private void processCancelledTasks() {
            for (;;) {
                HashedWheelTimeout timeout = cancelledTimeouts.poll();
                if (timeout == null) {
                    // all processed
                    break;
                }
                try {
                    timeout.remove();
                } catch (Throwable t) {
                    if (LOG.isWarnEnabled()) {
                        LOG.warn("An exception was thrown while process a cancellation task", t);
                    }
                }
            }
        }
Returns the number of pending timeouts of this {@link Timer}.
jraft-core/src/main/java/com/alipay/sofa/jraft/util/timer/HashedWheelTimer.java