多线程

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.*;

/**
 * @Description
 * @Date 2022-07-06 9:23 AM
 */
public class FeedProcessor extends AbstractFeedProcessor {

    private ExecutorService threadPool = Executors.newFixedThreadPool(6);

    private Map> resultList = new ConcurrentHashMap<>();

    public FeedProcessor() {

    }


    public void add(DataItem item) {
        threadPool.submit(new ProcessTask(item));
    }

    class ProcessTask implements Runnable {

        private DataItem item;

        ProcessTask(DataItem item) {
            this.item = item;
        }

        @Override
        public void run() {
            for(;;){
                int id = item.getId();
                List list = resultList.get(id);
                // 如果版本号为 1 则可以继续执行
                if(list == null && item.getVersion() == 1){
                    saveItem(item);
                    list = new ArrayList<>();
                    list.add(item.getVersion());
                    resultList.put(id, list);
                    break;
                } else {
                    // 最后一个版本号 + 1 等于自己的版本号，则轮到该任务执行
                    if(list != null && list.get(list.size() -1) + 1 == item.getVersion() ){
                        saveItem(item);
                        list.add(item.getVersion());
                        resultList.put(id, list);
                        break;
                    } else {
                        try {
                            TimeUnit.MILLISECONDS.sleep(20);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }


                }
            }


        }
    }

    public void shutdown() {
        threadPool.shutdown();
        try {
            threadPool.awaitTermination(60, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}