1 package MooseX::Daemonize::Core;
2 use strict; # cause Perl::Critic errors are annoying
3 use MooseX::Getopt; # to load the NoGetopt metaclass
10 # this should never be accessible
11 # from the command line
13 metaclass => 'NoGetopt',
19 has ignore_zombies => (
20 metaclass => 'Getopt',
26 has no_double_fork => (
27 metaclass => 'Getopt',
33 has dont_close_all_files => (
34 metaclass => 'Getopt',
41 my ($self, %options) = @_;
42 # backwards compability.. old code might be calling daemon_fork/_detach with options
43 foreach my $opt (qw( ignore_zombies no_double_fork dont_close_all_files )) {
44 $self->$opt( $options{ $opt } ) if ( defined $options{ $opt } );
50 my ($self, %options) = @_;
52 $self->_get_options( %options );
55 if $self->ignore_zombies;;
67 my ($self, %options) = @_;
69 return unless $self->is_daemon; # return if parent ...
71 $self->_get_options( %options );
72 # now we are in the daemon ...
74 (POSIX::setsid) # set session id
75 || confess "Cannot detach from controlling process";
77 unless ( $self->no_double_fork ) {
78 $SIG{'HUP'} = 'IGNORE';
82 chdir '/'; # change to root directory
83 umask 0; # clear the file creation mask
85 unless ( $self->dont_close_all_files ) {
86 # get the max numnber of possible file descriptors
87 my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX );
88 $openmax = 64 if !defined($openmax) || $openmax < 0;
91 POSIX::close($_) foreach (0 .. $openmax);
96 open(STDIN, "+>/dev/null")
97 or confess "Could not redirect STDOUT to /dev/null";
101 if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) {
102 open STDOUT, ">", $stdout_file
103 or confess "Could not redirect STDOUT to $stdout_file : $!";
106 open(STDOUT, "+>&STDIN")
107 or confess "Could not redirect STDOUT to /dev/null";
112 if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) {
113 open STDERR, ">", $stderr_file
114 or confess "Could not redirect STDERR to $stderr_file : $!";
117 open(STDERR, "+>&STDIN")
118 or confess "Could not redirect STDERR to /dev/null"; ;
121 # do a little house cleaning ...
123 # Avoid 'stdin reopened for output'
124 # warning with newer perls
125 open( NULL, '/dev/null' );
133 my ($self, %options) = @_;
134 $self->daemon_fork(%options);
135 $self->daemon_detach(%options);
146 MooseX::Daemonize::Core - A Role with the core daemonization features
153 with 'MooseX::Daemonize::Core';
159 # return from the parent,...
160 return unless $self->is_daemon;
161 # but continue on in the child (daemon)
166 This is the basic daemonization Role, it provides a few methods (see
167 below) and the minimum features needed to properly daemonize your code.
169 =head2 Important Notes
171 None of the methods in this role will exit the parent process for you,
172 it only forks and detaches your child (daemon) process. It is your
173 responsibility to exit the parent process in some way.
175 There is no PID or PID file management in this role, that is your
176 responsibility (see some of the other roles in this distro for that).
182 =item I<is_daemon (is => rw, isa => Bool)>
184 This attribute is used to signal if we are within the
185 daemon process or not.
187 =item I<no_double_fork (is => rw, isa => Bool)>
189 Setting this attribute to true will cause this method to not perform the
190 typical double-fork, which is extra added protection from your process
191 accidentally aquiring a controlling terminal. More information can be
192 found above, and by Googling "double fork daemonize".
194 If you the double-fork behavior off, you might want to enable the
197 =item I<ignore_zombies (is => rw, isa => Bool)>
199 Setting this attribute to a true value will result in setting the C<$SIG{CHLD}>
200 handler to C<IGNORE>. This tells perl to clean up zombie processes. By
201 default, and for the most part you don't I<need> it, only when you turn off
202 the double fork behavior (with the I<no_double_fork> attribute)
203 do you sometimes want this behavior.
205 =item I<dont_close_all_files (is => rw, isa => Bool)>
207 Setting this attribute to true will cause it to skip closing all the
208 filehandles. This is useful if you are opening things like sockets
209 and such in the pre-fork.
217 =item B<daemon_fork (?%options)>
219 This forks off the child process to be daemonized. Just as with
220 the built in fork, it returns the child pid to the parent process,
221 0 to the child process. It will also set the is_daemon flag
224 The C<%options> argument remains for backwards compatability, but
225 it is suggested that you use the attributes listed above instead.
