diff options
Diffstat (limited to 'pkg/tcpip/timer.go')
| -rw-r--r-- | pkg/tcpip/timer.go | 33 |
1 files changed, 28 insertions, 5 deletions
diff --git a/pkg/tcpip/timer.go b/pkg/tcpip/timer.go index f5f01f32f..59f3b391f 100644 --- a/pkg/tcpip/timer.go +++ b/pkg/tcpip/timer.go @@ -88,6 +88,9 @@ func (t *cancellableTimerInstance) stop() { // // The term "related work" is defined as some work that needs to be done while // holding some lock that the timer must also hold while doing some work. +// +// Note, it is not safe to copy a CancellableTimer as its timer instance creates +// a closure over the address of the CancellableTimer. type CancellableTimer struct { // The active instance of a cancellable timer. instance cancellableTimerInstance @@ -131,10 +134,14 @@ func (t *CancellableTimer) StopLocked() { func (t *CancellableTimer) Reset(d time.Duration) { // Create a new instance. earlyReturn := false + + // Capture the locker so that updating the timer does not cause a data race + // when a timer fires and tries to obtain the lock (read the timer's locker). + locker := t.locker t.instance = cancellableTimerInstance{ timer: time.AfterFunc(d, func() { - t.locker.Lock() - defer t.locker.Unlock() + locker.Lock() + defer locker.Unlock() if earlyReturn { // If we reach this point, it means that the timer fired while another @@ -150,12 +157,28 @@ func (t *CancellableTimer) Reset(d time.Duration) { } } -// MakeCancellableTimer returns an unscheduled CancellableTimer with the given +// Lock is a no-op used by the copylocks checker from go vet. +// +// See CancellableTimer for details about why it shouldn't be copied. +// +// See https://github.com/golang/go/issues/8005#issuecomment-190753527 for more +// details about the copylocks checker. +func (*CancellableTimer) Lock() {} + +// Unlock is a no-op used by the copylocks checker from go vet. +// +// See CancellableTimer for details about why it shouldn't be copied. +// +// See https://github.com/golang/go/issues/8005#issuecomment-190753527 for more +// details about the copylocks checker. +func (*CancellableTimer) Unlock() {} + +// NewCancellableTimer returns an unscheduled CancellableTimer with the given // locker and fn. // // fn MUST NOT attempt to lock locker. // // Callers must call Reset to schedule the timer to fire. -func MakeCancellableTimer(locker sync.Locker, fn func()) CancellableTimer { - return CancellableTimer{locker: locker, fn: fn} +func NewCancellableTimer(locker sync.Locker, fn func()) *CancellableTimer { + return &CancellableTimer{locker: locker, fn: fn} } |