使用队列集合完成排队操作

队列配置：

@Component
@Slf4j
public class QueueConfig {

    //队列最大容量
    private static final int MAX_CAPACITY = 3;
    //队列
    public final ConcurrentLinkedQueue<String> queue = new ConcurrentLinkedQueue<>();

    public  synchronized  ConcurrentLinkedQueue<String>  add (String userName){
        while (queue.size() >= MAX_CAPACITY){
            try {
                log.info("当前排队人数已满，请等待!");
                wait();
            }catch (Exception ignored){}
        }
        queue.add(userName);
        log.info("排队人数+1,目前排队数量:{}",queue.size());
        notifyAll();
        return queue;
    }


    public synchronized String getNext(){
        while (queue.isEmpty()){
            try {
                wait();
            } catch (InterruptedException ignored) {
            }
        }
        String remove = queue.remove();
        log.info("========{}:执行完毕,排队人数-1,目前排队数量:{}",remove,queue.size());
        notifyAll();
        return remove;
    }
}
}

使用：

@Service
@Slf4j
@RequiredArgsConstructor
public class QueueServiceImpl implements QueueService {

    public final QueueConfig queueConfig;
    @Override
    public void test(String name) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                queueConfig.add(name);
                exec();
            }
        }).start();
    }
    private final Lock lock = new ReentrantLock();
    private void exec() {
        if (queueConfig.queue.peek() != null){
            lock.lock();
            try {
                log.info("========={}:正在执行操作=========",queueConfig.queue.peek());
                try {
                    Thread.sleep(15000);
                } catch (InterruptedException e) {
                }
                //执行完毕移除当前
                queueConfig.getNext();
            }finally {
                lock.unlock();
            }
        }

    }
}

测试：

使用了4个请求来模拟操作，最大·队列是3：

2024-12-08 10:46:10.944  INFO 67308 --- [       Thread-2] com.study.question.config.QueueConfig    : 排队人数+1,目前排队数量:1
2024-12-08 10:46:10.945  INFO 67308 --- [       Thread-2] c.s.q.service.impl.QueueServiceImpl      : =========1:正在执行操作=========
2024-12-08 10:46:13.261  INFO 67308 --- [       Thread-3] com.study.question.config.QueueConfig    : 排队人数+1,目前排队数量:2
2024-12-08 10:46:15.587  INFO 67308 --- [       Thread-4] com.study.question.config.QueueConfig    : 排队人数+1,目前排队数量:3
2024-12-08 10:46:17.721  INFO 67308 --- [       Thread-5] com.study.question.config.QueueConfig    : 当前排队人数已满，请等待!
2024-12-08 10:46:25.949  INFO 67308 --- [       Thread-2] com.study.question.config.QueueConfig    : ========1:执行完毕,排队人数-1,目前排队数量:2
2024-12-08 10:46:25.949  INFO 67308 --- [       Thread-5] com.study.question.config.QueueConfig    : 排队人数+1,目前排队数量:3
2024-12-08 10:46:25.949  INFO 67308 --- [       Thread-3] c.s.q.service.impl.QueueServiceImpl      : =========2:正在执行操作=========
2024-12-08 10:46:40.960  INFO 67308 --- [       Thread-3] com.study.question.config.QueueConfig    : ========2:执行完毕,排队人数-1,目前排队数量:2
2024-12-08 10:46:40.960  INFO 67308 --- [       Thread-4] c.s.q.service.impl.QueueServiceImpl      : =========3:正在执行操作=========
2024-12-08 10:46:55.964  INFO 67308 --- [       Thread-4] com.study.question.config.QueueConfig    : ========3:执行完毕,排队人数-1,目前排队数量:1
2024-12-08 10:46:55.964  INFO 67308 --- [       Thread-5] c.s.q.service.impl.QueueServiceImpl      : =========4:正在执行操作=========
2024-12-08 10:47:10.971  INFO 67308 --- [       Thread-5] com.study.question.config.QueueConfig    : ========4:执行完毕,排队人数-1,目前排队数量:0

分析结果：

可以看到当第一个请求1过来时候会加到队列，然后直接执行操作，

后续有进来两个请求排队

当第4个请求进来时候·，队列已经满了，需要等待队列空位置

1执行完后，可以看到第4个请求入队，现在有3个在队列中

接着2执行，3执行....直到队列是空。