Date: Tue, 20 Apr 1999 12:09:17 +0200 From: Graham Wheeler <gram@cdsec.com> To: hackers@freebsd.org Subject: Re: Using select() to implement a delay Message-ID: <371C524D.36DBAC17@cdsec.com> References: <199904200945.LAA28715@bowtie.nl>
next in thread | previous in thread | raw e-mail | index | archive | help
Marc van Kempen wrote: > > Graham Wheeler wrote: > > > Hi all > > > > I have an interesting problem. I have a routine to implement delays: > > > > void Sleep(int secs, int usecs = 0) > > { > > struct timeval tv; > > tv.tv_sec = secs; > > tv.tv_usec = usecs; > > (void)select(0, 0, 0, 0, &tv); > > } > > > > I am using this both because it gives better resolution than sleep(), > > and also because it doesn't require the use of SIGALRM, which I am > > using elsewhere. > > > > On my development machine, Sleep(60) does exactly what is expected. On > > my clients machine, Sleep(60) returns immediately. Both are running > > FreeBSD 2.2.7. I don't have access to the clients machine, which is > > in another city, and has no development environment, so I can't run gdb, > > although it may not give away anything in any case. > > > > Does anyone have any ideas why the one works and the other doesn't? > > > > Did you try catching the return value from select, it might be getting a > signal. > I've changed the code to: void Sleep(int secs, int usecs = 0) { struct timeval tv; tv.tv_sec = secs; tv.tv_usec = usecs; if (select(0, 0, 0, 0, &tv)<0) syslog(LOG_INFO, "Sleep(): select: %m"); } and have asked the client to run the program. I'll post the results when I get them back. On the one hand, a signal seems like the only explanation; on the other, there are no calls to alarm() or other SIGALRM related routines in the code, and this is also happening with 100% consistency. -- Dr Graham Wheeler E-mail: gram@cdsec.com Citadel Data Security Phone: +27(21)423-6065/6/7 Firewalls/Virtual Private Networks Fax: +27(21)24-3656 Internet/Intranet Network Specialists Data Security Products WWW: http://www.cdsec.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?371C524D.36DBAC17>