On Wed, Mar 11, 2009 at 3:41 AM, dhruva
Hello,
----- Original Message ----
From: Stuart Dootson
I am looking for a memory mapped file based allocator that does not map the whole file into memory. The size may be huge and I would not want to map all the
One solution (which I've used with files of gigabyte size) that you could consider is writing a class to encapsulate memory mapped files that exposes the file contents only through a custom iterator class. These could work together to map and unmap portions of the file as the iterator position crosses 'page' boundaries. This would give you something close to on-demand paging.
Thank you for the suggestion. I have implemented it on windows using SEH (structured exception handling). Is there something similar in the UNIX world. Adding a signal handler will be for the whole process, I need to check if there is a way to add a signal handler for a specific thread that is doing the read/write and perform the unmap and map sequence to keep moving the read/write window. This would be a great feature to have it tucked somewhere in BOOST. Reading/writing large files is quite common. If I succeed in putting in a solution that works on M$ and NIX world, I will post it.
-dhruva
You don't need to use exceptions at all - in the iterator's 'dereference' method (see the iterator_facade documentation in Boost.Iterator for what that means), check if the item that the iterator references is in the currently mapped region. If not, map a region that does contain that item. Stuart Dootson