Redesign Config structure for improving performance

[izumin5210]

No description provided.

[codecov-io]

Codecov Report

Merging #25 into master will decrease coverage by 0.3%.
The diff coverage is 88.99%.

@@            Coverage Diff             @@
##           master      #25      +/-   ##
==========================================
- Coverage   86.36%   86.06%   -0.31%     
==========================================
  Files          13       14       +1     
  Lines         440      409      -31     
==========================================
- Hits          380      352      -28     
+ Misses         36       34       -2     
+ Partials       24       23       -1

Flag	Coverage Δ
#pb	77.04% <ø> (ø)	⬆️
#retry	88.23% <ø> (ø)	⬆️

Impacted Files	Coverage Δ
response_handler.go	81.69% <100%> (+0.26%)	⬆️
config.go	81.81% <100%> (+4.76%)	⬆️
request_handler.go	100% <100%> (ø)	⬆️
config_go1.13.go	100% <100%> (ø)
client.go	91.48% <66.66%> (-8.52%)	⬇️
option.go	85.56% <86.88%> (-2.93%)	⬇️

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[izumin5210]

:) % benchstat benchmark/log/bench-{20191113-090236-v0.2.0-18-ge78f5ee.log,20191113-094553-v0.2.0-26-g8cd308b.log}
name                      old time/op    new time/op    delta
POSTWithJSON/Resty-8        1.38ms ±81%    1.59ms ±72%     ~     (p=0.231 n=20+20)
POSTWithJSON/Sling-8        85.5µs ±45%    94.0µs ±36%   +9.93%  (p=0.008 n=17+19)
POSTWithJSON/Gentleman-8    94.1µs ± 8%   104.5µs ±12%  +11.01%  (p=0.000 n=17+20)
POSTWithJSON/Gorequest-8    1.51ms ±81%    1.57ms ±84%     ~     (p=0.678 n=20+20)
POSTWithJSON/Grequests-8    85.3µs ±31%    80.9µs ±19%     ~     (p=0.888 n=18+18)
POSTWithJSON/Hx-8           87.8µs ±16%    80.2µs ± 4%   -8.67%  (p=0.001 n=20+18)
POSTWithJSON/NetHTTP-8      76.9µs ± 8%    77.5µs ± 7%     ~     (p=0.257 n=19+17)
GETWithQuery/Resty-8        1.49ms ±82%    1.74ms ±84%     ~     (p=0.114 n=20+20)
GETWithQuery/Sling-8        91.1µs ±27%    88.3µs ±32%     ~     (p=0.161 n=18+18)
GETWithQuery/Gentleman-8     103µs ± 8%     105µs ±11%   +2.23%  (p=0.040 n=20+19)
GETWithQuery/Gorequest-8    1.61ms ±85%    1.39ms ±86%     ~     (p=0.289 n=20+20)
GETWithQuery/Grequests-8    89.4µs ±37%    89.4µs ±22%     ~     (p=0.753 n=18+19)
GETWithQuery/Hx-8           88.6µs ±16%    84.0µs ± 7%     ~     (p=0.070 n=19+18)
GETWithQuery/NetHTTP-8      78.4µs ± 6%    78.4µs ± 8%     ~     (p=0.988 n=19+18)

name                      old alloc/op   new alloc/op   delta
POSTWithJSON/Resty-8        30.8kB ± 6%    30.9kB ± 4%     ~     (p=0.743 n=17+16)
POSTWithJSON/Sling-8        7.83kB ± 1%    7.87kB ± 1%   +0.52%  (p=0.000 n=20+20)
POSTWithJSON/Gentleman-8    16.1kB ± 0%    16.2kB ± 1%   +0.81%  (p=0.000 n=19+20)
POSTWithJSON/Gorequest-8    23.2kB ± 1%    23.2kB ± 1%     ~     (p=0.931 n=19+17)
POSTWithJSON/Grequests-8    7.17kB ± 1%    7.24kB ± 1%   +0.86%  (p=0.000 n=19+19)
POSTWithJSON/Hx-8           8.32kB ± 0%    7.82kB ± 1%   -6.01%  (p=0.000 n=19+20)
POSTWithJSON/NetHTTP-8      6.68kB ± 1%    6.70kB ± 0%   +0.26%  (p=0.001 n=20+20)
GETWithQuery/Resty-8        32.2kB ± 3%    30.8kB ±13%   -4.37%  (p=0.005 n=16+20)
GETWithQuery/Sling-8        8.25kB ± 0%    8.25kB ± 0%     ~     (p=0.250 n=20+20)
GETWithQuery/Gentleman-8    17.9kB ± 0%    17.9kB ± 0%     ~     (p=0.405 n=20+18)
GETWithQuery/Gorequest-8    20.4kB ± 0%    20.4kB ± 0%     ~     (p=0.867 n=20+20)
GETWithQuery/Grequests-8    8.88kB ± 0%    8.87kB ± 0%     ~     (p=0.317 n=20+20)
GETWithQuery/Hx-8           9.73kB ± 0%    9.15kB ± 0%   -5.94%  (p=0.000 n=19+20)
GETWithQuery/NetHTTP-8      7.02kB ± 0%    7.03kB ± 0%     ~     (p=0.273 n=20+20)

name                      old allocs/op  new allocs/op  delta
POSTWithJSON/Resty-8           184 ± 1%       184 ± 1%     ~     (p=0.995 n=19+20)
POSTWithJSON/Sling-8           100 ± 0%       100 ± 0%     ~     (all equal)
POSTWithJSON/Gentleman-8       245 ± 0%       245 ± 0%     ~     (all equal)
POSTWithJSON/Gorequest-8       199 ± 0%       199 ± 0%     ~     (all equal)
POSTWithJSON/Grequests-8      87.0 ± 0%      87.0 ± 0%     ~     (all equal)
POSTWithJSON/Hx-8              120 ± 0%       110 ± 0%   -8.33%  (p=0.000 n=20+20)
POSTWithJSON/NetHTTP-8        83.0 ± 0%      83.0 ± 0%     ~     (all equal)
GETWithQuery/Resty-8           202 ± 1%       201 ± 1%   -0.34%  (p=0.031 n=19+19)
GETWithQuery/Sling-8           119 ± 0%       119 ± 0%     ~     (all equal)
GETWithQuery/Gentleman-8       271 ± 0%       271 ± 0%     ~     (all equal)
GETWithQuery/Gorequest-8       162 ± 0%       162 ± 0%     ~     (all equal)
GETWithQuery/Grequests-8       115 ± 0%       115 ± 0%     ~     (all equal)
GETWithQuery/Hx-8              137 ± 0%       128 ± 0%   -6.57%  (p=0.000 n=20+20)
GETWithQuery/NetHTTP-8        96.0 ± 0%      96.0 ± 0%     ~     (all equal)