1MooseX::Workers(3)    User Contributed Perl Documentation   MooseX::Workers(3)
2
3
4

NAME

6       MooseX::Workers - Simple sub-process management for asynchronous tasks
7

SYNOPSIS

9        EXAMPLE #1:
10           package Manager;
11           #    This example prints output from the children normally on both STDOUT and STDERR
12
13           use Moose;
14           with qw(MooseX::Workers);
15
16           sub run {
17               $_[0]->spawn( sub { sleep 3; print "Hello World\n" } );
18               warn "Running now ... ";
19               POE::Kernel->run();
20           }
21
22           # Implement our Interface
23           sub worker_stdout  { shift; warn join ' ', @_;  }
24           sub worker_stderr  { shift; warn join ' ', @_;  }
25
26           sub worker_manager_start { warn 'started worker manager' }
27           sub worker_manager_stop  { warn 'stopped worker manager' }
28
29           sub max_workers_reached  { warn 'maximum worker count reached' }
30           sub worker_error   { shift; warn join ' ', @_;  }
31           sub worker_finished { warn 'a worker has finished' }
32           sub worker_started { shift; warn join ' ', @_;  }
33           sub sig_child      { shift; warn join ' ', @_;  }
34           sub sig_TERM       { shift; warn 'Handled TERM' }
35
36           no Moose;
37
38           Manager->new->run();
39
40
41        EXAMPLE #2:
42           package Manager;
43
44           #    This example prints output from the children normally on
45           #    STDERR but uses STDOUT to returns a hashref from the child to
46           #    the parent
47
48           use Moose;
49           with qw(MooseX::Workers);
50           use POE qw(Filter::Reference Filter::Line);
51
52           sub run {
53               $_[0]->spawn(
54                   sub {
55                       sleep 3;
56
57                       #    Return a hashref (arrayref, whatever) to the parent using P::F::Reference
58                       print @{POE::Filter::Reference->new->put([ {msg => "Hello World"} ])}; # Note the [] around the return val
59
60                       #    Print normally using P::F::Line (shown for
61                       #    completeness; in practice, just don't bother
62                       #    defining the _filter method
63                       #
64                       print STDERR "Hey look, an error message";
65                   }
66               );
67
68               POE::Kernel->run();
69           }
70
71           # Implement our Interface
72           #    These two are both optional; if defined (as here), they
73           #    should return a subclass of POE::Filter.
74           sub stdout_filter  { POE::Filter::Reference->new }
75           sub stderr_filter  { POE::Filter::Line->new }
76
77           sub worker_stdout  {
78               my ( $self, $result ) = @_;  #  $result will be a hashref:  {msg => "Hello World"}
79                       print $result->{msg};
80
81               #    Note that you can do more than just print the message --
82               #    e.g. this is the way to return data from the children for
83               #    accumulation in the parent.
84               }
85           sub worker_stderr  {
86               my ( $self, $stderr_msg ) = @_;  #  $stderr_msg will be a string: "Hey look, an error message";
87               warn $stderr_msg;
88           }
89
90           #     From here down, this is identical to the previous example.
91           sub worker_manager_start { warn 'started worker manager' }
92           sub worker_manager_stop  { warn 'stopped worker manager' }
93
94           sub max_workers_reached  { warn 'maximum worker count reached' }
95           sub worker_error   { shift; warn join ' ', @_;  }
96           sub worker_finished { warn 'a worker has finished' }
97           sub worker_started { shift; warn join ' ', @_;  }
98           sub sig_child      { shift; warn join ' ', @_;  }
99           sub sig_TERM       { shift; warn 'Handled TERM' }
100
101           no Moose;
102
103           Manager->new->run();
104

DESCRIPTION

106       MooseX::Workers is a Role that provides easy delegation of long-running
107       tasks into a managed child process. Process management is taken care of
108       via POE and its POE::Wheel::Run module.
109

METHODS

111       spawn ($command)
112       fork ($command)
113       run_command ($command)
114           These three methods are the whole point of this module.  They pass
115           $command through to the MooseX::Worker::Engine which will take care
116           of running $command for you.
117
118           spawn() and fork() both invoke POE::Kernel call(), which is
119           synchronous.
120
121           run_command() invokes POE::Kernel yield(), which is asynchronous.
122
123           If max_workers() has been reached, run_command() warns and does
124           nothing. It is up to you to re-submit $command. See enqueue() if
125           you want us to run $command as soon as another worker is free.
126
127       enqueue($command)
128           Just like run_command(), only that if max_workers() has been set
129           and that number of workers has been reached, then we add $command
130           to a FIFO command queue. As soon as any running worker exits, the
131           first $command in queue (if any) will be run.
132
133       check_worker_threshold
134           This will check to see how many workers you have compared to the
135           max_workers limit. It returns true if the $num_workers is >=
136           $max_workers;
137
138       max_workers($count)
139           An accessor for the maximum number of workers. This is delegated to
140           the MooseX::Workers::Engine object.
141
142       has_workers
143           Check to see if we have *any* workers currently. This is delegated
144           to the MooseX::Workers::Engine object.
145
146       num_workers
147           Return the current number of workers. This is delegated to the
148           MooseX::Workers::Engine object.
149
150       meta
151           The Metaclass for MooseX::Workers::Engine see Moose's
152           documentation.
153

