Allow setting of PoolSpans from Config object

[mdubbyap]

Which problem is this PR solving?

• lack of support for enabling pooling of spans from config object

Short description of the changes

• add Config setter for PoolSpans and pipe it through to Tracer construction

[codecov]

Codecov Report

Merging #322 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #322      +/-   ##
==========================================
+ Coverage   87.15%   87.16%   +0.01%     
==========================================
  Files          54       54              
  Lines        2965     2969       +4     
==========================================
+ Hits         2584     2588       +4     
  Misses        269      269              
  Partials      112      112

Impacted Files	Coverage Δ
config/options.go	100% <100%> (ø)	⬆️
config/config.go	95.03% <100%> (+0.03%)	⬆️

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[yurishkuro]

Have you actually tried using the pooling? I don't think anyone has really used / tested it.

[mdubbyap]

It appears to work fine. Thanks for the heads up. I'll do a little more testing. Perhaps i'll add a metric for hit rate or something similar.

[yurishkuro]

Thanks, @mdubbyap !

FYI, see #381