news.utdallas.edu!wupost!howland.reston.ans.net!agate!dog.ee.lbl.gov!network.ucsd.edu!news.acns.nwu.edu!ftpbox!cssmp.corp.mot.com!mmuegel Thu Feb 25 11:53:18 CST 1993 Article: 1098 of comp.lang.perl Xref: feenix.metronet.com comp.lang.perl:1098 Newsgroups: comp.lang.perl Path: feenix.metronet.com!news.utdallas.edu!wupost!howland.reston.ans.net!agate!dog.ee.lbl.gov!network.ucsd.edu!news.acns.nwu.edu!ftpbox!cssmp.corp.mot.com!mmuegel From: mmuegel@cssmp.corp.mot.com (Michael S. Muegel) #Subject: Re: SUMMARY: Timeout on Connect Message-ID: <1993Feb18.090607.25547@ftpbox.mot.com> Keywords: Summary, sockets, connect, timeouts Sender: news@ftpbox.mot.com (C News) Organization: Corporate Information Office, Schaumburg, Illinois, Motorola, Inc. References: <1luq98INN7di@gap.caltech.edu> <1993Feb18.040748.27347@news.eng.convex.com> Date: Thu, 18 Feb 1993 09:06:07 GMT Lines: 140 Previously, tchrist@convex.COM (Tom Christiansen) wrote: > You don't have to use an extra process to zap the connect. As when > you're timing out reads, send yourself an alarm. Here's how I might > do it: > > $TIMEOUT = 15; > sub Timer { die "Alarm Clock" } > $SIG{ALRM} = Timer; > > socket(S, &AF_INET, &SOCK_STREAK, $proto) || die "socket: $!"; > bind (S, $this) || die "bind: $!"; > > eval { > alarm($TIMEOUT); > connect(S, $primary) || die "connect: $!"; > alarm(0); > }; > > if ($@ && $@ !~ /Alarm Clock/) { > die $@; > } An here is very similar code in a package, ready for reuse: ---- Cut Here and feed the following to sh ---- #/bin/sh # This is a shell archive (produced by shar 3.49) # To extract the files from this archive, save it to a file, remove # everything above the "!/bin/sh" line above, and type "sh file_name". # # made 02/18/1993 09:07 UTC by mmuegel@mot.com (Michael S. Muegel) # Source directory /usr/users/macc/mmuegel # # existing files will NOT be overwritten unless -c is specified # # This shar contains: # length mode name # ------ ---------- ------------------------------------------ # 2191 -r--r--r-- timeout.pl # # ============= timeout.pl ============== if test -f 'timeout.pl' -a X"$1" != X"-c"; then echo 'x - skipping timeout.pl (File already exists)' else echo 'x - extracting timeout.pl (Text)' sed 's/^X//' << 'SHAR_EOF' > 'timeout.pl' && ;# NAME ;# timeout.pl - execute Perl code with a built-in timeout ;# ;# AUTHOR ;# Michael S. Muegel (mmuegel@mot.com) ;# ;# RCS INFORMATION ;# $Author: mmuegel $ ;# $Header: /usr/local/lib/perl/RCS/timeout.pl,v 1.1 1992/05/29 03:07:35 mmuegel Exp $ X package Timeout; X # Messages sent to die from eval for alarm call $TIMEOUT = "timeout"; X ;############################################################################### ;# Timeout ;# ;# Executes the Perl code in $Code with a built-in timeout of $Timeout ;# seconds. This is very useful when parsing input from a user, socket, ;# or file and you wish to fix a timeout on your parse. ;# ;# $Code is executed with an eval. Thus you can use die to break out of ;# it prematurely. $Code is also executed in the package $Package. Thus your ;# Perl code can have access to other variables within its package. This also ;# means you can set variables in $Code and they will be available in the ;# package $Package. If $Package is not specified main is assumed. ;# ;# $Status is set to one of the following upon return: ;# ;# -1 Eval of $Code failed. This can be because of a Perl compiler ;# error or a die inside the code was used. See $Msg for reason ;# why. ;# ;# 0 A timeout occured. ;# ;# 1 No timeout occured. ;# ;# Arguments: ;# $Timeout, $Code, $Package ;# ;# Returns: ;# $Status, $Msg ;############################################################################### sub main'Timeout { X ($Timeout, $Code, $Package) = @_; X X # The main package is assumed X $Package = "main" if ($Package eq ""); X X # Save the interrupt handler vector and then override the handler for ALRM X %Save_SIG = %SIG; X $SIG {'ALRM'} = "Timeout'Alarm_Handler"; X X # Set up a timer for $Timeout seconds X alarm ($Timeout); X X # Do our thing here within eval in the $Package package. This way we can die X # from the interrupt handler. X eval "package $Package; $Timeout'Code"; X X # Restore signal handlers X %SIG = %Save_SIG; X X # Check eval status X alarm (0); X return (0) if ($@ =~ /^$TIMEOUT/); X return (-1, $@) if ($@); X return (1); X }; X sub Alarm_Handler { X die $TIMEOUT if ($_[0] eq "ALRM"); }; X 1; SHAR_EOF chmod 0444 timeout.pl || echo 'restore of timeout.pl failed' Wc_c="`wc -c < 'timeout.pl'`" test 2191 -eq "$Wc_c" || echo 'timeout.pl: original size 2191, current size' "$Wc_c" fi exit 0 -- +----------------------------------------------------------------------------+ | Michael S. Muegel | Internet E-Mail: mmuegel@mot.com | | UNIX Applications Startup Group | Moto Dist E-Mail: X10090 | | Corporate Information Office | Voice: (708) 576-0507 | | Motorola | ... these are my opinions, honest ... | +----------------------------------------------------------------------------+ news.utdallas.edu!wupost!sdd.hp.com!swrinde!network.ucsd.edu!news.acns.nwu.edu!ftpbox!cssmp.corp.mot.com!mmuegel Thu Feb 25 11:54:08 CST 1993 Article: 1135 of comp.lang.perl Xref: feenix.metronet.com comp.lang.perl:1135 Newsgroups: comp.lang.perl Path: feenix.metronet.com!news.utdallas.edu!wupost!sdd.hp.com!swrinde!network.ucsd.edu!news.acns.nwu.edu!ftpbox!cssmp.corp.mot.com!mmuegel From: mmuegel@cssmp.corp.mot.com (Michael S. Muegel) #Subject: Re: SUMMARY: Timeout on Connect Message-ID: <1993Feb22.032204.8979@ftpbox.mot.com> Keywords: Summary, sockets, connect, timeouts Sender: news@ftpbox.mot.com (C News) Organization: Corporate Information Office, Schaumburg, Illinois, Motorola, Inc. References: <1993Feb18.040748.27347@news.eng.convex.com> <1993Feb18.090607.25547@ftpbox.mot.com> <1993Feb22.020742.8870@news.eng.convex.com> Date: Mon, 22 Feb 1993 03:22:04 GMT Lines: 17 Previously, tchrist@convex.COM (Tom Christiansen) wrote: > From the keyboard of mmuegel@cssmp.corp.mot.com (Michael S. Muegel): > :And here is very similar code in a package, ready for reuse: > > Except that syntax errors in the eval block won't be caught > until run time rather than compile time. Well worth the reusability gained! -Mike -- +----------------------------------------------------------------------------+ | Michael S. Muegel | Internet E-Mail: mmuegel@mot.com | | UNIX Applications Startup Group | Moto Dist E-Mail: X10090 | | Corporate Information Office | Voice: (708) 576-0507 | | Motorola | ... these are my opinions, honest ... | +----------------------------------------------------------------------------+