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From Patricia Shanahan <p...@acm.org>
Subject Re: Question about JavaSpaces functionality
Date Mon, 31 Jan 2011 05:59:54 GMT
I wish it had been phrased in the same terms as the JLS. I know the 
write call completion happens-before the call to the read method. I 
think that means the same as "the write returns before the read 
commences" but I'm not sure.


> There is this, which I assume you have already seen?
> Operation Ordering
> Operations on a space are unordered. The only view of operation order can be a thread's
view of the order of the operations it performs. A view of inter-thread order can be imposed
only by cooperating threads that use an application-specific protocol to prevent two or more
operations being in progress at a single time on a single JavaSpaces service. Such means are
outside the purview of this specification.
> For example, given two threads T and U, if T performs a write operation and U performs
a read with a template that would match the written entry, the read may not find the written
entry even if the write returns before the read. Only if T and U cooperate to ensure that
the write returns before the read commences would the read be ensured the opportunity to find
the entry written by T (although it still might not do so because of an intervening take from
a third entity).
> On Jan 30, 2011, at 7:42 PM, Patricia Shanahan wrote:
>> Suppose thread A writes an item to a JavaSpace, thread B attempts to read it, and
A's call to the space's proxy write method happens-before B's call to the space's proxy read
method. There are no transactions involved
>> Should the read always succeed?
>> In other words, should a happens-before relationship between two actions in a client
imply a corresponding happens-before relationship between the corresponding actions in the
actual space, without depending on transaction semantics?
>> This question affects whether I'm working on a bug in outrigger or in one of its
>> Thanks for any information.
>> Patricia
> Michael McGrady
> Chief Architect
> Topia Technology, Inc.
> Cel 1.253.720.3365
> Work 1.253.572.9712 extension 2037
> mmcgrady@topiatechnology.com

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