[SPARK-4661][Core] Minor code and docs cleanup

[zsxwing]

No description provided.

[SparkQA]

Test build #23967 has started for PR 3521 at commit 16f41cd.

• This patch merges cleanly.

[SparkQA]

Test build #537 has started for PR 3521 at commit 16f41cd.

• This patch merges cleanly.

[SparkQA]

Test build #23967 has finished for PR 3521 at commit 16f41cd.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/23967/
Test FAILed.

[SparkQA]

Test build #537 has finished for PR 3521 at commit 16f41cd.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • trait ConnectionFactory extends Serializable
  • class MatrixFactorizationModel(
  • class CompressedSerializer(FramedSerializer):

[JoshRosen]

[warn] 6 warnings found
[error] /home/jenkins/workspace/NewSparkPullRequestBuilder/core/src/test/java/org/apache/spark/JavaAPISuite.java:1384: error: incompatible types
[error]     SomeCustomClass[] collected = rdd.rdd().retag(SomeCustomClass.class).collect();
[error]                                                                                 ^
[error]   required: SomeCustomClass[]
[error]   found:    Object
[error] Note: /home/jenkins/workspace/NewSparkPullRequestBuilder/core/src/test/java/org/apache/spark/JavaAPISuite.java uses or overrides a deprecated API.
[error] Note: Recompile with -Xlint:deprecation for details.
[error] 1 error

That's a really weird test failure. I think that some other PR must have broken the build; I'll investigate.

[JoshRosen]

Actually, nevermind; looks like that was caused by this PR's changes.

[zsxwing]

That's a really weird test failure. I think that some other PR must have broken the build; I'll investigate.

My mistake. I thought casting to SomeCustomClass[] was unnecessary and removed it. But it's necessary because the compiler cannot infer the type.

[SparkQA]

Test build #23969 has started for PR 3521 at commit 03cbe3f.

• This patch merges cleanly.

[SparkQA]

Test build #23969 has finished for PR 3521 at commit 03cbe3f.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/23969/
Test PASSed.

[rxin]

Merging in master & branch-1.2. Thanks.

[srowen]

@zsxwing I know it's too late, but the cast should also have a @SuppressWarnings("unchecked"), ideally, to avoid another warnings. I have some things like this taken care of in another open PR: https://www.github.com/apache/spark/pull/3157

[zsxwing]

but the cast should also have a @SuppressWarnings("unchecked"), ideally, to avoid another warnings. I have some things like this taken care of in another open PR:

@srowen, yes. Then it's better to add it in your PR :)