LinkedBlockingQueue是一个基于链表实现的可选容量的线程安全的阻塞队列。队头的元素是插入时间最早的，队尾的元素是最新插入的。新的元素将会被插入到队列的尾部。
LinkedBlockingQueue的容量限制是可选的，如果在初始化时没有指定容量，那么默认使用int的最大值作为队列容量。
LinkedBlockingQueue的逻辑存储效果如下图：
LinkedBlockingQueue的类定义当中有几个知识点需要注意一下：
public class LinkedBlockingQueue<E> extends AbstractQueue<E>
implements BlockingQueue<E>, java.io.Serializable {
private static final long serialVersionUID = -6903933977591709194L;
//存储节点的元素
static class Node<E> {
E item;
Node<E> next;
Node(E x) { item = x; }
}
//容量和当前节点的个数
private final int capacity;
private final AtomicInteger count = new AtomicInteger();
//头部指针和尾部指针
transient Node<E> head;
private transient Node<E> last;
// take操作的锁和对应的Condition
private final ReentrantLock takeLock = new ReentrantLock();
private final Condition notEmpty = takeLock.newCondition();
// put操作的锁和对应的Condition
private final ReentrantLock putLock = new ReentrantLock();
private final Condition notFull = putLock.newCondition();
public LinkedBlockingQueue() {
this(Integer.MAX_VALUE);
}
public LinkedBlockingQueue(int capacity) {
if (capacity <= 0) throw new IllegalArgumentException();
this.capacity = capacity;
last = head = new Node<E>(null);
}
// LinkedBlockingQueue不支持null元素
public LinkedBlockingQueue(Collection<? extends E> c) {
this(Integer.MAX_VALUE);
final ReentrantLock putLock = this.putLock;
putLock.lock(); // Never contended, but necessary for visibility
try {
int n = 0;
for (E e : c) {
if (e == null)
throw new NullPointerException();
if (n == capacity)
throw new IllegalStateException("Queue full");
enqueue(new Node<E>(e));
++n;
}
count.set(n);
} finally {
putLock.unlock();
}
}
}
take相关的操作逻辑按照下面的顺序执行：
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;
}
public E poll(long timeout, TimeUnit unit) throws InterruptedException {
E x = null;
int c = -1;
long nanos = unit.toNanos(timeout);
final AtomicInteger count = this.count;
final ReentrantLock takeLock = this.takeLock;
takeLock.lockInterruptibly();
try {
while (count.get() == 0) {
if (nanos <= 0)
return null;
nanos = notEmpty.awaitNanos(nanos);
}
x = dequeue();
c = count.getAndDecrement();
if (c > 1)
notEmpty.signal();
} finally {
takeLock.unlock();
}
if (c == capacity)
signalNotFull();
return x;
}
public E poll() {
final AtomicInteger count = this.count;
if (count.get() == 0)
return null;
E x = null;
int c = -1;
final ReentrantLock takeLock = this.takeLock;
takeLock.lock();
try {
if (count.get() > 0) {
x = dequeue();
c = count.getAndDecrement();
if (c > 1)
notEmpty.signal();
}
} finally {
takeLock.unlock();
}
if (c == capacity)
signalNotFull();
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;
}
private void signalNotFull() {
final ReentrantLock putLock = this.putLock;
putLock.lock();
try {
notFull.signal();
} finally {
putLock.unlock();
}
}
put相关的操作逻辑按照下面的顺序执行：
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();
}
public boolean offer(E e, long timeout, TimeUnit unit)
throws InterruptedException {
