From: "Thomas B." <tpreal@...>
Date: 2008-09-22T19:14:24+09:00
Subject: Re: ThreadError: not owner

Caleb Clausen wrote:
> On 9/22/08, Thomas B. <tpreal@gmail.com> wrote:
>> Thanks for your responses.
>>    [snip]
>> Unfortunately, Monitor does not allow this way of usage, too.
> 
> Really? After I looked into it, it seemed like maybe you could use a
> condition variable, but then I've never understood monitors or
> condition variables properly. A semaphore seems so much simpler, for
> this case, at any rate. I guess condition variables would have the
> advantage of being faster, (if they can be made to work) since they
> were presumably rendered into c as well.

As far as I know, the only difference between Mutex and Monitor in Ruby 
(apart from the internal implementation, I mean) is that Monitors are 
reentrant, meaning that a monitor can not only be locked or unlocked, 
but it can also be locked multiple times, if all the locks come from the 
same thread, so you can do this:
mon.synchronize{mon.synchronize{x}} and get no deadlock or anything. But 
still it has to be unlocked by the same thread that locked it.

As for condition variables, I don't think they could help in my 
situation. It's not what they are designed for, if I understand them 
well. I think that the Semaphore (or maybe I'll write my own Semaphore 
class) is the best solution here, only I hoped for a core class for 
doing this.
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