java 内存锁

import lombok.extern.slf4j.Slf4j;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
 * @author CW
 * @ClassName LockUtil.java
 * @createTime 2023年02月09日 16:24:00
 */
@Slf4j
public class LockUtil {
    private final static Map<String, Lock> map = new ConcurrentHashMap();
    private final static Map<String, Lock> map2 = new ConcurrentHashMap();

    public final static String SAVE_DTU_LOCK = "SAVE_DTU_LOCK:";

    /**
     * 细粒度lock，自定义 MyReentrantLock，会清理map中的lock
     * 若不清理lock对象，可能会导致内存溢出的情况，
     *
     * @param granular 冲突粒度，据此判断是否创建新lock对象
     * @author XHS-2021
     * @date 2022/7/2 16:56
     * @return java.util.concurrent.locks.Lock
     */
    public static Lock getLock(String granular){
        Lock lock = map.get(granular);
        if(lock != null){
            return lock;
        }else{
            lock = map.putIfAbsent(granular, new MyReentrantLock(granular));
            if(lock == null){
                return getLock(granular);
            }else{
                return lock;
            }
        }
    }

    /**
     * 【慎用】
     *  粗粒度lock，不会清理map中lock，会一直累计，长久下去要考虑内存溢出的情况
     *
     * @param granular
     * @author XHS-2021
     * @date 2022/7/2 16:57
     * @return java.util.concurrent.locks.Lock
     */
    public static Lock getCoarseGrainLock(String granular){
        Lock lock = map2.get(granular);
        if(lock != null){
            return lock;
        }else{
            lock = map2.putIfAbsent(granular, new ReentrantLock());
            if(lock == null){
                return getLock(granular);
            }else{
                return lock;
            }
        }
    }

    static class MyReentrantLock extends ReentrantLock{
        String granular;
        public MyReentrantLock(String granular) {
            super();
            this.granular = granular;
        }

        @Override
        public void unlock() {
            if(map.containsKey(granular)){
                map.remove(granular);
                try {
                    super.unlock();
                } catch (IllegalMonitorStateException e) {
//                log.error(e.getMessage(), e);
                }
            }
        }
    }


}


调用：

Lock lock = LockUtil.getLock(key);
if (lock.tryLock(10, TimeUnit.SECONDS)) {
    try {
        
    } finally {
        lock.unlock();
    }
}else{
    throw new RuntimeException("失败，请重试！");
}