From 5d76c3f75b8853d6fb47b2906d87ea77aa0efd6e Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Mon, 28 Jul 2025 02:37:45 +0000
Subject: [PATCH] Fix race condition in pill timer

---
 step10/main.go | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/step10/main.go b/step10/main.go
index 94b7707..b348985 100644
--- a/step10/main.go
+++ b/step10/main.go
@@ -259,20 +259,30 @@ func updateGhosts(ghosts []*ghost, ghostStatus GhostStatus) {
 }
 
 var pillTimer *time.Timer
+var pillCancel chan struct{}
 
 func processPill() {
 	pillMx.Lock()
+	defer pillMx.Unlock()
+
 	updateGhosts(ghosts, GhostStatusBlue)
-	if pillTimer != nil {
-		pillTimer.Stop()
+
+	if pillCancel != nil {
+		close(pillCancel)
 	}
-	pillTimer = time.NewTimer(time.Second * cfg.PillDurationSecs)
-	pillMx.Unlock()
-	<-pillTimer.C
-	pillMx.Lock()
-	pillTimer.Stop()
-	updateGhosts(ghosts, GhostStatusNormal)
-	pillMx.Unlock()
+	pillCancel = make(chan struct{})
+	timer := time.NewTimer(time.Second * cfg.PillDurationSecs)
+
+	go func(cancel chan struct{}) {
+		select {
+		case <-timer.C:
+			pillMx.Lock()
+			defer pillMx.Unlock()
+			updateGhosts(ghosts, GhostStatusNormal)
+		case <-cancel:
+			// timer cancelled
+		}
+	}(pillCancel)
 }
 
 func drawDirection() string {