On Thu, Dec 02, 2004 at 05:35:53PM +0000, Duncan Coutts wrote:
Yes, I've used mmap in a couple projects now just using the FFI. I think it would be nice to have a System.Posix.MMap module or something with a portable underlying implementation (see how many mmap variants there are in the ghc rts MBlock.c implementation to deal with different OSs). Of course we would have to agree some common interface(s), like do we get back a raw Ptr () or a managed ForeignPtr or what? We'd need current users to speak up and say what they're using it for and what interface they could live with. My initial guess is that we'd need a mmap_raw which gives back an unmanaged pointer and also a managed version that has a finaliser that calls munmap(). Then there is the range of flags that mmap supports on different OSs. Posix specifies the common ones, and then there is anonymous pages which can be implemented directly on some systems or emulated by opening /dev/null or some other similar trick. Both these interfaces should be implementable on win32 systems (via MapViewOfFile etc).
Someone showed me an example of darcs using mmap(). So now I just have to figure out how to translate that to get it to work with Linux' remap_file_pages() and some aio interface that can interoperate with it. -- wli