Fwd: Re: Question about threading implications of specification

[Sebastian Sickelmann]

Hi,

i am not quite sure what the specification says. But the sync on handler
and the notify on handler inside foo.read() ensures that it is invoked
in the right and expected order. Because the notify on handler must be inside 
a sync on handler or an synchronized method.

Kind regards
Sebastian
-------- Original-Nachricht --------
> Datum: Tue, 12 Jul 2011 08:00:45 -0700 (PDT)
> Von: Gili <cowwoc at bbs.darktech.org>
> An: nio-discuss at openjdk.java.net
> Betreff: Question about threading implications of specification

> Hi,
> 
> The specification for AsynchronousByteChannel.read() talks about the
> operation taking place asynchronously, but what happens when the end of
> stream has been reached? Is an implementation allowed to fire the
> completion
> handler (or set the future) within the thread that invoked read()? From
> the
> implementation's point of view, there is no reason to carry out this
> operation asynchronously, because we already know the result. A similar
> case
> occurs if a user attempts to read into a buffer where remaining() returns
> 0
> (so we know the read operation must return 0).
> 
> I ask because I've run into a race condition in my implementation. I'm
> invoking a completion handler that invokes notify() on itself when the
> operation completes. I then invoke the following user code:
> 
> synchronize (handler)
> {
>   foo.read(handler);
>   handler.wait();
> }
> 
> Note the user is assuming that the handler will be notified when the
> operation completes, but because read() runs synchronously at end of
> stream
> the handler gets notified before wait() and the latter will block forever.
> 
> Does the specification require me to update Future/CompletionHandler in a
> separate thread or should users be aware of the fact that the thread that
> invokes read() may update said objects itself?
> 
> Thank you,
> Gili
> 
> --
> View this message in context:
> http://nio-discuss.970641.n3.nabble.com/Question-about-threading-implications-of-specification-tp3162701p3162701.html
> Sent from the nio-discuss mailing list archive at Nabble.com.

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