Jeff Fearn > TheSchwartz > TheSchwartz

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NAME ^

TheSchwartz - reliable job queue

SYNOPSIS ^

    # MyApp.pm
    package MyApp;

    sub work_asynchronously {
        my %args = @_;

        my $client = TheSchwartz->new( databases => $DATABASE_INFO );
        $client->insert('MyWorker', \%args);
    }


    # myworker.pl
    package MyWorker;
    use base qw( TheSchwartz::Worker );

    sub work {
        my $class = shift;
        my TheSchwartz::Job $job = shift;

        print "Workin' hard or hardly workin'? Hyuk!!\n";

        $job->completed();
    }

    package main;

    my $client = TheSchwartz->new( databases => $DATABASE_INFO );
    $client->can_do('MyWorker');
    $client->work();

DESCRIPTION ^

TheSchwartz is a reliable job queue system. Your application can put jobs into the system, and your worker processes can pull jobs from the queue atomically to perform. Failed jobs can be left in the queue to retry later.

Abilities specify what jobs a worker process can perform. Abilities are the names of TheSchwartz::Worker sub-classes, as in the synopsis: the MyWorker class name is used to specify that the worker script can perform the job. When using the TheSchwartz client's work functions, the class-ability duality is used to automatically dispatch to the proper class to do the actual work.

TheSchwartz clients will also prefer to do jobs for unused abilities before reusing a particular ability, to avoid exhausting the supply of one kind of job while jobs of other types stack up.

Some jobs with high setup times can be performed more efficiently if a group of related jobs are performed together. TheSchwartz offers a facility to coalesce jobs into groups, which a properly constructed worker can find and perform at once. For example, if your worker were delivering email, you might store the domain name from the recipient's address as the coalescing value. The worker that grabs that job could then batch deliver all the mail for that domain once it connects to that domain's mail server.

USAGE ^

TheSchwartz->new( %args )

Optional members of %args are:

$client->list_jobs( %args )

Returns a list of TheSchwartz::Job objects matching the given arguments. The required members of %args are:

It is important to remember that this function does not lock anything, it just returns as many jobs as there is up to amount of databases * $client->{batch_size}

$client->lookup_job( $handle_id )

Returns a TheSchwartz::Job corresponding to the given handle ID.

$client->set_verbose( $verbose )

Sets the current logging function to $verbose if it's a coderef. If not a coderef, enables debug logging to STDERR if $verbose is true; otherwise, disables logging.

POSTING JOBS ^

The methods of TheSchwartz clients used by applications posting jobs to the queue are:

$client->insert( $job )

Adds the given TheSchwartz::Job to one of the client's job databases.

$client->insert( $funcname, $arg )

Adds a new job with function name $funcname and arguments $arg to the queue.

$client->insert_jobs( @jobs )

Adds the given TheSchwartz::Job objects to one of the client's job databases. All the given jobs are recorded in one job database.

$client->set_prioritize( $prioritize )

Set the prioritize value as described in the constructor.

$client->set_floor( $floor )

Set the floor<gt value as described in the constructor.

$client->set_batch_size( $batch_size )

Set the batch_size<gt value as described in the constructor.

WORKING ^

The methods of TheSchwartz clients for use in worker processes are:

$client->can_do( $ability )

Adds $ability to the list of abilities $client is capable of performing. Subsequent calls to that client's work methods will find jobs requiring the given ability.

$client->work_once()

Find and perform one job $client can do.

$client->work_until_done()

Find and perform jobs $client can do until no more such jobs are found in any of the client's job databases.

$client->work( [$delay] )

Find and perform any jobs $client can do, forever. When no job is available, the working process will sleep for $delay seconds (or 5, if not specified) before looking again.

$client->work_on($handle)

Given a job handle (a scalar string) $handle, runs the job, then returns.

$client->grab_and_work_on($handle)

Similar to $client->work_on($handle), except that the job will be grabbed before being run. It guarantees that only one worker will work on it (at least in the grab_for interval).

Returns false if the worker could not grab the job, and true if the worker worked on it.

$client->find_job_for_workers( [$abilities] )

Returns a TheSchwartz::Job for a random job that the client can do. If specified, the job returned matches one of the abilities in the arrayref $abilities, rather than $client's abilities.

$client->find_job_with_coalescing_value( $ability, $coval )

Returns a TheSchwartz::Job for a random job for a worker capable of $ability and with a coalescing value of $coval.

$client->find_job_with_coalescing_prefix( $ability, $coval )

Returns a TheSchwartz::Job for a random job for a worker capable of $ability and with a coalescing value beginning with $coval.

Note the TheSchwartz implementation of this function uses a LIKE query to find matching jobs, with all the attendant performance implications for your job databases.

$client->get_server_time( $driver )

Given an open driver $driver to a database, gets the current server time from the database.

THE SCOREBOARD ^

The scoreboards can be used to monitor what the TheSchwartz::Worker sub-classes are currently working on. Once the scoreboard has been enabled in the workers with set_scoreboard method the thetop utility (shipped with TheSchwartz distribution in the extras directory) can be used to list all current jobs being worked on.

$client->set_scoreboard( $dir )

Enables the scoreboard. Setting this to 1 or on will cause TheSchwartz to create a scoreboard file in a location it determines is optimal.

Passing in any other option sets the directory the TheSchwartz scoreboard directory should be created in. For example, if you set this to /tmp then this would create a directory called /tmp/theschwartz and a scoreboard file /tmp/theschwartz/scoreboard.pid in it (where pid is the current process pid.)

$client->scoreboard()

Returns the path to the current scoreboard file.

$client->start_scoreboard()

Writes the current job information to the scoreboard file (called by the worker in work_safely before it actually starts working)

$client->end_scoreboard()

Appends the current job duration to the end of the scoreboard file (called by the worker in work_safely once work has been completed)

$client->clean_scoreboard()

Removes the scoreboard file (but not the scoreboard directory.) Automatically called by TheSchwartz during object destruction (i.e. when the instance goes out of scope)

PASSING IN AN EXISTING DRIVER ^

You can pass in a existing Data::Object::Driver::DBI object which also allows you to reuse exist Database handles like so:

        my $dbh = DBI->connect( $dsn, "root", "", {
                RaiseError => 1,
                PrintError => 0,
                AutoCommit => 1,
            } ) or die $DBI::errstr;
        my $driver = Data::ObjectDriver::Driver::DBI->new( dbh => $dbh);
        return TheSchwartz->new(databases => [{ driver => $driver }]);

Note: it's important that the RaiseError and AutoCommit flags are set on the handle for various bits of functionality to work.

COPYRIGHT, LICENSE & WARRANTY ^

This software is Copyright 2007, Six Apart Ltd, cpan@sixapart.com. All rights reserved.

TheSchwartz is free software; you may redistribute it and/or modify it under the same terms as Perl itself.

TheSchwartz comes with no warranty of any kind.

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