# Movable Type (r) Open Source (C) 2001-2008 Six Apart, Ltd.
# This program is distributed under the terms of the
# GNU General Public License, version 2.
#
# $Id: TheSchwartz.pm 2769 2008-07-14 19:56:22Z bchoate $

package MT::TheSchwartz;

use strict;
use base qw( TheSchwartz );
use MT::ObjectDriver::Driver::DBI;
use List::Util qw( shuffle );

my $instance;

our $RANDOMIZE_JOBS = 0;
our $OBJECT_REPORT = 0;

sub instance {
    $instance ||= MT::TheSchwartz->new();
    return $instance;
}

sub debug {
    my $class = shift;
    $class->instance->SUPER::debug(@_);
}

sub insert {
    my $class = shift;
    $class->instance->SUPER::insert(@_);
}

sub default_logger {
    my ($msg, $job) = @_;
    # suppress TheSchwartz::Job's 'job completed'
    return if $msg eq 'job completed';

    $msg =~ s/\s+$//;
    print STDERR "$msg\n";
}

sub new {
    my $class = shift;
    $class->mt_schwartz_init();
    my (%param) = @_;
    my $workers = delete $param{workers} if exists $param{workers};
    $RANDOMIZE_JOBS = delete $param{randomize} if exists $param{randomize};

    # Reports object usage inbetween jobs if Devel::Leak::Object is loaded
    $OBJECT_REPORT = 1 if $Devel::Leak::Object::VERSION;

    $param{verbose} = \&default_logger
        if $param{verbose} && (ref $param{verbose} ne 'CODE');

    my $client = $class->SUPER::new(%param);

    if ($client) {
        $instance = $client;
        unless ( $workers ) {
            $workers = [];

            my $all_workers ||= MT->registry("task_workers") || {};

            foreach my $id (keys %$all_workers) {
                my $w = $all_workers->{$id};
                my $c = $w->{class} or next;
                push @$workers, $c;
            }
        }

        if (@$workers) {
            # Can we do this?
            foreach my $c ( @$workers ) {
                if (eval('require ' . $c)) {
                    # Yes, we can do this.
                    $client->can_do( $c );
                } else {
                    # No, we can't. Here's why...
                    print STDERR "Failed to load worker class '$c': $@\n";
                }
            }
        }
    }

    return $client;
}

our $initialized;

sub mt_schwartz_init {
    return if $initialized;

    # Update the datasource for these, since MT adds an addition 'schwartz_'
    # prefix for them.
    require TheSchwartz::FuncMap;
    require TheSchwartz::Job;
    require TheSchwartz::Error;
    require TheSchwartz::ExitStatus;
    TheSchwartz::FuncMap->properties->{datasource}    = 'ts_funcmap';
    TheSchwartz::Job->properties->{datasource}        = 'ts_job';
    TheSchwartz::Error->properties->{datasource}      = 'ts_error';
    TheSchwartz::ExitStatus->properties->{datasource} = 'ts_exitstatus';
    return $initialized = 1;
}

sub driver_for {
    my MT::TheSchwartz $client = shift;
    return MT::Object->dbi_driver;
}

sub shuffled_databases {
    my TheSchwartz $client = shift;
    return '1';
}

sub hash_databases {
    return 1;
}

sub mark_database_as_dead {
    return 1;
}

sub is_database_dead {
    return 0;
}

# Replacement for TheSchwartz::get_server_time
# to simply return value from dbd->sql_for_unixtime
# if it is a plain number (the driver has no function,
# it's just returning time())
sub get_server_time {
    my TheSchwartz $client = shift;
    my($driver) = @_;
    my $unixtime_sql = $driver->dbd->sql_for_unixtime;
    return $unixtime_sql if $unixtime_sql =~ m/^\d+$/;
    return $driver->rw_handle->selectrow_array("SELECT $unixtime_sql");
}

sub work_periodically {
    my TheSchwartz $client = shift;
    my ($delay) = @_;
    $delay ||= 5;
    my $last_task_run = 0;
    my $did_work = 0;

