[SPARK-18198][Doc][Streaming] Highlight code snippets

[lw-lin]

What changes were proposed in this pull request?

This patch uses {% highlight lang %}...{% endhighlight %} to highlight code snippets in the Structured Streaming Kafka010 integration doc and the Spark Streaming Kafka010 integration doc.

This patch consists of two commits:

• the first commit fixes only the leading spaces -- this is large
• the second commit adds the highlight instructions -- this is much simpler and easier to review

How was this patch tested?

SKIP_API=1 jekyll build

Screenshots

Before

After

[lw-lin]

Fix the leading spaces is needed, because without the fixing the code snippet would contain leading spaces as well(see the pic below), which is quite inconsistent with all other programming guides.

[lw-lin]

@koeninger @srowen it'd be great if you could also take a look at this too :)

Hint: this patch consists of two commits:

• the first commit fixes only the leading spaces -- this is large
• the second commit adds the highlight instructions -- this is much simpler and easier to review

[srowen]

That is nicer. Are there any other code snippets across the code base that need this treatment? seems like this is always the right thing to do.

[lw-lin]

@srowen thanks.

I'm afraid the streaming flume integration doc, kinesis integration doc, as well as kafka08 integration doc also need code highlights, but this {% hightlight %} syntax seem to be conflict with the indentation syntax (e.g. https://github.com/apache/spark/blame/branch-2.0/docs/streaming-flume-integration.md#L40-L73). I guess that's why the flume, kinesis, kafka08 docs don't have code highlights in the first place. structured streaming kafka010, spark streaming kafka010doc, on the other hand, don't have such conflicts -- so we're adding code highlights here.

And as far as I can tell, no other code snippets need this treatment.

[SparkQA]

Test build #67899 has finished for PR 15715 at commit 5f2c21b.

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

[srowen]

What about unindenting those blocks? I don't see why they have to be in the first place. They're HTML tags.

[lw-lin]

Please see the screenshot above -- this is flume doc -- I got this by unindenting the second block. Then:

• the second block's indent does not look as pretty as the first's and the third's
• the third block's numbering just goes wrong -- it should have been 3.

[srowen]

What about keeping the indent of the div tags but un-indenting only the code? it might look weird in markdown but does it look nice in the rendered output?

If it's any more trouble than that, forget it.

[lw-lin]

Good question!

Actually I had tried keeping the indent of the div tags but un-indenting only the code before I open this pr -- and it looked like this:

That was when I gave up trying more on the flume, kinesis, kafka08 docs. :-D

[srowen]

I guess we could restructure the headings to not have these numbered, indented sections to begin with, but that's a separate task I think.

[lw-lin]

Sounds good!

[koeninger]

LGTM

[HyukjinKwon]

+1

[srowen]

Merged to master

[lw-lin]

@srowen thanks -- could we also merge this into branch-2.1?

[srowen]

Oops, I see, we've cut branch 2.1. I must have missed that one too along with other dev@ lists going to spam. Yes I will go back and make sure a few I've just merged to master are in 2.1.