Hi wise monks.

I'm tempting to write and read into a BerkeleyDB Queue like that:

#Writer
use BerkeleyDB ;
use Carp ;

use strict ;

my $dbenv = BerkeleyDB::Env->new(
                                 -Home => './' ,
                                 -Flags =>  DB_CREATE|DB_INIT_CDB|DB_I
+NIT_MPOOL
                                 ) or confess("cannot open environment
+: $BerkeleyDB::Error\n");

my $dbq   = BerkeleyDB::Queue->new(
                                   -Filename => 'bigQ.queue' ,
                                   -Flags      => DB_CREATE,
                                   -Len        => 32,
                                   -Env        => $dbenv
                                   ) or confess("cannot open queue: $B
+erkeleyDB::Error\n");

$dbq->db_put(undef , 'toto');
[download]

And the reader:

# Reader
use BerkeleyDB ;
use Carp ;

use strict ;

my $dbenv = BerkeleyDB::Env->new(
                                 -Home => './' ,
                                 -Flags =>  DB_CREATE|DB_INIT_CDB|DB_I
+NIT_MPOOL
                                 ) or confess("cannot open environment
+: $BerkeleyDB::Error\n");

my $dbq   = BerkeleyDB::Queue->new(
                                   -Filename => 'bigQ.queue' ,
                                   -Flags      => DB_CREATE,
                                   -Len        => 32,
                                   -Env        => $dbenv
                                   ) or confess("cannot open queue: $B
+erkeleyDB::Error\n");

our $data = "" ;
my $status = $dbq->db_get(undef , $data , DB_CONSUME) ;

print "Status: $status\n" ;
print $data , "\n" ;
[download]

Actually, the reader do well when the queue is emptyy: it displays

Status: DB_NOTFOUND: No matching key/data pair found
[download]

, which is normal.

But in case there's something into the queue, I got a

Modification of a read-only value attempted at reader.pl line 19
[download]

Which is the line where $data is supposed to be filled by db_get .

Curiosly, when I remove the flag DB_CONSUME, $data is filled without problem, but it's a Queue so I want the data consumed on retrieving.

Any idea ?

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