Windows® via C/C++, Fifth Edition

Memory-Mapped Files and Coherence

The system allows you to map multiple views of the same data of a file. For example, you can map the first 10 KB of a file into a view and then map the first 4 KB of that same file into a separate view. As long as you are mapping the same file-mapping object, the system ensures that the viewed data is coherent. For example, if your application alters the contents of the file in one view, all other views are updated to reflect the changes. This is because even though the page is mapped into the process’ virtual address space more than once, the system really has the data in only a single page of RAM. If multiple processes are mapping views of a single data file, the data is still coherent because there is still ...