Avoid creating extra goroutines on nextIter (apache#1496)

moguchev · Oct 24, 2020 · 5913df4 · 5913df4
1 parent 393f0c9
commit 5913df4
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Showing 2 changed files with 13 additions and 5 deletions.
diff --git a/AUTHORS b/AUTHORS
@@ -115,3 +115,4 @@ Pavel Buchinchik <p.buchinchik@gmail.com>
 Rintaro Okamura <rintaro.okamura@gmail.com>
 Yura Sokolov <y.sokolov@joom.com>; <funny.falcon@gmail.com>
 Jorge Bay <jorgebg@apache.org>
+Dmitriy Kozlov <hummerd@mail.ru>
diff --git a/session.go b/session.go
@@ -1431,7 +1431,7 @@ func (iter *Iter) Scan(dest ...interface{}) bool {
 	}
 
 	if iter.next != nil && iter.pos >= iter.next.pos {
-		go iter.next.fetch()
+		iter.next.fetchAsync()
 	}
 
 	// currently only support scanning into an expand tuple, such that its the same
@@ -1526,10 +1526,17 @@ func (iter *Iter) NumRows() int {
 }
 
 type nextIter struct {
-	qry  *Query
-	pos  int
-	once sync.Once
-	next *Iter
+	qry   *Query
+	pos   int
+	oncea sync.Once
+	once  sync.Once
+	next  *Iter
+}
+
+func (n *nextIter) fetchAsync() {
+	n.oncea.Do(func() {
+		go n.fetch()
+	})
 }
 
 func (n *nextIter) fetch() *Iter {