ANNOUNCE: new module: Daemon::Generic

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     Daemon::Generic - framework to provide start/stop/reload for a daemon

     use Daemon::Generic;

     sub gd_run { ... stuff }
     sub gd_preconfig { ... stuff }


    Daemon::Generic provides a framework for starting, stopping,
    reconfiguring daemon-like programs. The framework provides for standard
    commands that work for as init.d files and as apachectl-like commands.

    Programs that use Daemon::Generic subclass Daemon::Generic to override
    its behavior. Almost everything that Genric::Daemon does can be
    overridden as needed.

    Unless overriden, the usage output for your program will look something
    like this:

     Usage: $progname [ -c file ] [ -f ] { start | stop | reload | restart |
help | version | check }
      -c            Specify configuration file (defaults to $configfile)
      -f            Run in the foreground (don't detach)
      start         Starts a new $progname if there isn't one running already
      stop          Stops a running $progname
      reload        Causes a running $progname to reload it's config file.
                    a new one if none is running.
      restart       Stops a running $progname if one is running.  Starts a new
      check         Check the configuration file and report the daemon state
      help          Display this usage info
      version       Display the version of $progname

    To hand control over to "Daemon::Generic", call "newdaemon()". Control
    will be handed back through method calls to functions you define.

    Your @ISA will be modified to include "Daemon::Generic" if if it isn't
    already there.

    These are the arguments to "newdaemon()". Defaults are in (parenthesis).

    progname       ($0) The name of this program. This will be used for
                   logging and for naming the PID file.

    configfile     ("/etc/$progname.conf") The location of the configuration
                   file for this daemon.

    pidbase        (/var/run/$progname) We include the configuration file
                   name as part of the pid file in case there are multiple
                   instances of this deamon. The pidbase is is the part of
                   the PID file that does not include the configuration file

    pidfile        ("$pidbase.$") The location of the process
                   id file.

    foreground     (0) Do not detach/daemon and run in the foreground

    debug          (0) Turn on debugging.

    no_srand       (0) Normall srand() is called. If no_srand is set then
                   srand() won't be called.

    options        () Additional arguments for Getopt::Long::GetOptions
                   which is used to parse @ARGV. Alternatively: define

    minimum_args   (1) Minimum number of @ARGV arguments after flags have
                   been processed.

    maximum_args   (1) Maximum number of @ARGV arguments after flags have
                   been processed.

    version        ($pkg::VERSION) The version number of the daemon.

    The package that subclasses Daemon::Generic must provide the following
    callback methods.

    gd_preconfig() "gd_preconfig()" is called to parse the configuration
                   file ("$self->"). Preconfig is called on all
                   invocations of the daemon ("daemon reload", "daemon
                   check", "daemon stop", etc). It shouldn't start anything
                   but it can and should verify that the config file is

                   The return value should be a hash. With one exception,
                   the return value is only used by "gd_postconfig()". The
                   exception is that "gd_preconfig()" may return a revised
                   PID file location (key "pidfile").

    gd_run()       This is where you put your main program.

    The package that subclasses Daemon::Generic does not have to override
    these methods but it may want to.

                   Postconfig() is called only when the daeamon is actually
                   starting up. (Or on reconfigs). It is passed the return
                   value from "gd_preconfig".

                   Set things up so that SIGHUP calls gd_reconfig_event()
                   and SIGINT calls gd_quit_event(). It will call these at
                   any time so if you want to delay signal delivery or
                   something you should override this method.

    gd_getopt()    This is invoked to parse the command line. Useful things
                   to modify are:

                   $self-> The location of the configuration
                                       file to be parsed by

                   $self-> Run in the foreground (don't

                   $self->      Use it yourself.

                   The supplied "gd_getopt()" method uses Getopt::Long.

                   Parse any additional command line arguments beyond what
                   "gd_getopt()" handled.

                   $ARGV[0] needs to be left alone if it is one of the
                   following standard items:

                   start     Start up a new daemon.

                   stop      Stop the running daemon.

                   restart   Stop the running daemon, start a new one.

                   reload    Send a signal to the running daemon, asking it
                             to reconfigure itself.

                   check     Just check the configuration file.

                   help      Print the help screen (probably usage()).

                   version   Display the daemon's version.

