Acquire write lock for pipeline creation into the database

server/store/datastore/pipeline.go

@@ -15,10 +15,13 @@
 package datastore
 
 import (
+	"fmt"
+	"sync"
 	"time"
 
 	"xorm.io/builder"
 	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
 
 	"go.woodpecker-ci.org/woodpecker/v3/server/model"
 )
@@ -127,7 +130,16 @@ func (s storage) GetPipelineCount() (int64, error) {
 	return s.engine.Count(new(model.Pipeline))
 }
 
+// createPipelineSQLiteLock is needed for CreatePipeline if sqlite is used
+// as sqlite don't support to upgrade the transaction lock to be exclusive
+var createPipelineSQLiteLock = &sync.Mutex{}
+
 func (s storage) CreatePipeline(pipeline *model.Pipeline, stepList ...*model.Step) error {
+	// TODO: xorm do not allow us to start an `EXCLUSIVE` transaction so we have to do it on our own
+	if s.engine.Dialect().URI().DBType == schemas.SQLITE {
+		createPipelineSQLiteLock.Lock()
+		defer createPipelineSQLiteLock.Unlock()
+	}
 	sess := s.engine.NewSession()
 	defer sess.Close()
 	if err := sess.Begin(); err != nil {
@@ -143,15 +155,39 @@ func (s storage) CreatePipeline(pipeline *model.Pipeline, stepList ...*model.Ste
 		return ErrorRepoNotExist{RepoID: pipeline.RepoID}
 	}
 
+	// get write lock
+	// TODO: upstream that to xorm
+	switch s.engine.Dialect().URI().DBType {
+	case schemas.SQLITE:
+		// we have an exclusive lock via createPipelineSQLiteLock already
+
+	case schemas.MYSQL:
+		if _, err := sess.SQL("LOCK TABLE `pipelines` WRITE").Exec(); err != nil {
+			return err
+		}
+		// session end does not unlock so we have to
+		defer func() {
+			sess.SQL("UNLOCK TABLES").Exec()
+		}()
+
+	case schemas.POSTGRES:
+		if _, err := sess.SQL("LOCK TABLE pipelines IN EXCLUSIVE MODE").Exec(); err != nil {
+			return err
+		}
+
+	default:
+		return fmt.Errorf("unsupported schema %s detected", s.engine.Dialect().URI().DBType)
+	}
+
 	// calc pipeline number
-	var number int64
+	var currMaxNumber int64
 	if _, err := sess.Select("MAX(number)").
 		Table(new(model.Pipeline)).
 		Where("repo_id = ?", pipeline.RepoID).
-		Get(&number); err != nil {
+		Get(&currMaxNumber); err != nil {
 		return err
 	}
-	pipeline.Number = number + 1
+	pipeline.Number = currMaxNumber + 1
 
 	pipeline.Created = time.Now().UTC().Unix()
 	// only Insert set auto created ID back to object