RE: Having trouble porting an application to MS-Windows

-----Original Message-----
From: Chas Owens [mailto:chas.owens@xxxxxxxxx]
Sent: Thursday, June 14, 2007 12:10 PM
To: Bob McConnell
Cc: beginners@xxxxxxxx
Subject: Re: Having trouble porting an application to MS-Windows

On 6/14/07, Chas Owens <chas.owens@xxxxxxxxx> wrote:
On 6/14/07, Bob McConnell <rvm@xxxxxxxxx> wrote:
In "perlport - Writing portable Perl" in the Alphabetic
list of Perl
Functions:

alarm SECONDS
alarm
Not implemented. (Win32)

I couldn't find anything in the ActiveState release notes that
contradicted that.
snip
the latest version of ActiveState Perl on Windows XP works.
snip

Are you using the latest version of ActiveState Perl? I
installed the
latest version this morning to test the code I sent and when I run

perldoc -T perlport | find /i alarm

I get not output. The first three functions listed are -X,
atan2, and binmode.


In fact, the reference to alarm drops out of perlport in version 5.8.3
(released in 2004).

from Perl 5.8.3's Changes file
[ 21895]
alarm() is now implemented on Win32.


I still can't get it to work, even without the fork. I am now running
ActivePerl 5.8.8.820 on Win2K SP4. Here are the code snippets after
pasting in the recommended alarm handling:

-----------------------------------
$port = 'COM4' unless $port;

$SIG{'INT'} = 'dokill'; # this allows me to kill it with
CTRL-Break
sub dokill {
kill 9,$child if $child;
}

sysopen( PORT, "$port", O_RDWR ) or die "Can't sysopen $port: $!";
binmode(PORT);

LINE: while (<IN>) { # Input records from input file.
chomp;
# loop on NAK or timeout with two retries
$done = 0;
$tries = 0;
do {
syswrite PORT, $_, length;

$timeout = 3;

eval {
local $SIG{ALRM} = sub { die "alarm\n" }; # NB:
\n required
alarm $timeout;
$nread = sysread PORT, $line, 1;
alarm 0;
};
if ($@) {
die unless $@ eq "alarm\n"; # propagate
unexpected errors
# timed out
print STDOUT " t/o";
}
else {
fprint STDOUT "sysread returned %d.\n", $nread;
if (ord $line == 21) {
print STDOUT " NAK";
}
if (ord $line == 6) {
print STDOUT " ACK";
$done = 1;
}
}
} while ($done == 0 && ++$tries < 3);
print STDOUT "\n";
if ($done == 0) {
next LINE;
}
#send response and wait for ACK/NAK here

}
-----------------------------------

This transmits the packet, but never comes out of the eval() if it
doesn't receive a character. Is there anything obvious that I missed?

Even if this does work, can I set simultaneous alarms in multiple
threads?

Thank you,

Bob McConnell
.

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