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1 | package MooseX::Daemonize::Core; |
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2 | use Moose::Role; |
3 | |
4 | our $VERSION = 0.01; |
5 | |
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6 | use POSIX (); |
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7 | |
8 | has is_daemon => ( |
9 | isa => 'Bool', |
10 | is => 'rw', |
11 | default => sub { 0 }, |
12 | ); |
13 | |
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14 | sub daemon_fork { |
15 | my ($self, %options) = @_; |
16 | |
17 | $SIG{CHLD} = 'IGNORE' |
18 | if $options{ignore_zombies}; |
19 | |
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20 | if (my $pid = fork) { |
21 | return $pid; |
22 | } |
23 | else { |
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24 | $self->is_daemon(1); |
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25 | return; |
26 | } |
27 | } |
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28 | |
29 | sub daemon_detach { |
30 | my ($self, %options) = @_; |
31 | |
32 | return unless $self->is_daemon; # return if parent ... |
33 | |
34 | # now we are in the daemon ... |
35 | |
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36 | (POSIX::setsid) # set session id |
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37 | || confess "Cannot detach from controlling process"; |
38 | |
39 | unless ($options{no_double_fork}) { |
40 | $SIG{'HUP'} = 'IGNORE'; |
41 | fork && exit; |
42 | } |
43 | |
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44 | chdir '/'; # change to root directory |
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45 | umask 0; # clear the file creation mask |
46 | |
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47 | # get the max numnber of possible file descriptors |
48 | my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX ); |
49 | $openmax = 64 if !defined($openmax) || $openmax < 0; |
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50 | |
51 | # close them all |
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52 | POSIX::close($_) foreach (0 .. $openmax); |
53 | |
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54 | open(STDIN, "+>/dev/null"); |
55 | |
56 | # Avoid 'stdin reopened for output' |
57 | # warning with newer perls |
58 | open( NULL, '/dev/null' ); |
59 | <NULL> if (0); |
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60 | |
61 | if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) { |
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62 | open STDOUT, ">", $stdout_file |
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63 | or confess "Could not redirect STDOUT to $stdout_file : $!"; |
64 | } |
65 | else { |
66 | open(STDOUT, "+>&STDIN"); |
67 | } |
68 | |
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69 | if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) { |
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70 | open STDERR, ">", "ERR.txt" |
d8985b7d |
71 | or confess "Could not redirect STDERR to $stderr_file : $!"; |
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72 | } |
d8985b7d |
73 | else { |
74 | open(STDERR, "+>&STDIN"); |
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75 | } |
ea9485d8 |
76 | } |
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77 | |
78 | sub daemonize { |
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79 | my ($self, %options) = @_; |
80 | $self->daemon_fork(%options); |
81 | $self->daemon_detach(%options); |
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82 | } |
83 | |
84 | 1; |
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85 | |
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86 | __END__ |
87 | |
d8985b7d |
88 | =pod |
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89 | |
d8985b7d |
90 | =head1 NAME |
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91 | |
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92 | MooseX::Daemonize::Core - A Role with the core daemonization features |
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93 | |
94 | =head1 SYNOPSIS |
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95 | |
96 | package My::Daemon; |
97 | use Moose; |
98 | |
99 | with 'MooseX::Daemonize::Core'; |
100 | |
101 | sub start { |
102 | my $self = shift; |
103 | # daemonize me ... |
104 | $self->daemonize; |
105 | # return from the parent,... |
106 | return unless $self->is_daemon; |
107 | # but continue on in the child (daemon) |
108 | } |
109 | |
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110 | =head1 DESCRIPTION |
111 | |
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112 | This is the basic daemonization Role, it provides a few methods (see |
113 | below) and the minimum features needed to properly daemonize your code. |
114 | |
115 | =head2 Important Notes |
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116 | |
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117 | None of the methods in this role will exit the parent process for you, |
118 | it only forks and detaches your child (daemon) process. It is your |
119 | responsibility to exit the parent process in some way. |
120 | |
121 | There is no PID or PID file management in this role, that is your |
122 | responsibility (see some of the other roles in this distro for that). |
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123 | |
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124 | =head1 ATTRIBUTES |
125 | |
126 | =over |
127 | |
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128 | =item I<is_daemon (is => rw, isa => Bool)> |
