database/sql: make Rows.Next returning false always implicitly call
Rows.Close.
Previously, callers that followed the example code (but not call
rows.Close after "for rows.Next() { ... }") could leak statements if
the driver returned an error other than io.EOF.
R=bradfitz, alex.brainman
CC=golang-dev, rsc
https://golang.org/cl/12677050
diff --git a/src/pkg/database/sql/sql.go b/src/pkg/database/sql/sql.go
index f0c86a8..d81f6fe 100644
--- a/src/pkg/database/sql/sql.go
+++ b/src/pkg/database/sql/sql.go
@@ -1293,7 +1293,7 @@
closed bool
lastcols []driver.Value
- lasterr error
+ lasterr error // non-nil only if closed is true
closeStmt driver.Stmt // if non-nil, statement to Close on close
}
@@ -1305,20 +1305,19 @@
if rs.closed {
return false
}
- if rs.lasterr != nil {
- return false
- }
if rs.lastcols == nil {
rs.lastcols = make([]driver.Value, len(rs.rowsi.Columns()))
}
rs.lasterr = rs.rowsi.Next(rs.lastcols)
- if rs.lasterr == io.EOF {
+ if rs.lasterr != nil {
rs.Close()
+ return false
}
- return rs.lasterr == nil
+ return true
}
// Err returns the error, if any, that was encountered during iteration.
+// Err may be called after an explicit or implicit Close.
func (rs *Rows) Err() error {
if rs.lasterr == io.EOF {
return nil
@@ -1353,10 +1352,7 @@
// is of type []byte, a copy is made and the caller owns the result.
func (rs *Rows) Scan(dest ...interface{}) error {
if rs.closed {
- return errors.New("sql: Rows closed")
- }
- if rs.lasterr != nil {
- return rs.lasterr
+ return errors.New("sql: Rows are closed")
}
if rs.lastcols == nil {
return errors.New("sql: Scan called without calling Next")
@@ -1375,9 +1371,9 @@
var rowsCloseHook func(*Rows, *error)
-// Close closes the Rows, preventing further enumeration. If the
-// end is encountered, the Rows are closed automatically. Close
-// is idempotent.
+// Close closes the Rows, preventing further enumeration. If Next returns
+// false, the Rows are closed automatically and it will suffice to check the
+// result of Err. Close is idempotent and does not affect the result of Err.
func (rs *Rows) Close() error {
if rs.closed {
return nil
