I use Storable (using its lock_xxx methods) to maintain data between a couple of processes, but in one instance I want to amend the data in the stored file.

So, I open the file to get a filehandle, lock it, then use the store_fd and retrieve_fd on the filehandle (to prevent possible race conditions between using lock_store and lock_retrieve from the other processes), but have discovered it doesn't work a I expected. Is this a problem with Storable or my understanding?

Update: Fixed thanks to zwon - was missing a truncate and seek before rewriting the file

#!/usr/bin/perl
use strict;
use warnings;
use Storable qw(retrieve store retrieve_fd store_fd);
use Fcntl qw(:flock);

my $file='/tmp/storable_test';
my %data = (
    item => 'Here I am',
);
store(\%data, $file);
#=====

# open & lock file
open(my $fh, '+<', $file);
flock($fh, LOCK_EX);

# get data, amend, put back
my $data = retrieve_fd(\*$fh);
print 'item: ', $data->{item},$/;

delete($data->{item});

print 'gone (error as expected): ', $data->{item},$/;

truncate $fh, 0; # <- *** WAS MISSING THIS ***
seek $fh, 0, 0;  # <- *** WAS MISSING THIS ***

store_fd($data, \*$fh);
close($fh);

#======
# now reload from the file
my $check_data = retrieve($file);
print 'why is this here? ', $check_data->{item},$/;
[download]

I am guessing its probably my understanding but cannot see why currently.

Thanks

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