1 package MooseX::Daemonize::Core;
2 use strict; # cause Perl::Critic errors are annoying
3 use MooseX::Getopt; # to load the NoGetopt metaclass
12 # this should never be accessible
13 # from the command line
15 metaclass => 'NoGetopt',
22 my ($self, %options) = @_;
25 if $options{ignore_zombies};
37 my ($self, %options) = @_;
39 return unless $self->is_daemon; # return if parent ...
41 # now we are in the daemon ...
43 (POSIX::setsid) # set session id
44 || confess "Cannot detach from controlling process";
46 unless ($options{no_double_fork}) {
47 $SIG{'HUP'} = 'IGNORE';
51 chdir '/'; # change to root directory
52 umask 0; # clear the file creation mask
54 unless ($options{dont_close_all_files}) {
55 # get the max numnber of possible file descriptors
56 my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX );
57 $openmax = 64 if !defined($openmax) || $openmax < 0;
60 POSIX::close($_) foreach (0 .. $openmax);
65 open(STDIN, "+>/dev/null")
66 or confess "Could not redirect STDOUT to /dev/null";
70 if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) {
71 open STDOUT, ">", $stdout_file
72 or confess "Could not redirect STDOUT to $stdout_file : $!";
75 open(STDOUT, "+>&STDIN")
76 or confess "Could not redirect STDOUT to /dev/null";
81 if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) {
82 open STDERR, ">", $stderr_file
83 or confess "Could not redirect STDERR to $stderr_file : $!";
86 open(STDERR, "+>&STDIN")
87 or confess "Could not redirect STDERR to /dev/null"; ;
90 # do a little house cleaning ...
92 # Avoid 'stdin reopened for output'
93 # warning with newer perls
94 open( NULL, '/dev/null' );
102 my ($self, %options) = @_;
103 $self->daemon_fork(%options);
104 $self->daemon_detach(%options);
115 MooseX::Daemonize::Core - A Role with the core daemonization features
122 with 'MooseX::Daemonize::Core';
128 # return from the parent,...
129 return unless $self->is_daemon;
130 # but continue on in the child (daemon)
135 This is the basic daemonization Role, it provides a few methods (see
136 below) and the minimum features needed to properly daemonize your code.
138 =head2 Important Notes
140 None of the methods in this role will exit the parent process for you,
141 it only forks and detaches your child (daemon) process. It is your
142 responsibility to exit the parent process in some way.
144 There is no PID or PID file management in this role, that is your
145 responsibility (see some of the other roles in this distro for that).
151 =item I<is_daemon (is => rw, isa => Bool)>
153 This attribute is used to signal if we are within the
154 daemon process or not.
162 =item B<daemon_fork (%options)>
164 This forks off the child process to be daemonized. Just as with
165 the built in fork, it returns the child pid to the parent process,
166 0 to the child process. It will also set the is_daemon flag
169 The C<%options> available for this function are:
173 =item I<ignore_zombies>
175 Setting this key to a true value will result in setting the C<$SIG{CHLD}>
176 handler to C<IGNORE>. This tells perl to clean up zombie processes. By
177 default, and for the most part you don't I<need> it, only when you turn off
178 the double fork behavior (with the I<no_double_fork> option) in C<daemon_detach>
179 do you sometimes want this behavior.
183 =item B<daemon_detach (%options)>
185 This detaches the new child process from the terminal by doing
186 the following things.
190 =item Becomes a session leader
192 This detaches the program from the controlling terminal, it is
193 accomplished by calling POSIX::setsid.
195 =item Performing the double-fork
197 See below for information on how to change this part of the process.
199 =item Changes the current working directory to "/"
201 This is standard daemon behavior, if you want a different working
202 directory then simply change it later in your daemons code.
204 =item Clears the file creation mask.
206 =item Closes all open file descriptors.
208 See below for information on how to change this part of the process.
210 =item Reopen STDERR, STDOUT & STDIN to /dev/null
212 This behavior can be controlled slightly though the MX_DAEMON_STDERR
213 and MX_DAEMON_STDOUT environment variables. It will look for a filename
214 in either of these variables and redirect STDOUT and/or STDERR to those
215 files. This is useful for debugging and/or testing purposes.
