package com.external.eventbus; final class PendingPostQueue { private PendingPost head; private PendingPost tail; synchronized void enqueue(PendingPost pendingPost) { if (pendingPost == null) { throw new NullPointerException("null cannot be enqueued"); } if (tail != null) { tail.next = pendingPost; tail = pendingPost; } else if (head == null) { head = tail = pendingPost; } else { throw new IllegalStateException("Head present, but no tail"); } notifyAll(); } synchronized PendingPost poll() { PendingPost pendingPost = head; if (head != null) { head = head.next; if (head == null) { tail = null; } } return pendingPost; } synchronized PendingPost poll(int maxMillisToWait) throws InterruptedException { if (head == null) { wait(maxMillisToWait); } return poll(); } }