3 package MooseX::Daemonize::Core;
5 use MooseX::Getopt; # to load the NoGetopt metaclass
12 # this should never be accessible
13 # from the command line
15 metaclass => 'NoGetopt',
21 has ignore_zombies => (
22 metaclass => 'Getopt',
28 has no_double_fork => (
29 metaclass => 'Getopt',
35 has dont_close_all_files => (
36 metaclass => 'Getopt',
43 my ($self, %options) = @_;
44 # backwards compatibility.. old code might be calling daemon_fork/_detach with options
45 foreach my $opt (qw( ignore_zombies no_double_fork dont_close_all_files )) {
46 $self->$opt( $options{ $opt } ) if ( defined $options{ $opt } );
52 my ($self, %options) = @_;
54 $self->_get_options( %options );
57 if $self->ignore_zombies;;
69 my ($self, %options) = @_;
71 return unless $self->is_daemon; # return if parent ...
73 $self->_get_options( %options );
74 # now we are in the daemon ...
76 (POSIX::setsid) # set session id
77 || confess "Cannot detach from controlling process";
79 unless ( $self->no_double_fork ) {
80 $SIG{'HUP'} = 'IGNORE';
84 chdir '/'; # change to root directory
85 umask 0; # clear the file creation mask
87 unless ( $self->dont_close_all_files ) {
88 # get the max number of possible file descriptors
89 my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX );
90 $openmax = 64 if !defined($openmax) || $openmax < 0;
93 POSIX::close($_) foreach (0 .. $openmax);
98 open(STDIN, "+>/dev/null")
99 or confess "Could not redirect STDOUT to /dev/null";
103 if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) {
104 open STDOUT, ">", $stdout_file
105 or confess "Could not redirect STDOUT to $stdout_file : $!";
108 open(STDOUT, "+>&STDIN")
109 or confess "Could not redirect STDOUT to /dev/null";
114 if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) {
115 open STDERR, ">", $stderr_file
116 or confess "Could not redirect STDERR to $stderr_file : $!";
119 open(STDERR, "+>&STDIN")
120 or confess "Could not redirect STDERR to /dev/null"; ;
123 # do a little house cleaning ...
125 # Avoid 'stdin reopened for output'
126 # warning with newer perls
127 open( NULL, '/dev/null' );
135 my ($self, %options) = @_;
136 $self->daemon_fork(%options);
137 $self->daemon_detach(%options);
148 MooseX::Daemonize::Core - A Role with the core daemonization features
155 with 'MooseX::Daemonize::Core';
161 # return from the parent,...
162 return unless $self->is_daemon;
163 # but continue on in the child (daemon)
168 This is the basic daemonization Role, it provides a few methods (see
169 below) and the minimum features needed to properly daemonize your code.
171 =head2 Important Notes
173 None of the methods in this role will exit the parent process for you,
174 it only forks and detaches your child (daemon) process. It is your
175 responsibility to exit the parent process in some way.
177 There is no PID or PID file management in this role, that is your
178 responsibility (see some of the other roles in this distro for that).
184 =item I<is_daemon (is => rw, isa => Bool)>
186 This attribute is used to signal if we are within the
187 daemon process or not.
189 =item I<no_double_fork (is => rw, isa => Bool)>
191 Setting this attribute to true will cause this method to not perform the
192 typical double-fork, which is extra added protection from your process
193 accidentally acquiring a controlling terminal. More information can be
194 found above, and by Googling "double fork daemonize".
196 If you the double-fork behavior off, you might want to enable the
199 =item I<ignore_zombies (is => rw, isa => Bool)>
201 Setting this attribute to a true value will result in setting the C<$SIG{CHLD}>
202 handler to C<IGNORE>. This tells perl to clean up zombie processes. By
203 default, and for the most part you don't I<need> it, only when you turn off
204 the double fork behavior (with the I<no_double_fork> attribute)
205 do you sometimes want this behavior.
207 =item I<dont_close_all_files (is => rw, isa => Bool)>
209 Setting this attribute to true will cause it to skip closing all the
210 filehandles. This is useful if you are opening things like sockets
211 and such in the pre-fork.
219 =item B<daemon_fork (?%options)>
221 This forks off the child process to be daemonized. Just as with
222 the built in fork, it returns the child pid to the parent process,
223 0 to the child process. It will also set the is_daemon flag
226 The C<%options> argument remains for backwards compatibility, but
227 it is suggested that you use the attributes listed above instead.
229 =item B<daemon_detach (?%options)>
231 This detaches the new child process from the terminal by doing
232 the following things.
