PERL Miscellaneous - Problem with Storable qw(store_fd fd

Author

Problem with Storable qw(store_fd fd_retrieve)

J.D. Baldwin

2007-06-25, 7:10 pm

Not sure why Storable's sister functions won't talk each other's
language. Here's a stripped down version of what I have:

#!/bin/perl

use strict;
use warnings;

use Storable qw(store_fd fd_retrieve);
use Data::Dumper;
my $uploaded_ref;

my $TRACKING_DATA_FILE='tracking.dat'; # Does not exist
my $LIST_FILE='biglist.txt'; # 64,109-line text file,
# one token per line

open my $fd, '>', $TRACKING_DATA_FILE;
open my $list_fd, '<', $LIST_FILE;

while ( <$list_fd> )
{
chomp;
$uploaded_ref->{$_} = 1;
}

store_fd($uploaded_ref, $fd);
close $fd;

open $fd, '>>', $TRACKING_DATA_FILE;
my $new_ref = fd_retrieve($fd);

my $numkeys = keys %{$new_ref};
print "Number: $numkeys\n";

This fails with

Magic number checking on storable file failed at blib/lib/Storable.pm
(autosplit into blib/lib/auto/Storable/fd_retrieve.al) line 398,
<$list_fd> line 64109, at ./init.pl line 27

Any ideas what is going on here? I have to use store_fd and
fd_retrieve because of the kind of locking my project requires.

Storable version is 2.16; Perl is 5.8.8.
--
_+_ From the catapult of |If anyone disagrees with any statement I make, I
_|70|___:)=}- J.D. Baldwin |am quite prepared not only to retract it, but also
\ / baldwin@panix.com|to deny under oath that I ever made it. -T. Lehrer
***~~~~-----------------------------------------------------------------------

Martijn Lievaart

2007-06-25, 7:10 pm

On Mon, 25 Jun 2007 18:49:15 +0000, J.D. Baldwin wrote:

> Not sure why Storable's sister functions won't talk each other's
> language. Here's a stripped down version of what I have:

(snip)

I'm not sure, but...

> open $fd, '>>', $TRACKING_DATA_FILE;

You open $fd for append...

> my $new_ref = fd_retrieve($fd);

.... and try to read from it.
>
> my $numkeys = keys %{$new_ref};
> print "Number: $numkeys\n";
>
> This fails with
>
> Magic number checking on storable file failed at
> blib/lib/Storable.pm
> (autosplit into blib/lib/auto/Storable/fd_retrieve.al) line 398,
> <$list_fd> line 64109, at ./init.pl line 27

As there is nothing to read, the magic number check fails.

HTH,
M4

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