227 =item B<daemon_detach (?%options)>
229 This detaches the new child process from the terminal by doing
230 the following things.
232 The C<%options> argument remains for backwards compatability, but
233 it is suggested that you use the attributes listed above instead.
237 =item Becomes a session leader
239 This detaches the program from the controlling terminal, it is
240 accomplished by calling POSIX::setsid.
242 =item Performing the double-fork
244 See below for information on how to change this part of the process.
246 =item Changes the current working directory to "/"
248 This is standard daemon behavior, if you want a different working
249 directory then simply change it later in your daemons code.
251 =item Clears the file creation mask.
253 =item Closes all open file descriptors.
255 See the I<dont_close_all_files> attribute for information on how to
256 change this part of the process.
258 =item Reopen STDERR, STDOUT & STDIN to /dev/null
260 This behavior can be controlled slightly though the MX_DAEMON_STDERR
261 and MX_DAEMON_STDOUT environment variables. It will look for a filename
262 in either of these variables and redirect STDOUT and/or STDERR to those
263 files. This is useful for debugging and/or testing purposes.
267 If called from within the parent process (the is_daemon flag is set to
268 false), this method will simply return and do nothing.
270 =item B<daemonize (?%options)>
272 This will simply call C<daemon_fork> followed by C<daemon_detach>.
274 The C<%options> argument remains for backwards compatability, but
275 it is suggested that you use the attributes listed above instead.
279 The C<meta()> method from L<Class::MOP::Class>
283 =head1 STUFF YOU SHOULD READ
287 =item Note about double fork
289 Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012>
290 in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>,
291 it is not the definitive statement on the issue, but it's clear and well
292 written enough so I decided to reproduce it here.
294 The first fork accomplishes two things - allow the shell to return,
295 and allow you to do a setsid().
297 The setsid() removes yourself from your controlling terminal. You
298 see, before, you were still listed as a job of your previous process,
299 and therefore the user might accidentally send you a signal. setsid()
300 gives you a new session, and removes the existing controlling terminal.
302 The problem is, you are now a session leader. As a session leader, if
303 you open a file descriptor that is a terminal, it will become your
304 controlling terminal (oops!). Therefore, the second fork makes you NOT
305 be a session leader. Only session leaders can acquire a controlling
306 terminal, so you can open up any file you wish without worrying that
307 it will make you a controlling terminal.
309 So - first fork - allow shell to return, and permit you to call setsid()
311 Second fork - prevent you from accidentally reacquiring a controlling
314 That said, you don't always want this to be the behavior, so you are
315 free to specify otherwise using the I<no_double_fork> attribute.
317 =item Note about zombies
319 Doing the double fork (see above) tends to get rid of your zombies since
320 by the time you have double forked your daemon process is then owned by
321 the init process. However, sometimes the double-fork is more than you
322 really need, and you want to keep your daemon processes a little closer
323 to you. In this case you have to watch out for zombies, you can avoid then
324 by just setting the I<ignore_zombies> attribute (see above).
328 =head1 ENVIRONMENT VARIABLES
330 These variables are best just used for debugging and/or testing, but
331 not used for actual logging. For that, you should reopen STDOUT/ERR on
336 =item B<MX_DAEMON_STDOUT>
338 A filename to redirect the daemon STDOUT to.
340 =item B<MX_DAEMON_STDERR>
342 A filename to redirect the daemon STDERR to.
348 L<Moose::Role>, L<POSIX>
350 =head1 INCOMPATIBILITIES
354 =head1 BUGS AND LIMITATIONS
356 No bugs have been reported.
358 Please report any bugs or feature requests to
359 C<bug-acme-dahut-call@rt.cpan.org>, or through the web interface at
360 L<http://rt.cpan.org>.
366 This code is based B<HEAVILY> on L<Proc::Daemon>, we originally
367 depended on it, but we needed some more flexibility, so instead
368 we just stole the code.
372 Stevan Little C<< <stevan.little@iinteractive.com> >>
374 =head1 LICENCE AND COPYRIGHT
376 Copyright (c) 2007-2011, Chris Prather C<< <perigrin@cpan.org> >>. All rights
379 Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood.
381 This module is free software; you can redistribute it and/or
382 modify it under the same terms as Perl itself. See L<perlartistic>.
384 =head1 DISCLAIMER OF WARRANTY
386 BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
387 FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
388 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
389 PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
390 EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
391 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
392 ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
393 YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
394 NECESSARY SERVICING, REPAIR, OR CORRECTION.
396 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
397 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
398 REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE
399 LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL,
400 OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
401 THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
402 RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
403 FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
404 SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF