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Date: Fri, 18 May 2001 14:41:19 -0400
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: [CYGWIN] Re: SIGTERM does not stop backend postgres processes immediately
Message-ID: <20010518144119.A8011@redhat.com>
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In-Reply-To: <5.1.0.14.2.20010518110716.01b581e8@pop3.cris.com>; from rrschulz@cris.com on Fri, May 18, 2001 at 11:23:30AM -0700

On Fri, May 18, 2001 at 11:23:30AM -0700, Randall R Schulz wrote:
>Here's a snippet from the Linux section 2 manual page:
>
>...
>int  select(int  n,  fd_set  *readfds,  fd_set  *writefds, fd_set 
>*exceptfds, struct timeval *timeout));
>...
>timeout  is  an  upper bound on the amount of time elapsed before select 
>returns. It may be zero, causing  select  to return  immediately. 
>If  timeout  is  NULL  (no timeout), select can block indefinitely.
>...
>
>Does the indefinite-timeout variant of select exist and work under Cygwin 
>(or Windows, as the case may be) compatibly with the Linux API spec?
>
>If so, why not use this variant of select? I agree with you, Chris, that 
>polling is very much to be avoided, but as work-arounds go, this approach 
>might be acceptable to me.

Corinna already supplied a patch to rectify this behavior so this is a non-issue.

To answer your specific question, however, cygwin implements select()
itself.  It isn't a Windows function (although it is a winsock
function).  To make select interruptible by Cygwin signals, it is
sometimes necessary to use polling.

I was actually wrong about polling in the case of sockets.  You don't
have to poll but, if you use the current method, you would have to
create a separate thread.  That's pretty expensive, too.

cgf

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