Use color cache map

[n10v]

printColor and printString create new Color object on every call. If user calls these functions more than one time, Color objects with the same Attribute are created. That consumes memory. I offer to cache already created objects and reuse them.

And this is strange, what these two functions are between print and string functions, so I place them in a top of these functions.

[fatih]

Hi @bogem. Thanks for the contribution. Using a map complicates it now a little bit. First we need to protect against racy conditions. For example if you call the same print function, they will exists and they both will try to add it. Second if you protect it via locks I think it''ll add another bottleneck. So this time we'll going to have impact on the speed rather than memory. What do you think?

[n10v]

Locks work not so slow. But of course we should run benchmarks. I will do it a little bit later

[n10v]

So, I did benchmarks.

No cache:

BenchmarkPrintNoCache             200000      8981 ns/op     120 B/op      10 allocs/op
BenchmarkStringNoCache           1000000      1375 ns/op     200 B/op      15 allocs/op

Cache without locks:

BenchmarkPrintCacheNoLocks            200000      6417 ns/op     120 B/op      10 allocs/op
BenchmarkStringCacheNoLocks          1000000      1295 ns/op     152 B/op      13 allocs/op

Cache with mutex locks:

BenchmarkPrintCacheLock              200000      6436 ns/op     120 B/op      10 allocs/op
BenchmarkStringCacheLocks           1000000      1303 ns/op     152 B/op      13 allocs/op

As you see, there is no significant difference by using the mutex locks. I update this PR and you can prove it by yourself.

[n10v]

Done

[fatih]

Thanks @bogem 👍

[n10v]

Thank you for this awesome package! Wait one more performance PR ;)