[Spread-users] [BUG][PATCH] fd to session troubles

[Ben Laurie]

Jonathan Stanton wrote:
> 
> On Fri, Jan 25, 2002 at 02:11:46PM -0500, Tim Peters wrote:
> > Good catch!  The "Windows bug" comment is incorrect, because sockets simply
> > aren't fds on Windows (or BeOS) -- they're a distinct datatype.  The handle
> > that represents a socket on Windows comes out of a handle space whose upper
> > bound cannot be predicted in advance.  FD_SETSIZE on Windows is simply the
> > maximum number *of* socket handles you can pass to the Windows select.
> >
> > Spread could also boost FD_SETSIZE on Windows (it's OK to #define this
> > yourself on Windows, before #include'ing winsock.h (in Python, we boost it
> > to 512 by default)), but there remains no relation between FD_SETSIZE and
> > the numerical magnitude of Windows socket handles.  An fd_set on Windows is
> > a contiguous vector of socket handles, not a bit map as on Unix:
> >
> > /* This is from winsock.h */
> > typedef struct fd_set {
> >         u_int   fd_count;               /* how many are SET? */
> >         SOCKET  fd_array[FD_SETSIZE];   /* an array of SOCKETs */
> > } fd_set;
> 
> So you are saying if we add a line
> #define FD_SETSIZE 1024
> 
> in the Windows section of our arch.h, then windows select will work with
> 1024 sockets at once? I just want to verify it because it seems like the
> windows libc/equivelent might have it's own compiled in knowledge of the
> size of the fd_set struct and think it is only 64.
> 
> The way I can imagine this working, is that the libc just looks at fd_count
> and trusts that the fd_array array is big enough to hold all the sockets
> the apps says are in it.  If it isn't, then that is the application's fault
> and the app will crash (ok), but as long as the app is ok, then the system
> is as well.

That's certainly how its supposed to work (with Unix, too).

Cheers,

Ben.

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