From cc0357f5252666ef67bb8f73f86b47ddbdb245be Mon Sep 17 00:00:00 2001
From: Matt Joiner <anacrolix@gmail.com>
Date: Tue, 5 Nov 2019 11:49:42 +1100
Subject: Optimize AtomicSet

---
 funcs.go |  6 +++---
 tx.go    |  7 -------
 var.go   | 11 +++++++++++
 3 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/funcs.go b/funcs.go
index 3d89cc5..bd7f0e9 100644
--- a/funcs.go
+++ b/funcs.go
@@ -69,9 +69,9 @@ func AtomicGet(v *Var) interface{} {
 
 // AtomicSet is a helper function that atomically writes a value.
 func AtomicSet(v *Var, val interface{}) {
-	Atomically(func(tx *Tx) {
-		tx.Set(v, val)
-	})
+	v.mu.Lock()
+	v.changeValue(val)
+	v.mu.Unlock()
 }
 
 // Compose is a helper function that composes multiple transactions into a
diff --git a/tx.go b/tx.go
index beb4cbb..4b6edf8 100644
--- a/tx.go
+++ b/tx.go
@@ -30,13 +30,6 @@ func (tx *Tx) verify() bool {
 func (tx *Tx) commit() {
 	for v, val := range tx.writes {
 		v.changeValue(val)
-		v.watchers.Range(func(k, _ interface{}) bool {
-			tx := k.(*Tx)
-			tx.mu.Lock()
-			tx.cond.Broadcast()
-			tx.mu.Unlock()
-			return true
-		})
 	}
 }
 
diff --git a/var.go b/var.go
index 4859643..facad56 100644
--- a/var.go
+++ b/var.go
@@ -19,6 +19,17 @@ func (v *Var) loadState() varSnapshot {
 func (v *Var) changeValue(new interface{}) {
 	version := v.loadState().version
 	v.state.Store(varSnapshot{version: version + 1, val: new})
+	v.wakeWatchers()
+}
+
+func (v *Var) wakeWatchers() {
+	v.watchers.Range(func(k, _ interface{}) bool {
+		tx := k.(*Tx)
+		tx.mu.Lock()
+		tx.cond.Broadcast()
+		tx.mu.Unlock()
+		return true
+	})
 }
 
 type varSnapshot struct {
-- 
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