[infinispan-dev] DIST.retrieveFromRemoteSource

[Bela Ban]

On 2/5/12 4:40 PM, Dan Berindei wrote:


>> Remember that a message might be retransmitted, so it is placed into a
>> retransmit buffer. If M1 has destination A and M2 has destination B, and
>> we send M1 first (to A), then change M1's destination to B, and send it,
>> everything is fine. However, if we later get a retransmit request from
>> B, we'd resend the message to A instead ! This is just 1 example,
>> modifications of headers is another one.
>>
>> Note that the copy does *not* copy the buffer (payload) itself, but only
>> references it, so this is fast. Of course, nobody is supposed to modify
>> the contents of the buffer itself...
>>
>
> I wasn't clear enough, but I didn't mean we should reuse the entire
> Message object. I meant we should copy the Message but not the buffer
> or the headers. I see now that protocols may be adding new headers, so
> it wouldn't be safe to reuse the headers collection.
>
> I think this line in
> RequestCorrelator.sendRequest(RequestCorrelator.java:152) means that
> the contents of the buffer is copied in the new message, not just the
> buffer reference:
>
>                  Message copy=msg.copy(true);


No, this does *not* copy the buffer, but simply references the same buffer.

-- 
Bela Ban
Lead JGroups (http://www.jgroups.org)
JBoss / Red Hat