}
type eventJSONPair struct {
EventNID types.EventNID
EventJSON []byte
}
func (s *eventJSONStatements) bulkSelectEventJSON(
ctx context.Context, eventNIDs []types.EventNID,
) ([]eventJSONPair, error) {
rows, err := s.bulkSelectEventJSONStmt.QueryContext(ctx, eventNIDsAsArray(eventNIDs))
if err != nil {
return nil, err
}
defer rows.Close() // nolint: errcheck
// We know that we will only get as many results as event NIDs
// because of the unique constraint on event NIDs.
// So we can allocate an array of the correct size now.
// We might get fewer results than NIDs so we adjust the length of the slice before returning it.
results := make([]eventJSONPair, len(eventNIDs))
i := 0
for ; rows.Next(); i++ {
result := &results[i]
var eventNID int64
if err := rows.Scan(&eventNID, &result.EventJSON); err != nil {
return nil, err
}
result.EventNID = types.EventNID(eventNID)
}
return results[:i], rows.Err()
}