@Override
        public void run() {
            // Initialize the startTime.
            startTime = System.nanoTime();
            if (startTime == 0) {
                // We use 0 as an indicator for the uninitialized value here, so make sure it's not 0 when initialized.
                startTime = 1;
            }

            // Notify the other threads waiting for the initialization at start().
            startTimeInitialized.countDown();

            do {
                final long deadline = waitForNextTick();
                if (deadline > 0) {
                    int idx = (int) (tick & mask);
                    processCancelledTasks();
                    HashedWheelBucket bucket = wheel[idx];
                    transferTimeoutsToBuckets();
                    bucket.expireTimeouts(deadline);
                    tick++;
                }
            } while (workerStateUpdater.get(HashedWheelTimer.this) == WORKER_STATE_STARTED);

            // Fill the unprocessedTimeouts so we can return them from stop() method.
            for (HashedWheelBucket bucket : wheel) {
                bucket.clearTimeouts(unprocessedTimeouts);
            }
            for (;;) {
                HashedWheelTimeout timeout = timeouts.poll();
                if (timeout == null) {
                    break;
                }
                if (!timeout.isCancelled()) {
                    unprocessedTimeouts.add(timeout);
                }
            }
            processCancelledTasks();
        }
Returns the number of pending timeouts of this {@link Timer}.
jraft-core/src/main/java/com/alipay/sofa/jraft/util/timer/HashedWheelTimer.java