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package pdatadb
import (
"context"
"database/sql"
"fmt"
"path"
"runtime"
"sort"
"strconv"
"strings"
"github.com/jmoiron/sqlx"
)
// TODO: support versions which can't be migrated down from
type migration struct {
Name string
Up func(context.Context, *sqlx.Tx) error
Down func(context.Context, *sqlx.Tx) error
}
var migrations = map[uint64]migration{}
func migrate(up, down func(context.Context, *sqlx.Tx) error) {
_, fn, _, ok := runtime.Caller(1)
if !ok {
panic("add migration: failed to get filename")
}
fn = path.Base(strings.ReplaceAll(fn, `\`, `/`))
if n, _, ok := strings.Cut(fn, "_"); !ok {
panic("add migration: failed to parse filename")
} else if v, err := strconv.ParseUint(n, 10, 64); err != nil {
panic("add migration: failed to parse filename: " + err.Error())
} else if v == 0 {
panic("add migration: version must not be 0")
} else {
migrations[v] = migration{strings.TrimSuffix(n, ".go"), up, down}
}
}
// Version gets the current and required database versions. It should be checked
// before using the database.
func (db *DB) Version() (current, required uint64, err error) {
if err = db.x.Get(¤t, `PRAGMA user_version`); err != nil {
err = fmt.Errorf("get version: %w", err)
return
}
for v := range migrations {
if v > required {
required = v
}
}
return
}
// MigrateUp migrates the database to the provided version.
func (db *DB) MigrateUp(ctx context.Context, to uint64) error {
tx, err := db.x.BeginTxx(ctx, &sql.TxOptions{})
if err != nil {
return fmt.Errorf("begin transaction: %w", err)
}
defer tx.Rollback()
var cv uint64
if err = tx.GetContext(ctx, &cv, `PRAGMA user_version`); err != nil {
return fmt.Errorf("get version: %w", err)
}
if to < cv {
return fmt.Errorf("target version %d is less than current version %d", to, cv)
}
var ms []uint64
foundC, foundT := cv == 0, to == 0
for v := range migrations {
if v == cv {
foundC = true
}
if v == to {
foundT = true
}
if v > cv && v <= to {
ms = append(ms, v)
}
}
if !foundC {
return fmt.Errorf("unsupported db version %d", cv)
}
if !foundT {
return fmt.Errorf("unknown db version %d", cv)
}
sort.Slice(ms, func(i, j int) bool {
return ms[i] < ms[j]
})
for _, v := range ms {
if err := migrations[v].Up(ctx, tx); err != nil {
return fmt.Errorf("migrate %d: %w", v, err)
}
}
if _, err := tx.ExecContext(ctx, `PRAGMA user_version = `+strconv.FormatUint(to, 10)); err != nil {
return fmt.Errorf("update version: %w", err)
}
if err := tx.Commit(); err != nil {
return fmt.Errorf("commit transaction: %w", err)
}
return nil
}
// MigrateDown migrates the database down to the provided version. This will
// probably eat your data.
func (db *DB) MigrateDown(ctx context.Context, to uint64) error {
tx, err := db.x.BeginTxx(ctx, &sql.TxOptions{})
if err != nil {
return fmt.Errorf("begin transaction: %w", err)
}
defer tx.Rollback()
var cv uint64
if err = tx.GetContext(ctx, &cv, `PRAGMA user_version`); err != nil {
return fmt.Errorf("get version: %w", err)
}
if cv < to {
return fmt.Errorf("current version %d is less than target version %d", cv, to)
}
var ms []uint64
foundC, foundT := cv == 0, to == 0
for v := range migrations {
if v == cv {
foundC = true
}
if v == to {
foundT = true
}
if v <= cv && v > to {
ms = append(ms, v)
}
}
if !foundC {
return fmt.Errorf("unsupported db version %d", cv)
}
if !foundT {
return fmt.Errorf("unknown db version %d", cv)
}
sort.Slice(ms, func(i, j int) bool {
return ms[i] > ms[j]
})
for _, v := range ms {
if err := migrations[v].Down(ctx, tx); err != nil {
return fmt.Errorf("migrate %d: %w", v, err)
}
}
if _, err := tx.ExecContext(ctx, `PRAGMA user_version = `+strconv.FormatUint(to, 10)); err != nil {
return fmt.Errorf("update version: %w", err)
}
if err := tx.Commit(); err != nil {
return fmt.Errorf("commit transaction: %w", err)
}
return nil
}
|
