Gearman::Client Return Value

bichonfrise74 has asked for the wisdom of the Perl Monks concerning the following question:

I playing with Gearman::Client and below are my codes. Basically what I wanted to do is to send a string from the client and have the worker split them and return two strings.

#!/usr/bin/perl
# worker.pl

use strict;
use Gearman::Worker;

my $worker = Gearman::Worker->new();
$worker->job_servers( '127.0.0.1:4730' );

$worker->register_function( 'split_it',  
  \&my_split_function );
$worker->work() while 1;

sub my_split_function {
    my $string = $_[0]->arg;

    my @new_string = split( ',',  $string );
    return \@new_string;
}

-------

#!/usr/bin/perl
# client.pl

use strict;
use Gearman::Client;

my $client = Gearman::Client->new();
$client->job_servers('127.0.0.1:4730');

my $result = $client->do_task( 'split_it', 'abc,def' );
print "Split: @$result\n";
[download]

When I run the client.pl, it will give an error output on the worker.pl something like

Not a SCALAR reference at
 /usr/local/share/perl/5.8.8/Gearman/Worker.pm line 365.
[download]

Does this mean that it is expecting the worker.pl to return a scalar reference? Since I'm trying to return an array reference, then it is failing?

Comment on Gearman::Client Return Value Select or Download Code

Replies are listed 'Best First'.
Re: Gearman::Client Return Value by kennethk (Abbot) on Oct 08, 2009 at 00:04 UTC
I'm not familiar with the module in question, but the line in question reads: `my $rv = ref $ret ? $$ret : $ret;` It checks if what was returned was a reference, and if so dereferences it for return assuming it was a scalar. That seems strange to me, but perhaps it makes sense in the broader context the module was intended for. You could perhaps try "out thinking" it by returning a ref to an array ref (`return \\@new_string;`), but that smacks of trouble to me. I would think since this seems to involve a serialization protocol, you'd just end up with a stringified reference in that case. What would seem more logical to me would be to plan on returning a delimited string in place of your array in the true case, and splitting in the client function.	[reply] [d/l] [select]
Re: Gearman::Client Return Value by runrig (Abbot) on Apr 05, 2010 at 21:27 UTC
You can only pass strings to and from gearman workers and clients. If you want to pass array references, you'll need to serialize/unserialize them with something like Storable freeze()/thaw() (or with JSON or some other option).	[reply]


Clear questions and runnable code get the best and fastest answer
	PerlMonks