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driver.go
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driver.go
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// Copyright 2021-present The Atlas Authors. All rights reserved.
// This source code is licensed under the Apache 2.0 license found
// in the LICENSE file in the root directory of this source tree.
package sqlite
import (
"context"
"database/sql"
"errors"
"fmt"
"net/url"
"os"
"path/filepath"
"strconv"
"strings"
"time"
"ariga.io/atlas/sql/internal/sqlx"
"ariga.io/atlas/sql/migrate"
"ariga.io/atlas/sql/schema"
"ariga.io/atlas/sql/sqlclient"
)
type (
// Driver represents a SQLite driver for introspecting database schemas,
// generating diff between schema elements and apply migrations changes.
Driver struct {
conn
schema.Differ
schema.Inspector
migrate.PlanApplier
}
// database connection and its information.
conn struct {
schema.ExecQuerier
// System variables that are set on `Open`.
version string
collations []string
}
)
// DriverName holds the name used for registration.
const DriverName = "sqlite3"
func init() {
sqlclient.Register(
DriverName,
sqlclient.DriverOpener(Open),
sqlclient.RegisterTxOpener(OpenTx),
sqlclient.RegisterCodec(MarshalHCL, EvalHCL),
sqlclient.RegisterFlavours("sqlite"),
sqlclient.RegisterURLParser(sqlclient.URLParserFunc(func(u *url.URL) *sqlclient.URL {
uc := &sqlclient.URL{URL: u, DSN: strings.TrimPrefix(u.String(), u.Scheme+"://"), Schema: mainFile}
if mode := u.Query().Get("mode"); mode == "memory" {
// The "file:" prefix is mandatory for memory modes.
uc.DSN = "file:" + uc.DSN
}
return uc
})),
)
}
// Open opens a new SQLite driver.
func Open(db schema.ExecQuerier) (migrate.Driver, error) {
var (
c = conn{ExecQuerier: db}
ctx = context.Background()
)
rows, err := db.QueryContext(ctx, "SELECT sqlite_version()")
if err != nil {
return nil, fmt.Errorf("sqlite: query version pragma: %w", err)
}
if err := sqlx.ScanOne(rows, &c.version); err != nil {
return nil, fmt.Errorf("sqlite: scan version pragma: %w", err)
}
if rows, err = db.QueryContext(ctx, "SELECT name FROM pragma_collation_list()"); err != nil {
return nil, fmt.Errorf("sqlite: query collation_list pragma: %w", err)
}
if c.collations, err = sqlx.ScanStrings(rows); err != nil {
return nil, fmt.Errorf("sqlite: scanning database collations: %w", err)
}
return &Driver{
conn: c,
Differ: &sqlx.Diff{DiffDriver: &diff{}},
Inspector: &inspect{c},
PlanApplier: &planApply{c},
}, nil
}
// Snapshot implements migrate.Snapshoter.
func (d *Driver) Snapshot(ctx context.Context) (migrate.RestoreFunc, error) {
r, err := d.InspectRealm(ctx, nil)
if err != nil {
return nil, err
}
if !(r == nil || (len(r.Schemas) == 1 && r.Schemas[0].Name == mainFile && len(r.Schemas[0].Tables) == 0)) {
return nil, &migrate.NotCleanError{Reason: fmt.Sprintf("found table %q", r.Schemas[0].Tables[0].Name)}
}
return func(ctx context.Context) error {
for _, stmt := range []string{
"PRAGMA writable_schema = 1;",
"DELETE FROM sqlite_master WHERE type IN ('table', 'index', 'trigger');",
"PRAGMA writable_schema = 0;",
"VACUUM;",
} {
if _, err := d.ExecContext(ctx, stmt); err != nil {
return err
}
}
return nil
}, nil
}
// CheckClean implements migrate.CleanChecker.
func (d *Driver) CheckClean(ctx context.Context, revT *migrate.TableIdent) error {
r, err := d.InspectRealm(ctx, nil)
if err != nil {
return err
}
switch n := len(r.Schemas); {
case n > 1:
return &migrate.NotCleanError{Reason: fmt.Sprintf("found multiple schemas: %d", len(r.Schemas))}
case n == 1 && r.Schemas[0].Name != mainFile:
return &migrate.NotCleanError{Reason: fmt.Sprintf("found schema %q", r.Schemas[0].Name)}
case n == 1 && len(r.Schemas[0].Tables) > 1:
return &migrate.NotCleanError{Reason: fmt.Sprintf("found multiple tables: %d", len(r.Schemas[0].Tables))}
case n == 1 && len(r.Schemas[0].Tables) == 1 && (revT == nil || r.Schemas[0].Tables[0].Name != revT.Name):
return &migrate.NotCleanError{Reason: fmt.Sprintf("found table %q", r.Schemas[0].Tables[0].Name)}
}
return nil
}
// Lock implements the schema.Locker interface.
func (d *Driver) Lock(_ context.Context, name string, timeout time.Duration) (schema.UnlockFunc, error) {
path := filepath.Join(os.TempDir(), name+".lock")
c, err := os.ReadFile(path)
if errors.Is(err, os.ErrNotExist) {
return acquireLock(path, timeout)
}
if err != nil {
return nil, fmt.Errorf("sql/sqlite: reading lock dir: %w", err)
}
expires, err := strconv.ParseInt(string(c), 10, 64)
if err != nil {
return nil, fmt.Errorf("sql/sqlite: invalid lock file format: parsing expiration date: %w", err)
}
if time.Unix(0, expires).After(time.Now()) {
// Lock is still valid.
return nil, fmt.Errorf("sql/sqlite: lock on %q already taken", name)
}
return acquireLock(path, timeout)
}
// Version returns the version of the connected database.
