replace begin/end with wrapper function

pkg/bus/bus.go

@@ -12,9 +12,8 @@ type Msg interface{}
 
 var ErrHandlerNotFound = errors.New("handler not found")
 
-type TransactionManager interface {
-	Begin(ctx context.Context) (context.Context, error)
-	End(ctx context.Context, err error) error
+type TransactionWrapper interface {
+	Wrapp(ctx context.Context, fn func(ctx context.Context) error) error
 }
 
 type Bus interface {
@@ -25,7 +24,7 @@ type Bus interface {
 	// InTransaction starts a transaction and store it in the context.
 	// The caller can then pass a function with multiple DispatchCtx calls that
 	// all will be executed in the same transaction. InTransaction will rollback if the
-	// callback returns an error.s
+	// callback returns an error.
 	InTransaction(ctx context.Context, fn func(ctx context.Context) error) error
 
 	AddHandler(handler HandlerFunc)
@@ -36,19 +35,11 @@ type Bus interface {
 	// SetTransactionManager allows the user to replace the internal
 	// noop TransactionManager that is responsible for manageing
 	// transactions in `InTransaction`
-	SetTransactionManager(tm TransactionManager)
+	SetTransactionManager(tm TransactionWrapper)
 }
 
 func (b *InProcBus) InTransaction(ctx context.Context, fn func(ctx context.Context) error) error {
-	ctxWithTran, err := b.transactionManager.Begin(ctx)
-	if err != nil {
-		return err
-	}
-
-	err = fn(ctxWithTran)
-	b.transactionManager.End(ctxWithTran, err)
-
-	return err
+	return b.transactionWrapper.Wrapp(ctx, fn)
 }
 
 type InProcBus struct {
@@ -56,7 +47,7 @@ type InProcBus struct {
 	listeners         map[string][]HandlerFunc
 	wildcardListeners []HandlerFunc
 
-	transactionManager TransactionManager
+	transactionWrapper TransactionWrapper
 }
 
 // temp stuff, not sure how to handle bus instance, and init yet
@@ -68,7 +59,7 @@ func New() Bus {
 	bus.listeners = make(map[string][]HandlerFunc)
 	bus.wildcardListeners = make([]HandlerFunc, 0)
 
-	bus.transactionManager = &NoopTransactionManager{}
+	bus.transactionWrapper = &noopTransactionManager{}
 
 	return bus
 }
@@ -78,12 +69,12 @@ func GetBus() Bus {
 	return globalBus
 }
 
-func SetTransactionManager(tm TransactionManager) {
+func SetTransactionManager(tm TransactionWrapper) {
 	globalBus.SetTransactionManager(tm)
 }
 
-func (b *InProcBus) SetTransactionManager(tm TransactionManager) {
-	b.transactionManager = tm
+func (b *InProcBus) SetTransactionManager(tm TransactionWrapper) {
+	b.transactionWrapper = tm
 }
 
 func (b *InProcBus) DispatchCtx(ctx context.Context, msg Msg) error {
@@ -208,6 +199,10 @@ func Publish(msg Msg) error {
 	return globalBus.Publish(msg)
 }
 
+// InTransaction starts a transaction and store it in the context.
+// The caller can then pass a function with multiple DispatchCtx calls that
+// all will be executed in the same transaction. InTransaction will rollback if the
+// callback returns an error.
 func InTransaction(ctx context.Context, fn func(ctx context.Context) error) error {
 	return globalBus.InTransaction(ctx, fn)
 }
@@ -216,7 +211,8 @@ func ClearBusHandlers() {
 	globalBus = New()
 }
 
-type NoopTransactionManager struct{}
+type noopTransactionManager struct{}
 
-func (*NoopTransactionManager) Begin(ctx context.Context) (context.Context, error) { return ctx, nil }
-func (*NoopTransactionManager) End(ctx context.Context, err error) error           { return err }
+func (*noopTransactionManager) Wrapp(ctx context.Context, fn func(ctx context.Context) error) error {
+	return nil
+}

pkg/services/sqlstore/shared.go

@@ -32,17 +32,16 @@ func inTransaction(callback dbTransactionFunc) error {
 
 func startSession(ctx context.Context) *DBSession {
 	value := ctx.Value(ContextSessionName)
-	var sess *xorm.Session
-	sess, ok := value.(*xorm.Session)
+	var sess *DBSession
+	sess, ok := value.(*DBSession)
 
 	if !ok {
-		return newSession()
+		newSess := newSession()
+		newSess.Begin()
+		return newSess
 	}
 
-	old := newSession()
-	old.Session = sess
-
-	return old
+	return sess
 }
 
 func withDbSession(ctx context.Context, callback dbTransactionFunc) error {

pkg/services/sqlstore/sqlstore.go

@@ -2,7 +2,6 @@ package sqlstore
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net/url"
 	"os"
@@ -26,6 +25,7 @@ import (
 	"github.com/go-xorm/xorm"
 	_ "github.com/lib/pq"
 	_ "github.com/mattn/go-sqlite3"
+	sqlite3 "github.com/mattn/go-sqlite3"
 
 	_ "github.com/grafana/grafana/pkg/tsdb/mssql"
 )
@@ -94,37 +94,49 @@ func (ss *SqlStore) Init() error {
 	return ss.ensureAdminUser()
 }
 
+// SQLTransactionManager begin/end transaction
 type SQLTransactionManager struct {
 	engine *xorm.Engine
 }
 
-func (stm *SQLTransactionManager) Begin(ctx context.Context) (context.Context, error) {
-	sess := stm.engine.NewSession()
-	err := sess.Begin()
-	if err != nil {
-		return ctx, err
-	}
+func (stm *SQLTransactionManager) Wrapp(ctx context.Context, fn func(ctx context.Context) error) error {
+	return stm.wrappInternal(ctx, fn, 0)
+}
+
+func (stm *SQLTransactionManager) wrappInternal(ctx context.Context, fn func(ctx context.Context) error, retry int) error {
+	sess := startSession(ctx)
+	defer sess.Close()
 
 	withValue := context.WithValue(ctx, ContextSessionName, sess)
 
-	return withValue, nil
-}
+	err := fn(withValue)
 
-func (stm *SQLTransactionManager) End(ctx context.Context, err error) error {
-	value := ctx.Value(ContextSessionName)
-	sess, ok := value.(*xorm.Session)
-	if !ok {
-		return errors.New("context is missing transaction")
+	// special handling of database locked errors for sqlite, then we can retry 3 times
+	if sqlError, ok := err.(sqlite3.Error); ok && retry < 5 {
+		if sqlError.Code == sqlite3.ErrLocked {
+			sess.Rollback()
+			time.Sleep(time.Millisecond * time.Duration(10))
+			sqlog.Info("Database table locked, sleeping then retrying", "retry", retry)
+			return stm.wrappInternal(ctx, fn, retry+1)
+		}
 	}
 
 	if err != nil {
 		sess.Rollback()
 		return err
+	} else if err = sess.Commit(); err != nil {
+		return err
 	}
 
-	defer sess.Close()
+	if len(sess.events) > 0 {
+		for _, e := range sess.events {
+			if err = bus.Publish(e); err != nil {
+				log.Error(3, "Failed to publish event after commit", err)
+			}
+		}
+	}
 
-	return sess.Commit()
+	return nil
 }
 
 func (ss *SqlStore) ensureAdminUser() error {