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https://issues.apache.org/jira/browse/HBASE-16838?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15656227#comment-15656227
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stack commented on HBASE-16838:
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Looking. Its much nicer now I think. We can work on the one-rpc small scan over
in the linked issue.
Pity names get to be like this: AsyncScanRegionRpcRetryingCaller... which runs
a AsyncScanRegionRpcRetryingCallables. The RpcRetryingCaller stuff and
RpcRetryingCallable was all there before you so not your fault... just saying.
Is a Scan always against a Region (is the Region redundant?).
Looking at the Response, we need Scan in there? The Scan in Response is
different from originalScan? nvm... I see this Scan carries state of the
general Scan as we progress.
locateToPreviousRegion is when a reverse Scan?
Thanks for comment on scan timeout. So scan timeout is different to operation
timeout? It is at least according to your comment up in rb: "As now we have
heartbeat support for scan, ideally a scan will never timeout unless the RS is
crash. The RS will always return something before the rpc timeout or scan
timeout to tell the client that it is still alive.
The scan timeout is used as operation timeout for every operations in a scan,
such as openScanner or next."
I think you should stick the above comment on the scan timeout so it is clear
what the scan timeout means. It helps.
Update doc on commit:
* The basic scan API uses the observer pattern. All results that
match the given scan object will
356 * be passed to the given {@code scanObserver} by calling {@link
ScanConsumer#onNext(Result[])}.
... you changed observer to be a consumer.
Is there example code on how I'd do an async Scan? I create a ScanConsumer and
pass it in then it will get called with Results as the Scan progresses? The
AsyncTable#scan returns immediately? Perhaps stick it in javadoc for the scan
method? Is SimpleScanObserver a good example or just a stop gap with its queue?
Dont kill me but should ScanConsumer be ScanResultConsumer (can do in followup
if makes sense) or just ScanResult?
CompleteResultScanResultCache should be CompleteScanResultCache to match
AllowPartialScanResultCache?
I'd be good committing this as is and addressing what remains in follow-on. +1
> Implement basic scan
> --------------------
>
> Key: HBASE-16838
> URL: https://issues.apache.org/jira/browse/HBASE-16838
> Project: HBase
> Issue Type: Sub-task
> Affects Versions: 2.0.0
> Reporter: Duo Zhang
> Assignee: Duo Zhang
> Fix For: 2.0.0
>
> Attachments: HBASE-16838-v1.patch, HBASE-16838-v2.patch,
> HBASE-16838-v3.patch, HBASE-16838.patch
>
>
> Implement a scan works like the grpc streaming call that all returned results
> will be passed to a ScanConsumer. The methods of the consumer will be called
> directly in the rpc framework threads so it is not allowed to do time
> consuming work in the methods. So in general only experts or the
> implementation of other methods in AsyncTable can call this method directly,
> that's why I call it 'basic scan'.
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