From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2007-06-03 04:28:42
Aaron W. LaFramboise wrote:
> In a multi-segment implementation, would an object like a vector be
able
> to span multiple segments? I think not, but I'm not sure.
No, because the memory must be contiguous. But other structures like
deque/map-set/list could be implemented.
> If general growing of managed segments is too hard, maybe an easier
> problem could be solved, like making shared memory containers that have
> special support for growing.
I think you reach the same problem. You need to allocate more pages from
the OS and map them atomically in every process sharing those pages.
> I agree with you about O_CREAT. But what about on Windows, with
> CreateFileMapping? "If the object exists before the function call, the
> function returns a handle to the existing object (with its current size,
> not the specified size), and GetLastError returns ERROR_ALREADY_EXISTS."
>
> It seems the API has a little bit of a POSIX bias. :)
It's not that I like POSIX, it's just it was easier to emulate POSIX for
Windows than doing the inverse. Shmem had a Windows approach but shared
memory lifetime was a real issue, so I changed to a POSIX-like approach.
I've tried to be portable, but maybe I should add extensions for systems
where the programmer can get more information.
Thanks for your comments,
Ion