234 The C<%options> argument remains for backwards compatibility, but
235 it is suggested that you use the attributes listed above instead.
239 =item Becomes a session leader
241 This detaches the program from the controlling terminal, it is
242 accomplished by calling POSIX::setsid.
244 =item Performing the double-fork
246 See below for information on how to change this part of the process.
248 =item Changes the current working directory to "/"
250 This is standard daemon behavior, if you want a different working
251 directory then simply change it later in your daemons code.
253 =item Clears the file creation mask.
255 =item Closes all open file descriptors.
257 See the I<dont_close_all_files> attribute for information on how to
258 change this part of the process.
260 =item Reopen STDERR, STDOUT & STDIN to /dev/null
262 This behavior can be controlled slightly though the MX_DAEMON_STDERR
263 and MX_DAEMON_STDOUT environment variables. It will look for a filename
264 in either of these variables and redirect STDOUT and/or STDERR to those
265 files. This is useful for debugging and/or testing purposes.
269 If called from within the parent process (the is_daemon flag is set to
270 false), this method will simply return and do nothing.
272 =item B<daemonize (?%options)>
274 This will simply call C<daemon_fork> followed by C<daemon_detach>.
276 The C<%options> argument remains for backwards compatibility, but
277 it is suggested that you use the attributes listed above instead.
281 The C<meta()> method from L<Class::MOP::Class>
287 =head1 STUFF YOU SHOULD READ
291 =item Note about double fork
293 Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012>
294 in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>,
295 it is not the definitive statement on the issue, but it's clear and well
296 written enough so I decided to reproduce it here.
298 The first fork accomplishes two things - allow the shell to return,
299 and allow you to do a setsid().
301 The setsid() removes yourself from your controlling terminal. You
302 see, before, you were still listed as a job of your previous process,
303 and therefore the user might accidentally send you a signal. setsid()
304 gives you a new session, and removes the existing controlling terminal.
306 The problem is, you are now a session leader. As a session leader, if
307 you open a file descriptor that is a terminal, it will become your
308 controlling terminal (oops!). Therefore, the second fork makes you NOT
309 be a session leader. Only session leaders can acquire a controlling
310 terminal, so you can open up any file you wish without worrying that
311 it will make you a controlling terminal.
313 So - first fork - allow shell to return, and permit you to call setsid()
315 Second fork - prevent you from accidentally reacquiring a controlling
318 That said, you don't always want this to be the behavior, so you are
319 free to specify otherwise using the I<no_double_fork> attribute.
321 =item Note about zombies
323 Doing the double fork (see above) tends to get rid of your zombies since
324 by the time you have double forked your daemon process is then owned by
325 the init process. However, sometimes the double-fork is more than you
326 really need, and you want to keep your daemon processes a little closer
327 to you. In this case you have to watch out for zombies, you can avoid then
328 by just setting the I<ignore_zombies> attribute (see above).
332 =head1 ENVIRONMENT VARIABLES
334 These variables are best just used for debugging and/or testing, but
335 not used for actual logging. For that, you should reopen STDOUT/ERR on
340 =item B<MX_DAEMON_STDOUT>
342 A filename to redirect the daemon STDOUT to.
344 =item B<MX_DAEMON_STDERR>
346 A filename to redirect the daemon STDERR to.
352 L<Moose::Role>, L<POSIX>
354 =head1 INCOMPATIBILITIES
358 =head1 BUGS AND LIMITATIONS
360 No bugs have been reported.
362 Please report any bugs or feature requests to
363 C<bug-acme-dahut-call@rt.cpan.org>, or through the web interface at
364 L<http://rt.cpan.org>.
370 This code is based B<HEAVILY> on L<Proc::Daemon>, we originally
371 depended on it, but we needed some more flexibility, so instead
372 we just stole the code.
376 Stevan Little C<< <stevan.little@iinteractive.com> >>
378 =head1 LICENCE AND COPYRIGHT
380 Copyright (c) 2007-2011, Chris Prather C<< <perigrin@cpan.org> >>. All rights
383 Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood.
385 This module is free software; you can redistribute it and/or
386 modify it under the same terms as Perl itself. See L<perlartistic>.
388 =head1 DISCLAIMER OF WARRANTY
390 BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
391 FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
392 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
393 PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
394 EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
395 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
396 ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
397 YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
398 NECESSARY SERVICING, REPAIR, OR CORRECTION.
400 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
401 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
402 REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE
403 LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL,
404 OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
405 THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
406 RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
407 FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
408 SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF