More generalized handling of lock errors

chain_events/listener.go

@@ -94,8 +94,9 @@ func (l *Listener) Start() *Listener {
 	}
 
 	if err := l.initHeight(); err != nil {
-		if strings.Contains(err.Error(), "could not obtain lock on row") {
-			// Skip as another listener is already handling this
+		_, ok := err.(*LockError)
+		if ok {
+			// Skip LockError as it means another listener is already handling this
 		} else {
 			panic(err)
 		}
@@ -132,8 +133,9 @@ func (l *Listener) Start() *Listener {
 				})
 
 				if lockErr != nil {
-					if strings.Contains(lockErr.Error(), "could not obtain lock on row") {
-						// Skip as another listener is already handling this round
+					_, ok := lockErr.(*LockError)
+					if ok {
+						// Skip on LockError as it means another listener is already handling this round
 						continue
 					}
 					l.handleError(lockErr)

chain_events/store.go

@@ -4,3 +4,11 @@ package chain_events
 type Store interface {
 	LockedStatus(func(*ListenerStatus) error) error
 }
+
+type LockError struct {
+	Err error
+}
+
+func (e *LockError) Error() string {
+	return e.Err.Error()
+}

chain_events/store_gorm.go

@@ -1,6 +1,8 @@
 package chain_events
 
 import (
+	"strings"
+
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
 )
@@ -18,7 +20,7 @@ func NewGormStore(db *gorm.DB) *GormStore {
 // It takes a function 'fn' as argument. In the context of 'fn' 'status' is locked.
 // Uses NOWAIT modifier on the lock so simultaneous requests can be ignored.
 func (s *GormStore) LockedStatus(fn func(status *ListenerStatus) error) error {
-	return s.db.Transaction(func(tx *gorm.DB) error {
+	txErr := s.db.Transaction(func(tx *gorm.DB) error {
 		status := ListenerStatus{}
 
 		if err := tx.Clauses(clause.Locking{Strength: "UPDATE", Options: "NOWAIT"}).FirstOrCreate(&status).Error; err != nil {
@@ -35,4 +37,11 @@ func (s *GormStore) LockedStatus(fn func(status *ListenerStatus) error) error {
 
 		return nil // commit
 	})
+
+	// Need to handle implementation specific error message
+	if txErr != nil && strings.Contains(txErr.Error(), "could not obtain lock on row") {
+		return &LockError{Err: txErr}
+	}
+
+	return txErr
 }