take()-s of two associated but distinct entries

Hello all,

Perhaps, this subject has been discussed before. If so, please point me
to the thread.

Suppose, there are three processes (could be threads too), interacting
through a Space. Two of them (A and B) produce Entries,
and the other (C) consumes the entries. Thorugh the Entries are
produced by two disconnected producers, there is a close assoication
betwevn them. Hence, the C need to take() the Entries together
before using them.

Producers may or may not produce entries (and write() into the space),
simultaneously. In other words, there could be a discernible time-gap
between two such write()-s. The Consumer has registered itself
for notification, for both type of entries. Obviously, there will be a
time-gap between two notifications that C gets from the Space.

So, A produces an Entry named, AE1 and write()s into the Space. C gets
the notification. Similarly, when B produces an Entry named, BE1 into
the Space, C again gets the notification. Now, C has to take AE1
and BE1.

What should C do?

a) Should C take() them under two different transactions?
b) Can C take() them under the same transactions? Will the same Txn
object work across two separate take()-s?

In a slightly different scenario, let us assume that there are two
instances of C (C1 and C2) running. A writes entries AE1 and AE2.
Similarly, B writes entries BE1 and BE2 (don't forget the time-gap).

Now, take() by either C1 or C2 has to happen in associated pairs;
in other words, whosoever takes AE1, has to take BE1 (ditto for
AE2 and BE2).

What is the most common (and efficient) pattern to be followed in such a case?

Will wait to hear from you.

Nirmalya

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