NAME
    TaskForest - Simple, powerful task scheduler

SYNOPSIS
      # Run the main program, checking for jobs to run.
      # By default, this will run until 23:55
      #
      use TaskForest;
      my $task_forest = TaskForest->new();
      $task_forest->runMainLoop();

      OR

      # Display the current status of all jobs scheduled to run today
      #
      use TaskForest;
      my $task_forest = TaskForest->new();
      $task_forest->status();
  
DESCRIPTION
    The TaskForest Job Scheduler (TF) is a simple but expressive job
    scheduling system. A job is defined as any executable program that
    resides on the file system. Jobs can depend on each other. Jobs can also
    have start times before which a job may not by run. Jobs can be grouped
    together into "Families." A family has a start time associated with it
    before which none of its jobs may run. A family also has a list of
    days-of-the-week associated with it. Jobs within a family may only run
    on these days of the week.

    Jobs and families are given simple names. A family is described in a
    family file whose name is the family name. Each family file is a text
    file that contains 1 or more job names. The layout of the job names
    within a family file determine the dependencies between the jobs (if
    any).

    Family names and job names should contain only the characters shown
    below: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_

    Let's see a few examples. In these examples the dashes (-), pipes (|)
    and line numbers are not parts of the files. They're only there for
    illustration purposes. The main script expects environment variables or
    command line options that specify the locations of the directory that
    contain family files, the directory that contains job files, and the
    directory where the logs will be written. The directory that contains
    family files should contain only family files.

    EXAMPLE 1 - Family file named F_ADMIN

        +---------------------------------------------------------------------
     01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
     02 |
     03 | J_ROTATE_LOGS()
     04 |
        +---------------------------------------------------------------------

    The first line in any family file always contains 3 bits of information
    about the family: the start time, the time zone, and the days on which
    this jobs in this family are run.

    In this case, this family starts at 2:00 a.m. Chicago time. The time is
    adjusted for daylight savings time. This family 'runs' on Monday,
    Wednesday and Friday only. Pay attention to the format: it's important.

    Valid days are 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun'. Days
    must be separated by commas.

    All start times (for families and jobs) are in 24-hour format. '00:00'
    is midnight, '12:00' is noon, '13:00' is 1:00 p.m. and '23:59' is one
    minute before midnight.

    There is only one job in this family - J_ROTATE_LOGS. This family will
    start at 2:00 a.m., at which time J_ROTATE_LOGS will immediately be run.
    Note the empty parentheses [()]. These are required.

    What does it mean to say that J_ROTATE_LOGS will be run? It means that
    the system will look for a file called J_ROTATE_LOGS in the directory
    that contains job files. That file should be executable. The system will
    execute that file (run that job) and keep track of whether it succeeded
    or failed. The J_ROTATE_LOGS script can be any executable file: a shell
    script, a perl script, a C program etc.

    To run the program, the system actually runs a wrapper script that
    invokes the job script. The location of the wrapper script is specified
    on the command line or in an environment variable.

    Now, let's look at a slightly more complicated example:


    EXAMPLE 2 - Job Dependencies

    This family file is named WEB_ADMIN

        +---------------------------------------------------------------------
     01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
     02 |
     03 |               J_ROTATE_LOGS()
     04 |
     05 | J_RESOLVE_DNS()               Delete_Logs_Older_Than_A_Year()
     06 |
     07 |               J_WEB_REPORTS()      
     08 |
     09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
     10 |
        +---------------------------------------------------------------------

    A few things to point out here: - Blank lines are ignored. - A hash (#)
    and anything after it, until the end of the line is treated as a comment
    and ignored - Job and family names do not have to start with J_ or be in
    upper case.

    Now then, all jobs on a single line are started AT THE SAME TIME. All
    jobs on a line are started only when all jobs on the previous line are
    executed successfully. If there are no jobs on a previous line (as in
    the case of line 3 above), all jobs on that line are started when the
    family starts (2:00 a.m. above). There is an exception to this rule that
    we'll see in the next example.

