Improve pooling and time retrieval mechanism to optimize performance

[louyuting]

1. pool EntryOption
2. optimize EntryContext pool
3. optimize time.Now

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[codecov-commenter]

Codecov Report

Merging #155 into master will decrease coverage by 0.19%.
The diff coverage is 32.83%.

@@            Coverage Diff             @@
##           master     #155      +/-   ##
==========================================
- Coverage   40.77%   40.57%   -0.20%     
==========================================
  Files          68       69       +1     
  Lines        3279     3322      +43     
==========================================
+ Hits         1337     1348      +11     
- Misses       1810     1839      +29     
- Partials      132      135       +3     

Impacted Files	Coverage Δ
api/init.go	0.00% <0.00%> (ø)
core/base/context.go	20.51% <0.00%> (-1.11%)	⬇️
core/config/config.go	24.46% <0.00%> (-0.54%)	⬇️
util/time_ticker.go	22.22% <22.22%> (ø)
util/time.go	81.81% <33.33%> (-18.19%)	⬇️
api/api.go	32.43% <35.29%> (+0.28%)	⬆️
core/base/slot_chain.go	92.40% <100.00%> (+0.62%)	⬆️
core/config/entity.go	75.00% <100.00%> (+0.64%)	⬆️
util/auto_recover.go	0.00% <0.00%> (-100.00%)	⬇️

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[sczyh30]

LGTM

[sczyh30]

Nice work. Cheers!