func (d *Driver) Version() string {
return d.conn.version
}
func acquireLock(path string, timeout time.Duration) (schema.UnlockFunc, error) {
lock, err := os.Create(path)
if err != nil {
return nil, fmt.Errorf("sql/sqlite: creating lockfile %q: %w", path, err)
}
if _, err := lock.Write([]byte(strconv.FormatInt(time.Now().Add(timeout).UnixNano(), 10))); err != nil {
return nil, fmt.Errorf("sql/sqlite: writing to lockfile %q: %w", path, err)
}
defer lock.Close()
return func() error { return os.Remove(path) }, nil
}
type violation struct {
tbl, ref string
row, index int
}
// OpenTx opens a transaction. If foreign keys are enabled, it disables them, checks for constraint violations,
// opens the transaction and before committing ensures no new violations have been introduced by whatever Atlas was
// doing.
func OpenTx(ctx context.Context, db *sql.DB, opts *sql.TxOptions) (*sqlclient.Tx, error) {
var on sql.NullBool
if err := db.QueryRowContext(ctx, "PRAGMA foreign_keys").Scan(&on); err != nil {
return nil, fmt.Errorf("sql/sqlite: querying 'foreign_keys' pragma: %w", err)
}
// Disable the foreign_keys pragma in case it is enabled, and
// toggle it back after transaction is committed or rolled back.
if on.Bool {
_, err := db.ExecContext(ctx, "PRAGMA foreign_keys = off")
if err != nil {
return nil, fmt.Errorf("sql/sqlite: set 'foreign_keys = off': %w", err)
}
}
tx, err := db.BeginTx(ctx, opts)
if err != nil {
return nil, err
}
cm, err := CommitFunc(ctx, db, tx, on.Bool)
if err != nil {
return nil, err
}
return &sqlclient.Tx{
Tx: tx,
CommitFn: cm,
RollbackFn: RollbackFunc(ctx, db, tx, on.Bool),
}, nil
}
// Tx wraps schema.ExecQuerier with the transaction methods.
type Tx interface {
schema.ExecQuerier
Commit() error
Rollback() error
}
// CommitFunc takes a transaction and ensures to toggle foreign keys back on after tx.Commit is called.
func CommitFunc(ctx context.Context, db schema.ExecQuerier, tx Tx, on bool) (func() error, error) {
var (
before []violation
err error
)
if on {
before, err = violations(ctx, tx)
if err != nil {
return nil, err
}
}
return func() error {
if on {
after, err := violations(ctx, tx)
if err != nil {
if err2 := tx.Rollback(); err2 != nil {
err = fmt.Errorf("%v: %w", err2, err)
}
return enableFK(ctx, db, on, err)
}
if vs := violationsDiff(before, after); len(vs) > 0 {
err := fmt.Errorf("sql/sqlite: foreign key mismatch: %+v", vs)
if err2 := tx.Rollback(); err2 != nil {
err = fmt.Errorf("%v: %w", err2, err)
}
return enableFK(ctx, db, on, err)
}
}
return enableFK(ctx, db, on, tx.Commit())
}, nil
}
// RollbackFunc takes a transaction and ensures to toggle foreign keys back on after tx.Rollback is called.
func RollbackFunc(ctx context.Context, db schema.ExecQuerier, tx Tx, on bool) func() error {
return func() error {
return enableFK(ctx, db, on, tx.Rollback())
}
}
func enableFK(ctx context.Context, db schema.ExecQuerier, do bool, err error) error {
if do {
// Re-enable foreign key checks if they were enabled before.
if _, err2 := db.ExecContext(ctx, "PRAGMA foreign_keys = on"); err2 != nil {
err2 = fmt.Errorf("sql/sqlite: set 'foreign_keys = on': %w", err2)
if err != nil {
return fmt.Errorf("%v: %w", err2, err)
}
return err2
}
}
return err
}
func violations(ctx context.Context, conn schema.ExecQuerier) ([]violation, error) {
rows, err := conn.QueryContext(ctx, "PRAGMA foreign_key_check")
if err != nil {
return nil, fmt.Errorf("sql/sqlite: querying 'foreign_key_check' pragma: %w", err)
}
defer rows.Close()
var vs []violation
for rows.Next() {
var v violation
if err := rows.Scan(&v.tbl, &v.row, &v.ref, &v.index); err != nil {
return nil, fmt.Errorf("sql/sqlite: querying 'foreign_key_check' pragma: scanning rows: %w", err)
}
vs = append(vs, v)
}
if err := rows.Err(); err != nil {
return nil, fmt.Errorf("sql/sqlite: querying 'foreign_key_check' pragma: scanning rows: %w", err)
}
return vs, nil
}
// equalViolations compares the foreign key violations before starting a transaction with the ones afterwards.
// It returns violations found in v2 that are not in v1.
func violationsDiff(v1, v2 []violation) (vs []violation) {
for _, v := range v2 {
if !contains(v1, v) {
vs = append(vs, v)
}
}
return vs
}
func contains(hs []violation, n violation) bool {
for _, v := range hs {
if v.row == n.row && v.ref == n.ref && v.index == n.index && v.tbl == n.tbl {
return true
}
}
return false
}
// SQLite standard data types as defined in its codebase and documentation.
// https://www.sqlite.org/datatype3.html
// https://github.com/sqlite/sqlite/blob/master/src/global.c
const (
TypeInteger = "integer" // SQLITE_TYPE_INTEGER
TypeReal = "real" // SQLITE_TYPE_REAL
TypeText = "text" // SQLITE_TYPE_TEXT
TypeBlob = "blob" // SQLITE_TYPE_BLOB
)
// SQLite generated columns types.
const (
virtual = "VIRTUAL"
stored = "STORED"
)