    So the above family can be interpreted in English as follows: "All
    WEB_ADMIN jobs are eligible to run after 2:00 a.m Chicago time on
    Mondays, Wedesdays and Fridays. The first job to be run is
    J_ROTATE_LOGS. If that succeeds, then J_RESOLVE_DNS and
    Delete_Logs_Older_Than_A_Year are started at the same time. If both
    these jobs succeed, then J_WEB_REPORTS is run. If that job succeeds, the
    J_EMAIL_WEB_RPT_done is run."


    EXAMPLE 3 - TIME DEPENDENCIES

    Let's say tha twe don't want J_RESOLVE_DNS to start before 9:00 a.m.
    because it's very IO-intensive and we want to wait until the relatively
    quiet time of 9:00 a.m. In that case, we can put a time dependency of
    the job. This adds a restriction to the job, saying that it may not run
    before the time specified. We would do this as follows:

        +---------------------------------------------------------------------
     01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
     02 |
     03 |               J_ROTATE_LOGS()
     04 |
     05 | J_RESOLVE_DNS(start => '09:00')    Delete_Logs_Older_Than_A_Year()
     06 |
     07 |               J_WEB_REPORTS()      
     08 |
     09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
     10 |
        +---------------------------------------------------------------------

    J_ROTATE_LOGS will still start at 2:00, as always. As soon as it
    succeeds, Delete_Logs_Older_Than_A_Year is started. If J_ROTATE_LOGS
    succeeds before 09:00, the system will wait until 09:00 before starting
    J_RESOLVE_DNS. It is possible that Delete_Logs_Older_Than_A_Year would
    have started and complete by then. J_WEB_REPORTS would not have started
    in that case, because it is dependent on two jobs, and both of them have
    to run successfully before it can run.

    For completeness, you may also specify a timezone for a job's time
    dependency as follows:

     05 | J_RESOLVE_DNS(start=>'10:00', tz=>'America/New_York')  Delete_Logs_Older_Than_A_Year()


     EXAMPLE 4 - JOB FORESTS

     You can see in the example above that line 03 is the start of a group of
     dependent job.  No job on any other line can start unless the job on line
     03 succeeds.  What if you wanted two or more groups of jobs in the same
     family that start at the same time (barring any time dependencies) and
     proceed independently of each other?

     To do this you would separate the groups with a line containing one or
     more dashes (only).  Consider the following family:
 
        +---------------------------------------------------------------------
     01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
     02 |
     03 |               J_ROTATE_LOGS()
     04 |
     05 | J_RESOLVE_DNS(start => '09:00')    Delete_Logs_Older_Than_A_Year()
     06 |
     07 |               J_WEB_REPORTS()      
     08 |
     09 |            J_EMAIL_WEB_RPT_DONE()  # send me a notification
     10 |
     11 |----------------------------------------------------------------------
     12 |
     13 | J_UPDATE_ACCOUNTS_RECEIVABLE()
     14 |
     15 | J_ATTEMPT_CREDIT_CARD_PAYMENTS()
     16 |
     17 |----------------------------------------------------------------------
     18 |
     19 | J_SEND_EXPIRING_CARDS_EMAIL()
     20 |
        +---------------------------------------------------------------------

     Because of the lines of dashes on lines 11 and 17, the jobs on lines 03,
     13 and 19 will all start at 02:00.  These jobs are independent of each
     other.  J_ATTEMPT_CREDIT_CARD_PAYMENT will not run if
     J_UPDATE_ACCOUNTS_RECEIVABLE fails.  That failure, however will not
     prevent J_SEND_EXPIRING_CARDS_EMAIL from running.

     Finally, you can specify a job to run repeatedly every 'n' minutes,
     as follows:

        +---------------------------------------------------------------------
     01 |start => '02:00', tz => 'America/Chicago', days => 'Mon,Wed,Fri'
     02 |
     03 | J_CHECK_DISK_USAGE(every=>'30', until=>'23:00')
     04 |
        +---------------------------------------------------------------------

     This means that J_CHECK_DISK_USAGE will be called every 30 minutes
     and will not run on or after 23:00.  By default, the 'until' time is
     23:59.  If the job starts at 02:00 and takes 25 minutes to run to
     completion, the next occurance will still start at 02:30, and not at
     02:55.  It is important to note that every repeat occurrance will
     only have one dependency - the time - and will not depend on earlier
     occurrances running successfully or even running at all.  If you want
     the job to run for the last time at 23:00, set the until time to
     23:01.

