Add fast path for TerminalRow.setChar

[michalbednarski]

Added fast path for TerminalRow.setChar for case where theres 1-to-1 mapping between characters and columns (that is no UTF-16 surrogate pairs and characters with width != 1)

Trying to fix #603, please test @evg-zhabotinsky

In my tests this highly improved performance of cat 500KBfile.txt test.

Still slower than Android Terminal Emulator, but difference is now much smaller and seems to be matter of redraw throttling, without redrawing Termux is now faster (For test commented out line in Termux and Android Terminal Emulator, press volume key in such version to redraw screen)

[evg-zhabotinsky]

Huh. So it was mostly paranoid unicode handling and not syncing?
Works fine for me, ~5MB hexdump file cating time is down to ~1.5 minutes from ~1 hour before the fix. vim also starts up instantly now. Could be faster, but at that point human is the bottleneck most of the time.

Still, it's a stopgap, and the other code path still needs to be optimized. Suggest keeping the issue open until then.

[its-pointless]

Works well here unless im geting placebo effect... Nice.

[fornwall]

@michalbednarski Sorry for the delay here! Looks interesting, nice gains without messing up the code.

I think mHasNonOneWidthOrSurrogateChars should be reset to false the clear() method, since otherwise over time all rows will end up having this set to true (as lines are reused after a while in the circular buffer).

[michalbednarski]

Rebased and added to flag reset to clear.

[fornwall]

Thanks! This will be in v0.62 of the app, to be released in a few days.