Re: PATCH: Support Windows in event-loop.c

[Mark Mitchell <mark@codesourcery.com>]

Daniel Jacobowitz wrote:

> Anyway, if Mark can come up with a select wrapper, then maybe we can
> drop the question entirely.

I'm sure I can, if that's the only way to get this functionality into 
GDB.  But, the emacs select wrapper is hardly a full implementation of 
select; for example, it only handles file descriptors waiting for 
"read", not "write".  To me, adding a partial emulation of a POSIX 
function, without real POSIX semantics and behavior, is confusing.  And 
adding a full emulation is going to be a lot more code than the present 
change -- and will perform worse to boot.

Windows isn't UNIX, and waiting for activity on file descriptors is one 
of the places where Windows made some rather different choices.  This is 
a low-level system-programming code, and so system details appear.  It's 
like dealing with different rules for interruptable syscalls, different 
signal-handling rules, and so forth.

Fortunately, it doesn't look like event-loop.c is a very active area of 
development.  It looks like the last substantive change was on 
2002-05-14.  It seems unlikely to me that this change is going to make 
it a lot harder for people to make other improvements to event-loop.c.

-- 
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304