From d200ba4a7b009fc8d5d1417e8ff6f870e65a9506 Mon Sep 17 00:00:00 2001
From: wxc <53962888+wxc421@users.noreply.github.com>
Date: Fri, 1 Jul 2022 12:41:32 +0800
Subject: [PATCH] feat: CompareAndSwapInt32 may be better than AddInt32 (#2077)

---
 core/mr/mapreduce.go | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/core/mr/mapreduce.go b/core/mr/mapreduce.go
index 23d70bd0..5e78e846 100644
--- a/core/mr/mapreduce.go
+++ b/core/mr/mapreduce.go
@@ -376,9 +376,7 @@ type onceChan struct {
 }
 
 func (oc *onceChan) write(val interface{}) {
-	if atomic.AddInt32(&oc.wrote, 1) > 1 {
-		return
+	if atomic.CompareAndSwapInt32(&oc.wrote, 0, 1) {
+		oc.channel <- val
 	}
-
-	oc.channel <- val
 }