JsonLayout - Reduce allocations when needing to escape string (44% time improvement)

[snakefoot]

Reuse truncated StringBuilder, instead of creating new.

Also skip the temporary StringBuilder, when using Encode=false. Performance optimization for nested JsonLayouts. But one can also consider using Encode=false for simple fields like ${longdate} or ${level} as it skips unnecessary validation.

[codecov]

Codecov Report

Merging #2743 into master will decrease coverage by <1%.
The diff coverage is 84%.

@@           Coverage Diff           @@
##           master   #2743    +/-   ##
=======================================
- Coverage      81%     81%   -<1%     
=======================================
  Files         326     326            
  Lines       24242   24293    +51     
  Branches     3073    3078     +5     
=======================================
+ Hits        19611   19633    +22     
- Misses       3801    3829    +28     
- Partials      830     831     +1

[snakefoot]

Think one could improve performance even more, by writing directly into the StringBuilder, and just truncate when needing to escape.

[snakefoot]

Now there is also a good performance improvement, even when NOT having to escape strings:

Logger Name	Messages	Size	Args	Threads	Loggers
JsonLogger	2.500.000	128	5	4	1

Test Name	Time (ms)	Msgs/sec	GC2	GC1	GC0	CPU (ms)	Alloc (MB)
This PR	15.972	156.514	1	10	20	24.828	2.238,2
NLog 4.5.5	23.073	108.348	1	29	57	26.421	3.736,2

[304NotModified]

nice, 44% improvement!

[snakefoot]

Think one could optimize all that inherits from WrapperLayoutRendererBuilderBase with the same technique used here (in my last commit).

[304NotModified]

Think one could optimize all that inherits from WrapperLayoutRendererBuilderBase with the same technique used here (in my last commit).

sound good :)