java - 我如何将ReentrantReadWriteLock.readLock或ReentrantReadWriteLock.writeLock转换为我的类对象

我想做的是一次获取当前线程持有的读取计数的数量。为此我写了一个包装器，但是我的问题是ReadLock（）方法返回的是ReentrantReadWriteLock.WriteLock，所以我没有多余的东西之后我想要的是getLockReadLockCount。我想要的是readLock（）方法应该返回我，以便我可以超出count方法。有任何想法吗。？

   private final ThreadLocal    readLocksHeldByThread;

private static class ReadCounts {
    public int  value   = 0;
}

public CustomReentrantReadWriteLock() {
    super(true);
    readLocksHeldByThread = new ThreadLocal() {
        @Override
        public Object initialValue() {
            return new ReadCounts();
        }
    };
}

@Override
public synchronized ReadLock readLock() {
    final ReadCounts myReadLocks = (ReadCounts) readLocksHeldByThread.get();
    ++myReadLocks.value;
    return super.readLock();
}

    public synchronized int getThreadReadLockCount() {
    final ReadCounts currentReadLocks = (ReadCounts) readLocksHeldByThread.get();
    return currentReadLocks.value;
}

最佳答案

您的代码仅计算线程请求readlock的次数，如果它在锁和释放之间进行了缓存，则会得出不同的结果：

Lock rl = var.readLock();
rl.lock();
try{
    //...
}finally{
    rl.unlock();
}

与

var.readLock().lock();
try{
    //...
}finally{
    var.readLock().unlock();
}

会给出不同的结果

您可以像这样包装返回的锁

@Override public Lock readLock() {
     final ReadCounts myReadLocks = (ReadCounts) readLocksHeldByThread.get();
     return new Lock(){
        Lock l = super.readLock();
        public void lock(){
            l.lock();
            ++myReadLocks.value;
        }

        public void lockInterruptibly() throws InterruptedException{
            l.lockInterruptibly();
            ++myReadLocks.value;
        }

        public boolean tryLock(){
            if(l.tryLock()){
                ++myReadLocks.value;
                return true;
            }else return false;
        }

        public boolean tryLock(long time, TimeUnit unit) throws InterruptedException{
            if(l.tryLock(time,unit)){
                ++myReadLocks.value;
                return true;
            }else return false;
        }

        public void unlock(){
            --myReadLocks.value;
            l.unlock();
        }

        public Condition newCondition(){
            return l.newCondition();
        }

     }
}