A reply from Jeffery Richter

最新推荐文章于 2025-08-08 11:34:53 发布

原创最新推荐文章于 2025-08-08 11:34:53 发布 · 874 阅读

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#file #windows #integer #application #disk

本文讨论了两个应用程序通过内存映射文件共享数据时的一致性问题。当一个应用更改并刷新内存映射文件中的值后，另一个应用是否能立即看到更新，还是需要重新打开文件才能获取最新值。

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I think I address this in the Coherence section on page 495.

But, in short, coherence is maintained between all instances of the same MMF and FlushFileBuffers does NOT have to be called. App#2 can just read the value after app #1 changes it and all is well.

-- Jeffrey Richter (http://Wintellect.com)

From: Chen, Michael

Sent: Tuesday, February 19, 2008 11:34 PM
To: Jeffrey Richter (Wintellect LLC)
Subject: Question about the memory-mapped file after reading Windows via c/c++

Hi Jeffrey,

Thanks for your another awesome version of your programming for windows series, which is Windows via c/c++.

After reading the contents about the chapter 17, which is about the memory-mapped file, and I’ve a instant question for you.

Here’s the scenario, let’s say, there’s a memory-mapped file in the disk and it contains an Integer value, 2 applications simply open it and map it into their application address respectively. If app#1 changed the value within the memory-mapped file then flushed the change into the disk file by calling FlushFileBuffer. What would happen to the view of memory-mapped file within the app#2? Can app#2 get the change immediately by re-get the value without reopen the file, or app#2 can’t be aware of the change until app#2 reopen/remaps the memory-mapped file?

Thanks,

Michael