Hello Tim Armstrong, Csaba Ringhofer, Joe McDonnell, Impala Public Jenkins,

I'd like you to reexamine a change. Please visit

    http://gerrit.cloudera.org:8080/11520

to look at the new patch set (#5).

Change subject: IMPALA-7543: Enhance scan ranges to support sub-ranges
......................................................................

IMPALA-7543: Enhance scan ranges to support sub-ranges

This commit enhances the ScanRange class to make it possible to only
read some smaller parts of the whole ScanRange. This functionality
is needed by IMPALA-5843.

A sub-range is an offset and length which is located within the scan
range. Sub-ranges can be added to a scan range when calling
ScanRange::Reset(). If done so, the ScanRange class will only read the
parts defined by the sub-ranges.

If we have sub-ranges for a cache read then the ScanRange won't
enqueue the whole cache buffer (which contains the whole ScanRange),
but memcpy() the sub-ranges to IO/client buffers.

Smaller refactorings needed to do:
 * remove scan_range_offset_ from BufferDescriptor
 * number of bytes read are bookkeeped by ScanRange again

Testing:
 * introduced CacheReaderTestStub to fake cache reads during testing
 * extended disk-io-mgr-test.cc with sub-ranges

Change-Id: Iea26ba386713990f7671aab5a372cf449b8d51e4
---
M be/src/runtime/io/CMakeLists.txt
A be/src/runtime/io/cache-reader-test-stub.h
M be/src/runtime/io/disk-io-mgr-stress.cc
M be/src/runtime/io/disk-io-mgr-test.cc
M be/src/runtime/io/disk-io-mgr.cc
D be/src/runtime/io/file-reader.cc
M be/src/runtime/io/file-reader.h
M be/src/runtime/io/hdfs-file-reader.cc
M be/src/runtime/io/hdfs-file-reader.h
M be/src/runtime/io/local-file-reader.cc
M be/src/runtime/io/local-file-reader.h
M be/src/runtime/io/request-context.cc
M be/src/runtime/io/request-context.h
M be/src/runtime/io/request-ranges.h
M be/src/runtime/io/scan-range.cc
15 files changed, 512 insertions(+), 158 deletions(-)


  git pull ssh://gerrit.cloudera.org:29418/Impala-ASF refs/changes/20/11520/5
--
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Gerrit-Project: Impala-ASF
Gerrit-Branch: master
Gerrit-MessageType: newpatchset
Gerrit-Change-Id: Iea26ba386713990f7671aab5a372cf449b8d51e4
Gerrit-Change-Number: 11520
Gerrit-PatchSet: 5
Gerrit-Owner: Zoltan Borok-Nagy <borokna...@cloudera.com>
Gerrit-Reviewer: Csaba Ringhofer <csringho...@cloudera.com>
Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com>
Gerrit-Reviewer: Joe McDonnell <joemcdonn...@cloudera.com>
Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com>
Gerrit-Reviewer: Zoltan Borok-Nagy <borokna...@cloudera.com>

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