LinkedBlockingQueue 源码分析-新增和删除
新增
put 方法，把 e 新增到队列的尾部，如果有可以新增的空间的话，直接新增成功，否则当前线程陷入等待，源码：
public void put(E e) throws InterruptedException { if (e == null) throw new NullPointerException(); int c = -1; Node<E> node = new Node<E>(e); final ReentrantLock putLock = this.putLock; final AtomicInteger count = this.count; putLock.lockInterruptibly(); try { while (count.get() == capacity) { notFull.await(); }
enqueue(node);
c = count.getAndIncrement();
if (c + 1 < capacity) notFull.signal();
} finally { putLock.unlock(); } if (c == 0) signalNotEmpty();}private void enqueue(Node<E> node) { last = last.next = node;}
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if (e == null) throw new NullPointerException(); 如果 e 为空，则抛出异常
int c = -1; 预先设置 c 为 -1，如果负数为则会新增失败
while (count.get() == capacity) { }队列满了则线程阻塞，等待其他线程的唤醒(其他线程 take 成功后就会唤醒此处被阻塞的线程，await 无限等待
enqueue(node); 队列没有满，直接新增到队列的尾部
c = count.getAndIncrement(); 新增计数赋值
if (c + 1 < capacity) 如果链表现在的大小 小于链表的容量，说明队列未满，尝试唤醒一个 put 的等待线程
if (c == 0) signalNotEmpty();c==0，代表队列里面有一个元素，尝试唤醒一个 take 的等待线程
删除
take 方法(阻塞拿数据)源码：
public E take() throws InterruptedException { E x; int c = -1; final AtomicInteger count = this.count; final ReentrantLock takeLock = this.takeLock; takeLock.lockInterruptibly(); try { while (count.get() == 0) { notEmpty.await(); } x = dequeue(); c = count.getAndDecrement(); if (c > 1) notEmpty.signal(); } finally { takeLock.unlock(); } if (c == capacity) signalNotFull(); return x;}private E dequeue() { Node<E> h = head; Node<E> first = h.next; h.next = h; // help GC head = first; E x = first.item; first.item = null; return x;}
public E peek() { if (count.get() == 0) return null; final ReentrantLock takeLock = this.takeLock; takeLock.lock(); try { Node<E> first = head.next; if (first == null) return null; else return first.item; } finally { takeLock.unlock(); }}
private E dequeue() { Node<E> h = head; Node<E> first = h.next; h.next = h; // help GC head = first; E x = first.item; first.item = null; return x;}
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int c = -1; 默认负数，代表失败
final AtomicInteger count = this.count; count 代表当前链表数据的真实大小
while (count.get() == 0) { notEmpty.await(); } 空队列时，阻塞，等待其他线程唤醒
x = dequeue(); 非空队列，从队列的头部拿一个出来
if (c > 1) notEmpty.signal();如果队列里面有值，从 take 的等待线程里面唤醒
if (c == capacity) signalNotFull(); 如果队列空闲还剩下一个，尝试从 put 的等待线程中唤醒
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