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
   8 # under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 3 of the License, or
  10 # (at your option) any later version.
  11 #
  12 # Koha is distributed in the hope that it will be useful, but
  13 # WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with Koha; if not, see <http://www.gnu.org/licenses>.
  19
  20 use Modern::Perl;
  21
  22 use vars qw(@ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
  23 use C4::Context;
  24 use Schedule::At;
  25
  26 BEGIN {
  27         require Exporter;
  28         @ISA = qw(Exporter);
  29         @EXPORT =
  30                 qw(get_jobs get_at_jobs get_at_job add_at_job remove_at_job);
  31 }
  32
  33 =head1 NAME
  34
  35 C4::Scheduler - Module for running jobs with the unix at command
  36
  37 =head1 SYNOPSIS
  38
  39   use C4::Scheduler;
  40
  41 =head1 DESCRIPTION
  42
  43 =cut
  44
  45 =head1 METHODS
  46
  47 =head2 get_jobs();
  48
  49 This will return all scheduled jobs
  50
  51 =cut
  52
  53 sub get_jobs {
  54     my $jobs = get_at_jobs();
  55 # add call to get cron jobs here too
  56     return ($jobs);
  57 }
  58
  59 =head2 get_at_jobs();
  60
  61 This will return all At scheduled jobs
  62
  63 =cut
  64
  65 sub get_at_jobs {
  66         my %jobs = Schedule::At::getJobs();
  67         return (\%jobs);
  68 }
  69
  70 =head2 get_at_job($id)
  71
  72 This will return the At job with the given id
  73
  74 =cut
  75
  76 sub get_at_job {
  77         my ($id)=@_;
  78         my %jobs = Schedule::At::getJobs(JOBID => $id);
  79 }
  80
  81 =head2 add_at_job ($time,$command)
  82
  83 Given a timestamp and a command this will schedule the job to run at that time.
  84
  85 Returns true if the job is added to the queue and false otherwise.
  86
  87 =cut
  88
  89 sub add_at_job {
  90         my ($time,$command) = @_;
  91     # FIXME - a description of the task to be run
  92     # may be a better tag, since the tag is displayed
  93     # in the job list that the administrator sees - e.g.,
  94     # "run report foo, send to foo@bar.com"
  95         Schedule::At::add(TIME => $time, COMMAND => $command, TAG => $command);
  96
  97     # FIXME - this method of checking whether the job was added
  98     # to the queue is less than perfect:
  99     #
 100     # 1. Since the command is the tag, it is possible that there is
 101     #    already a job in the queue with the same tag.  However, since
 102     #    the tag is what displays in the job list, we can't just
 103     #    give it a unique ID.
 104     # 2. Schedule::At::add() is supposed to return a non-zero
 105     #    value if it fails to add a job - however, it does
 106     #    not check all error conditions - in particular, it does
 107     #    not check the return value of the "at" run; it basically
 108     #    complains only if it can't find at.
 109     # 3. Similary, Schedule::At::add() does not do something more useful,
 110     #    such as returning the job ID.  To be fair, it is possible
 111     #    that 'at' does not allow this in any portable way.
 112     # 4. Although unlikely, it is possible that a job could be added
 113     #    and completed instantly, thus dropping off the queue.
 114     my $job_found = 0;
 115     eval {
 116             my %jobs = Schedule::At::getJobs(TAG => $command);
 117         $job_found = scalar(keys %jobs) > 0;
 118     };
 119     if ($@) {
 120         return 0;
 121     } else {
 122         return $job_found;
 123     }
 124 }
 125
 126 sub remove_at_job {
 127         my ($jobid)=@_;
 128         Schedule::At::remove(JOBID => $jobid);
 129 }
 130
 131 1;
 132 __END__
 133
 134 =head1 BUGS
 135
 136 At some point C<C4::Scheduler> should be refactored:
 137
 138 =over
 139
 140 =item At and C<Schedule::At> does not work on Win32.
 141
 142 =item At is not installed by default on all platforms.
 143
 144 =item The At queue used by Koha is owned by the httpd user.  If multiple
 145 Koha databases share an Apache instance on a server, everybody can
 146 see everybody's jobs.
 147
 148 =item There is no support for scheduling a job to run more than once.
 149
 150 =back
 151
 152 =head1 AUTHOR
 153
 154 Chris Cormack <crc@liblime.com>
 155
 156 =cut