I got the same problem when I was trying to implement something in production,
having read the same Recipie. Exactly the same error in fact. I replicated it
in the rails console when trying to query the worker. Dropping out of the
console and starting again actually worked but of course doesn't help when you
want to query straight away.
Packet::InvalidWorker
I got the impression that it was trying to query the worker just a fraction
before the worker was ready. I couldn't gather much more information than that.
In the end I had to abandon BackgrounDRb for my project and use a cronjob and
basic queue due to time constraints, so I'd really like to know what the
problem was so that I don't give up on BDRb alltogether. I have to say I found
the rubyforge site documentation far too lacking in details so again I look
forward to see more in depth examples.
If it is all fixed now then its a bit late for this project so maybe I'll give
it another look for the next time it BDRb seems like an appropriate solution.
RobL
hemant wrote:
On Sun, Jul 20, 2008 at 12:14 AM, Derrek Long <[EMAIL PROTECTED]> wrote:
Hello,
I'm trying to learn how to use BackgroundRB to run a long running process while
showing status to the user via a webpage.
1. I tried using Advanced Rails Recipe 43, however, it appears as though backgroundrb has been
updated since that book was published (2 months ago) as methods like "register_status",
"ask_stutus" no longer exist.
Being one of the contributors for the recipe. I am terribly sorry for
this, but newer caching policies are a lot more stable. I am trying to
talk with Mike for releasing a new pdf that covers new version.
2. I tried reading the everything on http://backgroundrb.rubyforge.org/
3. I tried to update the recipe code with what I learned from reading the
backgroundrb webpage
4. I failed spectacularly
Here's my code reworked to be simpler:
---------------
class BillingWorker < BackgrounDRb::MetaWorker
set_worker_name :billing_worker
set_no_auto_load(true)
def create(args = nil)
cache[worker_key] = 0
index = 0
args.times do
sleep(4)
index = index + 1
cache[worker_key] =(index * 100) / args
end
exit
end
end
class PaymentsController < ApplicationController
def async_test
session[:job_key] = Bill.find(1).start_test
redirect_to :action => 'check_async_test_status'
end
def check_async_test_status
@percent_complete = Bill.test_status(session[:job_key])
if request.xhr?
if @percent_complete == 100
render :update do |page|
flash[:notice] = "test is complete"
session[:job_key] = nil
page.redirect_to :action => "pending"
end
else
render :update do |page|
page[:billingStatus].setStyle :width => "[EMAIL PROTECTED] *2}px"
page[:billingStatus].replace_html "[EMAIL PROTECTED]"
end
end
end
end
end
class Bill < ActiveRecord::Base
def start_test
MiddleMan.new_worker(:worker => :billing_worker, :worker_key => "foobar", :data
=> 5)
end
def self.test_status(job_key)
MiddleMan.worker(:billing_worker, "foobar").ask_result(job_key)
# also tried MiddleMan.worker(:billing_worker).ask_result(job_key)
end
end
---------------
hitting /payments/async_test always results in
Packet::InvalidWorker
/usr/local/lib/ruby/gems/1.8/gems/packet-0.1.8/lib/packet/packet_connection.rb:52:in
`ask_worker'
/home/derrek/repos/prod/riderway/trunk/vendor/plugins/backgroundrb/server/lib/master_worker.rb:123:in
`get_result_object'
I can't seem to get at the cache[worker_key] value. Any help would be greatly
appreciated.
Two things are causing problem:
1. MiddleMan.new_worker(...) was not returning the "worker_key" with
which it was created and hence, your session[:job_key] was probably
wrong. I fixed it in latest git push and have added testcase to cover
that also, hence shouldn't happen again.
2. Now, in your worker, you are using worker_key to cache the result:
cache[worker_key] = 0
Think of cache object as hash and whatever key you used here, must be
used while getting the results back and hence your code for fetching
the results should be:
MiddleMan.worker(:billing_worker, "foobar").ask_result("foobar")
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