From: Eleanor McHugh <eleanor@...>
Date: 2009-09-06T00:17:33+09:00
Subject: Re: Problems with cross-thread violation

On 3 Sep 2009, at 03:08, Gin Mendi wrote:
> Thanks again for taking the time to read this!
>
> require 'feed_library'
>
> # my callback for the live feed
> FEED_CALLBACK = DL.callback('0PL') { |result_list, count| }
>  if result_list
>    record = FeedRecord.new(result_list)
>    puts record.code
>  end
> }
>
> # handle used to request for a feed
> handle = FeedLibrary::log_on("user", "password")
>
> session = get_live_feed(handle, FEED_CALLBACK)
>
> # my attempt to keep this running and waiting on the callback:
> while true
>
> end

No need to be uncivilised ;) Idiomatic Ruby for an endless loop is  
better expressed as:

	loop do
	end

although that shouldn't make any difference to your program.

> Here's one I tried. Been playing around with different approaches.  
> With
> this method I noticed I always get the cross-thread violation when I  
> use
> the FeedRecord structure. If I don't use the structure and do  
> something
> else like using the struct! method I'm able to get away with the
> callback being performed a couple of times then it eventually leads  
> to a
> cross-thread violation.


Does get_live_feed use a separate thread internally? If so the cross- 
thread violation could well be related to garbage collection of the  
callback in which case you may need a separate callback instance for  
each feed handle. Also I note that you're using a constant to hold the  
callback, have you tried using a variable instead? Try turning off  
garbage collection altogether and see whether that affects the errors  
you receive. I've had some very amusing results doing that with DL  
callbacks :)


Ellie

Eleanor McHugh
Games With Brains
http://slides.games-with-brains.net
----
raise ArgumentError unless @reality.responds_to? :reason