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
  17 # with Koha; if not, write to the Free Software Foundation, Inc.,
  18 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19
  20 use strict;
  21 #use warnings; FIXME - Bug 2505
  22
  23 use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
  24 use C4::Context;
  25 use Schedule::At;
  26
  27 BEGIN {
  28         # set the version for version checking
  29         $VERSION = 0.02;
  30         require Exporter;
  31         @ISA = qw(Exporter);
  32         @EXPORT =
  33                 qw(get_jobs get_at_jobs get_at_job add_at_job remove_at_job);
  34 }
  35
  36 =head1 NAME
  37
  38 C4::Scheduler - Module for running jobs with the unix at command
  39
  40 =head1 SYNOPSIS
  41
  42   use C4::Scheduler;
  43
  44 =head1 DESCRIPTION
  45
  46 =cut
  47
  48 =head1 METHODS
  49
  50 =head2 get_jobs();
  51
  52 This will return all scheduled jobs
  53
  54 =cut
  55
  56 sub get_jobs {
  57     my $jobs = get_at_jobs();
  58 # add call to get cron jobs here too
  59     return ($jobs);
  60 }
  61
  62 =head2 get_at_jobs();
  63
  64 This will return all At scheduled jobs
  65
  66 =cut
  67
  68 sub get_at_jobs {
  69         my %jobs = Schedule::At::getJobs();
  70         return (\%jobs);
  71 }
  72
  73 =head2 get_at_job($id)
  74
  75 This will return the At job with the given id
  76
  77 =cut
  78
  79 sub get_at_job {
  80         my ($id)=@_;
  81         my %jobs = Schedule::At::getJobs(JOBID => $id);
  82 }
  83
  84 =head2 add_at_job ($time,$command)
  85
  86 Given a timestamp and a command this will schedule the job to run at that time.
  87
  88 Returns true if the job is added to the queue and false otherwise.
  89
  90 =cut
  91
  92 sub add_at_job {
  93         my ($time,$command) = @_;
  94     # FIXME - a description of the task to be run
  95     # may be a better tag, since the tag is displayed
  96     # in the job list that the administrator sees - e.g.,
  97     # "run report foo, send to foo@bar.com"
  98         Schedule::At::add(TIME => $time, COMMAND => $command, TAG => $command);
  99
 100     # FIXME - this method of checking whether the job was added
 101     # to the queue is less than perfect:
 102     #
 103     # 1. Since the command is the tag, it is possible that there is
 104     #    already a job in the queue with the same tag.  However, since
 105     #    the tag is what displays in the job list, we can't just
 106     #    give it a unique ID.
 107     # 2. Schedule::At::add() is supposed to return a non-zero
 108     #    value if it fails to add a job - however, it does
 109     #    not check all error conditions - in particular, it does
 110     #    not check the return value of the "at" run; it basically
 111     #    complains only if it can't find at.
 112     # 3. Similary, Schedule::At::add() does not do something more useful,
 113     #    such as returning the job ID.  To be fair, it is possible
 114     #    that 'at' does not allow this in any portable way.
 115     # 4. Although unlikely, it is possible that a job could be added
 116     #    and completed instantly, thus dropping off the queue.
 117     my $job_found = 0;
 118     eval {
 119             my %jobs = Schedule::At::getJobs(TAG => $command);
 120         $job_found = scalar(keys %jobs) > 0;
 121     };
 122     if ($@) {
 123         return 0;
 124     } else {
 125         return $job_found;
 126     }
 127 }
 128
 129 sub remove_at_job {
 130         my ($jobid)=@_;
 131         Schedule::At::remove(JOBID => $jobid);
 132 }
 133
 134 1;
 135 __END__
 136
 137 =head1 BUGS
 138
 139 At some point C<C4::Scheduler> should be refactored:
 140
 141 =over
 142
 143 =item At and C<Schedule::At> does not work on Win32.
 144
 145 =item At is not installed by default on all platforms.
 146
 147 =item The At queue used by Koha is owned by the httpd user.  If multiple
 148 Koha databases share an Apache instance on a server, everybody can
 149 see everybody's jobs.
 150
 151 =item There is no support for scheduling a job to run more than once.
 152
 153 =back
 154
 155 =head1 AUTHOR
 156
 157 Chris Cormack <crc@liblime.com>
 158
 159 =cut