get_page_by_path() and get_page_by_title() lack caching

[Viper007Bond]

get_page_by_path() and get_page_by_title() always hit the database. We should add caching and caching invalidation for these two functions.

[Viper007Bond]

See also: #11373

[scribu]

Similar: #13170

[shidouhikari]

cache optimization is always important, let database rest a bit!

[Viper007Bond]

Can anyone think of a good way to do this with existing caches? Or should these functions just make their own cache groups?

[johnbillion]

get_page_by_path() was patched in r16206, get_page_by_title() needs the same treatment.

[Viper007Bond]

Closing as a dupe of #11373, opened a new ticket for just get_page_by_title(): #15805