Improve database error handling

database/services/all.go

@@ -1,9 +1,8 @@
 package services
 
 import (
-	"encoding/json"
-
 	"github.com/mesg-foundation/core/service"
+	"github.com/sirupsen/logrus"
 )
 
 // All returns all deployed services.
@@ -16,11 +15,17 @@ func All() ([]*service.Service, error) {
 	var services []*service.Service
 	iter := db.NewIterator(nil, nil)
 	for iter.Next() {
-		var service service.Service
-		if err := json.Unmarshal(iter.Value(), &service); err != nil {
-			return nil, err
+		service, err := decode(string(iter.Key()), iter.Value())
+		if err != nil {
+			// Ignore all decode errors (possibly due to a service structure change or database corruption)
+			if decodeErr, ok := err.(*DecodeError); ok {
+				logrus.WithField("service", decodeErr.Hash).Warning(decodeErr.Error())
+			} else {
+				return nil, err
+			}
+		} else {
+			services = append(services, service)
 		}
-		services = append(services, &service)
 	}
 	iter.Release()
 	return services, iter.Error()

database/services/encode.go

@@ -0,0 +1,21 @@
+package services
+
+import (
+	"encoding/json"
+
+	"github.com/mesg-foundation/core/service"
+)
+
+// encode returns the marshaled version of the service
+func encode(service *service.Service) ([]byte, error) {
+	return json.Marshal(service)
+}
+
+// decode decodes the data and return an DecodeError if not possible
+func decode(hash string, data []byte) (*service.Service, error) {
+	s := &service.Service{}
+	if err := json.Unmarshal(data, s); err != nil {
+		return nil, &DecodeError{Hash: hash}
+	}
+	return s, nil
+}

database/services/encode_test.go

@@ -0,0 +1,14 @@
+package services
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestDecodeError(t *testing.T) {
+	hash := "IDToTest"
+	_, err := decode(hash, []byte("oaiwdhhiodoihwaiohwa"))
+	require.Error(t, err)
+	require.IsType(t, &DecodeError{}, err)
+}

database/services/errors.go

@@ -1,6 +1,8 @@
 package services
 
 import (
+	"fmt"
+
 	leveldbErrors "github.com/syndtr/goleveldb/leveldb/errors"
 )
 
@@ -10,7 +12,7 @@ type NotFound struct {
 }
 
 func (e NotFound) Error() string {
-	return "Database services: Service with hash '" + e.Hash + "' not found"
+	return fmt.Sprintf("Database services: Service %q not found", e.Hash)
 }
 
 func handleErrorNotFound(err error, hash string) error {
@@ -19,3 +21,12 @@ func handleErrorNotFound(err error, hash string) error {
 	}
 	return err
 }
+
+// DecodeError represents a service impossible to decode
+type DecodeError struct {
+	Hash string
+}
+
+func (e *DecodeError) Error() string {
+	return fmt.Sprintf("Database services: Could not decode service %q.", e.Hash)
+}

database/services/get.go

@@ -1,8 +1,6 @@
 package services
 
 import (
-	"encoding/json"
-
 	"github.com/mesg-foundation/core/service"
 )
 
@@ -18,6 +16,5 @@ func Get(id string) (*service.Service, error) {
 		err = handleErrorNotFound(err, id)
 		return nil, err
 	}
-	s := &service.Service{}
-	return s, json.Unmarshal(bytes, s)
+	return decode(id, bytes)
 }

database/services/save.go

@@ -1,14 +1,12 @@
 package services
 
 import (
-	"encoding/json"
-
 	"github.com/mesg-foundation/core/service"
 )
 
 // Save stores a service in the database.
 func Save(service *service.Service) error {
-	bytes, err := json.Marshal(service)
+	bytes, err := encode(service)
 	if err != nil {
 		return err
 	}