From 02a620e7a531b97005bb52830244e7b6b0a00fb0 Mon Sep 17 00:00:00 2001
From: Daniel Nelson <daniel.nelson@influxdb.com>
Date: Wed, 13 May 2020 14:53:28 -0700
Subject: [PATCH 1/2] Fix data race between Reset and Add

---
 clock.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clock.go b/clock.go
index ab7ebc5..1887795 100644
--- a/clock.go
+++ b/clock.go
@@ -272,8 +272,8 @@ func (t *Timer) Reset(d time.Duration) bool {
 		return t.timer.Reset(d)
 	}
 
-	t.next = t.mock.now.Add(d)
 	t.mock.mu.Lock()
+	t.next = t.mock.now.Add(d)
 	defer t.mock.mu.Unlock()
 
 	registered := !t.stopped

From 8d5f46b7dee5e3d45d746ba14507ac80207702cc Mon Sep 17 00:00:00 2001
From: Daniel Nelson <daniel.nelson@influxdb.com>
Date: Wed, 13 May 2020 15:01:57 -0700
Subject: [PATCH 2/2] Unlock mutex before running gosched

---
 clock.go      |  3 +--
 clock_test.go | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/clock.go b/clock.go
index 1887795..14ee076 100644
--- a/clock.go
+++ b/clock.go
@@ -296,9 +296,8 @@ func (t *internalTimer) Tick(now time.Time) {
 	}
 	t.mock.removeClockTimer((*internalTimer)(t))
 	t.mock.mu.Lock()
-	defer t.mock.mu.Unlock()
-
 	t.stopped = true
+	t.mock.mu.Unlock()
 	gosched()
 }
 
diff --git a/clock_test.go b/clock_test.go
index 70cc7c7..275f5b9 100644
--- a/clock_test.go
+++ b/clock_test.go
@@ -211,6 +211,30 @@ func TestClock_Timer_Reset(t *testing.T) {
 	}
 }
 
+// Ensure reset can be called immediately after reading channel
+func TestClock_Timer_Reset_Unlock(t *testing.T) {
+	clock := NewMock()
+	timer := clock.Timer(1 * time.Second)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		select {
+		case <-timer.C:
+			timer.Reset(1 * time.Second)
+		}
+
+		select {
+		case <-timer.C:
+		}
+	}()
+
+	clock.Add(2 * time.Second)
+	wg.Wait()
+}
+
 // Ensure that the mock's After channel sends at the correct time.
 func TestMock_After(t *testing.T) {
 	var ok int32