package MooseX::Daemonize::Core;
-use strict; # because Kwalitee is pedantic
+use strict; # cause Perl::Critic errors are annoying
+use MooseX::Getopt; # to load the NoGetopt metaclass
use Moose::Role;
our $VERSION = 0.01;
use POSIX ();
has is_daemon => (
- isa => 'Bool',
- is => 'rw',
- default => sub { 0 },
+ # NOTE:
+ # this should never be accessible
+ # from the command line
+ # - SL
+ metaclass => 'NoGetopt',
+ isa => 'Bool',
+ is => 'rw',
+ default => sub { 0 },
);
-sub daemon_fork { fork }
-sub daemon_detach {
- # ignore these signals
- for (qw(TSTP TTIN TTOU PIPE POLL STOP CONT CHLD)) {
- $SIG{$_} = 'IGNORE' if (exists $SIG{$_});
+sub daemon_fork {
+ my ($self, %options) = @_;
+
+ $SIG{CHLD} = 'IGNORE'
+ if $options{ignore_zombies};
+
+ if (my $pid = fork) {
+ return $pid;
+ }
+ else {
+ $self->is_daemon(1);
+ return;
+ }
+}
+
+sub daemon_detach {
+ my ($self, %options) = @_;
+
+ return unless $self->is_daemon; # return if parent ...
+
+ # now we are in the daemon ...
+
+ (POSIX::setsid) # set session id
+ || confess "Cannot detach from controlling process";
+
+ unless ($options{no_double_fork}) {
+ $SIG{'HUP'} = 'IGNORE';
+ fork && exit;
}
-
- POSIX::setsid; # set session id
+
chdir '/'; # change to root directory
- umask 0; # clear the file creation mask
-
+ umask 0; # clear the file creation mask
+
# get the max numnber of possible file descriptors
my $openmax = POSIX::sysconf( &POSIX::_SC_OPEN_MAX );
$openmax = 64 if !defined($openmax) || $openmax < 0;
-
- # close them all
+
+ # close them all
POSIX::close($_) foreach (0 .. $openmax);
- open(STDIN, "+>/dev/null");
- open(STDOUT, "+>&STDIN");
- open(STDERR, "+>&STDIN");
+ # fixup STDIN ...
+
+ open(STDIN, "+>/dev/null")
+ or confess "Could not redirect STDOUT to /dev/null";
+
+ # fixup STDOUT ...
+
+ if (my $stdout_file = $ENV{MX_DAEMON_STDOUT}) {
+ open STDOUT, ">", $stdout_file
+ or confess "Could not redirect STDOUT to $stdout_file : $!";
+ }
+ else {
+ open(STDOUT, "+>&STDIN")
+ or confess "Could not redirect STDOUT to /dev/null";
+ }
+
+ # fixup STDERR ...
+
+ if (my $stderr_file = $ENV{MX_DAEMON_STDERR}) {
+ open STDERR, ">", "ERR.txt"
+ or confess "Could not redirect STDERR to $stderr_file : $!";
+ }
+ else {
+ open(STDERR, "+>&STDIN")
+ or confess "Could not redirect STDERR to /dev/null"; ;
+ }
+
+ # do a little house cleaning ...
+
+ # Avoid 'stdin reopened for output'
+ # warning with newer perls
+ open( NULL, '/dev/null' );
+ <NULL> if (0);
+
+ # return success
+ return 1;
}
sub daemonize {
- my ($self) = @_;
- return if $self->daemon_fork;
- $self->daemon_detach;
- $self->is_daemon(1);
+ my ($self, %options) = @_;
+ $self->daemon_fork(%options);
+ $self->daemon_detach(%options);
}
1;
+
__END__
-=head1 NAME
+=pod
-MooseX::Daemonize::Core - provides a Role the core daemonization features
+=head1 NAME
-=head1 VERSION
+MooseX::Daemonize::Core - A Role with the core daemonization features
=head1 SYNOPSIS
-
+
+ package My::Daemon;
+ use Moose;
+
+ with 'MooseX::Daemonize::Core';
+
+ sub start {
+ my $self = shift;
+ # daemonize me ...
+ $self->daemonize;
+ # return from the parent,...
