Date: Tue, 20 Apr 1999 12:00:18 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Graham Wheeler <gram@cdsec.com> Cc: hackers@FreeBSD.ORG Subject: Re: Using select() to implement a delay Message-ID: <199904201900.MAA99210@apollo.backplane.com> References: <199904200921.LAA09941@cdsec.com>
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: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?
:
:TIA
:Dr Graham Wheeler E-mail: gram@cdsec.com
Well, select() breaks out when the process gets a signal. I
recommend checking select()'s return code & errno. I don't
think select() is restartable.
What you would have to do is use gettimeofday() and then call select().
Check the return value, and if select() was interrupted call gettimeofday()
again to figure out how much time elapsed, fixup the tv structure, and
loop up.
-Matt
Matthew Dillon
<dillon@backplane.com>
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