code: func (m *timedMutex) Unlock() {
  	unlockedTimestamp := m.lockedAt.Load()
  	m.lockedAt.Store(time.Time{})
  	m.Mutex.Unlock()
  	lockedFor := time.Since(unlockedTimestamp.(time.Time))
  	storeLockDurationTimer.Update(lockedFor)
  }
docs: // Unlocks the timedMutex and captures the duration
  // for which it was locked in a metric.