与S3锁定 [英] Locking with S3

问题描述

什么是配合使用的推荐方法来实现一个简单的锁定机制，S3？

What's the recommended way to implement a simple locking mechanism to be used in conjunction with S3?

是我想要做的例子：

• 按对象ID获取锁
• 从S3阅读对象
• 修改数据
• 写对象为S3
• 在释放锁

在理想情况下寻找一个基于云的锁定机制。我可以使用memcached的地方，但我必须处理标定。我没有看到实现轻量级锁定任何AWS API的一个明显的方式，但它似乎是一个常见的​​问题。

Ideally looking for a cloud based locking mechanism. I could use memcached locally, but then I have to deal with scaling that. I don't see an obvious way to implement lightweight locking with any AWS APIs, but it seems like a common problem.

我不知道你是否可以使用SimpleDB的做一个原子获取锁定操作。有没有人试过？

I wonder if you could use SimpleDB to do an atomic acquire lock operation. Has anyone tried that?

推荐答案

好吧，我花了一些时间今天上午博托玩，我觉得我有一个解决方案，工程使用的SimpleDB。您需要最新的博托释放，使有条件的看跌期权和一致的读取支持。

Ok, I spent some time this morning playing with boto and I think I have a solution that works using SimpleDB. You need the latest boto release so that conditional puts and consistent reads are supported.

例如code在这里： http://pastebin.com/3XzhPqfY

Example code here: http://pastebin.com/3XzhPqfY

请发表意见/建议。我相信这code应该是相当安全的 - 我在测试的main（）有10个线程试图就

Please post comments/suggestions. I believe this code should be fairly safe -- my test in main() tries it with 10 threads.

有一件事情我还没有解决的是，S3读取并不一致（右？），所以理论上一个线程可能会在S3价值的旧副本操作。它看起来像有可能是一种解决方法是如下描述：

One thing I haven't addressed is that S3 reads are not consistent (right?), so in theory a thread may be operating on an old copy of the S3 value. It looks like there may be a workaround for that as described here:

<一个href="http://www.shlomoswidler.com/2009/12/read-after-write-consistency-in-amazon.html">http://www.shlomoswidler.com/2009/12/read-after-write-consistency-in-amazon.html

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