Re: [HACKERS] Current Win32 port status

[Andrew Dunstan <andrew(at)dunslane(dot)net>]

Magnus Hagander wrote:

> > Bruce Momjian wrote:
> >    
> >
> > > > 	* a workable pipe replacement
> > > >        
> > > I don't have 'pipe' mentioned on the win32 patch.  Can you
> > > give details?
> > >      
> > Yeah you do. The second point under "Problems with select()".
> >
> > Basically, the Win32 call to pipe() returns a file descriptor 
> > which is invalid to pass on to Win32 select() (as it only 
> > takes socket handles).
> >
> > So, we need to replace the select'ing mechanism under Win32 
> > (yech), or write a Win32 pipe() replacement that returns two 
> > socket endpoints (good enough for our purposes), or something else...
> >    
>
> I think you want to be investigating
> WSAEventSelect() and then WaitForMultipleObjectsEx(). 
>
> WSAEventSelect() claims it needs a WSAEVENT, but according to docs
> otherwhere it should accept a standard event handle on NT+ platforms.
>
> WaitForMultiple... will accept pipes, events, anything. (The Ex function
> will also allow dispatching of user APCs, see related discussion about
> signals)
>
>  

Using a socket or a pair of sockets is a very common practice in porting 
this sort of code from Unix to Windows. IIRC this is what Cygwin does 
under the hood.

That would help to preserve the programming paradigms already in use in 
Postgres. If it proves to be a performance bottleneck then it could be 
revisited, but it seems unlikely.

Tom (rightly) admonished me not long ago that we do not need to use 
every last part of the Unix API in our code. The same goes a fortiori 
for the Windows API, IMNSHO. Minimal disturbance and acceptable 
performance should be the initial goals.

cheers

andrew