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129 | |
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130 | This attribute is used to signal if we are within the |
131 | daemon process or not. |
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132 | |
133 | =back |
134 | |
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135 | =head1 METHODS |
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136 | |
137 | =over |
138 | |
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139 | =item B<daemon_fork (%options)> |
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140 | |
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141 | This forks off the child process to be daemonized. Just as with |
142 | the built in fork, it returns the child pid to the parent process, |
143 | 0 to the child process. It will also set the is_daemon flag |
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144 | appropriately. |
145 | |
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146 | The C<%options> available for this function are: |
147 | |
148 | =over 4 |
149 | |
150 | =item I<ignore_zombies> |
151 | |
152 | Setting this key to a true value will result in setting the C<$SIG{CHLD}> |
153 | handler to C<IGNORE>. This tells perl to clean up zombie processes. By |
154 | default, and for the most part you don't I<need> it, only when you turn off |
155 | the double fork behavior (with the I<no_double_fork> option) in C<daemon_detach> |
156 | do you sometimes want this behavior. |
157 | |
158 | =back |
159 | |
160 | =item B<daemon_detach (%options)> |
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161 | |
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162 | This detaches the new child process from the terminal by doing |
163 | the following things. |
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164 | |
165 | =over 4 |
166 | |
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167 | =item Becomes a session leader |
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168 | |
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169 | This detaches the program from the controlling terminal, it is |
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170 | accomplished by calling POSIX::setsid. |
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171 | |
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172 | =item Performing the double-fork |
173 | |
174 | See below for information on how to change this part of the process. |
175 | |
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176 | =item Changes the current working directory to "/" |
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177 | |
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178 | This is standard daemon behavior, if you want a different working |
179 | directory then simply change it later in your daemons code. |
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180 | |
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181 | =item Clears the file creation mask. |
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182 | |
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183 | =item Closes all open file descriptors. |
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184 | |
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185 | =item Reopen STDERR, STDOUT & STDIN to /dev/null |
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186 | |
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187 | This behavior can be controlled slightly though the MX_DAEMON_STDERR |
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188 | and MX_DAEMON_STDOUT environment variables. It will look for a filename |
189 | in either of these variables and redirect STDOUT and/or STDERR to those |
190 | files. This is useful for debugging and/or testing purposes. |
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191 | |
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192 | -back |
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193 | |
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194 | The C<%options> available for this function are: |
195 | |
196 | =over 4 |
197 | |
198 | =item I<no_double_fork> |
199 | |
200 | Setting this option to true will cause this method to not perform the |
201 | typical double-fork, which is extra added protection from your process |
202 | accidentally aquiring a controlling terminal. More information can be |
203 | found above, and by Googling "double fork daemonize". |
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204 | |
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205 | If you the double-fork behavior off, you might want to enable the |
206 | I<ignore_zombies> behavior in the C<daemon_fork> method. |
207 | |
208 | =back |
209 | |
210 | B<NOTE> |
211 | |
212 | If called from within the parent process (the is_daemon flag is set to |
213 | false), this method will simply return and do nothing. |
214 | |
215 | =item B<daemonize (%options)> |
216 | |
217 | This will simply call C<daemon_fork> followed by C<daemon_detach>, it will |
218 | pass any C<%options> onto both methods. |
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219 | |
220 | =item meta() |
221 | |
222 | The C<meta()> method from L<Class::MOP::Class> |
223 | |
224 | =back |
225 | |
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226 | =head1 STUFF YOU SHOULD READ |
227 | |
228 | =over 4 |
229 | |
230 | =item Note about double fork |
231 | |
232 | Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012> |
233 | in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>, |
234 | it is not the definitive statement on the issue, but it's clear and well |
