From c35a2c748c6ad053344c9f15f6f86246e48628e0 Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Fri, 2 Oct 2020 17:35:11 +1000
Subject: Only wake Tx if they're still reading a modified value

---
 var.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

(limited to 'var.go')

diff --git a/var.go b/var.go
index f3b8d40..3f43096 100644
--- a/var.go
+++ b/var.go
@@ -27,9 +27,11 @@ func (v *Var) wakeWatchers(new VarValue) {
 		// We have to lock here to ensure that the Tx is waiting before we signal it. Otherwise we
 		// could signal it before it goes to sleep and it will miss the notification.
 		tx.mu.Lock()
-		tx.cond.Broadcast()
-		for !tx.waiting && !tx.completed {
-			tx.cond.Wait()
+		if read := tx.reads[v]; read != nil && read.Changed(new) {
+			tx.cond.Broadcast()
+			for !tx.waiting && !tx.completed {
+				tx.cond.Wait()
+			}
 		}
 		tx.mu.Unlock()
 		return !v.value.Load().(VarValue).Changed(new)
-- 
cgit v1.2.3