    # holds state of objects at start
    my %obj_start;
    if ($OBJECT_REPORT) {
        %obj_start = %Devel::Leak::Object::OBJECT_COUNT;
    }

    while (1) {
        my %obj_pre;
        if ($OBJECT_REPORT) {
            %obj_pre = %Devel::Leak::Object::OBJECT_COUNT;
        }

        if ($client->work_once) {
            $did_work = 1;
        }

        if ($last_task_run + 60 * 5 < time) {
            MT->run_tasks();
            $did_work = 1;
            $last_task_run = time;
        }

        if ($did_work) {
            my $driver = MT::Object->driver;
            $driver->clear_cache
                if $driver->can('clear_cache');
            MT->request->reset();
            $did_work = 0;
            if ($OBJECT_REPORT) {
                my $report = leak_report(\%obj_start, \%obj_pre, \%Devel::Leak::Object::OBJECT_COUNT);
                $client->debug($report) if $report ne '';
            }
        }

        sleep $delay;
    }
}

our %persistent;
BEGIN {
    %persistent = map { $_ => 1 } qw( MT::Callback MT::Task MT::Plugin MT::Component MT::ArchiveType MT::TaskMgr MT::WeblogPublisher MT::Serializer TheSchwartz::Job TheSchwartz::JobHandle );
}
sub leak_report {
    my ($start, $pre, $post) = @_;
    my $reported;
    my $report = '';
    foreach my $class (sort keys %$post) {
        # skip reporting classes that are persistent in nature
        next if exists $persistent{$class};

        my $post_count = $post->{$class};
        next if ! $post_count;
        my $pre_count = $pre->{$class} || 0;
        my $start_count = $start->{$class} || 0;
        next if $post_count == 1;  # ignores most singletons
        if (($pre_count != $post_count) || ($post_count != $start_count)) {
            $report .= "Leak report (class, total, delta from last job(s), delta since process start):\n" unless $reported;
            $report .= sprintf("%-40s %-10d %-10d %-10d\n", $class, $post_count, $post_count - $pre_count, $post_count - $start_count);
            $reported = 1;
        }
    }
    return $report;
}

sub _grab_a_job {
    my TheSchwartz $client = shift;
    my $hashdsn = shift;
    my $driver = $client->driver_for($hashdsn);

    ## Got some jobs! Randomize them to avoid contention between workers.
    my @jobs = $RANDOMIZE_JOBS ? shuffle(@_) : @_;

  JOB:
    while (my $job = shift @jobs) {
        ## Convert the funcid to a funcname, based on this database's map.
        $job->funcname( $client->funcid_to_name($driver, $hashdsn, $job->funcid) );

        ## Update the job's grabbed_until column so that
        ## no one else takes it.
        my $worker_class = $job->funcname;
        my $old_grabbed_until = $job->grabbed_until;

        my $server_time = $client->get_server_time($driver)
            or die "expected a server time";

        $job->grabbed_until($server_time + ($worker_class->grab_for || 1));

        ## Update the job in the database, and end the transaction.
        if ($driver->update($job, { grabbed_until => $old_grabbed_until }) < 1) {
            ## We lost the race to get this particular job--another worker must
            ## have got it and already updated it. Move on to the next job.
            $TheSchwartz::T_LOST_RACE->() if $TheSchwartz::T_LOST_RACE;
            next JOB;
        }

        ## Now prepare the job, and return it.
        my $handle = TheSchwartz::JobHandle->new({
            dsn_hashed => $hashdsn,
            jobid      => $job->jobid,
        });
        $handle->client($client);
        $job->handle($handle);
        return $job;
    }

    return undef;
}

1;
__END__

=head1 NAME

MT::TheSchwartz - Movable Type

=head1 SYNOPSIS

    use MT;
    use MT::TheSchwartz;
    my $mt = MT->new;
    my $schwartz = MT::TheSchwartz->new(%cfg);
    $schwartz->work_until_done;

=head1 DESCRIPTION

A subclass of C<TheSchwartz>, a job queue system. The MT subclass is
responsible for configuring TheSchwartz to work with the MT database
configuration and supplies TheSchwartz worker classes from the MT
registry.

=head1 METHODS

=head2 MT::TheSchwartz->instance

Returns the singleton instance for the C<MT::TheSchwartz> class.

=head2 MT::TheSchwartz->debug

Static (or instance) method that simply forwards the parameters given on
to the singleton instance.

=head2 MT::TheSchwartz->insert

Static (or instance) method that simply forwards the parameters given on
to the singleton instance.

=head2 $schwartz->default_logger($msg, $job)

Handles logging messages for C<TheSchwartz>. When a log message is issued,
this method takes over. In this case, this subclass suppresses the
"job completed" messages issued by C<TheSchwartz>.

=head2 $schwartz->work_periodically([$delay])

Invokes C<TheSchwartz> to process available jobs, then queries the MT
session table for available MT registered tasks that may be ready to
run. MT tasks such as publishing scheduled posts, expiration of
spam comments and trackbacks, etc. This routine runs in an infinite
loop-- after scheduled tasks are run, it will delay C<$delay> seconds
(default of 5 seconds), then checks for more Schwartz jobs to process.

=cut