if (e == null) throw new NullPointerException();
long nanos = unit.toNanos(timeout);
int c = -1;
final ReentrantLock putLock = this.putLock;
final AtomicInteger count = this.count;
putLock.lockInterruptibly();
try {
while (count.get() == capacity) {
if (nanos <= 0)
return false;
nanos = notFull.awaitNanos(nanos);
}
enqueue(new Node<E>(e));
c = count.getAndIncrement();
if (c + 1 < capacity)
notFull.signal();
} finally {
putLock.unlock();
}
if (c == 0)
signalNotEmpty();
return true;
}
public boolean offer(E e) {
if (e == null) throw new NullPointerException();
final AtomicInteger count = this.count;
if (count.get() == capacity)
return false;
int c = -1;
Node<E> node = new Node<E>(e);
final ReentrantLock putLock = this.putLock;
putLock.lock();
try {
if (count.get() < capacity) {
enqueue(node);
c = count.getAndIncrement();
if (c + 1 < capacity)
notFull.signal();
}
} finally {
putLock.unlock();
}
if (c == 0)
signalNotEmpty();
return c >= 0;
}
private void enqueue(Node<E> node) {
// assert putLock.isHeldByCurrentThread();
// assert last.next == null;
last = last.next = node;
}
private void signalNotEmpty() {
final ReentrantLock takeLock = this.takeLock;
takeLock.lock();
try {
notEmpty.signal();
} finally {
takeLock.unlock();
}
}
迭代器这边跟ArrayBlockingQueue差不多，就不多说了，估计看也看的懂，无非就是初始化、移动指针，返回当前元素的值。
public Iterator<E> iterator() {
return new Itr();
}
private class Itr implements Iterator<E> {
private Node<E> current;
private Node<E> lastRet;
private E currentElement;
Itr() {
fullyLock();
try {
current = head.next;
if (current != null)
currentElement = current.item;
} finally {
fullyUnlock();
}
}
public boolean hasNext() {
return current != null;
}
private Node<E> nextNode(Node<E> p) {
for (;;) {
Node<E> s = p.next;
if (s == p)
return head.next;
if (s == null || s.item != null)
return s;
p = s;
}
}
public E next() {
fullyLock();
try {
if (current == null)
throw new NoSuchElementException();
E x = currentElement;
lastRet = current;
current = nextNode(current);
currentElement = (current == null) ? null : current.item;
return x;
} finally {
fullyUnlock();
}
}
}
微信关注我们
转载内容版权归作者及来源网站所有！
低调大师中文资讯倾力打造互联网数据资讯、行业资源、电子商务、移动互联网、网络营销平台。持续更新报道IT业界、互联网、市场资讯、驱动更新,是最及时权威的产业资讯及硬件资讯报道平台。
马里奥是站在游戏界顶峰的超人气多面角色。马里奥靠吃蘑菇成长，特征是大鼻子、头戴帽子、身穿背带裤，还留着胡子。与他的双胞胎兄弟路易基一起，长年担任任天堂的招牌角色。
Nacos /nɑ:kəʊs/ 是 Dynamic Naming and Configuration Service 的首字母简称，一个易于构建 AI Agent 应用的动态服务发现、配置管理和AI智能体管理平台。Nacos 致力于帮助您发现、配置和管理微服务及AI智能体应用。Nacos 提供了一组简单易用的特性集，帮助您快速实现动态服务发现、服务配置、服务元数据、流量管理。Nacos 帮助您更敏捷和容易地构建、交付和管理微服务平台。
Rocky Linux（中文名：洛基）是由Gregory Kurtzer于2020年12月发起的企业级Linux发行版，作为CentOS稳定版停止维护后与RHEL（Red Hat Enterprise Linux）完全兼容的开源替代方案，由社区拥有并管理，支持x86_64、aarch64等架构。其通过重新编译RHEL源代码提供长期稳定性，采用模块化包装和SELinux安全架构，默认包含GNOME桌面环境及XFS文件系统，支持十年生命周期更新。
WebStorm 是jetbrains公司旗下一款JavaScript 开发工具。目前已经被广大中国JS开发者誉为“Web前端开发神器”、“最强大的HTML5编辑器”、“最智能的JavaScript IDE”等。与IntelliJ IDEA同源，继承了IntelliJ IDEA强大的JS部分的功能。
扫码在手机上查看文章
扫描二维码，手机阅读更方便
有任何问题或合作意向欢迎联系我们
Email: 99873273@qq.com
QQ: 99873273