Hello,

I wrote some code that needs to open a storable file and keep a lock on it until I say to let go (because I am modifying the data while I have it open). I thought the best way to do this would be to write a routine to open and lock a filehandle, which would then pass that filehandle into the routine that would read it through storable. Unfortunately I seemed to have coded myself into a circle and can't get this to quite work right. Any ideas? Many thanks!

#!/usr/bin/perl -w
use strict;
use Fcntl qw(:DEFAULT :flock);
use Storable qw(store_fd fd_retrieve);
use Data::Dumper;
$Data::Dumper::Deepcopy=1;
$Data::Dumper::Purity=1;
$Data::Dumper::Sortkeys=1;

sub db_load {
   my $fh = $_[0];
   return fd_retrieve($fh);
}

sub db_save {
   my ($fh, $db_hashref) = @_;
   store_fd($db_hashref, $fh);
   return $fh;
}

sub fileopenandlock {
   my ($fh, $file) = @_;
   sysopen($fh, $file, O_RDWR|O_CREAT, 0777) or
      die("I can't open the filehandle $fh for file $file in order to 
+lock it\n");
   flock($fh, LOCK_EX) or
      die("I can't get an exclusive lock LOCK_EX on the file handle $f
+h\n");
   return $fh;
}

sub filecloseandunlock {
   my $fh = $_[0];
   flock($fh, LOCK_UN) or
      croak("I can't unlock LOCK_UN the file handle $fh\n");
   close($fh) or
      croak("I can't close the filehandle $fh\n");
   return 1;
}

my %data = ( 1 => 'FEE',
             2 => 'FYE',
             3 => 'FOH',
             4 => 'FUM', );

my $db_file = "./giant.db";


# open and read db
my $db_fh = do { local *DB };
my $db = db_load(fileopenandlock($db_fh,$db_file));

print "First read dump:\n";
print Dumper($db) . "\n\n"; # should dump empty

# fill it up with data
$db->{$_} = $data{$_} for sort keys %data;

print "Dump before write:\n";
print Dumper($db) . "\n\n"; # should dump full

# save db
filecloseandunlock(db_save($db_fh,$db));


# test read - did it work?
my $db_fhnew = do { local *DBNEW };
my $dbnew = db_load(fileopenandlock($db_fhnew,$db_file));

print "Second read dump:\n";
print Dumper($dbnew) . "\n\n"; # should dump full

filecloseandunlock($dbnew);
[download]

Thanks

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