File Coverage

blib/lib/Gearman/Worker.pm

Criterion	Covered	Total	%
statement	126	248	50.8
branch	31	124	25.0
condition	4	19	21.0
subroutine	17	22	77.2
pod	7	7	100.0
total	185	420	44.0

package Gearman::Worker;
use version;
$Gearman::Worker::VERSION = qv("2.001_001");

use strict;
use warnings;

use base "Gearman::Objects";

=head1 NAME

Gearman::Worker - Worker for gearman distributed job system

=head1 SYNOPSIS

    use Gearman::Worker;
    my $worker = Gearman::Worker->new;
    $worker->job_servers('127.0.0.1');
    $worker->register_function($funcname => $subref);
    $worker->work while 1;

=head1 DESCRIPTION

I is a worker class for the Gearman distributed job system,
providing a framework for receiving and serving jobs from a Gearman server.

Callers instantiate a I object, register a list of functions
and capabilities that they can handle, then enter an event loop, waiting
for the server to send jobs.

The worker can send a return value back to the server, which then gets
sent back to the client that requested the job; or it can simply execute
silently.

=head1 USAGE

=head2 Gearman::Worker->new(%options)

Creates a new I object, and returns the object.

If I<%options> is provided, initializes the new worker object with the
settings in I<%options>, which can contain:

=over 4

=item * job_servers

Calls I (see below) to initialize the list of job
servers. It will be ignored if this worker is running as a child
process of a gearman server.

=item * prefix

Calls I (see below) to set the prefix / namespace.

=back

=head2 $client-Eprefix($prefix)

Sets the namespace / prefix for the function names.  This is useful
for sharing job servers between different applications or different
instances of the same application (different development sandboxes for
example).

The namespace is currently implemented as a simple tab separated
concatenation of the prefix and the function name.

=head1 EXAMPLES

=head2 Summation

This is an example worker that receives a request to sum up a list of
integers.

    use Gearman::Worker;
    use Storable qw( thaw );
    use List::Util qw( sum );
    my $worker = Gearman::Worker->new;
    $worker->job_servers('127.0.0.1');
    $worker->register_function(sum => sub { sum @{ thaw($_[0]->arg) } });
    $worker->work while 1;

See the I documentation for a sample client sending the
I job.

=head1 METHODS

=cut

#TODO: retries?
#
use Gearman::Util;
use Gearman::Job;
use Carp ();

use fields (
    'sock_cache',           # host:port -> IO::Socket::IP
    'last_connect_fail',    # host:port -> unixtime
    'down_since',           # host:port -> unixtime
    'connecting',           # host:port -> unixtime connect started at
    'can',        # ability -> subref     (ability is func with optional prefix)
    'timeouts',   # ability -> timeouts
    'client_id',  # random identifier string, no whitespace
    'parent_pipe',  # bool/obj:  if we're a child process of a gearman server,
                    #   this is socket to our parent process.  also means parent
                    #   sock can never disconnect or timeout, etc..
);

BEGIN {
    my $storable = eval { require Storable; 1 }
        if !defined &THROW_EXCEPTIONS || THROW_EXCEPTIONS();

    $storable ||= 0;

    if (defined &THROW_EXCEPTIONS) {
        die "Exceptions support requires Storable: $@";
    }
    else {
        eval "sub THROW_EXCEPTIONS () { $storable }";
        die "Couldn't define THROW_EXCEPTIONS: $@\n" if $@;
    }
} ## end BEGIN

sub new {
    my ($class, %opts) = @_;
    my $self = $class;
    $self = fields::new($class) unless ref $self;

    if ($ENV{GEARMAN_WORKER_USE_STDIO}) {
        open my $sock, '+<&', \*STDIN
            or die "Unable to dup STDIN to socket for worker to use.";
        $self->{job_servers} = [$sock];
        $self->{parent_pipe} = $sock;

        die "Unable to initialize connection to gearmand"
            unless $self->_on_connect($sock);
        if ($opts{job_servers}) {
            warn join ' ', __PACKAGE__,
                'ignores job_servers if $ENV{GEARMAN_WORKER_USE_STDIO} is set';

            delete($opts{job_servers});
        }
    } ## end if ($ENV{GEARMAN_WORKER_USE_STDIO...})

    $self->SUPER::new(%opts);

    $self->{sock_cache}        = {};
    $self->{last_connect_fail} = {};
    $self->{down_since}        = {};
    $self->{can}               = {};
    $self->{timeouts}          = {};
    $self->{client_id} = join("", map { chr(int(rand(26)) + 97) } (1 .. 30));

    return $self;
} ## end sub new

#
# _get_js_sock($ipport, %opts)
#
sub _get_js_sock {
    my ($self, $ipport, %opts)  = @_;
    $ipport || return;

    my $on_connect = delete $opts{on_connect};

