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From "Sailesh Mukil (Code Review)" <ger...@cloudera.org>
Subject [Impala-ASF-CR] IMPALA-3905: HdfsScanner::GetNext() for Avro, RC, and Seq scans.
Date Wed, 21 Jun 2017 18:53:40 GMT
Sailesh Mukil has posted comments on this change.

Change subject: IMPALA-3905: HdfsScanner::GetNext() for Avro, RC, and Seq scans.
......................................................................


Patch Set 5:

(1 comment)

http://gerrit.cloudera.org:8080/#/c/6527/5/be/src/exec/kudu-scan-node.cc
File be/src/exec/kudu-scan-node.cc:

Line 179:       if (materialized_row_batches_->AddBatchWithTimeout(move(row_batch), 1000000))
{
> You could add an output parameter to BlockingPutWithTimeout() (rather than 
unique_ptr is already a move only class, which means it's limited to using move semantics
and copying isn't allowed, something that rvalue refs try to provide for non-move-only classes/data
types. That means that moving to an rvalue ref of a move only class is redundant, save for
one subtle difference noted below. So the only difference between taking:

func(unique_ptr<> arg)

and

func(unique_ptr<>&& arg)

is that in the first case, the caller knows that after calling func, they're not supposed
to use the unique_ptr member that was passed to arg.

In the second case, the value of the unique_ptr member passed is dependent on what func()
does with arg. In the above code, we're relying on this behavior to conditionally relinquish
or retain the ownership of row_batch.

Unless I got something wrong?


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Gerrit-MessageType: comment
Gerrit-Change-Id: Ie18f57b0d3fe0052a8ccd361b6a5fcdf979d0669
Gerrit-PatchSet: 5
Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-Owner: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Alex Behm <alex.behm@cloudera.com>
Gerrit-Reviewer: Henry Robinson <henry@cloudera.com>
Gerrit-Reviewer: Marcel Kornacker <marcel@cloudera.com>
Gerrit-Reviewer: Sailesh Mukil <sailesh@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstrong@cloudera.com>
Gerrit-Reviewer: anujphadke <aphadke@cloudera.com>
Gerrit-HasComments: Yes

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