Re: NSOperation status

[David Chisnall]

On 19 Jan 2009, at 07:51, Sebastian Nowicki wrote:

> In the release notes for v1.16.0 [1] it is mentioned that  
> NSOperation is on the to-do list. I'm wondering what the status of  
> that is. As far as I can tell there's no support for it whatsoever.  
> This is unfortunate as I would like to use this instead of NSThread  
> for my cross-platform framework (Cocoa & GNUstep). I'm not sure  
> whether to just use NSOperation and wait for it to be supported in  
> GNUstep or use NSThread and switch later.

If you're looking for a cross-platform wrapper around threads, you  
might want to take a look at EtoileThread (part of EtoileFoundation),  
which works on OS X and GNUstep and allows you to send messages  
asynchronously to threads and get a future back.  We use it in Mélodie  
to put the decoder in a different thread - the main thread sends  
messages to it periodically to information for the GUI and only blocks  
when it sends messages to the objects that are returned from messages  
that have not completed executing in the other thread.  It also  
supports calling an idle method when the message queue is empty.  This  
is used to (synchronously) decode the next frame and play it.  It uses  
an efficient lockless ring buffer when there are messages in the queue  
and switches to sleeping on a condition variable when the thread is  
idle.  The main overhead is the cost of forwardInvocation: when the  
thread is busy.

I spent a lot of time a few months ago stress testing and debugging  
it, and I haven't had any bug reports since then.  I wrote a bit more  
about how I'm using it here:

http://etoileos.com/news/archive/2008/07/29/0231/

As always, it's BSD licensed, so feel free to do whatever you want  
with it,

David