    # Someday should warn when called with extra opts.

    warn "getting job server socket: $ipport" if $self->debug;

    # special case, if we're a child process of a gearman::server
    # parent process, talking over a unix pipe...
    return $self->{parent_pipe} if $self->{parent_pipe};

    if (my $sock = $self->{sock_cache}{$ipport}) {
        return $sock if getpeername($sock);
        delete $self->{sock_cache}{$ipport};
    }

    my $now        = time;
    my $down_since = $self->{down_since}{$ipport};
    if ($down_since) {
        warn "job server down since $down_since" if $self->debug;

        my $down_for = $now - $down_since;
        my $retry_period = $down_for > 60 ? 30 : (int($down_for / 2) + 1);
        if ($self->{last_connect_fail}{$ipport} > $now - $retry_period) {
            return undef;
        }
    } ## end if ($down_since)

    warn "connecting to '$ipport'" if $self->debug;

    my $sock = $self->socket($ipport, 1);
    unless ($sock) {
        $self->debug && warn "$@";

        $self->{down_since}{$ipport} ||= $now;
        $self->{last_connect_fail}{$ipport} = $now;

        return;
    } ## end unless ($sock)

    delete $self->{last_connect_fail}{$ipport};
    delete $self->{down_since}{$ipport};

    $sock->autoflush(1);
    $self->sock_nodelay($sock);

    $self->{sock_cache}{$ipport} = $sock;

    unless ($self->_on_connect($sock) && $on_connect && $on_connect->($sock)) {
        delete $self->{sock_cache}{$ipport};
        return;
    }

    return $sock;
} ## end sub _get_js_sock

#
# _on_connect($sock)
#
# Housekeeping things to do on connection to a server. Method call
# with one argument being the 'socket' we're going to take care of.
# returns true on success, false on failure.
#
sub _on_connect {
    my ($self, $sock) = @_;

    my $cid_req
        = Gearman::Util::pack_req_command("set_client_id", $self->{client_id});
    return undef unless Gearman::Util::send_req($sock, \$cid_req);

    # get this socket's state caught-up
    foreach my $ability (keys %{ $self->{can} }) {
        my $timeout = $self->{timeouts}->{$ability};
        unless ($self->_set_ability($sock, $ability, $timeout)) {
            return undef;
        }
    } ## end foreach my $ability (keys %...)

    return 1;
} ## end sub _on_connect

#
# _set_ability($sock, $ability, $timeout)
#
sub _set_ability {
    my ($self, $sock, $ability, $timeout) = @_;
    my $req;
    if (defined $timeout) {
        $req = Gearman::Util::pack_req_command("can_do_timeout",
            "$ability\0$timeout");
    }
    else {
        $req = Gearman::Util::pack_req_command("can_do", $ability);
    }
    return Gearman::Util::send_req($sock, \$req);
} ## end sub _set_ability

=head2 reset_abilities

tell all the jobservers that this worker can't do anything

=cut

sub reset_abilities {
    my $self = shift;
    my $req  = Gearman::Util::pack_req_command("reset_abilities");
    foreach my $js (@{ $self->{job_servers} }) {
        my $jss = $self->_get_js_sock($js)
            or next;

        unless (Gearman::Util::send_req($jss, \$req)) {
            $self->uncache_sock("js", "err_write_reset_abilities");
        }
    } ## end foreach my $js (@{ $self->{...}})

    $self->{can}      = {};
    $self->{timeouts} = {};
} ## end sub reset_abilities

=head2 uncache_sock($ipport, $reason)

close TCP connection

=cut

sub uncache_sock {
    my ($self, $ipport, $reason) = @_;

    # we can't reconnect as a child process, so all we can do is die and hope our
    # parent process respawns us...
    die "Error/timeout talking to gearman parent process: [$reason]"
        if $self->{parent_pipe};

    # normal case, we just close this TCP connection and we'll reconnect later.
    delete $self->{sock_cache}{$ipport};
} ## end sub uncache_sock

=head2 work(%opts)

Endless loop takes a job and wait for the next one.
You can pass "stop_if", "on_start", "on_complete" and "on_fail" callbacks in I<%opts>.

