maxStep in requestContext for Finder

[deniszh]

This PR adding URL parameter named maxStep which will be added to requestContext (if defined in URL parameters) and then finder plugin can use it.

Some context and explanation.

We have requestContext parameter, which used in Graphite-web code. It can be used for transferring some data between functions (i.e. providing context). This context parameter also accepting by Finder plugins, but by default Finder ignores it. Both changes trying to help fix long standing issue in Graphite, when datapoint period becoming less then windowSize parameter in some functions these functions return empty or wrong result. That can happen with hitcount(), summarize(), smartSummarize(), movingAverage/Min/Max/Median/Sum/Window() and exponentialMovingAverage(). Unfortunately, that issue is not possible to fix in case of Whisper - if we have only aggregated data in low resolution archive we just can't get high resolution data from it. But issue can be solvable with storages that (at least potentially) can do live aggregation - then we can or transfer desired step directly (using maxStep parameter described above) - or Finder plugin can calculate desired step using target list which is already provided in context starting from v1.1.8.

[deniszh]

Rebased, looks better now.

[codecov-commenter]

Codecov Report

Merging #2724 (df473d0) into master (2e58d21) will decrease coverage by 0.01%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #2724      +/-   ##
==========================================
- Coverage   77.10%   77.09%   -0.02%     
==========================================
  Files         176      176              
  Lines       18968    18972       +4     
  Branches     4032     4034       +2     
==========================================
  Hits        14626    14626              
- Misses       3812     3814       +2     
- Partials      530      532       +2     

Impacted Files	Coverage Δ
webapp/graphite/render/views.py	69.66% <0.00%> (-0.34%)	:arrow_down:
graphite/render/views.py	69.66% <0.00%> (-0.34%)	:arrow_down:
graphite/tags/redis.py	87.03% <0.00%> (ø)
webapp/graphite/tags/redis.py	87.03% <0.00%> (ø)

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[DanCech]

We can't use normal target parameter for it, so, I creating second one, named targets_serialized.

I'm confused by what we gain by having a pickled version of the same data that's already in targets, can you explain what you mean here?

[deniszh]

Easy - target is not in context. I couldn’t trace what removes it and why but target just not present in requestContext in Finder. :(

On Wed, 3 Nov 2021 at 21:16, Dan Cech @.***> wrote:

We can't use normal target parameter for it, so, I creating second one, named targets_serialized.

I'm confused by what we gain by having a pickled version of the same data that's already in targets, can you explain what you mean here?

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[deniszh]

But you probably right, it's worth to at least find why current setup is not working.

[deniszh]

@DanCech : yes, looks like I started from different version and just missed @replay 's commit which bringing targets into context. 😵‍💫 Removed it and amended description.

[deniszh]

💚 All backports created successfully

Status	Branch	Result
✅	1.1.x