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Subject: Re: Volatile happens before question
Date: Wed, 18 Jan 2012 10:12:54 -0800
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On 1/18/2012 8:34 AM, raphfrk@gmail.com wrote:
> On Jan 18, 3:32 pm, Peter Duniho<NpOeStPe...@NnOwSlPiAnMk.com>  wrote:
>> On Wed, 18 Jan 2012 06:24:54 -0800 (PST), raph...@gmail.com wrote:
>>> http://mailinator.blogspot.com/2007/05/readerwriter-in-java-in-nonblo...
>>> [...]
>>
>> It looks correct to me.
>
> I don't understand why it is ok.  Doesn't it suffer from the same
> issue as my example?


Yeah, it's a trick.  Or at least isn't great documentation.  To figure 
it out, you have to read the introduction to the AtomicInteger 
documentation, which tells you that you need to read the package 
documentation for "the properties of atomic variables."

In the package documentation, it eventually explains that:

   "get has the memory effects of reading a volatile variable.
   "set has the memory effects of writing (assigning) a volatile variable. "

So you are synchronizing here just as if you were reading and writing to 
a volatile.  I don't think the implementation uses volatile, I think it 
uses native methods which have the same effect, but you can think of the 
internal values as using a volatile to hold the atomic values.

Voila!