[MacRuby-devel] some gcd issues

[B. Ohr]

Hi,

yesterday I did my first steps with GCD: parsing a very big CSV-file, processing and filtering it and displaying the result in a table view. Before GCD the UI was blocked for more than a minute, now the user can continue working instantly. Hey that’s really, really great!

There are some issues I don’t understand:

1. @job.group.notify(Dispatch::Queue.main) {}  # gives an error...
   @job.group.notify(Dispatch::Queue.concurrent) {} # …..while is working

2. @job.group.notify(Dispatch::Queue.concurrent) {}  # the block is called twice or more times

3. the proxy object does not work here (I’m not sure, that I am using it correctly)

I made a small Xcode project demo out my project and attached it to this mail. (you can multi-click on the job button)

- Bernd

######

require 'dispatch'

class AppController

 attr_accessor :calculations, :running

 def initialize
   self.calculations = []
	@prefix = 1
	@job = Dispatch::Job.new
	#the main queue is used here because the UI is bound to the calculations array 
	@calc_queue = Dispatch::Queue.main
 end

 def calc_sync &block
   @calc_queue.async { block.call }
 end
   	
 def nextPrefix
	prefix = @prefix
	@prefix += 1
	prefix
 end

 def calc1
	# @calc_proxy = Dispatch::Proxy.new(self.calculations, at job.group, at calc_queue)
	@job.add do
	  prefix = nextPrefix
	  10.times do |i|
	    dur = rand / 4 + 0.2
		sleep(dur)
	    c = Calculation.new("#{prefix}:#{i}",dur)
       calc_sync { self.calculations += [c] }
       # proxy does not work here:
		# @calc_proxy += [c]
	  end
	  #NSLog self.calculations.inspect
	end
	# why can the notify block be called twice ore more?
	# if true
	if !running
	  self.running = true
	  # notifying on the main queue is crashing here:
	  # @job.group.notify(@calc_queue) { NSLog "notify“; self.running = false }
	  @job.group.notify(Dispatch::Queue.concurrent) { NSLog "notify"; self.running = false }
	end
 end

 def jobAction sender
   calc1
 end

 def clearAction sender
	self.calculations = []
 end

end


-------------- next part --------------
A non-text attachment was scrubbed...
Name: gcd_demo.zip
Type: application/zip
Size: 28576 bytes
Desc: not available
URL: <http://lists.macosforge.org/pipermail/macruby-devel/attachments/20100604/c27990dd/attachment-0001.zip>
-------------- next part --------------