=cut

sub work {
    my ($self, %opts) = @_;
    my $stop_if     = delete $opts{'stop_if'} || sub {0};
    my $complete_cb = delete $opts{on_complete};
    my $fail_cb     = delete $opts{on_fail};
    my $start_cb    = delete $opts{on_start};
    die "Unknown opts" if %opts;

    my $grab_req     = Gearman::Util::pack_req_command("grab_job");
    my $presleep_req = Gearman::Util::pack_req_command("pre_sleep");

    my $last_job_time;

    my $on_connect = sub {
        return Gearman::Util::send_req($_[0], \$presleep_req);
    };

    # "Active" job servers are servers that have woken us up and should be
    # queried to see if they have jobs for us to handle. On our first pass
    # in the loop we contact all servers.
    my %active_js = map { $_ => 1 } @{ $self->{job_servers} };

    # ( js => last_update_time, ... )
    my %last_update_time;

    while (1) {

        # "Jobby" job servers are the set of server which we will contact
        # on this pass through the loop, because we need to clear and use
        # the "Active" set to plan for our next pass through the loop.
        my @jobby_js = keys %active_js;

        %active_js = ();

        my $js_count  = @jobby_js;
        my $js_offset = int(rand($js_count));
        my $is_idle   = 0;

        for (my $i = 0; $i < $js_count; $i++) {
            my $js_index = ($i + $js_offset) % $js_count;
            my $js       = $jobby_js[$js_index];
            my $jss      = $self->_get_js_sock($js, on_connect => $on_connect)
                or next;

            # TODO: add an optional sleep in here for the test suite
            # to test gearmand server going away here.  (SIGPIPE on
            # send_req, etc) this testing has been done manually, at
            # least.

            unless (Gearman::Util::send_req($jss, \$grab_req)) {
                if ($!{EPIPE} && $self->{parent_pipe}) {

                    # our parent process died, so let's just quit
                    # gracefully.
                    exit(0);
                } ## end if ($!{EPIPE} && $self...)
                $self->uncache_sock($js, "grab_job_timeout");
                delete $last_update_time{$js};
                next;
            } ## end unless (Gearman::Util::send_req...)

            # if we're a child process talking over a unix pipe, give more
            # time, since we know there are no network issues, and also
            # because on failure, we can't "reconnect".  all we can do is
            # die and hope our parent process respawns us.
            my $timeout = $self->{parent_pipe} ? 5 : 0.50;
            unless (Gearman::Util::wait_for_readability($jss->fileno, $timeout))
            {
                $self->uncache_sock($js, "grab_job_timeout");
                delete $last_update_time{$js};
                next;
            } ## end unless (Gearman::Util::wait_for_readability...)

            my $res;
            do {
                my $err;
                $res = Gearman::Util::read_res_packet($jss, \$err);
                unless ($res) {
                    $self->uncache_sock($js, "read_res_error");
                    delete $last_update_time{$js};
                    next;
                }
            } while ($res->{type} eq "noop");

            if ($res->{type} eq "no_job") {
                unless (Gearman::Util::send_req($jss, \$presleep_req)) {
                    delete $last_update_time{$js};
                    $self->uncache_sock($js, "write_presleep_error");
                }
                $last_update_time{$js} = time;
                next;
            } ## end if ($res->{type} eq "no_job")

            unless ($res->{type} eq "job_assign") {
                my $msg = "Uh, wasn't expecting a $res->{type} packet.";
                if ($res->{type} eq "error") {
                    $msg .= " [${$res->{blobref}}]\n";
                    $msg =~ s/\0/ -- /g;
                }
                die $msg;
            } ## end unless ($res->{type} eq "job_assign")

            ${ $res->{'blobref'} } =~ s/^(.+?)\0(.+?)\0//
                or die "Uh, regexp on job_assign failed";
            my ($handle, $ability) = ($1, $2);
            my $job
                = Gearman::Job->new($ability, $res->{'blobref'}, $handle, $jss);

            my $jobhandle = "$js//" . $job->handle;
            $start_cb->($jobhandle) if $start_cb;

            my $handler = $self->{can}{$ability};
            my $ret     = eval { $handler->($job); };
            my $err     = $@;
            warn "Job '$ability' died: $err" if $err;

            $last_update_time{$js} = $last_job_time = time();

            if (THROW_EXCEPTIONS && $err) {
                my $exception_req
                    = Gearman::Util::pack_req_command("work_exception",
                    join("\0", $handle, Storable::nfreeze(\$err)));
                unless (Gearman::Util::send_req($jss, \$exception_req)) {
                    $self->uncache_sock($js, "write_res_error");
                    next;
                }
            } ## end if (THROW_EXCEPTIONS &&...)

