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migrate.go
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migrate.go
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// Copyright (C) 2017 ScyllaDB
// Use of this source code is governed by a ALv2-style
// license that can be found in the LICENSE file.
package migrate
import (
"bytes"
"context"
"fmt"
"io"
"io/fs"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"sort"
"strings"
"time"
"github.com/gocql/gocql"
"github.com/scylladb/gocqlx/v3"
"github.com/scylladb/gocqlx/v3/qb"
)
// DefaultAwaitSchemaAgreement controls whether checking for cluster schema agreement
// is disabled or if it is checked before each file or statement is applied.
// The default is not checking before each file or statement but only once after every
// migration has been run.
var DefaultAwaitSchemaAgreement = AwaitSchemaAgreementDisabled
type awaitSchemaAgreement int
// Options for checking schema agreement.
const (
AwaitSchemaAgreementDisabled awaitSchemaAgreement = iota
AwaitSchemaAgreementBeforeEachFile
AwaitSchemaAgreementBeforeEachStatement
)
// ShouldAwait decides whether to await schema agreement for the configured DefaultAwaitSchemaAgreement option above.
func (as awaitSchemaAgreement) ShouldAwait(stage awaitSchemaAgreement) bool {
return as == stage
}
const (
infoSchema = `CREATE TABLE IF NOT EXISTS gocqlx_migrate (
name text,
checksum text,
done int,
start_time timestamp,
end_time timestamp,
PRIMARY KEY(name)
)`
selectInfo = "SELECT * FROM gocqlx_migrate"
)
// Info contains information on migration applied on a database.
type Info struct {
StartTime time.Time
EndTime time.Time
Name string
Checksum string
Done int
}
// List provides a listing of applied migrations.
func List(ctx context.Context, session gocqlx.Session) ([]*Info, error) {
if err := ensureInfoTable(ctx, session); err != nil {
return nil, err
}
q := session.ContextQuery(ctx, selectInfo, nil)
var v []*Info
if err := q.SelectRelease(&v); err == gocql.ErrNotFound {
return nil, nil
} else if err != nil {
return v, err
}
sort.Slice(v, func(i, j int) bool {
return v[i].Name < v[j].Name
})
return v, nil
}
// Pending provides a listing of pending migrations.
func Pending(ctx context.Context, session gocqlx.Session, f fs.FS) ([]*Info, error) {
applied, err := List(ctx, session)
if err != nil {
return nil, err
}
// Create a set of applied migration names
appliedNames := make(map[string]struct{}, len(applied))
for _, migration := range applied {
appliedNames[migration.Name] = struct{}{}
}
fm, err := fs.Glob(f, "*.cql")
if err != nil {
return nil, fmt.Errorf("list migrations: %w", err)
}
pending := make([]*Info, 0)
for _, name := range fm {
baseName := filepath.Base(name)
// Check if the migration is not in the applied set
if _, exists := appliedNames[baseName]; !exists {
c, err := fileChecksum(f, name)
if err != nil {
return nil, fmt.Errorf("calculate checksum for %q: %w", name, err)
}
info := &Info{
Name: baseName,
StartTime: time.Now(),
Checksum: c,
}
pending = append(pending, info)
}
}
return pending, nil
}
func ensureInfoTable(ctx context.Context, session gocqlx.Session) error {
return session.ContextQuery(ctx, infoSchema, nil).ExecRelease()
}
// Migrate is a wrapper around FromFS.
// It executes migrations from a directory on disk.
//
// Deprecated: use FromFS instead
func Migrate(ctx context.Context, session gocqlx.Session, dir string) error {
return FromFS(ctx, session, os.DirFS(dir))
}
// FromFS executes new CQL files from a file system abstraction (io/fs.FS).
// The provided FS has to be a flat directory containing *.cql files.
//
// It supports code based migrations, see Callback and CallbackFunc.