INTERFACE

155       MooseX::Worker::Engine supports the following callbacks:
156
157       worker_manager_start
158           Called when the managing session is started
159
160       worker_manager_stop
161           Called when the managing session stops
162
163       max_workers_reached
164           Called when we reach the maximum number of workers
165
166       stdout_filter
167           OPTIONAL.  If defined, this should return an object that isa
168           POE::Filter.  If it doesn't, the results are undefined.  Anything
169           that a child proc sends on STDOUT will be passed through the
170           relevant filter.
171
172       stderr_filter
173           OPTIONAL.  If defined, this should return an object that isa
174           POE::Filter.  If it doesn't, the results are undefined.  Anything
175           that a child proc sends on STDERR will be passed through the
176           relevant filter.
177
178       worker_stdout
179           Called when a child prints to STDOUT.  If "stdout_filter" was
180           defined, the output will be filtered appropriately, as described
181           above.  This is useful to allow child processes to return data to
182           the parent (generally via POE::Filter::Reference).
183
184       worker_stderr
185           Called when a child prints to STDERR.  Filtered through the result
186           of "stderr_filter" if that method is defined.
187
188       worker_error
189           Called when there is an error condition detected with the child.
190
191       worker_finished
192           Called when a worker completes $command.
193
194           If the command was a MooseX::Workers::Job, it will get the removed
195           job instance as the first parameter.
196
197       worker_done
198           *DEPRECATED*
199
200           This is called before the worker is removed, so "num_workers" and
201           "has_workers" does not reflect that a worker has just finished. Use
202           "worker_finished" instead.
203
204           Gets the MooseX::Workers::Job instance, if the $command was a job,
205           and the POE::Wheel::Run id otherwise.
206
207       worker_started
208           Called when a worker starts $command
209
210       sig_child
211           Called when the mangaging session recieves a SIG CHLD event
212
213       sig_*
214           Called when the underlying POE Kernel receives a signal; this is
215           not limited to OS signals (ie. what you'd usually handle in Perl's
216           %SIG) so will also accept arbitrary POE signals (sent via
217           POE::Kernel->signal), but does exclude SIGCHLD/SIGCHILD, which is
218           instead handled by sig_child above.
219
220           These interface methods are automatically inserted when
221           MooseX::Worker::Engine detects that your manager class contains any
222           methods beginning with sig_.  Signals are case-sensitive, so if you
223           wish to handle a TERM signal, you must define a sig_TERM() method.
224           Note also that this action is performed upon MooseX::Worker::Engine
225           startup, so any run-time modification of your class which 'does'
226           MooseX::Workers is not likely to be detected.
227
228           See the sig_TERM handler in the SYNOPSIS for an example.
229
230       See MooseX::Workers::Engine for more details.  Also see
231       MooseX::Workers::Job if you'd like to give your tasks names, or set
232       timeouts on them.
233

WIN32 NOTES

235       You don't need to binmode the STDIN/STDOUT/STDERR streams in your
236       coderefs, this is done for you. If you need utf8, it is safe to re-
237       binmode them to ":encoding(UTF-8)".
238
239       Coderef workers that time out are killed with a SIGINT rather than a
240       SIGTERM, because TERM does not behave compatibly (thanks Rocco!) This
241       is done with a:
242
243           local $SIG{INT} = sub { exit 0 };
244
245       that wraps the coderef.
246
247       You cannot catch a TERM sent to the parent process (see "kill" in
248       perlport, use INT instead.
249
250       External programs are run with Win32::Job by POE::Wheel::Run. They are
251       prepended with "cmd /c" so that builtin cmd commands also work. Use a
252       MooseX::Workers::Job with a string program and arrayref args for this.
253       If you are using POE::Filter::Line with an external program (which is
254       the default if you don't set the filter) the CRs from line ends will be
255       removed automatically.
256

BUGS AND LIMITATIONS

258       Please report any bugs or feature requests to
259       "bug-moosex-workers@rt.cpan.org", or through the web interface at
260       <http://rt.cpan.org>.
261
262       Version control: <https://github.com/jhannah/moosex-workers>
263

AUTHORS

265       Chris Prather "<perigrin@cpan.org>"
266
267       Tom Lanyon "<dec@cpan.org>"
268
269       Jay Hannah "<jay@jays.net>"
270
271       Justin Hunter "<justin.d.hunter@gmail.com>"
272
273       David K. Storrs "<david.storrs@gmail.com>"
274
275       Rafael Kitover "<rkitover@cpan.org>"
276
278       Copyright (c) 2007-2013, Chris Prather "<perigrin@cpan.org>". Some
279       rights reserved.
280
281       This module is free software; you can redistribute it and/or modify it
282       under the same terms as Perl itself. See perlartistic.
283

DISCLAIMER OF WARRANTY

285       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
286       FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
287       WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
288       PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
289       EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
290       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
291       ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
292       YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
293       NECESSARY SERVICING, REPAIR, OR CORRECTION.
294
295       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
296       WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
297       REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
298       TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
299       CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
300       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
301       RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
302       FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
303       SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
304       DAMAGES.
305
306
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308perl v5.32.0                      2020-07-28                MooseX::Workers(3)
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