Keep your batch jobs under control.
Say you have a thousand images to process. You write a script, fire it and go to bed, only to realize the morning after that an exception was raised and the script was aborted. Well, no more frustration: now you can use Batch to make sure your script continues working despite those exceptions, and you can now get a nice report to read while you drink your morning coffee.
require "batch"
Batch.each(Model.all) do |model|
# do something with model
# and see the overall progress
end
Given that Model.all responds to each and size, you'll get a nice
progress report:
0% ...........................................................................
25% ...........................................................................
50% ...........................................................................
75% ...........................................................................
100%
If errors occur, they are handled so that your long-running scripts don't get interrupted right after you go to bed:
0% .......E...................................................................
25% ..........................................E................................
50% ....................E......................................................
75% ...........................................................................
100%
Some errors occured:
# ... detailed exceptions here
You can determine the line width by setting the environment variable
BATCH_WIDTH, which defaults to 75.
On some environments, like a non-interactive shell, you probably want Batch
to still run your stuff and skip errors, but you don't want all the progress
output. For this purpose you can tweak BATCH_INTERACTIVE:
$ BATCH_INTERACTIVE=0 rake foo
It's probably useful to have BATCH_INTERACTIVE set to 0 on your crontabs.
If you want Batch to halt as soon as there's an exception (just like a regular
each loop would do), set BATCH_DEBUG:
$ BATCH_DEBUG=1 ruby <your-batch-script>
Batch will also honor the $DEBUG flag and halt if an exception is caught.
$ gem install batch