GoToSocial/internal/db/bundb/wrap.go

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2023-07-25 10:34:05 +02:00
// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package bundb
import (
"context"
"database/sql"
"time"
"github.com/superseriousbusiness/gotosocial/internal/db"
"github.com/superseriousbusiness/gotosocial/internal/gtserror"
"github.com/uptrace/bun"
"github.com/uptrace/bun/dialect"
)
// WrappedDB wraps a bun database instance
// to provide common per-dialect SQL error
// conversions to common types, and retries
// on returned busy errors (SQLite only for now).
type WrappedDB struct {
errHook func(error) error
*bun.DB // underlying conn
}
// WrapDB wraps a bun database instance in our own WrappedDB type.
func WrapDB(db *bun.DB) *WrappedDB {
var errProc func(error) error
switch name := db.Dialect().Name(); name {
case dialect.PG:
errProc = processPostgresError
case dialect.SQLite:
errProc = processSQLiteError
default:
panic("unknown dialect name: " + name.String())
}
return &WrappedDB{
errHook: errProc,
DB: db,
}
}
// BeginTx wraps bun.DB.BeginTx() with retry-busy timeout.
func (db *WrappedDB) BeginTx(ctx context.Context, opts *sql.TxOptions) (tx bun.Tx, err error) {
err = retryOnBusy(ctx, func() error {
tx, err = db.DB.BeginTx(ctx, opts)
err = db.ProcessError(err)
return err
})
return
}
// ExecContext wraps bun.DB.ExecContext() with retry-busy timeout.
func (db *WrappedDB) ExecContext(ctx context.Context, query string, args ...any) (result sql.Result, err error) {
err = retryOnBusy(ctx, func() error {
result, err = db.DB.ExecContext(ctx, query, args...)
err = db.ProcessError(err)
return err
})
return
}
// QueryContext wraps bun.DB.QueryContext() with retry-busy timeout.
func (db *WrappedDB) QueryContext(ctx context.Context, query string, args ...any) (rows *sql.Rows, err error) {
err = retryOnBusy(ctx, func() error {
rows, err = db.DB.QueryContext(ctx, query, args...)
err = db.ProcessError(err)
return err
})
return
}
// QueryRowContext wraps bun.DB.QueryRowContext() with retry-busy timeout.
func (db *WrappedDB) QueryRowContext(ctx context.Context, query string, args ...any) (row *sql.Row) {
_ = retryOnBusy(ctx, func() error {
row = db.DB.QueryRowContext(ctx, query, args...)
err := db.ProcessError(row.Err())
return err
})
return
}
// RunInTx is functionally the same as bun.DB.RunInTx() but with retry-busy timeouts.
func (db *WrappedDB) RunInTx(ctx context.Context, fn func(bun.Tx) error) error {
// Attempt to start new transaction.
tx, err := db.BeginTx(ctx, nil)
if err != nil {
return err
}
var done bool
defer func() {
if !done {
// Rollback (with retry-backoff).
_ = retryOnBusy(ctx, func() error {
err := tx.Rollback()
return db.errHook(err)
})
}
}()
// Perform supplied transaction
if err := fn(tx); err != nil {
return db.errHook(err)
}
// Commit (with retry-backoff).
err = retryOnBusy(ctx, func() error {
err := tx.Commit()
return db.errHook(err)
})
done = true
return err
}
func (db *WrappedDB) NewValues(model interface{}) *bun.ValuesQuery {
return bun.NewValuesQuery(db.DB, model).Conn(db)
}
func (db *WrappedDB) NewMerge() *bun.MergeQuery {
return bun.NewMergeQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewSelect() *bun.SelectQuery {
return bun.NewSelectQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewInsert() *bun.InsertQuery {
return bun.NewInsertQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewUpdate() *bun.UpdateQuery {
return bun.NewUpdateQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewDelete() *bun.DeleteQuery {
return bun.NewDeleteQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewRaw(query string, args ...interface{}) *bun.RawQuery {
return bun.NewRawQuery(db.DB, query, args...).Conn(db)
}
func (db *WrappedDB) NewCreateTable() *bun.CreateTableQuery {
return bun.NewCreateTableQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewDropTable() *bun.DropTableQuery {
return bun.NewDropTableQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewCreateIndex() *bun.CreateIndexQuery {
return bun.NewCreateIndexQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewDropIndex() *bun.DropIndexQuery {
return bun.NewDropIndexQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewTruncateTable() *bun.TruncateTableQuery {
return bun.NewTruncateTableQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewAddColumn() *bun.AddColumnQuery {
return bun.NewAddColumnQuery(db.DB).Conn(db)
}
func (db *WrappedDB) NewDropColumn() *bun.DropColumnQuery {
return bun.NewDropColumnQuery(db.DB).Conn(db)
}
// ProcessError processes an error to replace any known values with our own error types,
// making it easier to catch specific situations (e.g. no rows, already exists, etc)
func (db *WrappedDB) ProcessError(err error) error {
if err == nil {
return nil
}
return db.errHook(err)
}
// Exists checks the results of a SelectQuery for the existence of the data in question, masking ErrNoEntries errors
func (db *WrappedDB) Exists(ctx context.Context, query *bun.SelectQuery) (bool, error) {
exists, err := query.Exists(ctx)
switch err {
case nil:
return exists, nil
case sql.ErrNoRows:
return false, nil
default:
return false, err
}
}
// NotExists is the functional opposite of conn.Exists()
func (db *WrappedDB) NotExists(ctx context.Context, query *bun.SelectQuery) (bool, error) {
exists, err := db.Exists(ctx, query)
return !exists, err
}
// retryOnBusy will retry given function on returned 'errBusy'.
func retryOnBusy(ctx context.Context, fn func() error) error {
var backoff time.Duration
for i := 0; ; i++ {
// Perform func.
err := fn()
if err != errBusy {
// May be nil, or may be
// some other error, either
// way return here.
return err
}
// backoff according to a multiplier of 2ms * 2^2n,
// up to a maximum possible backoff time of 5 minutes.
//
// this works out as the following:
// 4ms
// 16ms
// 64ms
// 256ms
// 1.024s
// 4.096s
// 16.384s
// 1m5.536s
// 4m22.144s
backoff = 2 * time.Millisecond * (1 << (2*i + 1))
if backoff >= 5*time.Minute {
break
}
select {
// Context cancelled.
case <-ctx.Done():
// Backoff for some time.
case <-time.After(backoff):
}
}
return gtserror.Newf("%w (waited > %s)", db.ErrBusyTimeout, backoff)
}