devicemap-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Reza Naghibi <reza.nagh...@yahoo.com.INVALID>
Subject Re: Pattern.rank
Date Tue, 30 Dec 2014 15:31:06 GMT
Is this because the JVM may optimize and reorder the code? So I come from a c and assembly
background, just trying to better understand... :)




<div>-------- Original message --------</div><div>From: Volkan Yazıcı
<volkan.yazici@gmail.com> </div><div>Date:12/30/2014  9:55 AM  (GMT-05:00)
</div><div>To: dev@devicemap.apache.org </div><div>Cc:  </div><div>Subject:
Re: Pattern.rank </div><div>
</div>You're right Reza, it is not unsafe. I confused it with leaking "this" in
ctor -- even in that case "final" modifier of the fields impose the
happens-before relationship constraint, which is also fine. It needed quite
some debate on FreeNode to get things resolved. Sorry for the wrong alarm.


On Tue, Dec 30, 2014 at 3:04 PM, Reza Naghibi <
reza.naghibi@yahoo.com.invalid> wrote:

> Hmm... can you provide a reference or some kind of example showing that a
> single threaded read after write is unreliable? I'm thinking if this is
> true, huge swaths of programs would be deemed unsafe since read after write
> is quite a common memory pattern... :) No?
>
>
>
> <div>-------- Original message --------</div><div>From: Volkan Yazıcı
<
> volkan.yazici@gmail.com> </div><div>Date:12/30/2014  8:31 AM  (GMT-05:00)
> </div><div>To: dev@devicemap.apache.org </div><div>Cc:
> </div><div>Subject: Re: Pattern.rank </div><div>
> </div>A related excerpt from the Java Concurrency in Practice: "An object
> is in a
> predictable, consistent state only after its constructor returns, ..." In
> its current form of Pattern:
>
> Pattern(...) {
>     ...
>     this.boost = boost;
>     this.rank = rank();
> }
>
> public long rank() {
>     // access to this.boost
> }
>
>
> this.boost might not have been completely initialized when rank() tries to
> access to it.
>
> On Tue, Dec 30, 2014 at 2:14 PM, Reza Naghibi <
> reza.naghibi@yahoo.com.invalid> wrote:
>
> > Interesting... you cannot access instance variables in the constructor?
> >
> > Also, this hasn't been fully implemented. Boost is going to be a DRR
> > pattern attribute which will allow 1 pattern to be configured to rank
> > higher than another.
> >
> >
> >
> >
> > <div>-------- Original message --------</div><div>From: Volkan
YAZICI <
> > volkan.yazici@gmail.com> </div><div>Date:12/30/2014  4:41 AM
> (GMT-05:00)
> > </div><div>To: dev@devicemap.apache.org </div><div>Cc:
> > </div><div>Subject: Pattern.rank </div><div>
> > </div>Hi,
> >
> > I have an objection and a question about Pattern class in Java client.
> >
> > *Objection:* Pattern.rank() instance method gets called in ctor and
> > accesses to instance variables, which might not have been initialized yet
> > due to JMM semantics. I propose to fix it as in DMAP-115
> > <https://issues.apache.org/jira/browse/DMAP-115>.
> >
> > *Question:* Shall we remove boost option on Pattern ctor? It is neither
> > used, nor available in .NET client.
> >
> > Best.
> >
>
Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message