Felix Martini wrote:
I have made a prototype for overlapped IO that works with a modified version of Takano Akio's SSC library.
Great! (I don't know what Takano Akio's SSC library is though)
I have been trying to add it to GHC's IO implementation but there are some issues. Instead of file descriptors windows handles are needed.
Yes, I thought that might be a problem. You will probably have to replace the existing FD in a Handle with a more complex type, maybe something like type WinHandle = FileHandle HANDLE | Socket FD perhaps pipes fit into FileHandle, I'm not sure. Maybe there should be an alternative for Console? I think we should be avoiding the CRT for I/O and using Win32 exclusively. I can believe this might be a lot of work, though.
The GHC handle implementation is currently based around fd's and many functions would need a separate windows API version. In some cases there is no simple conversion of existing functionality like the binary/text modes.
binary/text would have to be implemented in the Haskell IO library?
An additional complication is that Haskell handles can be a lot of things other than files. Finally, a threaded rts is needed for the worker pool that processes the IO completions, so the current single threaded IO support must also remain.
At least getting the threaded RTS version working first would be a good step, then we can think about how to do the single-threaded version. Cheers, Simon