Ensure mysql rows responses are closed (#1132)

Co-authored-by: dm-2 <[email protected]>

Author: timvaillancourt

.golangci.yml

@@ -9,4 +9,6 @@ linters:
   enable:
     - gosimple
     - govet
+    - rowserrcheck
+    - sqlclosecheck
     - unused

go/logic/applier.go

@@ -381,10 +381,13 @@ func (this *Applier) ReadMigrationMinValues(uniqueKey *sql.UniqueKey) error {
 	if err != nil {
 		return err
 	}
+
 	rows, err := this.db.Query(query)
 	if err != nil {
 		return err
 	}
+	defer rows.Close()
+
 	for rows.Next() {
 		this.migrationContext.MigrationRangeMinValues = sql.NewColumnValues(uniqueKey.Len())
 		if err = rows.Scan(this.migrationContext.MigrationRangeMinValues.ValuesPointers...); err != nil {
@@ -393,8 +396,7 @@ func (this *Applier) ReadMigrationMinValues(uniqueKey *sql.UniqueKey) error {
 	}
 	this.migrationContext.Log.Infof("Migration min values: [%s]", this.migrationContext.MigrationRangeMinValues)
 
-	err = rows.Err()
-	return err
+	return rows.Err()
 }
 
 // ReadMigrationMaxValues returns the maximum values to be iterated on rowcopy
@@ -404,10 +406,13 @@ func (this *Applier) ReadMigrationMaxValues(uniqueKey *sql.UniqueKey) error {
 	if err != nil {
 		return err
 	}
+
 	rows, err := this.db.Query(query)
 	if err != nil {
 		return err
 	}
+	defer rows.Close()
+
 	for rows.Next() {
 		this.migrationContext.MigrationRangeMaxValues = sql.NewColumnValues(uniqueKey.Len())
 		if err = rows.Scan(this.migrationContext.MigrationRangeMaxValues.ValuesPointers...); err != nil {
@@ -416,8 +421,7 @@ func (this *Applier) ReadMigrationMaxValues(uniqueKey *sql.UniqueKey) error {
 	}
 	this.migrationContext.Log.Infof("Migration max values: [%s]", this.migrationContext.MigrationRangeMaxValues)
 
-	err = rows.Err()
-	return err
+	return rows.Err()
 }
 
 // ReadMigrationRangeValues reads min/max values that will be used for rowcopy.
@@ -478,10 +482,13 @@ func (this *Applier) CalculateNextIterationRangeEndValues() (hasFurtherRange boo
 		if err != nil {
 			return hasFurtherRange, err
 		}
+
 		rows, err := this.db.Query(query, explodedArgs...)
 		if err != nil {
 			return hasFurtherRange, err
 		}
+		defer rows.Close()
+
 		iterationRangeMaxValues := sql.NewColumnValues(this.migrationContext.UniqueKey.Len())
 		for rows.Next() {
 			if err = rows.Scan(iterationRangeMaxValues.ValuesPointers...); err != nil {