            my $work_req;
            if (defined $ret) {
                my $rv = ref $ret ? $$ret : $ret;
                $work_req = Gearman::Util::pack_req_command("work_complete",
                    "$handle\0$rv");
                $complete_cb->($jobhandle, $ret) if $complete_cb;
            } ## end if (defined $ret)
            else {
                $work_req
                    = Gearman::Util::pack_req_command("work_fail", $handle);
                $fail_cb->($jobhandle, $err) if $fail_cb;
            }

            unless (Gearman::Util::send_req($jss, \$work_req)) {
                $self->uncache_sock($js, "write_res_error");
                next;
            }

            $active_js{$js} = 1;
        } ## end for (my $i = 0; $i < $js_count...)

        my @jss;

        foreach my $js (@{ $self->{job_servers} }) {
            my $jss = $self->_get_js_sock($js, on_connect => $on_connect)
                or next;
            push @jss, [$js, $jss];
        }

        $is_idle = 1;
        my $wake_vec = '';

        foreach my $j (@jss) {
            my ($js, $jss) = @$j;
            my $fd = $jss->fileno;
            vec($wake_vec, $fd, 1) = 1;
        }

        my $timeout = keys %active_js ? 0 : (10 + rand(2));

        # chill for some arbitrary time until we're woken up again
        my $nready = select(my $wout = $wake_vec, undef, undef, $timeout);

        if ($nready) {
            foreach my $j (@jss) {
                my ($js, $jss) = @$j;
                my $fd = $jss->fileno;
                $active_js{$js} = 1
                    if vec($wout, $fd, 1);
            } ## end foreach my $j (@jss)
        } ## end if ($nready)

        $is_idle = 0 if keys %active_js;

        return if $stop_if->($is_idle, $last_job_time);

        my $update_since = time - (15 + rand 60);

        while (my ($js, $last_update) = each %last_update_time) {
            $active_js{$js} = 1 if $last_update < $update_since;
        }
    } ## end while (1)

} ## end sub work

=head2 $worker->register_function($funcname, $subref)

=head2 $worker->register_function($funcname, $timeout, $subref)

Registers the function I<$funcname> as being provided by the worker
I<$worker>, and advertises these capabilities to all of the job servers
defined in this worker.

I<$subref> must be a subroutine reference that will be invoked when the
worker receives a request for this function. It will be passed a
I object representing the job that has been received by the
worker.

I<$timeout> is an optional parameter specifying how long the jobserver will
wait for your subroutine to give an answer. Exceeding this time will result
in the jobserver reassigning the task and ignoring your result. This prevents
a gimpy worker from ruining the 'user experience' in many situations.

The subroutine reference can return a return value, which will be sent back
to the job server.
=cut

sub register_function {
    my $self    = shift;
    my $func    = shift;
    my $timeout = shift unless (ref $_[0] eq 'CODE');
    my $subref  = shift;

    my $prefix = $self->prefix;
    my $ability = defined($prefix) ? "$prefix\t$func" : "$func";

    my $req;
    if (defined $timeout) {
        $req = Gearman::Util::pack_req_command("can_do_timeout",
            "$ability\0$timeout");
        $self->{timeouts}{$ability} = $timeout;
    }
    else {
        $req = Gearman::Util::pack_req_command("can_do", $ability);
    }

    $self->_register_all($req);
    $self->{can}{$ability} = $subref;
} ## end sub register_function

=head2 unregister_function($funcname)

=cut

sub unregister_function {
    my ($self, $func) = @_;
    my $prefix = $self->prefix;
    my $ability = defined($prefix) ? "$prefix\t$func" : "$func";

    my $req = Gearman::Util::pack_req_command("cant_do", $ability);

    $self->_register_all($req);
    delete $self->{can}{$ability};
} ## end sub unregister_function

#
# _register_all($req)
#
sub _register_all {
    my ($self, $req) = @_;

    foreach my $js (@{ $self->{job_servers} }) {
        my $jss = $self->_get_js_sock($js)
            or next;

        unless (Gearman::Util::send_req($jss, \$req)) {
            $self->uncache_sock($js, "write_register_func_error");
        }
    } ## end foreach my $js (@{ $self->{...}})
} ## end sub _register_all

=head2 job_servers(@servers)

override L method to skip job server initialization
if defined C<$ENV{GEARMAN_WORKER_USE_STDIO}>

Calling this method will do nothing in a worker that is running as a child
process of a gearman server.

=cut

sub job_servers {
    my $self = shift;
    return if ($ENV{GEARMAN_WORKER_USE_STDIO});

    return $self->SUPER::job_servers(@_);
} ## end sub job_servers

1;
__END__