[8.4.x]: SQLStore: Prevent concurrent migrations (#44101) (#45447)

* SQLStore: Prevent concurrent migrations (#44101)

* SQLStore: Prevent concurrent migrations

* Hide behind a feature toggle

* Configurable locking attempt timeout

* Update docs/sources/administration/configuration.md

Co-authored-by: Igor Suleymanov <radiohead@users.noreply.github.com>
Co-authored-by: achatterjee-grafana <70489351+achatterjee-grafana@users.noreply.github.com>
(cherry picked from commit d718ee1918)

* Resolve dependency cycle (#45427)

(cherry picked from commit 6a38ce2307)

pkg/services/sqlstore/sqlstore.go

@@ -56,8 +56,7 @@ type SQLStore struct {
 	tracer                      tracing.Tracer
 }
 
-func ProvideService(cfg *setting.Cfg, cacheService *localcache.CacheService, bus bus.Bus, migrations registry.DatabaseMigrator, tracer tracing.Tracer,
-) (*SQLStore, error) {
+func ProvideService(cfg *setting.Cfg, cacheService *localcache.CacheService, bus bus.Bus, migrations registry.DatabaseMigrator, tracer tracing.Tracer) (*SQLStore, error) {
 	// This change will make xorm use an empty default schema for postgres and
 	// by that mimic the functionality of how it was functioning before
 	// xorm's changes above.
@@ -67,7 +66,7 @@ func ProvideService(cfg *setting.Cfg, cacheService *localcache.CacheService, bus
 		return nil, err
 	}
 
-	if err := s.Migrate(); err != nil {
+	if err := s.Migrate(cfg.IsFeatureToggleEnabled(featuremgmt.FlagMigrationLocking)); err != nil {
 		return nil, err
 	}
 
@@ -150,7 +149,7 @@ func newSQLStore(cfg *setting.Cfg, cacheService *localcache.CacheService, bus bu
 // Migrate performs database migrations.
 // Has to be done in a second phase (after initialization), since other services can register migrations during
 // the initialization phase.
-func (ss *SQLStore) Migrate() error {
+func (ss *SQLStore) Migrate(isDatabaseLockingEnabled bool) error {
 	if ss.dbCfg.SkipMigrations {
 		return nil
 	}
@@ -158,7 +157,7 @@ func (ss *SQLStore) Migrate() error {
 	migrator := migrator.NewMigrator(ss.engine, ss.Cfg)
 	ss.migrations.AddMigration(migrator)
 
-	return migrator.Start()
+	return migrator.Start(isDatabaseLockingEnabled, ss.dbCfg.MigrationLockAttemptTimeout)
 }
 
 // Sync syncs changes to the database.
@@ -440,6 +439,7 @@ func (ss *SQLStore) readConfig() error {
 
 	ss.dbCfg.CacheMode = sec.Key("cache_mode").MustString("private")
 	ss.dbCfg.SkipMigrations = sec.Key("skip_migrations").MustBool()
+	ss.dbCfg.MigrationLockAttemptTimeout = sec.Key("locking_attempt_timeout_sec").MustInt()
 	return nil
 }
 
@@ -547,7 +547,7 @@ func initTestDB(migration registry.DatabaseMigrator, opts ...InitTestDBOpt) (*SQ
 			return nil, err
 		}
 
-		if err := testSQLStore.Migrate(); err != nil {
+		if err := testSQLStore.Migrate(false); err != nil {
 			return nil, err
 		}
 
@@ -607,23 +607,24 @@ func IsTestDBMSSQL() bool {
 }
 
 type DatabaseConfig struct {
-	Type             string
-	Host             string
-	Name             string
-	User             string
-	Pwd              string
-	Path             string
-	SslMode          string
-	CaCertPath       string
-	ClientKeyPath    string
-	ClientCertPath   string
-	ServerCertName   string
-	ConnectionString string
-	IsolationLevel   string
-	MaxOpenConn      int
-	MaxIdleConn      int
-	ConnMaxLifetime  int
-	CacheMode        string
-	UrlQueryParams   map[string][]string
-	SkipMigrations   bool
+	Type                        string
+	Host                        string
+	Name                        string
+	User                        string
+	Pwd                         string
+	Path                        string
+	SslMode                     string
+	CaCertPath                  string
+	ClientKeyPath               string
+	ClientCertPath              string
+	ServerCertName              string
+	ConnectionString            string
+	IsolationLevel              string
+	MaxOpenConn                 int
+	MaxIdleConn                 int
+	ConnMaxLifetime             int
+	CacheMode                   string
+	UrlQueryParams              map[string][]string
+	SkipMigrations              bool
+	MigrationLockAttemptTimeout int
 }