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