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From Stack <st...@duboce.net>
Subject Re: Quick question about HRegionServer.addScanner(...)
Date Mon, 08 Aug 2011 23:07:26 GMT
On Fri, Aug 5, 2011 at 11:13 PM, lars hofhansl <lhofhansl@yahoo.com> wrote:
> I see this code in there:
>
>
>     scannerId = rand.nextLong();
>     String scannerName = String.valueOf(scannerId);
>     scanners.put(scannerName, s);
>
>
> It would be rare that rand.nextLong() would return the same id while an older scanner
is still in progress, but if that happens,
> it seems the result would be pretty bad (i.e. the old client scanner now returning result
from a different server scanner).
> We could just have an incrementing long (with 2^63, we'll never run our of numbers, and
if we're worried about that we could reset the counter every time the scanners map is empty).
>

This seems like a good idea.  Mind filing a JIRA Lars?


> I am probably not understanding this sufficiently, yet... Hence the question.
>

Your understanding looks fine to me.


>
> Also why is scanners declared as:
>   final Map<String, InternalScanner> scanners =
>     new ConcurrentHashMap<String, InternalScanner>();
>
>
> And not as
>
>   final Map<Long, InternalScanner> scanners =
>     new ConcurrentHashMap<Long, InternalScanner>();
>
>
> All places except (ScannerListener) receive a long and calls either String.valueOf or
Long.toString to convert the passed long to a String.
> Using Long still does autoboxing but it still seems better. Is the motivation to more
descriptive names in the future?
>

I do not know why it does the above.   It seems off to me (May be
vestige of an incomplete refactoring).

Thanks for digging in here Lars,
St.Ack

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