+ return unless $self->is_daemon;
+ # but continue on in the child (daemon)
+ }
+
=head1 DESCRIPTION
+This is the basic daemonization Role, it provides a few methods (see
+below) and the minimum features needed to properly daemonize your code.
+
+=head2 Important Notes
+
+None of the methods in this role will exit the parent process for you,
+it only forks and detaches your child (daemon) process. It is your
+responsibility to exit the parent process in some way.
+
+There is no PID or PID file management in this role, that is your
+responsibility (see some of the other roles in this distro for that).
+
=head1 ATTRIBUTES
=over
-=item is_daemon Bool
+=item I<is_daemon (is => rw, isa => Bool)>
-If true, the process is the backgrounded process. This is useful for example
-in an after 'start' => sub { } block
+This attribute is used to signal if we are within the
+daemon process or not.
=back
-=head1 METHODS
+=head1 METHODS
=over
-=item daemon_fork()
+=item B<daemon_fork (%options)>
+
+This forks off the child process to be daemonized. Just as with
+the built in fork, it returns the child pid to the parent process,
+0 to the child process. It will also set the is_daemon flag
+appropriately.
+
+The C<%options> available for this function are:
+
+=over 4
+
+=item I<ignore_zombies>
+
+Setting this key to a true value will result in setting the C<$SIG{CHLD}>
+handler to C<IGNORE>. This tells perl to clean up zombie processes. By
+default, and for the most part you don't I<need> it, only when you turn off
+the double fork behavior (with the I<no_double_fork> option) in C<daemon_detach>
+do you sometimes want this behavior.
+
+=back
+
+=item B<daemon_detach (%options)>
+
+This detaches the new child process from the terminal by doing
+the following things.
+
+=over 4
+
+=item Becomes a session leader
-=item daemon_detach()
+This detaches the program from the controlling terminal, it is
+accomplished by calling POSIX::setsid.
-=item daemonize()
+=item Performing the double-fork
-Calls C<Proc::Daemon::Init> to daemonize this process.
+See below for information on how to change this part of the process.
-=item setup_signals()
+=item Changes the current working directory to "/"
-Setup the signal handlers, by default it only sets up handlers for SIGINT and SIGHUP
+This is standard daemon behavior, if you want a different working
+directory then simply change it later in your daemons code.
-=item handle_sigint()
+=item Clears the file creation mask.
-Handle a INT signal, by default calls C<$self->stop()>
+=item Closes all open file descriptors.
-=item handle_sighup()
+=item Reopen STDERR, STDOUT & STDIN to /dev/null
-Handle a HUP signal. By default calls C<$self->restart()>
+This behavior can be controlled slightly though the MX_DAEMON_STDERR
+and MX_DAEMON_STDOUT environment variables. It will look for a filename
+in either of these variables and redirect STDOUT and/or STDERR to those
+files. This is useful for debugging and/or testing purposes.
+
+=back
+
+The C<%options> available for this function are:
+
+=over 4
+
+=item I<no_double_fork>
+
+Setting this option to true will cause this method to not perform the
+typical double-fork, which is extra added protection from your process
+accidentally aquiring a controlling terminal. More information can be
+found above, and by Googling "double fork daemonize".
+
+If you the double-fork behavior off, you might want to enable the
+I<ignore_zombies> behavior in the C<daemon_fork> method.
+
+=back
+
+B<NOTE>
+
+If called from within the parent process (the is_daemon flag is set to
+false), this method will simply return and do nothing.
+
+=item B<daemonize (%options)>
+
+This will simply call C<daemon_fork> followed by C<daemon_detach>, it will
+pass any C<%options> onto both methods.
=item meta()
=back
-=head1 DEPENDENCIES
+=head1 STUFF YOU SHOULD READ
-=for author to fill in:
- A list of all the other modules that this module relies upon,
- including any restrictions on versions, and an indication whether
- the module is part of the standard Perl distribution, part of the
- module's distribution, or must be installed separately. ]
+=over 4
-Obviously L<Moose>, and L<Proc::Daemon>
+=item Note about double fork
-=head1 INCOMPATIBILITIES
+Taken from L<http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66012>
+in a comment entitled I<The second fork _is_ necessary by Jonathan Bartlett>,
+it is not the definitive statement on the issue, but it's clear and well
+written enough so I decided to reproduce it here.
