[ANN] bj-0.0.3


A

ara.t.howard

NAME
bj

SYNOPSIS
bj (migration_code|generate_migration|migrate|setup|plugin|run|
submit|list|set|config|pid) [options]+

DESCRIPTION
________________________________
Overview
--------------------------------

Backgroundjob (Bj) is a simple to use background priority queue
for rails.
Although not yet tested on windows, the design of bj is such
that operation
should be possible on any operating system, including M$.

Jobs can be submitted to the queue directly using the api or
from the
commandline using the 'bj' script. For example

code:
Bj.submit 'cat /etc/password'

cli:
bj submit cat /etc/password

When used from inside a rails application bj arranges that
another process
will always be running in the background to process the jobs
that you submit.
By using a separate process to run jobs bj does not impact the
resource
utilization of your rails application at all and enables several
very cool
features:

1) Bj allows you to sumbit jobs to any of your configured
databases and,
in each case, spawns a separate background process to run jobs
from that
queue

Bj.in :production do
Bj.submit 'production_job.exe'
end

Bj.in :development do
Bj.submit 'development_job.exe'
end

2) Although bj ensures that a process is always running to
process
your jobs, you can start a proces manually. This means that
any machine
capable of seeing your RAILS_ROOT can run jobs for your
application, allowing
one to setup a cluster of machines doing the work of a single
front end rails
applicaiton.

________________________________
Install
--------------------------------

Bj can be installed two ways: as a gem or as a plugin.

gem:
1) $sudo gem install bj
2) add "require 'bj'" to config/environment.rb
3) bj setup

plugin:
1) ./script/plugin install http://
codeforpeople.rubyforge.org/svn/rails/plugins/bj
2) ./script/bj setup

________________________________
Api
--------------------------------

submit jobs for background processing. 'jobs' can be a string
or array of
strings. options are applied to each job in the 'jobs', and the
list of
submitted jobs is always returned. options (string or symbol)
can be

:rails_env => production|development|key_in_database_yml
when given this keyword causes bj to submit jobs
to the
specified database. default is RAILS_ENV.

:priority => any number, including negative ones. default is
zero.

:tag => a tag added to the job. simply makes searching easier.

:env => a hash specifying any additional environment vars the
background
process should have.

:stdin => any stdin the background process should have.

eg:

jobs = Bj.submit 'echo foobar', :tag => 'simple job'

jobs = Bj.submit '/bin/cat', :stdin => 'in the hat', :priority
=> 42

jobs = Bj.submit './script/runner ./scripts/a.rb', :rails_env
=> 'production'

jobs = Bj.submit './script/runner /dev/stdin',
:stdin => 'p RAILS_ENV',
:tag => 'dynamic ruby code'

jobs Bj.submit array_of_commands, :priority => 451

when jobs are run, they are run in RAILS_ROOT. various attributes
are
available *only* once the job has finished. you can check whether
or not a
job is finished by using the #finished method, which simple does a
reload and
checks to see if the exit_status is non-nil.

eg:

jobs = Bj.submit list_of_jobs, :tag => 'important'
...

jobs.each do |job|
if job.finished?
p job.exit_status
p job.stdout
p job.stderr
end
end

See lib/bj/api.rb for more details.

________________________________
Sponsors
--------------------------------
http://www.engineyard.com/
http://quintess.com/
http://eparklabs.com/

PARAMETERS
--rails_root=rails_root, -R (0 ~> rails_root=)
the rails_root will be guessed unless you set this
--rails_env=rails_env, -E (0 ~> rails_env=development)
set the rails_env
--log=log, -l (0 ~> log=STDERR)
set the logfile
--help, -h

AUTHOR
(e-mail address removed)

URIS
http://codeforpeople.com/lib/ruby/
http://rubyforge.org/projects/codeforpeople/
http://codeforpeople.rubyforge.org/svn/rails/plugins/

HISTORY
0.0.3:
- *many* small bug fixes
- plugin install should now pick up dependancies from plugin
dir, last
release had LOAD_PATH/gem issues and was picking up globally
installed
gems
- automatic management of the background processing can be
turned off if you
want to manage your own processes
- all jobs are automatically restartable unless submitted with
:restartable => false
this means that, should a runner ever die, upon restart any
jobs that were
mid-process will automatically be restarted
- signal based parent lifeline move out of thread and into even
loop
- :lock => true added to a few AR finds to support true write
serializable
transaction isolation when the db supports it
- all migrations now use :force => true and
- running 'bj setup' will always generate a new migration, even
if you've
already run it before. this allows easy version upgrades.
- a few command would blow up on windows because they weren't
prefixed with
'ruby'. gotta love the lack of #shebang line on windoze...
- ./script/bj is searched first before system path env var
- a default PATH is provided for whacky systems without one
- database.yml is filtered through ERB ala rails

FUTURE
- windows version around the corner
- time to live on running jobs

THANKS
- testing/feedback by steve steve midgley
- testing/feedback by andrew stewart
- testing/feedback by dave ringoen
- testing/feedback by ezra zygmuntowicz


enjoy bj.


a @ http://codeforpeople.com/
 
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