Close cursor before returning from All.

GODRIVER-1246

Change-Id: I907f4113c4f8c8428b176622edcb2bedc34fc9a6

Author: Alice Thum

mongo/cursor.go

@@ -156,6 +156,7 @@ func (c *Cursor) Close(ctx context.Context) error {
 // All iterates the cursor and decodes each document into results.
 // The results parameter must be a pointer to a slice. The slice pointed to by results will be completely overwritten.
 // If the cursor has been iterated, any previously iterated documents will not be included in results.
+// The cursor will be closed after the method has returned.
 func (c *Cursor) All(ctx context.Context, results interface{}) error {
 	resultsVal := reflect.ValueOf(results)
 	if resultsVal.Kind() != reflect.Ptr {
@@ -167,6 +168,8 @@ func (c *Cursor) All(ctx context.Context, results interface{}) error {
 	var index int
 	var err error
 
+	defer c.Close(ctx)
+
 	batch := c.batch // exhaust the current batch before iterating the batch cursor
 	for {
 		sliceVal, index, err = c.addFromBatch(sliceVal, elementType, batch, index)

mongo/cursor_test.go

@@ -13,6 +13,7 @@ import (
 type testBatchCursor struct {
 	batches []*bsoncore.DocumentSequence
 	batch   *bsoncore.DocumentSequence
+	closed  bool
 }
 
 func newTestBatchCursor(numBatches, batchSize int) *testBatchCursor {
@@ -74,6 +75,7 @@ func (tbc *testBatchCursor) Err() error {
 }
 
 func (tbc *testBatchCursor) Close(context.Context) error {
+	tbc.closed = true
 	return nil
 }
 
@@ -133,6 +135,17 @@ func TestCursor(t *testing.T) {
 				require.Equal(t, doc, bson.D{{"foo", int32(index)}})
 			}
 		})
+
+		t.Run("cursor is closed after All is called", func(t *testing.T) {
+			var docs []bson.D
+
+			tbc := newTestBatchCursor(1, 5)
+			cursor, err := newCursor(tbc, nil)
+			err = cursor.All(context.Background(), &docs)
+
+			require.Nil(t, err)
+			require.True(t, tbc.closed)
+		})
 	})
 }