C4/Scheduler.pm

   1 package C4::Scheduler;
   2
   3 # Copyright 2007 Liblime Ltd
   4 #
   5 # This file is part of Koha.
   6 #
   7 # Koha is free software; you can redistribute it and/or modify it under the
   8 # terms of the GNU General Public License as published by the Free Software
   9 # Foundation; either version 2 of the License, or (at your option) any later
  10 # version.
  11 #
  12 # Koha is distributed in the hope that it will be useful, but WITHOUT ANY
  13 # WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  14 # A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  15 #
  16 # You should have received a copy of the GNU General Public License along with
  17 # Koha; if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  18 # Suite 330, Boston, MA  02111-1307 USA
  19
  20 use strict;
  21
  22 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
  23 use C4::Context;
  24 use Schedule::At;
  25
  26 BEGIN {
  27         # set the version for version checking
  28         $VERSION = 0.02;
  29         require Exporter;
  30         @ISA = qw(Exporter);
  31         @EXPORT =
  32                 qw(get_jobs get_at_jobs get_at_job add_at_job remove_at_job);
  33 }
  34
  35 =head1 NAME
  36
  37 C4::Scheduler - Module for running jobs with the unix at command
  38
  39 =head1 SYNOPSIS
  40
  41   use C4::Scheduler;
  42
  43 =head1 DESCRIPTION
  44
  45
  46 =head1 METHODS
  47
  48 =over 2
  49
  50 =cut
  51
  52 =item get_jobs();
  53
  54 This will return all scheduled jobs
  55
  56 =cut
  57
  58 sub get_jobs {
  59     my $jobs = get_at_jobs();
  60 # add call to get cron jobs here too
  61     return ($jobs);
  62 }
  63
  64 =item get_at_jobs();
  65
  66 This will return all At scheduled jobs
  67
  68 =cut
  69
  70 sub get_at_jobs {
  71         my %jobs = Schedule::At::getJobs();
  72         return (\%jobs);
  73 }
  74
  75 =item get_at_job($id)
  76
  77 This will return the At job with the given id
  78
  79 =cut
  80
  81 sub get_at_job {
  82         my ($id)=@_;
  83         my %jobs = Schedule::At::getJobs(JOBID => $id);
  84 }
  85
  86 =item add_at_job ($time,$command)
  87
  88 Given a timestamp and a command this will schedule the job to run at that time.
  89
  90 Returns true if the job is added to the queue and false otherwise.
  91
  92 =cut
  93
  94 sub add_at_job {
  95         my ($time,$command) = @_;
  96     # FIXME - a description of the task to be run
  97     # may be a better tag, since the tag is displayed
  98     # in the job list that the administrator sees - e.g.,
  99     # "run report foo, send to foo@bar.com"
 100         Schedule::At::add(TIME => $time, COMMAND => $command, TAG => $command);
 101
 102     # FIXME - this method of checking whether the job was added
 103     # to the queue is less than perfect:
 104     #
 105     # 1. Since the command is the tag, it is possible that there is
 106     #    already a job in the queue with the same tag.  However, since
 107     #    the tag is what displays in the job list, we can't just
 108     #    give it a unique ID.
 109     # 2. Schedule::At::add() is supposed to return a non-zero
 110     #    value if it fails to add a job - however, it does
 111     #    not check all error conditions - in particular, it does
 112     #    not check the return value of the "at" run; it basically
 113     #    complains only if it can't find at.
 114     # 3. Similary, Schedule::At::add() does not do something more useful,
 115     #    such as returning the job ID.  To be fair, it is possible
 116     #    that 'at' does not allow this in any portable way.
 117     # 4. Although unlikely, it is possible that a job could be added
 118     #    and completed instantly, thus dropping off the queue.
 119     my $job_found = 0;
 120     eval {
 121             my %jobs = Schedule::At::getJobs(TAG => $command);
 122         $job_found = scalar(keys %jobs) > 0;
 123     };
 124     if ($@) {
 125         return 0;
 126     } else {
 127         return $job_found;
 128     }
 129 }
 130
 131 sub remove_at_job {
 132         my ($jobid)=@_;
 133         Schedule::At::remove(JOBID => $jobid);
 134 }
 135
 136 1;
 137 __END__
 138
 139 =back
 140
 141 =head1 BUGS
 142
 143 At some point C<C4::Scheduler> should be refactored:
 144
 145 =over 4
 146
 147 =item At and C<Schedule::At> does not work on Win32.
 148
 149 =item At is not installed by default on all platforms.
 150
 151 =item The At queue used by Koha is owned by the httpd user.  If multiple
 152 Koha databases share an Apache instance on a server, everybody can
 153 see everybody's jobs.
 154
 155 =item There is no support for scheduling a job to run more than once.
 156
 157 =back
 158
 159 =head1 AUTHOR
 160
 161 Chris Cormack <crc@liblime.com>
 162
 163 =cut