java.util.concurrent.locks.Lock的AutoCloseable包装中的任何风险？ [英] Any risk in a AutoCloseable wrapper for java.util.concurrent.locks.Lock?

问题描述

使用 try-with-resource ，我惊讶地发现 锁定 尚未改装为 AutoCloseable 。它看起来相当简单，所以我自己添加如下：

With try-with-resource introduced in Java 7, I was surprised to see that that the Lock has not been retrofitted to be an AutoCloseable. It seemed fairly simple, so I have added it myself as follows:

class Lock implements AutoCloseable {
    private final java.util.concurrent.locks.Lock _lock;
    Lock(java.util.concurrent.locks.Lock lock) {
        _lock = lock;
        _lock.lock();
    }
    @Override 
    public void close() {
        _lock.unlock();
    }
}

这适用于 AutoCloseableReentrantReadWiteLock 类和用法如下：

This works with an AutoCloseableReentrantReadWiteLock class and usage is as follows:

try (AutoCloseableReentrantReadWiteLock.Lock l = _lock.writeLock()) {
    // do something
}        

因为这看起来很简单规范使用自动关闭 RAII 我认为必须有一个很好的理由不应该这样做。有人知道吗？

Since this seems so straightforward and canonical use of auto-closing RAII I am thinking there must be a good reason this should not be done. Anybody know?

推荐答案

当尝试使用资源于2009年2月/ 3月提出。

This was a big debate when try-with-resources was proposed in February/March 2009.

该提案的作者Josh Bloch说：这个结构只针对一件事，一件事：资源管理。它不是为锁定而设计的。

Josh Bloch, the author of the proposal, said "This construct was designed for one thing and one thing only: resource management. It was not designed for locking."

有一个单独的提案单独覆盖锁，但它没有到达任何地方。

There was a separate proposal to cover locks separately, but it didn't get anywhere.

我认为锁的主要原因是未涵盖的是：

I think the main reasons locks were not covered were:

• 无法在Java 7中向接口添加方法


• 性能命中创建一个实现正确接口的额外包装器对象


• 哲学异议 Lock 是一种与文件句柄不同的资源（例如创建 Lock 不需要调用 lock 方法）

• not possible to add methods to an interface in Java 7
• performance hit of creating an extra wrapper object that implemented the correct interface
• philosophical objections to Lock being a different kind of resource from file handles (e.g. creation of a Lock does not entail invoking the lock method)

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