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From: skp@stl.stc.co.uk (Steve Perryman )
Newsgroups: comp.unix.questions,comp.unix.wizards
Subject: sockets and signals (in C)
Message-ID: <3304@stl.stc.co.uk>
Date: 10 Aug 90 08:45:16 GMT
Sender: news@stl.stc.co.uk
Reply-To: "Steve Perryman " <skp@stl.stc.co.uk>
Organization: STC Technology Limited, London Road, Harlow, Essex, UK
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Does anyone know of a way to set up a signal handler such that if a flood
of data comes in to a socket, the SIGIO/SIGPOLL (maybe even SIGURG) signal
can invoke a handler fast enough such that a variable can be incremented to
represent the correct number of data items at the socket.

The signal handler will be :

void catch()
{
   signal(SIGIO,catch) ;
   count++ ;
   ...
   /* Process the signal */
   ...
}

I've used fcntl to allow the socket to interrupt :

fcntl(sock,F_SETOWN,getpid()) ;
fcntl(sock,F_SETFL,F_ASYNC) ;
...
...

This works but it can't log the correct number of items received if they come
in as bursts of data (5+ items per burst). Can this timing problem be resolved
using SIGIO , or is another way required ???




skp