// Any comment in form `-- CALL <name>;` will trigger an CallComment callback.
func FromFS(ctx context.Context, session gocqlx.Session, f fs.FS) error {
// get database migrations
dbm, err := List(ctx, session)
if err != nil {
return fmt.Errorf("list migrations: %s", err)
}
// get file migrations
fm, err := fs.Glob(f, "*.cql")
if err != nil {
return fmt.Errorf("list migrations: %w", err)
}
if len(fm) == 0 {
return fmt.Errorf("no migration files found")
}
sort.Strings(fm)
// verify migrations
if len(dbm) > len(fm) {
return fmt.Errorf("database is ahead")
}
for i := 0; i < len(dbm); i++ {
if dbm[i].Name != fm[i] {
return fmt.Errorf("inconsistent migrations found, expected %q got %q at %d", dbm[i].Name, fm[i], i)
}
c, err := fileChecksum(f, fm[i])
if err != nil {
return fmt.Errorf("calculate checksum for %q: %s", fm[i], err)
}
if dbm[i].Checksum != c {
return fmt.Errorf("file %q was tampered with, expected md5 %s", fm[i], dbm[i].Checksum)
}
}
// apply migrations
if len(dbm) > 0 {
last := len(dbm) - 1
if err := applyMigration(ctx, session, f, fm[last], dbm[last].Done); err != nil {
return fmt.Errorf("apply migration %q: %s", fm[last], err)
}
}
for i := len(dbm); i < len(fm); i++ {
if err := applyMigration(ctx, session, f, fm[i], 0); err != nil {
return fmt.Errorf("apply migration %q: %s", fm[i], err)
}
}
if err = session.AwaitSchemaAgreement(ctx); err != nil {
return fmt.Errorf("awaiting schema agreement: %s", err)
}
return nil
}
func applyMigration(ctx context.Context, session gocqlx.Session, f fs.FS, path string, done int) error {
file, err := f.Open(path)
if err != nil {
return err
}
b, err := ioutil.ReadAll(file)
file.Close()
if err != nil {
return err
}
info := Info{
Name: filepath.Base(path),
StartTime: time.Now(),
Checksum: checksum(b),
}
stmt, names := qb.Insert("gocqlx_migrate").Columns(
"name",
"checksum",
"done",
"start_time",
"end_time",
).ToCql()
update := session.ContextQuery(ctx, stmt, names)
defer update.Release()
if DefaultAwaitSchemaAgreement.ShouldAwait(AwaitSchemaAgreementBeforeEachFile) {
if err = session.AwaitSchemaAgreement(ctx); err != nil {
return fmt.Errorf("awaiting schema agreement: %s", err)
}
}
i := 0
r := bytes.NewBuffer(b)
for {
stmt, err := r.ReadString(';')
if err == io.EOF {
if strings.TrimSpace(stmt) != "" {
// handle missing semicolon after last statement
err = nil
} else {
break
}
}
if err != nil {
return err
}
i++
if i <= done {
continue
}
if Callback != nil && i == 1 {
if err := Callback(ctx, session, BeforeMigration, info.Name); err != nil {
return fmt.Errorf("before migration callback: %s", err)
}
}
if DefaultAwaitSchemaAgreement.ShouldAwait(AwaitSchemaAgreementBeforeEachStatement) {
if err = session.AwaitSchemaAgreement(ctx); err != nil {
return fmt.Errorf("awaiting schema agreement: %s", err)
}
}
// trim new lines and all whitespace characters
stmt = strings.TrimSpace(stmt)
if cb := isCallback(stmt); cb != "" {
if Callback == nil {
return fmt.Errorf("statement %d: missing callback handler while trying to call %s", i, cb)
}
if err := Callback(ctx, session, CallComment, cb); err != nil {
return fmt.Errorf("callback %s: %s", cb, err)
}
} else {
q := session.ContextQuery(ctx, stmt, nil).RetryPolicy(nil)
if err := q.ExecRelease(); err != nil {
return fmt.Errorf("statement %d: %s", i, err)
}
}
// update info
info.Done = i
info.EndTime = time.Now()
if err := update.BindStruct(info).Exec(); err != nil {
return fmt.Errorf("migration statement %d: %s", i, err)
}
}
if i == 0 {
return fmt.Errorf("no migration statements found in %q", info.Name)
}
if Callback != nil && i > done {
if err := Callback(ctx, session, AfterMigration, info.Name); err != nil {
return fmt.Errorf("after migration callback: %s", err)
}
}
return nil
}
var cbRegexp = regexp.MustCompile("^-- *CALL +(.+);$")
func isCallback(stmt string) (name string) {
s := cbRegexp.FindStringSubmatch(stmt)
if len(s) == 0 {
return ""
}
return s[1]
}