219 The C<%options> available for this function are:
223 =item I<no_double_fork>
225 Setting this option to true will cause this method to not perform the
226 typical double-fork, which is extra added protection from your process
227 accidentally aquiring a controlling terminal. More information can be
228 found above, and by Googling "double fork daemonize".
230 If you the double-fork behavior off, you might want to enable the
231 I<ignore_zombies> behavior in the C<daemon_fork> method.
233 =item I<dont_close_all_files>
235 Setting this option to true will cause it to skip closing all the
236 filehandles, this is useful if you are opening things like sockets
237 and such in the pre-fork.
243 If called from within the parent process (the is_daemon flag is set to
244 false), this method will simply return and do nothing.
246 =item B<daemonize (%options)>
248 This will simply call C<daemon_fork> followed by C<daemon_detach>, it will
249 pass any C<%options> onto both methods.
253 The C<meta()> method from L<Class::MOP::Class>
257 =head1 STUFF YOU SHOULD READ
261 =item Note about double fork
263 Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012>
264 in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>,
265 it is not the definitive statement on the issue, but it's clear and well
266 written enough so I decided to reproduce it here.
268 The first fork accomplishes two things - allow the shell to return,
269 and allow you to do a setsid().
271 The setsid() removes yourself from your controlling terminal. You
272 see, before, you were still listed as a job of your previous process,
273 and therefore the user might accidentally send you a signal. setsid()
274 gives you a new session, and removes the existing controlling terminal.
276 The problem is, you are now a session leader. As a session leader, if
277 you open a file descriptor that is a terminal, it will become your
278 controlling terminal (oops!). Therefore, the second fork makes you NOT
279 be a session leader. Only session leaders can acquire a controlling
280 terminal, so you can open up any file you wish without worrying that
281 it will make you a controlling terminal.
283 So - first fork - allow shell to return, and permit you to call setsid()
285 Second fork - prevent you from accidentally reacquiring a controlling
288 That said, you don't always want this to be the behavior, so you are
289 free to specify otherwise using the C<%options>.
291 =item Note about zombies
293 Doing the double fork (see above) tends to get rid of your zombies since
294 by the time you have double forked your daemon process is then owned by
295 the init process. However, sometimes the double-fork is more than you
296 really need, and you want to keep your daemon processes a little closer
297 to you. In this case you have to watch out for zombies, you can avoid then
298 by just setting the C<ignore_zombies> option (see above).
302 =head1 ENVIRONMENT VARIABLES
304 These variables are best just used for debugging and/or testing, but
305 not used for actual logging. For that, you should reopen STDOUT/ERR on
310 =item B<MX_DAEMON_STDOUT>
312 A filename to redirect the daemon STDOUT to.
314 =item B<MX_DAEMON_STDERR>
316 A filename to redirect the daemon STDERR to.
322 L<Moose::Role>, L<POSIX>
324 =head1 INCOMPATIBILITIES
328 =head1 BUGS AND LIMITATIONS
330 No bugs have been reported.
332 Please report any bugs or feature requests to
333 C<bug-acme-dahut-call@rt.cpan.org>, or through the web interface at
334 L<http://rt.cpan.org>.
340 This code is based B<HEAVILY> on L<Proc::Daemon>, we originally
341 depended on it, but we needed some more flexibility, so instead
342 we just stole the code.
346 Stevan Little C<< <stevan.little@iinteractive.com> >>
348 =head1 LICENCE AND COPYRIGHT
350 Copyright (c) 2007-2008, Chris Prather C<< <perigrin@cpan.org> >>. All rights
353 Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood.
355 This module is free software; you can redistribute it and/or
356 modify it under the same terms as Perl itself. See L<perlartistic>.
358 =head1 DISCLAIMER OF WARRANTY
360 BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
361 FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
362 OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
363 PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
364 EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
365 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
366 ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
367 YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
368 NECESSARY SERVICING, REPAIR, OR CORRECTION.
370 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
371 WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
372 REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE
373 LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL,
374 OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
375 THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
376 RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
377 FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
378 SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF