Add log configuration

[yzj0911]

[codecov-commenter]

Codecov Report

Merging #63 (770bffd) into master (949046a) will increase coverage by 1.10%. The diff coverage is 72.17%.

@@            Coverage Diff             @@
##           master      #63      +/-   ##
==========================================
+ Coverage   45.73%   46.83%   +1.10%     
==========================================
  Files          48       48              
  Lines        2683     2797     +114     
==========================================
+ Hits         1227     1310      +83     
- Misses       1374     1394      +20     
- Partials       82       93      +11     

Impacted Files	Coverage Δ
log/logger.go	58.47% <72.17%> (+6.39%)	:arrow_up:
buffer/iobuffer.go	77.97% <0.00%> (+0.34%)	:arrow_up:

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[taoyuanyuan]

add testcase