                   There is no default "gd_parse_argv()".

    gd_check($pidfile, $pid)
                   Normal behavior: return. Define additional checks to run
                   when the "check" command is given. A $pid will only be
                   supplied if there is a daemon running.

    gd_version()   Normal behavior: display a version message and exit.

    gd_help()      Normal behavior: call "gd_usage()".

                   Used by "gd_usage()": provide information on additional
                   commands beyond "start", "stop", "reload", etc. Return is
                   an array of key value pairs.

                    sub gd_commands_more
                           return (
                                   savestate => 'Tell xyz server to save its
                                   reset     => 'Tell xyz servr to reset',

    gd_flags_more  Like "gd_commands_more()" but defines additional command
                   line flags. There should also be a "gd_more_opt()" or an
                   "options" argument to "new()".

                   Like "gd_commands_more()" but defines positional

    gd_usage()     Display a usage message. The return value from
                   "gd_usage()" is the exit code for the program.

    gd_more_opt()  () Additional arguments for Getopt::Long::GetOptions
                   which is used to parse @ARGV. Alternatively: pass
                   "options" to "new()".

    gd_pidfile()   Figure out the PID file should be.

    gd_error()     Print out an error (call die?)

    gd_other_cmd() Called $ARGV[0] isn't one of the commands that
                   Daemon::Generic knows by default. Default behavior: call
                   "gd_usage()" and exit(1).

    gd_daemonize() Normal behavior: "fork()", "fork()", detach from tty.

                   Normal behavior: redirect "STDOUT" and "STDERR" to
                   "logger -t $progname[$$]". Used by "gd_daemonize()".

    gd_logname()   Normal behavior: $progname[$$]. Used by

                   Normal behavior: call "gd_postconfig(gd_preconfig))".
                   Only referenced by "gd_setup_signals()".

                   Normal behavior: exit. Only referenced by

    gd_kill($pid)  Used by the "stop" and "restart" commands to get rid of
                   the old daemon. Normal behavior: send a SIGINT. Check to
                   see if process $pid has died. If it has not, keep
                   checking and if it's still alive. After
                   $Daemon::Generic::force_quit_delay seconds, send a
                   SIGTERM. Keep checking. After another
                   $Daemon::Generic::force_quit_delay seconds, send a
                   SIGKILL (-9). Keep checking. After
                   "$Daemon::Generic::force_quit_delay * 4" seconds or 60
                   seconds (whichever is smaller), give up and exit(1).

    gd_install     Installs the daemon so that it runs automatically at next
                   reboot. Currently done with a symlink to $0 and
                   "/usr/sbin/update-rc.d". Please send patches for other

    gd_can_install Returns a function to do an "gd_install" if installation
                   is possible. Returns 0 otherwise.

                   Normal behavior: return. Called just before doing an
                   installation. The method indicates the installation
                   method (currently always "update-rc.d".)

                   Normal behavior: return. Called just after doing an

    gd_uninstall   Will remove the daemon from the automatic startup regime.

                   Returns a function to do the work for "gd_uninstall" if
                   it's possible. 0 otherwise.

                   Normal behavior: return. Called just before doing an
                   un-installation. The method indicates the installation
                   method (currently always "update-rc.d".)

                   Normal behavior: return. Called just after doing an

    Since you need to subclass Daemon::Generic, you need to know what the
    internal data structures for Daemon::Generic are. With two exceptions,
    all of the member data items begin with the prefix "gd_".

    configfile     The location of the configuration file. (Not used by

    debug          Display debugging? (Not used by Daemon::Generic)

    gd_args        The original %args passed to "new".

    gd_progname    The process name. (defaults to $0)

    gd_pidfile     The location of the process ID file.

    gd_foreground  Are we running in the foreground?

     my $sleeptime = 1;

            progname        => 'ticktockd',
            pidfile         => '/var/run/',
            configfile      => '/etc/ticktockd.conf',

     sub gd_preconfig
            my ($self) = @_;
            open(CONFIG, "<$self->") or die;
            while(<CONFIG>) {
                    $sleeptime = $1 if /^sleeptime\s+(\d+)/;
            return ();

     sub gd_run
            while(1) {
                    print scalar(localtime(time))."\n";

    With a while(1) and delayed signal delivery: Daemon::Generic::While1.

    With Event: Daemon::Generic::Event.

    Other modules that do similar things: Net::Daemon, Net::Server,
    Net::Server::Daemonize, NetServer::Generic, Proc::Application::Daemon,
    Proc::Daemon, Proc::Forking.

    be used and distributed on the same terms as Perl itself.


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