USAGE
      There are a few simple scripts in the bin directory that simplify
      usage.  To run the program you must let it know where it can find
      the necessary files and directories. This can be done by environment
      variables, or via the command line:

      export TF_JOB_DIR=/foo/jobs
      export TF_LOG_DIR=/foo/logs
      export TF_FAMILY_DIR=/foo/families
      export TF_RUN_WRAPPER=/foo/bin/run
      taskforest

      OR

      taskforest -run_wrapper=/foo/bin/run \
        --log_dir=/foo/logs \
        --job_dir=/foo/jobs \
        --family_dir=/foo/families

      All jobs will run as the user who invoked taskforest.

      To get the status of all currently running and recently run jobs,
      enter the following command:

      status

OPTIONS
     The following command line options are required.  If they are not
     specified on the command line, the environment will be searched for
     corresponding environment variables.

     --run_wrapper=/a/b/r  [or environment variable TF_RUN_WRAPPER]
    
       This is the location of the run wrapper that is used to execute the
       job files.  The run wrapper is also responsible for creating the
       semaphore files that denote whether a job ran successfully or not.
       You can use the provided run wrapper (bin/run).  If you need more
       functionality, like logging status to a database, you can create
       your own run wrapper, as long as it preserves the functionality of
       the default run_wrapper.   
    
     --log_dir=/a/b/l  [or environment variable TF_LOG_DIR]
    
       This is called the root log directory.  Every day a dated directory
       named in the form YYYYMMDD will be created and the semaphore files
       will be created in that directory.

     --job_dir=/a/b/j  [or environment variable TF_JOB_DIR]
    
       This is the location of all the job files.  Each job file should be
       an executable file (e.g.: a binary file, a shell script, a perl or
       python script).  The file names are used as job names in the family
       configuration files.  Job names may only contain the characters
       a-z, A-Z, 0-9 and _.  You may create aliases to jobs within this
       directory.

       If a job J1 is present in a family config file, any other
       occurrance of J1 in that family refers TO THAT SAME JOB INSTANCE.
       It does not mean that the job will be run twice.
   
       If you want the same job running twice, you will have to put it in
       different families, or make soft links to it and have the soft
       link(s) in the family file along with the actual file name.

       If a job is to run repeatedly every x minutes, you could specify
       that using the 'repeat/every' syntax shown above.

     --family_dir=/a/b/f  [or environment variable TF_FAMILY_DIR]

       This is the location of all the family files.  As is the case with
       jobs, family names are the file names.  Family names may only
       contain the characters a-z, A-Z, 0-9 and _.
   
     The following command line options are optional
    
     --once_only

       If this option is set, the system will check each family once, run
       any jobs in the Ready state and then exit.  This is useful for
       testing, or if you want to invoke the program via cron or some
       similar system, or if you just want the program to run on demand,
       and not run and sleep all day.

     --end_time=HH:MM
   
       If once_only is not set, this option determines when the main
       program loop should end.  This refers to the local time in 24-hour
       format.  By default it is set to 23:55.  This is the recommended
       maximum.

     --wait_time

       This is the amount of seconds to sleep at the end of every loop.

     --verbose

       Print a lot of debugging information

     --help

       Display help text
 
BUGS
     For an up-to-date bug listing and to submit a bug report, please
     visit our website at http://sourceforge.net/projects/taskforest/

SUPPORT
     For support, please visit our website at
     http://sourceforge.net/projects/taskforest/

AUTHOR
     Aijaz A. Ansari
     http://sourceforge.net/projects/taskforest/

     If you're using this program, I would love to hear from you.  Please
     visit our project website and let me know what you think of it.

COPYRIGHT
    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself - specifically, the Artistic
    License.

    The full text of the license can be found in the LICENSE file included
    with this module.

SEE ALSO
    perl(1).

