ColoredConsoleTarget performance improvements.

[bhaeussermann]

Fixes #980

I've identified the expensive operations to be the ForegroundColor and BackgroundColor properties (both get and set), and the TextWriter.Write() and TextWriter.WriteLine() methods.

I've applied two performance enhancements:

1. When there are no word highlighting rules, then we WriteLine(message) the message instead of doing a Write(message) followed by a WriteLine(). This saves one expensive Write() call per log.
2. We set the colors only if they must change (i.e. the matching rule's color is different).

To test the performance I built a program that logs 2000 messages and every 13th message is done with a different log level causing that message to appear in a different color. All other messages appear in the default console colors.

Before applying any of the improvements, the logging took 0.8 seconds on average. The ConsoleTarget takes about 0.25 seconds to log the same messages.

Change (1) yields an improvement of about 38 %, and change (2) yields an improvement of about 46 %.
Together, the two changes decrease the running time from 0.8 seconds to about 0.33 seconds; a total improvement of about 59 %. It is also quite close to the ConsoleTarget time of 0.25 seconds.

[codecov-io]

Current coverage is 73.35%

Merging #1112 into master will increase coverage by +0.03% as of 9af56f7

@@            master   #1112   diff @@
======================================
  Files          264     264       
  Stmts        14944   14945     +1
  Branches      1636    1638     +2
  Methods          0       0       
======================================
+ Hit          10958   10963     +5
- Partial        417     418     +1
+ Missed        3569    3564     -5

Review entire Coverage Diff as of 9af56f7

---

Uncovered Suggestions

1. +0.10% via ...nternal/AspHelper.cs#206...218
2. +0.10% via ...nternal/AspHelper.cs#188...200
3. +0.10% via ...nternal/AspHelper.cs#170...182
4. See 7 more...

Powered by Codecov. Updated on successful CI builds.

[304NotModified]

This is an unneeded breaking change?

[bhaeussermann]

I reverted the breaking change in ConsoleWordHighlightingRule. Thanks!

[304NotModified]

Can we extract this to a method? (DRY)

[bhaeussermann]

Done.

[304NotModified]

Hi, Thanks for this PR!

Just reviewed the code. two notes. Also, I think I think it would be nice to remove the regex fully when it's just a string replace, although I can be hard to keep that backwards-compatible. What do you think?

[bhaeussermann]

I think I think it would be nice to remove the regex fully when it's just a string replace, although I can be hard to keep that backwards-compatible. What do you think?

I tested this and it yields no significant difference in performance, so it's probably not worth adding the additional complexity to the code.

[bhaeussermann]

Xamarin license issue again :(

[304NotModified]

My local machine seems to incorrectly unload the licenses. :(

[304NotModified]

fixed. The deadlocked machines took some Xamarin licenses as my PC (deactivated now)

[304NotModified]

I think this is easier to read:

var didChangeForegroundColor  = ColorDoesChange(matchingRule.ForegroundColor, oldForegroundColor)`
if(didChangeForegroundColor  ){}

what do you think?

[bhaeussermann]

Thanks for the good proposals! I agree and I applied them.

[304NotModified]

Great! Thanks! 👍