KYLIN-3908 KylinClient's HttpRequest.releaseConnection is not needed in retrieveMetaData & executeKylinQuery

[leonliao]

This update intends to make the code to handle HTTP connection releasing not confusing.
Issue description is at https://issues.apache.org/jira/browse/KYLIN-3908

[asfgit]

Can one of the admins verify this patch?

[asfgit]

Can one of the admins verify this patch?

[coveralls]

Pull Request Test Coverage Report for Build 4310

• 12 of 14 (85.71%) changed or added relevant lines in 1 file are covered.
• 1296 unchanged lines in 28 files lost coverage.
• Overall coverage increased (+1.0%) to 27.85%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
jdbc/src/main/java/org/apache/kylin/jdbc/KylinClient.java	12	14	85.71%

Files with Coverage Reduction	New Missed Lines	%
core-cube/src/main/java/org/apache/kylin/cube/CubeInstance.java	1	41.43%
core-common/src/main/java/org/apache/kylin/common/persistence/FileResourceStore.java	1	72.62%
core-dictionary/src/main/java/org/apache/kylin/dict/lookup/cache/RocksDBLookupTable.java	1	81.08%
core-dictionary/src/main/java/org/apache/kylin/dict/MultipleDictionaryValueEnumerator.java	2	93.55%
engine-mr/src/main/java/org/apache/kylin/engine/mr/steps/UpdateCubeInfoAfterBuildStep.java	2	0.0%
core-metadata/src/main/java/org/apache/kylin/metadata/model/TableDesc.java	3	51.2%
core-metadata/src/main/java/org/apache/kylin/measure/topn/TopNAggregator.java	5	0.0%
core-cube/src/main/java/org/apache/kylin/cube/inmemcubing/MemDiskStore.java	5	77.81%
core-metadata/src/main/java/org/apache/kylin/measure/topn/TopNCounter.java	5	86.87%
core-storage/src/main/java/org/apache/kylin/storage/StorageFactory.java	7	58.82%

Totals
Change from base Build 4284:	1.0%
Covered Lines:	22586
Relevant Lines:	81100

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💛 - Coveralls

[codecov-io]

Codecov Report

Merging #551 into master will increase coverage by 0.93%.
The diff coverage is 71.42%.

@@             Coverage Diff              @@
##             master     #551      +/-   ##
============================================
+ Coverage     24.43%   25.36%   +0.93%     
- Complexity     5027     5795     +768     
============================================
  Files          1161     1371     +210     
  Lines         70461    81100   +10639     
  Branches      10020    11369    +1349     
============================================
+ Hits          17216    20570    +3354     
- Misses        51513    58518    +7005     
- Partials       1732     2012     +280

Impacted Files	Coverage Δ	Complexity Δ
...c/main/java/org/apache/kylin/jdbc/KylinClient.java	62.38% <71.42%> (ø)	34 <0> (ø)	⬇️
...in/java/org/apache/kylin/common/util/TimeUtil.java	60.78% <0%> (-33.16%)	8% <0%> (ø)
.../java/org/apache/kylin/storage/StorageFactory.java	47.05% <0%> (-7.49%)	3% <0%> (ø)
...he/kylin/dict/lookup/cache/RocksDBLookupTable.java	72.97% <0%> (-5.41%)	6% <0%> (-1%)
...org/apache/kylin/rest/util/QueryRequestLimits.java	35.71% <0%> (-4.77%)	5% <0%> (-1%)
...c/main/java/org/apache/kylin/cube/CubeSegment.java	49.55% <0%> (-3.56%)	63% <0%> (ø)
...ava/org/apache/kylin/measure/topn/TopNCounter.java	75.75% <0%> (-2.37%)	23% <0%> (ø)
.../apache/kylin/cube/cuboid/TreeCuboidScheduler.java	63.84% <0%> (-2.31%)	0% <0%> (ø)
...rg/apache/kylin/cube/inmemcubing/MemDiskStore.java	69.3% <0%> (-1.83%)	7% <0%> (ø)
...he/kylin/common/persistence/FileResourceStore.java	59.52% <0%> (-1.2%)	24% <0%> (-1%)
... and 231 more

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[shaofengshi]

LGTM, thank you Leon!