-=for author to fill in:
- A list of any modules that this module cannot be used in conjunction
- with. This may be due to name conflicts in the interface, or
- competition for system or program resources, or due to internal
- limitations of Perl (for example, many modules that use source code
- filters are mutually incompatible).
+ The first fork accomplishes two things - allow the shell to return,
+ and allow you to do a setsid().
-None reported.
+ The setsid() removes yourself from your controlling terminal. You
+ see, before, you were still listed as a job of your previous process,
+ and therefore the user might accidentally send you a signal. setsid()
+ gives you a new session, and removes the existing controlling terminal.
+ The problem is, you are now a session leader. As a session leader, if
+ you open a file descriptor that is a terminal, it will become your
+ controlling terminal (oops!). Therefore, the second fork makes you NOT
+ be a session leader. Only session leaders can acquire a controlling
+ terminal, so you can open up any file you wish without worrying that
+ it will make you a controlling terminal.
-=head1 BUGS AND LIMITATIONS
+ So - first fork - allow shell to return, and permit you to call setsid()
+
+ Second fork - prevent you from accidentally reacquiring a controlling
+ terminal.
+
+That said, you don't always want this to be the behavior, so you are
+free to specify otherwise using the C<%options>.
+
+=item Note about zombies
+
+Doing the double fork (see above) tends to get rid of your zombies since
+by the time you have double forked your daemon process is then owned by
+the init process. However, sometimes the double-fork is more than you
+really need, and you want to keep your daemon processes a little closer
+to you. In this case you have to watch out for zombies, you can avoid then
+by just setting the C<ignore_zombies> option (see above).
+
+=back
+
+=head1 ENVIRONMENT VARIABLES
-=for author to fill in:
- A list of known problems with the module, together with some
- indication Whether they are likely to be fixed in an upcoming
- release. Also a list of restrictions on the features the module
- does provide: data types that cannot be handled, performance issues
- and the circumstances in which they may arise, practical
- limitations on the size of data sets, special cases that are not
- (yet) handled, etc.
+These variables are best just used for debugging and/or testing, but
+not used for actual logging. For that, you should reopen STDOUT/ERR on
+your own.
+
+=over 4
+
+=item B<MX_DAEMON_STDOUT>
+
+A filename to redirect the daemon STDOUT to.
+
+=item B<MX_DAEMON_STDERR>
+
+A filename to redirect the daemon STDERR to.
+
+=back
+
+=head1 DEPENDENCIES
+
+L<Moose::Role>, L<POSIX>
+
+=head1 INCOMPATIBILITIES
+
+None reported.
+
+=head1 BUGS AND LIMITATIONS
No bugs have been reported.
=head1 SEE ALSO
-L<Proc::Daemon>, L<Daemon::Generic>, L<MooseX::Getopt>
-
-=head1 AUTHOR
+L<Proc::Daemon>
-Chris Prather C<< <perigrin@cpan.org> >>
+This code is based B<HEAVILY> on L<Proc::Daemon>, we originally
+depended on it, but we needed some more flexibility, so instead
+we just stole the code.
-=head1 THANKS
-
-Mike Boyko, Matt S. Trout, Stevan Little, Brandon Black, Ash Berlin and the
-#moose denzians
+=head1 AUTHOR
-Some bug fixes sponsored by Takkle Inc.
+Stevan Little C<< <stevan.little@iinteractive.com> >>
=head1 LICENCE AND COPYRIGHT
-Copyright (c) 2007, Chris Prather C<< <perigrin@cpan.org> >>. All rights
+Copyright (c) 2007, Chris Prather C<< <perigrin@cpan.org> >>. All rights
reserved.
+Portions heavily borrowed from L<Proc::Daemon> which is copyright Earl Hood.
+
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself. See L<perlartistic>.
-
=head1 DISCLAIMER OF WARRANTY
BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
SUCH DAMAGES.
+
+=cut
projects / gitmo/MooseX-Daemonize.git / blobdiff