235 | written enough so I decided to reproduce it here. |
236 | |
237 | The first fork accomplishes two things - allow the shell to return, |
238 | and allow you to do a setsid(). |
239 | |
240 | The setsid() removes yourself from your controlling terminal. You |
241 | see, before, you were still listed as a job of your previous process, |
242 | and therefore the user might accidentally send you a signal. setsid() |
243 | gives you a new session, and removes the existing controlling terminal. |
244 | |
245 | The problem is, you are now a session leader. As a session leader, if |
246 | you open a file descriptor that is a terminal, it will become your |
247 | controlling terminal (oops!). Therefore, the second fork makes you NOT |
248 | be a session leader. Only session leaders can acquire a controlling |
249 | terminal, so you can open up any file you wish without worrying that |
250 | it will make you a controlling terminal. |
251 | |
252 | So - first fork - allow shell to return, and permit you to call setsid() |
253 | |
254 | Second fork - prevent you from accidentally reacquiring a controlling |
255 | terminal. |
256 | |
257 | That said, you don't always want this to be the behavior, so you are |
258 | free to specify otherwise using the C<%options>. |
259 | |
260 | =item Note about zombies |
261 | |
262 | Doing the double fork (see above) tends to get rid of your zombies since |
263 | by the time you have double forked your daemon process is then owned by |
264 | the init process. However, sometimes the double-fork is more than you |
265 | really need, and you want to keep your daemon processes a little closer |
266 | to you. In this case you have to watch out for zombies, you can avoid then |
267 | by just setting the C<ignore_zombies> option (see above). |
268 | |
269 | =back |
270 | |
271 | =head1 ENVIRONMENT VARIABLES |
272 | |
273 | These variables are best just used for debugging and/or testing, but |
274 | not used for actual logging. For that, you should reopen STDOUT/ERR on |
275 | your own. |
276 | |
277 | =over 4 |
278 | |
279 | =item B<MX_DAEMON_STDOUT> |
280 | |
281 | A filename to redirect the daemon STDOUT to. |
282 | |
283 | =item B<MX_DAEMON_STDERR> |
284 | |
285 | A filename to redirect the daemon STDERR to. |
286 | |
287 | =back |
288 | |
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289 | =head1 DEPENDENCIES |
290 | |
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291 | L<Moose::Role>, L<POSIX> |
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292 | |
293 | =head1 INCOMPATIBILITIES |
294 | |
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295 | None reported. |
296 | |
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297 | =head1 BUGS AND LIMITATIONS |
298 | |
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299 | No bugs have been reported. |
300 | |
301 | Please report any bugs or feature requests to |
302 | C<bug-acme-dahut-call@rt.cpan.org>, or through the web interface at |
303 | L<http://rt.cpan.org>. |
304 | |
305 | =head1 SEE ALSO |
306 | |
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307 | L<Proc::Daemon> |
308 | |
d8985b7d |
309 | This code is based B<HEAVILY> on L<Proc::Daemon>, we originally |
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310 | depended on it, but we needed some more flexibility, so instead |
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311 | we just stole the code. |
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312 | |
313 | =head1 AUTHOR |
314 | |
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315 | Stevan Little C<< <stevan.little@iinteractive.com> >> |
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316 | |
18cc5c89 |
317 | =head1 LICENCE AND COPYRIGHT |
318 | |
d8985b7d |
319 | Copyright (c) 2007, Chris Prather C<< <perigrin@cpan.org> >>. All rights |
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320 | reserved. |
321 | |
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322 | Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood. |
323 | |
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324 | This module is free software; you can redistribute it and/or |
325 | modify it under the same terms as Perl itself. See L<perlartistic>. |
326 | |
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327 | =head1 DISCLAIMER OF WARRANTY |
328 | |
329 | BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY |
330 | FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN |
331 | OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES |
332 | PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER |
333 | EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
334 | WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE |
335 | ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH |
336 | YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL |
337 | NECESSARY SERVICING, REPAIR, OR CORRECTION. |
338 | |
339 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING |
340 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR |
341 | REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE |
342 | LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, |
343 | OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE |
344 | THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING |
345 | RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A |
346 | FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF |
347 | SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF |
348 | SUCH DAMAGES. |
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349 | |
350 | =cut |